Macauley BIOL 106 Summer 2014 Lecture 8 6/5

so it’s thursday the 5th of june already and we are going to be discussing material related to exam number two in biology 106 so you may have already checked your email earlier today and in the email i explained to you the dilemma that i have every summer and that is that during the fall and during the winter i have so many instructional hours to get through the material and in the in those semesters my my lecture’s only an hour and a half and so my exam takes up an hour and a half and in the summer time my lectures are two hours and ten minutes and every exam i give i lose instructional time because i let you go longer on the exams it’s the same exact exam so two or three times during the semester i kind of get up against a spot where i’m behind and i’m already at one of those and some of you already said oh there’s only two lectures before the next exam and that’s that’s true there’s only two periods of time what i did though this next exam as you look at your syllabus is going to cover the autonomic nervous system chapter 15 the autonomic nervous system is you know the fight-or-flight sympathetic parasympathetic nervous systems and and that’s something that i’m really not expecting you to know a lot more about than what we already covered in 105. so what i did is this morning i spent an hour going through the chapter 15 powerpoints and that lecture has already been posted for you on youtube it’s already there it’s one hour long and it’s all i want you to know about the autonomic nervous system again you will find that it’s not hugely more than anything you already know now this next exam is about the autonomic nervous system and about the endocrine system now the endocrine system is a greater unknown to you in biology 106 i only uh discussed basically what are the endocrine organs you learned about a couple of hormones along the way now the endocrine system is a really difficult sort of a an odd system to teach and the reason is this almost every system that we’ll we will discuss even the very first day when i was talking about the hypothalamus and thirst i mentioned adh so throughout this course we’re going to see hormones mentioned and before we get too much further along the way i need to do a better job of of introducing the entire endocrine system to you so you better understand how hormones work and get a better appreciation of it now the autonomic nervous system chapter 15 and the endocrine system chapter 7 are both probably the two systems that do the most to maintain your homeostasis right you’ve got the autonomic nervous system doing everything involuntarily keeping your blood pressure and everything in check at the same time there are a lot of hormones that are also assisting with it or complementing that homeostasis so really this whole exam is largely about homeostasis and how does the body maintain that so uh if you also look on the on the syllabus you will see that today is the day that i’m going to introduce to you the case studies so i want to do that take a couple moments just to introduce that to you and then those are due a way off and you can be looking at that i’ll introduce this assignment to you also as you’re getting ready for next week’s exam don’t forget that there are the guided reading assignments and those will help you they’re also the quizzes on connect so before i get too far out of order let me go ahead i’m in blackboard i’m under lecture materials and there you will find a link for the case studies the case studies are meant to be a group activity this is not something you get to do by yourself or with a pair of people i want groups of three or four okay this is not something that’s negotiable uh some people oh i want to all my own i don’t like to work well with others well we need to fix this and those who want groups of six will know you’re not doing enough work right to earn your points so three to four students and what i’ve done is i’ve collected a group of case studies from a national library and i’ve grouped them sort of by topic so if you look under case study number one there are actually two case studies that you will do there’s a group one and a group two group one all of these five or six case studies here all deal with something to do with the scientific method or maybe musculoskeletal physiology the second group of the second group of them down here are going to deal with um what is it neuroscience and endocrinology okay so we’ve got two different sets of these case studies each group will choose one from group

one and one from group two so just click on the links it’ll bring you to a topic these are little short stories basically maybe two or three pages long and then followed by some questions now some of those questions you’ll already know the answer to just based upon reading the little article others will require you to look them up if you look up something make sure you cite it every one of these case studies should have citations at the end where did you go to get that information now the case studies are due when is it the first one 26. so it’s a little ways off now how you decide to do this within a group is up to you most of you in your labs are already in groups of three or four people if there’s two tables with two people in it you guys can become a group if you find that you are completely out of a group and you don’t know where to go contact me soon and i will put some people together if you uh want to be in a different group you know we can work that out the um one of the other things is that at the very top of this there’s a little form that you’ll fill out it says right here um right here case study group form okay and what that form is is basically everyone in the group will sign it saying that they all did equal amounts of work now what you decide within your group is equal is up to you but all of you have to sign this form and put down what percentage of the work you did i hope everyone plays well in the playground and you all do equal amounts of work now if there’s a group of four two of you in the group could decide to do one of the case studies and the other two could choose to do the other case study and then just make sure before the end you do compare notes and check over each other’s work for completeness and then submit it as a group you will submit this to safeassign there’s a link on here at the very top and the safeassign link only one of you but one of you from the group will upload one of you from the group will upload your answers to the safeassign link and that’s just a way of making sure that you’re not copying the work over from another group last semester okay so anti-plagiarism tool so look through them look at topics look at the work that you’re asked to do and then let me know if there’s any problems and next week is gonna be a very very busy lab uh in tuesday and in thursday labs i’m gonna warn you right now that it’s going to be uh almost a double lab as far as time goes so this summer we have labs that go three hours and 45 minutes we’re likely going to use up much of that time now i know for the tuesday group you’re thinking okay that’s not so bad for the thursday group you’re already a little bit worried because next thursday we have an exam especially the thursday afternoon group okay you’re probably the most affected by this it’ll be okay it’s going to work out but just know that next week you’re going to come in and do your eye works lab on muscle physiology and then you’re going to turn right around and create your own experiment and do some do another experiment you can still get it all done in a reasonable amount of time but if you’ll come in as prepared as possible next week that will really really help out with lab so you’ve got your case study so let me know if you have any problems with that also don’t forget that under election materials you do have the guided readings there’s one for 15 and 17 that is the autonomic nervous system and the endocrine system and there’s another one for chapter seven i also recognize that i’m going a little bit out of order from the syllabus so hang in there but this is what will be on the next test so this one is for both 15 and 17. it has some questions in here about the autonomic nervous system and about the endocrine system i gave you a hint in the email i sent you that on the exam next week make sure that you can very clearly compare and contrast the sympathetic versus the parasympathetic nervous system so as you’re going through that presentation on youtube and you’re listening to that make sure you’re really focusing on can i compare and contrast the sympathetic and parasympathetic nervous systems you’ll also want to be able to compare the the autonomic nervous system with the endocrine system one being nervous system one being the endocrine system and how are those systems different how do they work similarly how do they work differently the biggest learning curve over the next week for you is going to be on the hormones you may have heard of the hormones but you don’t know exactly what they do it is a rather large body of knowledge and i hate the word memorize but before we member before we can know things we have to memorize them in some way so what i’ve done is on this guided reading i have given you

