Fluid, Electrolyte, and Acid Base Balance

this week’s lecture material is based on information from chapter 27 in your textbook fluid electrolyte and acid-base balance in the body let’s review the definitions of intracellular space and extracellular space intracellular space refers to that area inside of the cell or the space inside of the cell and the extracellular space is that area outside of the cell or between cells so if we were to add up all of the intracellular space so the of each cell in the body of the billions of cells in the body we add up all of those intracellular spaces that gives us the intracellular compartment of the body if we were to add up all of the extracellular space all of the space outside of the cells in between cells in the body then that’s known as the extracellular compartment intracellular fluid then is the fluid found inside of cells in the intracellular compartment extracellular fluid on the other hand will be the fluid found outside of cells and in between cells and when we’re talking about blood the blood within blood vessels the extracellular fluid that’s found outside of blood cells in blood is known as plasma and everywhere else in the body the fluid found outside of cells and in between cells in the tissues is known as interstitial fluid this chart or this image will show you the the distribution of water throughout the body between the two major compartments so the intracellular compartment and the extracellular compartment we know that in healthy males approximately 60% of body weight is due to water in females the the numbers a little bit lower approximately 50% of body weight is due to water and the difference being that you find skelita muscle has a lot more water as opposed to adipose tissue or fat tissue and generally females have a higher fat percentage in their body content as well they have less little muscle so that reflects the difference in the percentage of total body weight that’s due to water you’ll see that the intracellular fluid volume is approximately two-thirds of the the water in the in the body is in intracellular compartment and so the other one-third will be in the extracellular compartment and remember that the intracellular fluid or the intracellular compartment refers to all of that fluid inside all of the cells of the body whereas the extracellular fluid is the fluid found outside of cells and in between cells and recall that fluid in blood in the blood vessels outside of the blood cells is known as plasma and the interstitial fluid then is the fluid found outside of cells throughout all other tissues in the body water is known as the universal solvent and this is what this refers to is the fact that many substances particularly particularly polar substances molecules that have charges associated with them can easily move within water or be dissolved in water so this has to do with the structure of the water molecule h2o we see that the oxygen atom has a slight negative charge and the hydrogen atoms have slight positive charges so if we take a molecule of sodium chloride which is salt we see that the positive charge on the sodium ion is attracted to the negative charge of the oxygen atom and the negative charge on the chlorine atom ion is attracted to the positive charges of the hydrogen atom so this will dissociate or break apart the sodium chloride molecule and basically dissolve within water so in this case the we know that water is the solvent it’s the fluid that we reversing the sodium chloride in and the solute then would be sodium chloride but anything that is is able to interact or to be put into a solvent like water is known as the solute we look at the different categories of solutes that we find in the body we have two broad categories electrolytes and on electrolytes electrolytes generally refer to substances that are potentially create a electric current so there tends to be significant charges associated with these structures positive and negative charges examples being sodium

ions potassium ions chlorine ions salts bases some proteins that we find in the body are all electrolytes non-electrolytes then are structures like glucose fats lipids creatinine and urea which are byproducts of cell metabolism that for the most part don’t have charges significant charges associated with them so in effect could not really be used if we wanted to create an electrical current we can’t use non electrolytes to to do that so this is a very important point electrolytes structures that have charges positive negative charges associated with it when we have these electrolytes and association with water electrolytes have a very powerful effect in being able to move water so when we want to shift water fluids between compartments between intracellular and extracellular compartments in the body we can move electrolytes first to create that movement of water so for example if we wanted to first move sodium a positively charged ion across a cell membrane we know that the positive charge of the sodium ion will then attract the negative charge of the chlorine atom so the chlorine will tend to follow sodium when you cross a membrane and then the we know that water will want to follow the sodium chlorite now so sodium and chloride together make up salt we know that water is attracted to salt so these electrolytes have the ability to move