i think an easy to follow worksheet and it basically you know lists the gland uh tell asks a couple questions about the structure the hormones that are released what do those hormones do and what regulates them so this is you know four or five six pages of what is that hormone name that hormone what’s its function what target tissues are involved so i would recommend printing that out and using that as creating a study guide for the hormones okay so lots to do related to the endocrine system lastly there are two quizzes for you for this exam and when you go on to connect they’re already there for you one of them is for one of them is for chapter 15. so that’s the autonomic nervous system that’s a standalone quiz it’s not that many questions as i recall so this won’t take you very long and then there’s only 17 questions on that quiz and then the second quiz is actually a double quiz and you will do that second quiz now remember that these quizzes are not timed and therefore you can go in and do them and leave so don’t feel like you have to wait till next tuesday to start this quiz after today’s presentation on the endocrine system you can certainly go into that second quiz answer any and all endocrine questions exit wait till next tuesday after the skeletal talk there won’t be that much that quiz is mostly endocrine and then you can answer the few questions on the skeletal system because of that time crunch from tuesday to thursday exam i’ve extended the deadline for these quizzes till wednesday at noon so not midnight like they were but it’s wednesday at noon the day before the exam 11 59 a.m and then once we get past that noon hour they’ll become reviewable so you’ll still have 24 hours to review the exams but keep that in mind those deadlines are posted on blackboard and they’re posted on connect for you so that’s lots going on as we start thinking about this exam any questions for me at this point any questions for me about exam two it’s coming fast i know the first exam had six lectures on it there were a lot of there was a lot of material i’m almost done i i anticipate being done tonight with the grading of those i still i just picked up a few more from the testing center and once i get through those i’ll be able to calculate grades determine if there’s going to be any kind of curve or not and get those grades posted for you so i hope that before i leave here tonight i have it done i’m not going to make a promise it’s a hope okay i have to sleep too so um if i don’t get it done by one or two this you know tonight i won’t have it done okay so if at two o’clock you can stop pushing what’s going on so i stayed up to two this morning grading exams and uh i can see you i i can actually if i choose i can go on and track who’s checking blackboard like every five minutes and and i can see the frequency of how often you’re checking your grades tell you what i will post the grades and then i will send an email that says the grades have now been posted so don’t even look until you see an email that says the grades have now been posted and then you can go be ocd right but until then just just relax take a big breath you’re going to be fine and just know that those grades uh it’s the short answer question there will not be short answer on this next exam so that’s a gift to you maybe so you don’t have to worry about preparing a short answer question on exam number two okay so let’s get going into the endocrine system and the first thing you’ll see is that i’m skipping over the first 73 slides in this presentation now i’m not going to talk through those first 73 slides i’m instead i’m just going to fast forward through it and help you get oriented in these slides as to what i want you to focus on as you’re looking at this again some instructors don’t teach a lecture on the endocrine system instead they just wait until the hormones weave their way into the content and then they say oh here’s a hormone that does x y and z i’ve done that before but then i find that students kind of lack the basic understanding that’s common to all hormones so i want to make sure that that gets stated today i want you to have an introductory understanding of a hormone if you hear for example fsh follicle stimulating hormone you need to know that it’s released from the anterior pituitary and you need to know that it’s targeting

right the reproductive organs you need to have that kind of understanding then when we get to the reproductive system we’ll look at those hormones more specifically and find out more about their control but for now you need to be able to recognize the hormone know from what gland it is released and maybe not completely understand its function but certainly have an idea of what it’s involved in okay so that’s our focus here now the as i mentioned earlier the nervous system and the endocrine systems are working together but they do so in a very different way you know that the nervous system uses neurotransmitters you know those neurotransmitters are released from axons and you know that about action potentials you have a better understanding of that now the endocrine system is using hormones those hormones are released into the blood or are in released into the interstitial fluid the fluid around the cells and they’re certainly having an influence on the neighboring cells or even cells far far away if we think about the endocrine system hormones are secreting and being released through the entire body so we we see that they work in very different ways so again you want to be able to compare and contrast the mechanism how do these two systems uh do their job and how do they react so the endocrine system again i’m not going to go through all of these but i will hit a few highlights here in the first 73 slides or so there are four ways that cells communicate one with another one gap junctions gap junctions we have seen in the epithelial tissues we know that these are little pores found in cell membranes and that molecules are able to go back and forth between cells through these gap junctions so those are cell to cell connectors right next door cells talking with each other and we’ve talked about neurotransmitters we know neurotransmitters are released from neurons they travel there’s a signal that travels down an axon and neurotransmitters are released and those neurotransmitters communicate to the post-synaptic cell or to the effect or if it’s a muscle or gland there’s also however paracrine another way of thinking about this is local local control so a cell can release a hormone into the fluid around in the neighborhood and have a localized effect right so that would be paracrine and there’s still hormones but it’s not being sent through the blood to a far far away place is just being released into the neighborhood fluid around the cell and then there are quote the true hormones or the true endocrines and these are chemical signals they’re going to travel through the bloodstream and can go to any place in the body and they’re only going to have an effect on tissues which are equipped with receptors that can receive that hormone so you can have hormones floating through your blood from multiple places but they’re only going to affect those organs which have the receptors for that particular hormone so we’re talking about the endocrine system we’re talking about the study of endocrinology you would go see an endocrinologist if you were concerned about perhaps some hormone dysfunction in your body and again the big thing is is that we are releasing these hormones from one place in the body some gland and they’re having an effect somewhere else we also will appreciate that the hormones are going to travel through the blood but then exchange in and out of the bloodstream at the capillaries we’ll get to the capillaries more completely when we get to the cardiovascular system but not only are capillaries places where nutrients and gases are exchanged but it’s also at those very delicate capillaries where hormones are able to get out if you will of the bloodstream and to communicate oftentimes with the cells so you know or you should be able to identify the organs here right in 105 we spent a little bit of time naming the endocrine organs so you should be able to identify the hypothalamus the pituitary gland you know where the thyroid gland is the thymus sitting toward the top of the heart the pancreas the adrenal glands the testes the ovaries so those are the major endocrine organs and so hopefully identifying them won’t be a problem i don’t know if i just said a moment ago the thyroid but there’s also behind it the little parathyroid glands so what you’re going to be doing now is figuring out which hormones are released from which gland and again those guided reading pages are going to help you other people will make flash cards but you want to have a working vocabulary knowledge of these hormones so this would be a very important slide to look at

because here we’re comparing and contrasting how is it that the autonomic nervous system and the endocrine systems differ both through their types of molecules how quickly they work how quickly the body adapts to them and the area of effect that these different systems have so that should be something you can appreciate and we’re also going to see that there’s a there’s a crossover i say neurotransmitter you think neurons in the nervous system when i say hormones you’re thinking glands in the endocrine system but we’re going to see that there are some hormones and that act sort of like neurotransmitters and some neurotransmitters that themselves act like hormones and so there is a crossing over here and we’ll discuss that more in a few minutes function as both a hormone and a neurotransmitter one that may come to mind right off would be norepinephrine or epinephrine you’ve heard about epinephrine uh you know it’s that molecule that is released during a sympathetic surge when the bear walks in the room and you’ve got a you’ve got an adrenaline rush or uh epinephrine rush that molecule is released by neurons but it does travel through the body like a hormone so we see that there is a crossing over here anti-diuretic hormone do you recall i said it was made in the hypothalamus and stored in the posterior pituitary well what made it were neurons okay that are in the hypothalamus and the neurotransmitter the adh is released into the posterior pituitary and then as needed it’s released through the blood so again we’ve got sort of this crossing over between a neurotransmitter and a hormone some hormones are also secreted by what we call neuroendocrine cells so that’s kind of a weird sound right a cell right we’ve talked about neurons and we can talk about endocrine cells but there are actually these cells that sort of morph in and this is where the oxytocin and the catecholamines when you hear the word calcolamine think epinephrine okay epinephrine or adrenaline is a catecholamine so these molecules do cross over in their description also each other we’re going to see that the neurons right the nervous system can trigger hormones and hormones can trigger neurons so again there is a cyclic or a feedback mechanism that’s going on here between these two systems whereas a neuron can only release one neurotransmitter remember i said that some neurons release acetylcholine some neurons release serotonin some neurons release gaba tissues cells can have receptors for multiple neuro neurotransmitters or multiple hormones so we’ll see that the target organs can have a lot it can be receiving signals from many different places hormones or neurotransmitters so again this is a comparison slide right we’re comparison we’re comparing the action potentials of a neuron with the hormones traveling through the bloodstream compare contrast compare contrast the rest of this is going to be a quick anatomical review about the different glands again your primary job here is can you identify the gland can can you point to it if i ask you to identify it can you identify the gland and then can you tell me which hormones are released from it so this is very small i know it’s my fault but what you’re seeing here is the pituitary gland now the pituitary gland is actually two glands side by side we’re going to see this theme occur twice we’re going to see this gland in gland or two different things happen in the adrenal glands here uh and and here in the um pituitary glands so you’ve heard about the posterior pituitary and the anterior pituitary they’re totally different the posterior pituitary is made up of nervous tissue the anterior pituitary is made up more of epithelial tissues it’s more of a true gland so we’ve got two different structures sitting side by side collectively we call them