water across cell membranes from one compartment to another so electrolytes generally have a much stronger effect than non electrolytes in moving water from one compartment to another we know that the intracellular and extracellular fluids have different concentrations of electrolytes positively charged electrolytes are known as cat ions and negatively charged electrolytes are known as anions so if we look at the intracellular space the intracellular compartment the chief cation is potassium we have much more potassium on the inside of the cell than we do on the outside of the cell and the chief anion in the intracellular space is phosphate phosphate is a negatively charged structure a negative electrolyte if we look at the extracellular space or the extracellular compartment the chief cation is sodium we have much more sodium on the outside of the cell than on the inside and the chief anion is chlorine we have much more chlorine outside of the cell than we do on the inside of the cell remember that in the cell membrane that we have sodium and potassium leaky channels so both sodium and potassium will want to diffuse across the cell membrane down their concentration gradient and if it was allowed to continue this would continue until the sodium potassium would have equal concentrations on both side of the of the membrane and that’s not what we want because we want to create a negative resting membrane potential the inside of the cell membrane needs to be negatively charged at rest and this was what creates this ability of nerve cells to create a action potential or a nerve impulse so remember that we have to have the sodium potassium pumps in the cell membrane that will continually readjust that concentration gradient of sodium potassium so we always have more sodium on the outside than inside and more potassium on the inside of the cell than on the outside this figure is in your textbook and again it’s just illustrating the concentration differences of the electrolytes in the intracellular and the extracellular compartments in the body so remember that blood plasma represented by the red our and interstitial fluid represented by the blue barb are both components of the extracellular compartment or extracellular fluid and then the that the tan colored or light colored bar will be representing the intracellular fluid so again you see that in the extracellular compartment sodium is as a high concentration as opposed to the intracellular compartment and in the intracellular fluid we have much more potassium than in the extracellular fluid and again chlorine much higher in the exercise of their fluid then on the intracellular space and phosphate which is hpo4 to negative much more on the inside of the cell than on the outside

of the cell the on average human beings lose about two and a half liters of water a day and so water that’s lost has to be replaced so to me remain properly hydrated water intake must equal water output so where we get water from we’re going to get approximately a liter and a half of that to Nath leaders will come from the fluids that we drink 30% will come from the food water within the food that we consume and about 10 percent will come from the water of metabolism so this is the as a recall in the electron transport chain the final acceptor of the high-energy electrons is oxygen and that the oxygen combines with protons hydrogen ions to make water so that’s the water metabolism and then we lose the the two and a half liters a day that we lose so both 60% will be in the form of urine and then we have what’s known as insensible losses so this is a fluid loss that’s not obvious it for example sweat is we can normally can see sweat so about 80 percent of fluid losses due to sweat but other types of losses that can occur through the skin that will cause basically an evaporate raishin of the fluid so it doesn’t look at like visible sweat but we’re still losing that fluid so these are known as insensible losses same as when we breathe out are the air that we breathe out of our body when we exhale is humidified so it’s not more than you see but we’re still losing moisture so these are insensible losses through the skin and the lungs and then finally also in our feces when we have a bowel movement we’re also losing water in our feces as well so we have to have a proper balance to remain properly hydrated the water that we lose each day has to be replaced by intake if water loss is greater than gained through the day then we start to become dehydrated and we know that if we’re becoming dehydrated that we will develop a sensation of thirst that we want to consume fluids there’s an area in the brain that’s called the hypothalamus and the hypothalamus is able to monitor plasma osmolarity so this is dealing with the concentration of solute in blood plasma so the fluid in or the extracellular fluid of blood if you are becoming dehydrated then the amount of water in blood is becoming less so in effect the solute all the different substances proteins cations and Iser and blood that concentration of that stuff will start to increase as you’re losing or the relative concentration as you’re losing water so in you know the what the blood itself actually becomes more sticky or what’s known as more increased viscosity so this is also reflected in what’s called plasma osmolarity so the more dehydrated you become the less water in the plasma which means that there is relatively more stuff in the plasma and the hypothalamus can monitor this and if plasma osmolarity is increasing due to dehydration it will stimulate the thirst center that we’ll make you want to consume fluids the major stimulus then for stimulating the thirst center in the brain is plasma osmolality when plasma osmolality increases due to dehydration the Osmo receptors in the hypothalamus will fire and then that will tell the thirst center that’s in the hypothalamus to create a sensation of thirst so that it will make you want to drink water fluids something to try to satiate that thirst and then as we’re consuming these fluids we’re going to have other receptors in the mouth and the throat that are going to respond to that moisture as well stretch receptors in the stomach as water is entering and in the intestine will stimulate or start to satiate that sensation of thirst make you feel less thirsty and then as water is being absorbed out of the GI tract and back into your blood the plasma osmolality will begin to decrease and now the Osmo receptors are going to stop firing in the hypothalamus and that’s going to take away that sensation of thirst another mechanism is stimulated as you become dehydrated and this is related to the release of antidiuretic hormone from

the pituitary gland so the antidiuretic hormone is made by the hypothalamus but it’s stored in the pituitary gland pituitary is a structure in the brain as well and when plasma osmolality is increasing due to dehydration your pituitary will release antidiuretic hormone antidiuretic hormone acts on the kidneys to create a more concentrated urine which means it’s going to not allow as much water to be lost in the urine and we know that if you drink several drinks of alcohol for example you start to notice that you’re not your volume of your urine starts to increase and also it becomes more dilute so there’s less color you’ll say drink beer be clear and that’s because alcohol inhibits the release of antidiuretic hormone from the pituitary so it results in you creating a very dilute urine you’re losing water more water in your urine the name antidiuretic diuresis refers to the act of urination so if you take a diuretic for example diuretics or a class of medications that people take for blood pressure trying to reduce their blood pressure diuretics make you pee more so that you lose more volume of water in your urine which will decrease your blood volume which will help to decrease blood pressure now so if you have low levels of antidiuretic hormone that’s being released so in the case where you’re if you’re very hydrated if you’ve drank a lot of water we want to get rid of some of that water so m in this case you’re going to have decreasing plasma osmolality because you’re very hydrated your blood is very hydrated in that case and the inhibition of release of antidiuretic hormone will result in the kidneys making a more dilute urine so again these this action is being monitored by the Osmo receptors in the hypothalamus the slide again will emphasize the actions of antidiuretic hormone antidiuretic hormone is also known as vasopressin so if you see that term vasopressin it’s referring to antidiuretic hormone so if we look at first we talked about increasing our molality in the blood so due to dehydration this can also be correlated with an increasing sodium concentration in the plasma so if you have a lot of sodium in your in your plasma then it’s going to effectively cause an increase in osmolality this will stimulate osmol receptors in the hypothalamus the hypothalamus then we’ll tell the posterior pituitary to squirt out antidiuretic hormone which goes into your circulatory system and then the ADH diuretic hormone will act on the kidneys that’s the target of the antidiuretic hormone it will cause the kidneys to increase water reabsorption so to take water out of the urine filtrate that’s being made and put that water back into the circulatory system back into your blood vessels and as this happens this is going to result any a scant or a concentrated urine and also the blood osmolality will start to decrease and the plasma volume will increase and as plasma volume increases and blood osmolality decreases this is going to tell then the Osmo receptors in the hypothalamus to stop releasing antidiuretic hormone so that’s known as a negative feedback inhibition that occurs so this is how we monitor or create a homeostatic level of osmolality that and blood volume that that we require in the body if you look on the right side of this of this flow chart as well we see there’s another stimulus decreasing plasma volume or decreasing blood pressure will also cause a release of antidiuretic hormone in this case with decreasing blood pressure and plasma volume we have stretch receptors in the walls of a couple of the major arteries in our body and if these and these are called baroreceptors and if these baroreceptors are not being stretched enough because because the blood volume is decreased or blood pressure is too low that will stimulate the posterior pituitary as well to release antidiuretic hormone and the overall effect of that then is to increase blood volume increase plasma volume which will also result in an increase of blood pressure as remember we need to have enough blood pressure as