the pituitary gland but they’re really two totally different things side by side and they communicate one with another and remember that the hypothalamus is right up here isn’t it so the hypothalamus is right up above the pituitary gland and you can see these yellow nerve endings and there are neurons that are going to go down and release their products directly into the posterior pituitary okay and that’s the way that the oxytocin story or the um that’s the way the um antidiuretic hormone is is dealt with so let’s start off with the anterior pituitary now this is where i’m going to let you guys go just take off and do the guided reading on this but there are going to be six hormones released by the hypothalamus we’ll start there so in the hypothalamus again every hormone that’s released from the hypothalamus or at least not most of them have the word in them releasing or inhibiting so if you see a hormone with an r in it or an i in it something releasing hormone or something inhibiting hormone you know immediately that it was made by the hypothalamus the other two hormones are oxytocin and adh okay now even those are different because what do we know about oxytocin and adh do you recall that those are both released from the posterior pituitary these other six these releasing and inhibiting hormones all affect the anterior pituitary now what the endocrine system is confusing in that there are one hormone goes from one gland to another gland and then it stimulates the release or inhibits the release of another hormone which then travels somewhere else so you have hormone affecting gland affecting another hormone affecting another hormone how is that similar or different from the nervous system how is this multiple hormone system similar to the ner to the nervous system what did we say about the nervous system it’s not just a neuron that travels from the spinal cord directly to the effect remember we talked about lots of second and third order neurons a lot of times there were two or three neurons in a row that allowed for more what the fact that there’s two or three neurons along a pathway it increases the control right increases the the the control that the body can have over those signals same thing is true here by having multiple hormones released and affecting other organs and tissues there’s more options there’s more control so in that way it’s very very similar now these releasing hormones tell you exactly what they do okay so that’s the nice thing about these hormones so we’ve got the trh any idea thyroid releasing hormone gonadotropin releasing hormone okay growth hormone releasing hormone so these releasing hormones are going to go where they’re going to go from the hypothalamus down to the anterior pituitary and tell them tell the anterior pituitary to release something right or there are inhibiting so there’s the prolactin-inhibiting hormone so we’ll see inhibiting or releasing there were two other hormones made from the hypothalamus oxytocin ot or antidiuretic hormone adh again they were they’re made by the hypothalamus but then they are released and stored from the posterior pituitary the anterior pituitary is going to be making up six hormones that you need to at least recognize follicle stimulating hormone going down to the ovaries but it’s also important in male sperm production the luteinizing hormone we’ll discuss again when we get to the reproductive systems it is assisting with ovulation but it’s also important for testosterone secretion and sperm production thyroid stimulating hormone sounds like it does what stimulates the thyroid right so we see this again one hormone after another after another affecting

the next insect hormone is going to go where the adrenal glands but more specifically to the cortex of the adrenal gland we’ll describe the difference between the cortex and the medulla in a few minutes and then also while we’re here doing vocabulary what does tropic mean whenever you see tropic in a hormone’s name i have a hormone that influences the adrenal cortex right adrenal corticotropic hormone acth there’s also prolactin we think of prolactin as being involved with milk production but again these hormones that that are more famously involved with female follicles or ovulation are also required and important in testicular and sperm health and then there’s also growth hormone which is probably the one that’s most famous or the one that’s most recognized has a lot to do with stimulating mitosis and overall body growth especially during developing years so we’ll talk about the hypothalamo pituitary relationship again there’s a what we call the axis right there is a hormone axis so the hypothalamus influences the pituitary gland and then the pituitary gland the anterior is sending out these hormones to their targets okay we’re up in the hypothalamus here there are neurons right cell bodies a bunch of cell bodies is a nucleus so there’s a group of them and they are releasing in this case oxytocin and antidiuretic hormone into the posterior pituitary the posterior pituitary makes nothing okay all the posterior pituitary does is receive oxytocin and adh from the hypothalamus and then those hormones are released as needed so this is that good connection so at first what would you call these molecules they’re released they’re made by from the posterior pituitary so in that case they are neurotransmitters but then once they’re stored there they’re releasing the blood and now they become hormones so that’s a great example of how one molecule is first identified as a neurotransmitter but then is used as a hormone um it’s only here so that’s the special job the the neurons that are here in the hypothalamus that’s the neurotransmitter that they make they make it and they keep releasing it into the posterior pituitary right right that’s it that’s it that’s it that’s the only place that those neurons release directly into the posterior pituitary it’s stored there until released okay okay so there’s the adh and we talked about adh quite a bit we know it’s all about increasing water retention and reducing urine volume now you will see in some literature the word vasopressin vasopressin is the same exact thing as adh so in old lane in old uh literature and maybe even once in a while you’ll see it now vasopressin so what does that word suggest to you vasopressin i n it’s a protein has something to do with the vessels and what does adh do it can also cause vasoconstriction so it can cause a pressing if you will of the vessels right increasing the blood pressure so historically it was vasopressin it was found to have more jobs than just constriction of the blood vessels and so its name was changed to adh but some some folks will still refer to vasopressin

oxytocin there is a surge of oxytocin during sexual arousal during orgasm but it’s also important in uterine uh contraction and propulsion of semen so there this is this oxytocin is not just childbirth right we get the idea that oxytocin is just a hormone involved with uterine contractions during labor but it also isn’t is dealing with milk and um mothers and infants as well as sexual arousal so a couple little videos to look at you’ll see those also in your connect assignments and the other thing i need you to be thinking about when it comes to hormones is that secretion is not constant you don’t have these hormones being released in a constant state at the same time oftentimes they’re pulsatile that means that they are there’s peaks and valleys they’re released in 24-hour cycles some of these are released in monthly cycles so there’s a lot of variation in the levels of the hormones again having a lot to do with your overall homeostasis and also feedback from the target organs just like in any chemical reaction the body is not going to continue to release a hormone that it doesn’t need to release all proteins are expensive to make right there’s a lot of energy needed to make proteins so the body is only going to make what it needs and release what it needs and so there’s always very intricate negative feedback mechanisms that will shut down and stop the production of hormones okay so again this idea of negative feedback you’re familiar with that let’s just take a look at this example this is with thyroid hormone this is a classic example so from the hypothalamus it produces trh thyroid releasing hormone that trh only has to go a short distance it travels from the hypothalamus down to the anterior pituitary and here as the name suggests it’s going to release thyroid hormone that thyroid hormone is going to travel through i’m sorry it’s going to release thyroid stimulating hormone tsh and that thyroid stimulating hormone is now going to travel through the blood down to the thyroid and then the thyroid will itself release thyroid hormone okay so we’ve got trh tsh and then th well when there’s plenty of thyroid hormone around there will be negative feedback in other words the thyroid will go back and feed back to the anterior pituitary and go back to the hypothalamus and say enough’s enough we don’t need anymore right now so that whole idea of negative feedback is very much alive and well in the endocrine system to go through this list these first slides grab the gland make sure you know where the gland is in the body make sure you know what hormone is being released by that gland and what is the basic function of that hormone okay so the pineal gland largely about circadian rhythms your 24-hour clock and the hormone here is melatonin okay so again you just want to you want to associate these words pineal circadian rhythm and melatonin and this is a hormone that right now is uh not as much of an issue at summer time we get lots of light but in the winter time melatonin levels can start messing with us as we have short days identifying this gland is very very small it is in the shape of a little pine tone and you see it here how would you describe this part of the brain where are we here this is what this is the corpus callosum this would be the mess what would this be that’s the cela turcica so in that cela turcica is the pituitary gland and right above the pituitary gland in this area would be the hypothalamus okay so this is an area referred to oftentimes as the epithalamus okay the epithalamus it’s on the thalamus if you will so the epithalamus is continuing with our labeling uh what is this

right here ponds and then this would be the medulla very good very good now the pineal gland when it’s out of whack is responsible for sad right seasonal uh affective disorder which maybe some of you experience especially during winter months those short days moving on again very short just a couple of slides per gland the thymus a little gland sitting on top of the heart very very important in development of your t cells and your immune cells not something we’ve discussed yet in this class when you take microbiology you’ll get a whole unit on the t cells and the immune cells and that whole story is coming your way in full flurry but it won’t we don’t have to worry about it here uh but the thymus is sort of an interesting organ in that it is a culmination of the endocrine the immune and the lymphatic systems all coming together just know that it’s important in the development of your t cells of your some of your lymphocytes and the hormones produced here just recognize them they all have thyme in them so they’re not so hard to recognize right and they’re all related to the production and and uh overall it’s a well-being organ to identify it’s in the media steinum area on the superior sections of the heart in a young child it’s much more substantial because in a young child you have more t cell and your immune system is is is rolling along and really in high gear as you’re developing your immune system so it does tend to involute or get smaller with age thyroid gland we recognize the thyroid gland right a little butterfly shaped gland below the thyroid cartilage this is actually the largest endocrine gland this is really quite large it’s even larger than the pancreas and very very red and this is true of most endocrine glands very red so why would endocrine glands be very red lots and lots of blood right because any hormone that’s being produced has to be released into the bloodstream so endocrine glands by their very nature are very vascular structures the thyroid gland again i don’t think any problem identifying it and it’s releasing a number of hormones uh they’re breathing in t3 and t4 thyroxine try you’ll just hear called t3 and t4 so don’t worry about the naming of it but what you will see is that iodine is very very important to your thyroid gland and in fact oh i guess about 100 years ago when mr morton got together with the government and decided you know we want to make sure that everyone in our general population has a healthy thyroid and so they started adding iodine to our salt and that was sort of a like fluoride in the water to help our teeth and then we got iodine in our salt to help our thyroid glands and now with as much salt as we consume as americans our thyroids are in no problem when it comes to to iodine but it used to be an issue and if the thyroid gland does not get enough iodine it becomes a goiter it becomes very much enlarged so we don’t see goiters anymore in this country because we all consume copious amounts of salt and iodine okay on the on the posterior side of the thyroid gland there’s a variable number of little glands two to six this one shows four these are the parathyroid glands very simply they release parathyroid hormone very simple when i get to bone homeostasis next tuesday i’ll be telling you more about parathyroid hormone and how it’s involved with calcium regulation so we’ll pick up on this story down here in bone resorption on tuesday again each one of these each one of these glands each one of these hormones will be discussed in greater detail at the appropriate time as we go through the course you may recognize too that all these solid black background pictures are from apr so any of these images you see i’ve grabbed from there let’s go down to the adrenal glands this is incredibly important to the autonomic nervous system as well as to the endocrine system so the energy glands really are like the pituitary glands two glands in one there is a cortical region the cortex and the cortex makes a totally different set of hormones so this is actually a blow up of the cortex and then in the center you have the medulla so two completely different regions sitting side by side

they are sitting on the superior border of the kidneys they like the kidneys are also retroperitoneal so this is just showing you the fact that there’s a cortical region around the outside and the medullary area is more central to that let’s start off talking about the medulla the medulla is the inner portion it’s a smaller percentage of the overall gland it is dually endocrine and nervous it acts as a really a sympathetic ganglion now the endocrine sorry the autonomic nervous system lecture that i recorded this morning will bring you back to a better understanding of the sympathetic nervous system and will remind you of that significance but basically what you have is you have neurons sending signals to the sympathetic ganglion which then are going to release some hormones and so these this adrenal medulla is basically a connection between the autonomic nervous system and the endocrine system when stimulated the adrenal medulla is going to release catecholamines as a class of molecules in that group epinephrine norepinephrine dopamine so when you hear those three molecules epinephrine norepinephrine or dopamine those are all different types of catecholamines okay and what’s the other name for epinephrine adrenaline same thing so just depends upon the book um and norepinephrine is the same as nor adrenaline so you’ll see noradrenaline or norepinephrine you’ll see epinephrine or adrenaline so don’t think oh what is that that’s different it’s just a different name for the same thing it’s not the opposite it’s another molecule when we talk about the sympathetic nervous system and this big surge you know and epinephrine being released um we’ll look at the breakdown of this but it’s just another molecule for the purposes of this course i’m not going to try to separate them very much okay i’m not going to try to separate what does epinephrine do differently from norepinephrine think of them both sort of as stimulants to the sympathetic nervous system for now for now now here’s a big difference when the adrenal medulla releases epinephrine it has a much longer effect as a as a hormone than it does as a neurotransmitter right and we get back to the differences here once you release a hormone into the bloodstream it’s it’s out there it’s difficult to pull it back it’s difficult to regulate that as well so we know that when you become on when you become scared and you have an epinephrine or a norepinephrine rush it takes a while for your heart rate to come back down it takes a while for your respiration rate to come back down you can’t turn that on and then turn it off right so once those those neurotransmitters are once that hormones released into the bloodstream it is much slower to to pull back so you know that when you have a sympathetic surge those catecholamines are going to cause a increase in your blood pressure an increase in your heart rate more flow of blood to your muscles greater pulmonary flow and respiration and an increase in your metabolic rate and when the bear walks in the room you’re also going to have a decrease in your digestive function and urine production so we’ve discussed those things before and you’ll be reminded of that also in that chapter 15 discussion they do stay in your blood until they get filtered out or used up so as they’re received by tissues then they are being broken down by the liver they’re being released in part through the kidneys so yeah but there’s not as strong a mechanism to get rid of them as there are some other neurotransmitters now that was the medulla right again this is very basic i i’m hoping your head’s not spinning too fast i know i’m going fast through this but you need to go back and just make those flash cards up name that gland name that hormone what’s it basically doing the adrenal cortex the outer layer is the home where about 25 different steroid hormones are made totally different so the inside is catecholamines the medulla is the catecholamines the epinephrine