well to be able to perfuse organs and tissues in the body if blood pressure becomes too low organ failure can start to occur where we’re not getting enough oxygen and nutrients to those tissues a major premise in the body is the movement of water in relation to sodium and chloride so generally throughout the body when we’re trying to move water from one compartment to another first we will move sodium that tends to be the primary cation or electrolyte that is moved and then sodium is a positively charged ion we know that chlorine negatively charged will follow sodium and then we now we have salt sodium and chloride together as it has a very strong attraction for water so we want to move water across a cell membrane from one compartment to the next we can actively transport sodium first chlorine will follow the sodium across the membrane and then water will follow the sodium and chloride so extent of urinary salt loss is the main factor that determines body fluid volume if we want to increase the amount of body fluid and that we lose through urine we can add more sodium chloride into the urine filtrate and water will follow sodium chloride which means that that will be excreted in the urine and we can reduce the amount of fluid or water in our body fluids our body compartments the main factor that determines body fluid osmolarity then is how much water we lose in the urine as we lose more water in the urine our plasma osmolarity or osmolality will increase we have three hormones in the body that will help to regulate the renal or kidney sodium and chloride reabsorption angiotensin ii and aldosterone these two hormones will promote the kidneys to reabsorb sodium and chloride out of the urine filtrate and back into the blood so when we move sodium and chlorine out of the urine filtrate back into the blood water will follow sodium and chloride by osmosis and this is a mechanism that occurs when we’re becoming dehydrated the other third hormone is called atrial natriuretic peptide and pee the word first of all atrial is refers to a chamber in the heart the atrium and there are cells in the wall of the atrium that produce this hormone now natura dec the word natural attic Nate rien atri refers to sodium and this is where we get na for sodium the chemical symbol for sodium is na comes from Natura which I believe is either Greek or Latin for sodium so this is a hormone that’s produced by the the atrium a chamber in the heart and these cells are able to respond to increase stretch in the wall of the atrium so if there’s an increased blood pressure blood volume if there’s a high volume of blood coming back into the heart that causes a stretch in the walls of the atrium and the atrium will release ANP atrial natriuretic peptide and this again acts on the kidney and it results in the kidney excreting more sodium and chlorine into the urine filtrate and again water will follow the sodium and chloride and results in an increased volume of urine along with the sodium and chlorine and ultimately results in a decreasing blood volume so now that’s going to cause less stretch in the atrium in the chamber of the heart which will then stop the atrial cells from secreting atrial natriuretic peptide the slide will illustrate the effects of the renin-angiotensin-aldosterone mechanism so if we look at the top of this flowchart we see that the the stimulus is going to be either decreasing sodium ion concentration or an increase in potassium concentration in the blood and these two ions are normally act opposite to each other because they tend to go in the opposite direction across a cell membrane so if you’ve got more sodium going one way across the membrane you tend to have more potassium going the opposite way and this has to do with the

sodium potassium channels pumps that we know about so either low sodium or high potassium concentration in the blood will stimulate the renin-angiotensin mechanism that starts in the kidney angiotensin will and we’ll do this in more detail when we look at the kidney physiology in second half of the semester but once we’ve made angiotensin angiotensin will act on the adrenal cortex the adrenal glands sit on top of the kidneys left and right kidneys we have the adrenal glands and the the angiotensin will stimulate the adrenal cortex the bark of the adrenal gland to secrete aldosterone aldosterone is a hormone that’s going to act on the kidney so the kidney tubules will result in them reabsorbing more sodium so you’re going to pee less sodium you’re going to pull more sodium out of the urine filtrate back into the blood and conversely as sodium is going into the blood means that more potassium is going into the urine filtrate so you’ll tend to urinate more potassium out and as a result eventually you restore the homeostatic plasma levels of both sodium and potassium these ions sodium potassium and particularly potassium has a very narrow range of homeostatic levels you can’t have too much or too little potassium there’s a very narrow range that is normal otherwise you can start to create very serious problems especially dealing with the heart and atrial fibrillation arrhythmias that can occur due to potassium levels being too high or too low sodium is the major electrolyte a major cation that is responsible for the movement of other electrolytes and water in the