the norepinephrine and the dopamine the cortex is made up of layers and all of these layers are making up different steroid hormones corticosteroids now what was the hormone that’s going to influence these the adrenocorticotropic remember that acth made by the anterior pituitary was going to travel down and influence somehow the adrenal medulla and here we’re going to be making corticosteroids you’ll also hear them called corticoids so there are five major steroids coming from these layers and i do want you to grab these we’ll be talking about them at different times in the cortex there are three layers of the cortex they’re each called different zones there’s the zona glomerulosa the the zona fasiculata and the zona reticularis aren’t those great names now everything from the glomerulus is releasing mineral corticosteroids or mineral corticoids that is these are steroid hormones that regulate your electrolyte balance minerals right electrolytes then there is a middle layer of the cortex here you’re releasing cortical steroids that is hormones that somehow regulate sugar and then there is the reticularis it’s the inner layer and here you are secreting sex steroids this is where women produce their testosterone right women do have an amount of testosterone produced in their body and is produced from their adrenal glands it’s certainly not from their testes right they don’t have those right but women do have testosterone and men make estrogens and they make some of those hormones that we think of as being female hormones and they’re made here in the male as well so you’re i’m never i would never never ask you to label these three layers but i do want you to maybe see that you’ve got three distinct layers so this would be the medulla down here and then the three layers one two and three of the cortex and we would have what was the deeper one reticularis was the inner right so this would be the reticularis fasciculata and the glomerulosa right so what letters do they make gfr now maybe you remember the gfr the glomerular filtration rate you may have seen that word when we get to the urinary system we’ll talk about that more but those three letters gfr if it means something to you but i’m not going to have you go back to those layers by by any means when i mention those three layers though i do want you to know the glomerulosa responsible for mineral corticoids the one hormone that you need to know from here is aldosterone aldosterone did come up in our conversation about water retention didn’t it when we were talking about adh there’s also conversation about aldosterone so you know it is a hormone that regulates minerals think sodium and potassium then in the fasciculata there is this hormone called cortisol cortisol is a hormone that is involved with regulating your overall fat and protein catabolism breakdown of your of your fats and proteins but it’s also responsible for gluconeogenesis break down that word for me gluconeogenesis genesis the making of the formation of in the beginning new neo sugar your body can make sugar did you know that i mean if you’re on an atkins diet and all you’re eating all day is fat and protein have you heard that the brain needs glucose to survive right and if all you’re taking into your body is fat and protein on an atkins kind of diet and you’re not eating any sugars or any fruits or getting in much you know carbs in your diet your brain still needs sugar and your body will make it for it through this process of gluconeogenesis okay then there are sex steroids made from the zona reticular here again are the androgens and the estradiol or the estrogens again men have estrogens and women have testosterone because of the levels that are released from the adrenal cortex this is a whole bunch right 25 or more

hormones are made there in the adrenal cortex very very important now they are sitting side by side but they are not completely independent these two portions of the adrenal glands are speaking to each other and they they they do have some crosstalk moving on to the pancreas everyone recognize the pancreas what’s the pancreas job i’m hearing insulin immediately and that’s what we normally think of and so the insulin is a hormone so we think of the pancreas as being endocrine but that’s actually a very small job collectively of the pancreas the biggest job of the pancreas is to produce digestive enzymes which are released from the pancreas into the duodenum so we see that the pancreas is both endocrine and exocrine right it is releasing digestive enzymes into the gut that’s exocrine releasing hormones into the bloodstream that is endocrine other parts fine yeah the other part’s largely fine josh what’s in the pancreas or what’s called the eyelets now i the word is islet but you can think island there are these little clusters these little sections of cells within the greater pancreas which are responsible for making the hormones and so it’s just a as far as territory goes the hormone producing uh job of the pancreas is very very small now these little eyelets okay there’s four different types of these islets and the hormones here are important for you to know so glucagon is a hormone is produced by the alpha cells of the pancreas now glucagon is sort of the yin-yang hormone to insulin we don’t hear about it as much but glucagon is released between meals your blood glucose starts to fall so maybe you haven’t had anything since lunch your blood sugar levels are dropping right some of you are fading right now right you’re just keeping me awake but your body is right now releasing glucagon now what is that glucagon doing it’s going to your liver and say hey liver we don’t have enough sugar to keep the brain going so we need to up regulate our gluconeogenesis we need to make some more glucose our brain is sleepy right some of you are falling asleep on me right now your liver is not keeping up with your body’s needs also the glucagon is going to increase glycogenolysis break this word down for me lysis the breakdown of glycogen glycogen is a storage molecule in your body so when you don’t have enough sugar what’s your body going to do make more gluconeogenesis and break down your energy stores glycogenolysis lysis break down into the individual sugar molecules now glucagon has a direct connection with adipose and we’re learning a lot more about uh obesity and diabetes and the pancreas and the nervous system and how all of that goes together that’s a really huge area of research right now now i would never ask you to figure this out but within the pancreas again you have these little islands these little eyelids and within those eyelets there are the alpha and beta cells and this is just showing you that within this eyelet some of the cells are considered alpha cells you could never identify them right by eye now there are also the beta cells and these are the cells that probably have the most fame the beta cells of these islets are producing the insulin insulin is produced during and after a meal telling the body what what’s insulin tell the body to do take up the glucose right it’s the sign to the body’s cells hey hey this guy just ate and let’s take up the glucose but what happens to a person whose insulin levels are not sufficient their blood their body doesn’t know to take up the glucose and as a result their blood sugar levels stay high and we know that that high blood sugar level over time has some negative effects on the body so it’s important for a diabetic to self-medicate with insulin if they’re a type 1 diabetic and they got to keep their blood sugar under control because over time high blood sugar damages nerves high blood sugar over time damages capillaries and we know that keeping those levels in

check goes a long way to maintaining a normal healthy life for a diabetic and the complications are much greater if they’re not able to keep either not able or not willing to work really hard to keep their blood sugar levels as as level as possible so insulin and glucagon are sort of yin-yang hormones one is being released while the other one is not and their job is to keep your blood glucose level as constant as possible at least within a normal homeostatic range again different cells are beta cells now also there are delta cells within these eyelets the delta cells are releasing somatostatin another hormone and what somatostatin does is it inhibits digestion and absorption but prolongs abs uh sorry inhibits digestion and prolongs absorption of nutrients again all of these hormones from the pancreas are involved with your digestive system they’re all involved with regulating your overall digestion speeding it up slowing it down because if you why would you want to inhibit nutrient digestion it inhibits the breakdown so that you can do what prolong absorption so there’s a real balance here how quickly do you want the food to be broken down how quickly do you want it to be absorbed and these hormones glucagon insulin somatostatin are all involved with that there’s also a hormone not very imaginatively called the pancreatic polypeptide it’s released by the f cells again other cells within the eyelets there’s also gastrin that’s released by the g cells again you’ll see that they’re all really they’re all involved with regulating stomach acid regulating pancreatic enzymes regulating how quickly the stomach can empty or how quickly it’ll move food through the digestive system some hormones will raise your blood sugar some hormones will lower your blood sugar we’ll deal with that later just know that there’s a lot of regulation going on here moving down to the gonads ovaries and testes i think we probably have this one down again we’ll deal with this more specifically later in the course but from the ovary there’s estrogen progesterone from the testes testosterone also a little bit of estrogen some other androgens as well now just know the estrogen the progesterone and the testosterone i’ll deal with the specifics of the ovaries and all of this definitely when we get to that time in the course okay now those are the major endocrine organs but we don’t want to forget that there are other organs in the body that are producing hormones even your skin is endocrine in that it does release hormones turns out that your skin cells are converting a cholesterol-like molecule into vitamin d or at least a precursor of vitamin d and you need uv radiation for that to occur so most of us are are vitamin d deficient during the winter months the liver is producing hormones um angiotensinogen erythropoietin there’s one we’ve at least talked about in the past right erythropoietin when you think of a virtuopolitan where do you normally think of it being produced in the kidneys right and with under remember epo when you go to higher altitudes the kidneys are upset they’re not getting enough oxygen and they put out epo and epo then goes your blood stream goes to your bone marrow and up regulates your your erythrocytes a little bit of epo is also made in the liver and then the kidneys the kidneys are releasing some hormone we’ll talk about calcitriol we’ll talk about renin we’ll talk about these more again 85 of your epo is made by the kidneys the heart is also releasing hormones we mentioned anp didn’t we didn’t that one come up in passing with water regulation that when the blood pressure is too high and the stretch receptors in the carotid sinuses in the aortic arch sense that increased pressure the heart releases anp atrionatritic peptide which then works on the kidneys just do what increase output right let’s get rid of some of that fluid let’s decrease uh the blood pressure and then the stomach also

is really really busy producing some hormones all of which are involved with regulation of digestion adipose fats releasing leptin man about maybe even about 15 20 years ago there was a huge deal when they discovered leptin pro problems with leptin levels in a mouse model for for obese there’s a there’s a mouse called the obese mouse and you can feed this mouse exactly the same amount of food as a normal little skinny mouse and this mouse will just bloom right it’ll be a part of my family just a huge mouse but the the metabolism the exercise and the diet the calories everything else is exactly the same and they’ve been studying this mouse for years trying to figure out well what are some of the what are some of the the triggers the differences between the metabolism of the skinny mouse the normal mouse and the obese mouse and it came out that leptin this hormone was produced by the fat cells and they thought this is the ma the master switch and it seemed to have a lot more influence in the mouse than it did in the human and so it never really panned out but since that time we have learned that there are a lot of hormonal signals much more than we ever imagined going between the brain the stomach the pancreas there’s a lot going on and we’ll talk more about that when we get to the digestive system and some of the hormones and the regulation that’s going on it’s an exciting area of research there is also bone you may not think about it but your bones are also releasing hormones and those are having an impact on your overall metabolism as well and the placenta during pregnancy is also releasing some hormones so my point is there are a whole lot of organs that release hormones right something that’s released into the bloodstream that go far far away and influence some cell that has a receptor for that hormone so your job right that’s what i was going to skip over but i spent an hour on it anyway because i don’t feel good about just saying look at this on your own so i hope that you walked away saying okay what do i need to do flash cards maybe or fill out that guided reading and just keep track this gland makes this hormone this hormone does what basic thing in the body once you get there we’ll we’ll pick up on this knowledge test by test system by system and we’ll understand more completely what these hormones do as we move through the rest of our course let me take a break there and we’ll come back and we’ll look at hormone chemistry what two things are going to help you focus well the guided readings yes but then you still may be wondering how much detail does he want me to know and then when you go to the connect assignments and then when you go to the quiz right and you do those that’s really gonna tell you right what i’m expecting you to know so it may make really good sense to peek at the quiz before you do the guided reading it might be far more efficient right open the quiz look at it look through the questions get an idea of the kind of information i’m asking about and then go fill in your guided reading or your flash cards and then right and then go back and do the quiz so just just a suggestion to be more efficient and more productive in your time okay so we’ve talked about naming that gland we we know there’s all these hormones and i i get it it’s it’s it’s confusing um there’s a lot of different terms that are new for you and because you don’t yet have a basic understanding of what all these hormones do it really does seem like random facts it really does i i agree it is very much random this hormone that hormone this gland and you don’t know the story yet and you’re not going to know the story until we get to that particular system so it is at this point random facts that you’ve got to keep straight maybe this will help a little bit though as we describe the chemistry of the hormones hormones come in three basic classes three chemical groups number one steroids steroid hormones now what are steroids what what they belong to what group of molecules steroids are lipids they’re fats they’re lipids so they’re all derived from cholesterol again you have to have sufficient cholesterol levels in your body to make your sex hormones and your steroids your your steroids so when you think about your gonadal or your adrenal gland right those those mineral cortical steroids those glucocortical steroids they’re all hormones made from cholesterol then there are peptides proteins right that are

uh hormones and the hormones produced from your pituitary gland the hormones produced from your hypothalamus as well as adh and oxytocin those are all protein hormones they oftentimes end in i n but not always so don’t don’t let that be your final answer but what you will find as a general rule is that if it ends in sterone right steroid steroid if it ends with steroid it’s a steroid so that’s a that’s a pretty decent clue it’s not every every time but most of the time and if it ends in i n as in oxytocin it’s oftentimes i’ll go not always a peptide or a protein now the third group are what’s called the monoamines or the biogenic amines now these are smaller they’re still derived from amino acids but they’re very very small peptides so in this group you’ve got epinephrine norepinephrine melatonin thyroid hormone the pineal pineal the melatonin these are all very small molecules that are basically one or two amino acids and that’s all there is to them so that means that either made from cholesterol or from amino acids right we’ve got to have those building blocks in order to make our hormones i’m not going to ask you to recognize any of these chemicals but you may notice that this is cholesterol you’re not going to memorize it but it has this very characteristic four ring structure to it and all these other hormones boy from across the room they all kind of look the same don’t they so all of those hormones this is your progesterone your testosterone your estrogen all of those look like cholesterol because they’re all derived from it that’s all i want you to see there now the peptides are all again made from proteins they’re made just like any other protein so we think back to uh transcription and translation and the making of proteins let me back up would there be a gene for testosterone do you have a gene for testo you have a gene for collagen right it’s a protein you have a gene for elastin you have a gene for hemoglobin right proteins dna goes on to make mrna which makes proteins but do you have a gene for testosterone or for estrogen or for any hormone steroid hormone no right because dna goes on to make mrna goes on to make proteins it does not go on to make directly lipids so you don’t have a gene that is just for testosterone now not to confuse you but you do have genes that make enzymes which might be necessary in making testosterone but you don’t have a testosterone gene but you do have genes for these other right for the proteins the hormones that are proteins you do have genes for these now what do we know about hormones they’re being they’re they’re being released through the body but we need to have regulation over them so we wouldn’t want to have the hormones floating through the blood always activated or always on so most of these hormones are first produced as a inactive as an inactive and what that means is that it’s produced but it’s not yet active it’s turned off and then as it goes through uh the endoplasmic reticulum and goes into the golgi then it gets packaged as a final hormone so there’s just levels of steps needed for production so i’ll demonstrate this with insulin with you insulin is produced it ends in i n pretty good clue that it’s a what it’s a protein right this is a protein hormone um that means it’s made up of many amino acids and you do have a gene for insulin there is an insulin gene and if we look at this we’re looking at you know what i’ve got the wrong picture on here this isn’t helping so i’m talking about insulin but i’ve got a picture about thyroid hormone that’s not going to help so i grabbed the wrong picture here let me let me go ahead