body so as a basic premise when we want to move fluid or water from one compartment to another or we want to move electrolytes from one compartment to another we’re going to move sodium first well we can actively transport sodium across the cell membrane and other electrolytes will follow either in the same direction or opposite direction and as well water tends to follow sodium so if we look at the hormonal regulation of sodium and chloride in the body we start at the top here we see that if we intake if we have an increased intake of sodium and chlorine so for consuming salt that’s going to increase the blood concentration plasma concentration of sodium and chloride ions and by osmosis water is it going to be attracted to that sodium and chloride that’s in our blood so from the interstitial fluid the fluid in the tissues will be drawn into the blood vessels towards the increased concentration of sodium and chloride and this is going to result in increasing blood volume so as blood volume increases it’s going to cause a stretch in the atria the walls of the atria and the heart these cells and the atria then we’ll release atrial natriuretic peptide and this is a hormone that will act on the kidneys to reduce the amount of sodium being being recovered from the urine filtrate so this means that more sodium stays in your urine water will be attracted to the sodium as well as chlorine and so which means that you will pee out more sodium and chloride and and you will pee out more water and the overall effect of this is that you will have a decrease in the volume of water in your blood which will decrease blood volume and also decrease blood pressure as well we see back up to the middle of that flow chart with increased blood volume that means less or sorry more blood is being filtered through the kidneys which means there will be less of the renin-angiotensin mechanism that will be stimulated which means less aldosterone will be released by the adrenal cortex and again as a result remember aldosterone acts to increase recovery of sodium from the urine filtrate so in effect it’s going to cause you to put more sodium into the urine and remember when we move sodium chloride Falls sodium into the urine and as well water will then follow the sodium the chloride we’re now going to look at acid-base balance within the body and how the body is able to maintain homeostatic levels of pH of the body fluids this is a major

homeostatic challenge because most metabolic reactions that occur in the body create acids so with with acid formation we’re creating increased acidity of fluids and tissues cells are very sensitive to pH levels or the acidic acidity of the fluids themselves so it’s a challenge to be constantly trying to maintain a very narrow range of pH and trying to neutralize these acids that are being produced when we look at proteins for example we know that proteins are essential for all functions that occur in cells and in the body and remember that the three-dimensional shape of the protein that’s created in protein synthesis that we learned about associated with the ribosome that that 3 3 dimensional shape really is important for the functioning of the protein and with increasing acidity these three-dimensional shapes are very sensitive to the pH of the fluids that they’re in and if the fluids are becoming to a siddik they can actually start to damage or rearrange that 3-dimensional shape and the proteins become inactivated we know generally that diets that have large amounts of proteins so if you consume a lot of meat in your diet you tend to create much more acids as opposed to bases which tends to create a in an acidified blood normal pH of body fluids is 7 between 7.35 and 7.45 so you do have to know that number remember that the pH scale goes from 0 to 14 7 is neutral everything below 7 is acidic and everything above 7 is basic another word for being basic or I have more base than acid is alkalosis or Alka leimia so Amir refers to blood whenever you see that suffix emia is referring to blood so alkyl emia refers to increased alkaline alkalinity of the blood so arterial blood that is going to have a pH above 7.45 then because remember homeostatic level is 7.35 to 7.45 so if your pH is above 7.45 it means that you’re becoming alkaline that you have more base than acidic more base than acid in your blood so this is known as alkalosis or Alka leimia on the other hand if you have a pH that is below arterial blood is pH is below 7.35 this is known as acidosis or acidemia so even though 7.35 is above neutral remember in body fluids the normal pH is 7.35 to 7.45 so if you drop below seven point three five you’re becoming more acidic so this is known as acidosis or acidemia if your pH is below seven point three five and recall that pH is determined by hydrogen ion concentration so the the term pH refers to the partial pressure of hydrogen ions or the concentration of hydrogen ions so the more hydrogen ions you have in your fluids the more acidic you are the lower your pH is most of the hydrogen ions that that are developed in the body originate from cellular metabolic reactions for example breaking down proteins will result in a release of phosphoric acid into the extracellular fluid the anaerobic respiration of glucose that we’ve learned about in the cytoplasm of the cell can produce lactic acid using fat as a source of fuel so fat metabolism will result in the production of ketone bodies known as ketoacidosis and transporting carbon dioxide in blood as bicarbonate ion releases hydrogen ions and we’ll see that in more detail when we look at blood respiration but all of these are normal metabolic reactions that occur in the cells of the body and they all result in the production of hydrogen ions or acidity so they contribute to the acidity of body fluids and we have to have systems available in the body to neutralize these acids otherwise we’ll become too acidic we basically have three lines of defense