but i will tell you that insulin is going to first be made as a pre pro insulin and then it will become pro insulin and then eventually it will be made into final insulin but this picture is not related that’s my my error and then let me give you an example of a monoamine the biogenic amines another example this would be melatonin now yes this is where it gets a little confusing melatonin does end in in it is a protein but it’s a one of these really really short kind of hormones so there is a little bit of memorization going on here melatonin is basically um synthesized from one of the 20 amino acids called tryptophan and it’s it’s just a very small molecule okay so thyroid hormone and melatonin put those two in a category under monoamines basically if you go back about four slides and you take a look at these lists so the monoamines right include thyroid hormone melatonin epinephrine norepinephrine and then if you go back a page it says that the peptide hormones are oxytocin adh the six hormones from the pituitary anterior pituitary what were those six hormones let’s go back here what were those six hormones anterior pituitary fsh lh tsh prolactin prl growth hormone and acth right all those hormones are what peptides right they’re proteins they’re proteins so go ahead just make those lists and start associating these hormones with different classes and then all the steroid hormones again pretty easily most of them have sterone in their name so here we go so this picture is about thyroid hormone thyroid hormone is a monoamine so this picture is correct and uh where is thyroid hormone made it’s not a trick question it’s made in the thyroid gland and so the thyroid gland is going to release this molecule but we see iodine as in this picture so iodine is critical to this uh being produced and and then what happens thyroid hormone um we’ve got t3 and t4 we’ll come back to that story a little bit more when we get later in the course but we’ll see how those molecules are transported through the blood so we’ll come back to this in more it’ll make more sense in a few minutes we’ll come back to that picture let me try to describe more of the background to you right now so in the thyroid gland there are cells called follicular cells it’s just a kind of cell within the thyroid gland and here you’re going to be absorbing a lot of iodine from the blood i’ve already said to you that if you don’t have enough iodine your thyroid is not happy you need iodine to make the thyroid hormones and it’s stored there in fact if you have a thyroid tumor if you have any kind of thyroid cancer they will give you radioactive iodine and that radioactive iodine is selectively taken up by the thyroid gland and will destroy that cancer and iodine really doesn’t get absorbed by any other tissue so you can give someone radioactive iodine and it will only travel to the thyroid and destroy those those cancer cells and what we’ll see is that the the tyrosine that was the precursor for the um thyroid hormone and the iodine are going to combine to make these molecules t4 or thyroxine okay now t4 gets its name as we’ll see in a minute because of the number of iodines that are attached to it so guess what t4 has four iodines and t3 has three iodines and i’m not going to get into the specific function of those two at this

point so tell you what i’m going to do i’m going to probably just x this little story out yes just cross through this slide i’m not going to worry about the chemistry of the thyroid hormone the t3 t4 story don’t worry about that distinction yet now thinking back to hormones for a molecule to travel through the blood would that molecule be more hydrophilic or more hydrophobic if you’re going to expect a molecule a hormone something to be transported through the blood blood is largely water water you know plasma is largely water so that means that that molecule should be by default what hydrophilic right and that’s true right what about steroids they’re lipids and the characteristic of lipids is that all lipids are hydrophobic they are nonpolar they don’t dissolve in water so what we need to do is figure out here is how do these different types of hormones transport through the blood some of them are able to transport directly through the blood because they are hydrophilic and they can interact with water but other hormones like the steroid hormones are not going to be able to directly travel through the blood because they are themselves hydrophobic and we have to come up with another mechanism to transport them so let’s take a look at if that makes sense to you let’s take a look at this slide most monoamines and peptide hormones are hydrophilic so they can directly interact with and travel through the blood no problems however steroid hormones and as an exception thyroid hormone they would not be able to be transported directly through the water they must travel through or be transported by another protein so what you’ll see is that steroid hormones and thyroid hormone are going to piggyback on another protein a transporter and that is what’s going to transport it through the blood sort of protects it from that hydrophilic environment of the blood okay so this is why well we’ll talk about some different meds here in a minute um now hormones that are bound to a carrier have a longer half-life who can tell me what a half-life is i mean what a half-life of a drug is half-life has to do with basically this if i take a medicaid if i take 1 000 milligrams of a drug right now in how much time will my body only have 500 milligrams left right the time it takes for the drug to become half of what it was why do you take some drugs four times a day and some only once a day if you take a drug only once a day it’s more of a slower release medication and its half-life is longer if you are forced to take a drug three or four times a day it’s because it is quickly broken down and its half-life is shorter okay so if a protein or if a hormone is bound to one of these carriers it is more protected and therefore is hanging around longer in your bloodstream and we would say has has a longer half-life what organs are breaking down drugs the liver detoxifying and the kidneys are filtering and you’re urinating out your meds so again if a medication is not being broken down quickly by the liver and is not being readily filtered out by the kidneys then it’s going to hang around longer and have a longer half-life so if the molecule is unbound then it’s more likely going to be broken down by the liver or leave through the capillaries or get into the urine well what sorts of proteins carry these hormones well you’ve heard of albumin albumin is the most common protein in your blood it is when i described albumin last semester i said albumin was the molecule that helped to regulate fluid movement in and out of your blood and that’s true but albumin is also one of the important hormone carrying transporters and then there’s another one thyroxine binding globulin so this is a protein that specifically grabs onto thyroxine and carries it through the blood

another thing is that steroid hormones can bind to globulins what are globulins a short word for immunoglobulins antibodies right so it’s possible for your steroid hormones to kind of jump jump ship or hitch a ride on some of your antibodies your immunoglobulins just give you an example aldosterone what kind of molecule is that aldosterone it’s a steroid enzyme steroid it’s made where where were the steroid hormones made adrenal glands specifically in the cortex right and this was the one mineral corticoid i told you to know right so this was aldosterone it’s a steroid it’s made in the adrenal cortex and it’s regulating sodium and water levels as an example it has a relatively short half-life and and the reason it has a relatively short half-life is that most aldosterone is unbound that means it’s not being well protected and so it’s quickly broken down only 15 of it binds up with albumin and other carriers so it has a short half-life right it’s not protected whereas if we look at other hormones that are more protected they would have a longer half-life now what else we know about hormones hormones need to be able to travel through the blood but then they have to interact with a receptor right they they have to interact with a receptor on a cell if the hormone is bound up guess what it can’t interact it it’s you know it’s like trying to um if you’re if you’re getting a ride on something you can’t get off very easily so you you have to be unconnected to have an effect so receptors when we talk about hormone receptors what are we talking about hormone receptors are typically proteins or they might be glycoproteins and oftentimes where are they where do you think about these receptors being do you picture receptors when you dream about receptors where are they right you’re picturing a hormone traveling through the blood and it’s going to have an effect on a cell that has a receptor that receptor must be on the surface of that cell so it has to be in the plasma membrane it has to be facing out if you will looking for or being exposed to the blood so you’re going to find these receptors oftentimes on the plasma membrane sometimes in the cytoplasm and we’ll see why you can have even receptors in the nucleus in a moment but these receptors are like switches right once that hormone comes in contact with the receptor it flips the switch and something happens as a result so the hormone comes along flips the switch the cell now is activated or somehow is being told to do something differently than before when the switch was not switched now i know that in our cartoon pictures of the cell and maybe in our own mind when we think about a cell we picture a cell because this is what textbooks do and oh on the cell there’s a receptor or maybe there’s two receptors right but in fact on the surface of a cell there could be thousands of receptors those receptors could be receiving signals from different hormones or there could be even hundreds or thousands of the same kind of receptor on the surface there is a very specific interaction here it’s almost like the lock and key of enzymes not exactly but very very similar so a hormone can only affect a cell which has a very particular receptor for it so it is you know like that lock and key enzyme type of mechanism there’s a there’s a specific receptor for each hormone so if you’re insulin there are insulin receptors if you are testosterone there are testosterone receptors if you’re estrogen there’s an estrogen receptor whatever we’re talking about there’s a receptor for every hormone in the body that is another level of organization another level of control it’s also possible though for receptors to become saturated

that is if there’s only 10 receptors on a cell and all of them are receiving hormone even if there’s more hormone the cell can’t do any more so because these receptors are proteins it’s possible for them to become saturated for all of them to be engaged and so more can’t more effect cannot be made so let’s take a look here this is a hydrophobic hormone i’m telling you that okay it’s a hydrophobic hormone what does that mean to you afraid of water must be a steroid or what we say what were our hydrophobic hormones the steroid hormones and thyroid hormone those those that’s true that’s your thinking okay so hydrophobic all the steroids and thyroid hormone well what can harm what can hydrophobic molecules do what can they do that a hydrophilic molecule can’t do a hydrophobic molecule can penetrate directly through the cell membrane remember because the cell membrane is that phospholipid bilayer it’s got a fatty acid center and so hydrophobic molecules yeah they have more difficulty traveling through the blood they have to be carried but man they got a cool trick they can penetrate directly into a cell so we see that the receptor is not on the surface of the cell because the molecule the hormone can go straight in in fact the the receptor so here we here we look at it um hydrophobic so we’re looking at these little blue dudes okay these little blue rectangles that’s the hormone it’s a hydrophobic hormone most of them are going to be bound to this green rectangle the green rectangle is the carrier okay now if it’s being carried by that green rectangle that hormone cannot unhitch itself it cannot interact but if there is a free hormone like this one here or this one here it’s able to get out of the blood and directly go into the cell okay it goes directly into the cell so there’s no receptor on the surface of the cell and that molecule can get right into the cytoplasm and even go directly into the nucleus and directly interact with dna so it turns out that steroid hormones once they get to the tissue they can get right through the membrane they can get right through the nuclear membrane and they directly interact with the dna in the nucleus okay so that’s true of your estrogen your progesterone your thyroid hormone but it takes a while for them to do their job because once those hormones get into the nucleus they now have to affect gene expression affect transcription and translation so it takes a while for steroid hormones that take effect it can change the genetic profile it’s also true that you would not want to whenever you’re doing dealing with hormones you don’t want to take hormones and then come off them quickly there’s a lot of feedback regulation with that so typically you’re weaned on and weaned off from hormones to help out with some of the negative feedback issues now what if you’re a hydrophilic molecule so the hydrophilic molecules are the yellow ones they’re already freely floating in the blood they don’t need a carrier but in order for them to interact with the cell there must be a what a receptor so we see there’s a receptor in the membrane and when that hormone binds there’s something that happens inside the cell through a second messenger activation system and these can can act very very quickly or a hydrophilic hormone you don’t need a carrier you don’t need a transporter but you do need a receptor on the membrane of the cell if you’re a hydrophobic hormone you need a transporter through the blood but you can directly get into the cell right so there’s sort of a pros and cons to being a hydrophilic or a hydrophobic hormone so here’s just the same picture again same idea but now we’re looking at t3 and t4 thyroid hormones again what are they they are hydrophobic they have to be bound and carried through the blood

and only if they are released and are free can they penetrate into the cell go right through the cell membrane directly into the nucleus and interact with the dna okay direct direct direct again ask you to worry about t3 versus t4 just know that they are hydrophobic hormones now what does the thyroid hormone what does a thyroid do when you hear the word thyroid you know that the thyroid overall is involved in regulating your metabolism right has a lot to do with your metabolism so when thyroid hormones activate a cell what sorts of things do they activate turns out that thyroid hormone activates and makes more muscle protein okay and there are a lot of other things going on that have overall metabolic changes so a person who has hypothyroidism hypothyroidism what might some of their symptoms be weight gain tired weight gain if you have hyperthyroidism you might have weight loss or overall have a quote faster metabolism right and so but we see that these hormones are directly affecting gene expression so again a couple little videos if this story is making sense fantastic if it’s not making sense watch those videos re-listen to this it’ll all come together for you now let’s go that was hydrophobic and hydrophilic let’s take a look at these peptides these really small and the catecholamines what are calcolamines again epinephrine norepinephrine and dopamine okay so when you see that big word catecholamines be thinking about dopamine and epinephrine norepinephrine now these molecules are hydrophobic or hydrophilic hydrophilic so that means they’re going to have to bind to a cell surface receptor so here’s the hormone it’s binding the little little triangle there that’s the hormone it binds to its receptor that’s shown in green and something happens inside the cell right the hormone binds it activates something and inside the cell there are lots of things that happen now at the bottom of this whole thing it says oh there are various metabolic effects and that’s true so by the hormone binding to the receptor inside the cell it turns on different effects and we’ll call it a mysterious black box for right now but within the cell all sorts of things happen now ultimately you affect ultimately you affect the synthesis of molecules the secretion of molecules you might even change the membrane potential oh right you might even change that negative 70 of a neuron or we’ll see there are other cells that have a resting membrane potential so we won’t worry about the intermediate i’m not going to worry about how proteins work we’re going to say sort of this big mystery at this point but as the hormone comes in it is definitely going to have effects inside the cell so this slide is getting into some of those specifics that i’m going to skip over so i don’t want you to get excited about this again what’s happening a hormone comes in binds to its receptor and magical things happen inside the cell having some internet connectivity issues with the computer here okay so it looks like i’m having some connectivity issues so what i’m going to do is end here give me a second end here and we’ll pick up with this last little bit review the main ideas of

the endocrine system now we can you i can wait but you cannot wait until next tuesday to start getting serious about this exam okay it’s going to come really fast at you so this weekend listen to that powerpoint lecture on youtube for the autonomic nervous system this one will also be there for you to review and then we’ll pick up at the end of this and finish up now chapter seven there’s not a whole lot it’s a little bit about bones remember the osteoclast an osteoblast story and there was also some information about um bone development and then a little bit about calcium metabolism the other thing i want to tell you was that now i’ve forgotten what it was so do your do your connect assignments to your connect quizzes and oh i know what it was the syllabus is a typo so under exam number two on the syllabus it has the wrong chapter numbers okay so on exam two it says chapters 7 11 and 17 oh no no no okay so it’s 7 15 17. okay seven is the skeletal 15 is the autonomic nervous system and 17 is the endocrine 11 is the muscle and we’ll deal with that on exam 3 so push 11 off and add 15 for exam number two on your syllabus okay that does it for now