when we’re trying to neutralize the acids that are being built due to cellular metabolism the first our first line of defense would be the chemical buffer systems that are in the blood and these act very quickly within seconds that try to neutralize these acids that are being built due to due to cellular metabolism secondly the respiratory center in the brain stem will determine how quickly we breathe and and what our depth of respiration is and this is important because carbon dioxide which is carried in our blood remember carbon dioxide is a waste product of cellular metabolism carbon dioxide is directly correlated with acidity so the more co2 carbon dioxide you have in your blood the more acidic your blood is so if we increase our rate of respiration we can blow off more co2 to try to lower our acidity in the blood so this occurs within one three minutes as a second line of defense and then the third line of defense will be the kidneys the kidneys are very powerful mechanisms or have very powerful mechanisms in trying to normalize pH levels in the blood but these mechanisms normally take a little bit longer to kick in they could take hours two days before these renal mechanisms have their effect in neutralizing the acids look at the chemical buffer systems first that are present in blood and these systems act very quickly remember they’re the first line of defense defense and what they’ll do is act by binding to these hydrogen ions to try to neutralize the acidity so they don’t actually get rid of the hydrogen ions from the body or the acids from the body and that’s when we look at renal or kidney mechanisms they’ll see that too the kidneys can actually excrete acids or hydrogen ions so you’re actually peeing out acids to try to make yourself less acidic but these buffer these chemical buffer systems will just bind hydrogen ions or the acids to neutralize them so three major chemical buffer systems that we have in blood as the bicarbonate buffer system phosphate buffer system and then the protein buffer system and we’ll look at each of these individually the most abundant chemical buffer system is the protein buffer system that we see in the intracellular compartment fluids and in the blood plasma so in red blood cells for example hemoglobin which we’ll learn more about later in the course hemoglobin is the protein that binds oxygen in the red blood cell but hemoglobin is a protein that will also act as a buffer and as well in the blood plasma we have a one of the proteins that we have is called albumin and it’s also acts as a major buffer system for the acid-base balance in blood so if we were to look at the at the bottom of this slide the basic idea of a protein structure we have a carbon backbone of some sort and you could these can be very very large carbon structures but somewhere on the protein structure you’re also going to have a carboxyl group which is the carbon with two oxygen and a hydrogen ion and then we also have an amine group which is the NH two that you see so if the if the blood is we’ll see first we’ll talk about this scenario if the blood is too basic so which means that it’s not acidic enough and so in this case what we want to do is to try to make the the blood more acidic because remember it’s a it’s a homeostatic range of 7.35 to 7.45 of pH and if our pH is above seven point four five it means we’re too alkaline or too basic so we want to add acidity to the blood to get it back to a homeostatic level so in this case we can use the hydrogen ions that’s associated or the hydrogen atom that is associated with the carboxyl group the hydrogen can dissociate from that carboxyl group and become a free hydrogen plus ion or atom or protons or that will add to the acidity of the fluid that it’s in so in effect it’s going to help to decrease the pH to get you back towards a homeostatic range on the other hand if your blood is too acidic it means that there’s too much

free hydrogen ions h+ ions so what we can do now with the proteins is that the NH two part of the protein can bind another hydrogen to become nh3 and in doing so it’s neutralizing that hydrogen taking it out of the out of the fluid and effectively neutralizing it by binding it to that NH 3 protein component of the protein structure the second component of the chemical buffer system is the carbonic acid bicarbonate buffer system and this has to do with the respiratory system regulation of acid-base balance so this is a reaction the two equations you see at the bottom of this screen are referring to the reactions that occur within the red blood cell and we’ll cover these a little bit more detail when we do our tutorial this week so I want to make sure everybody understands this this process mol we’ll talk about it by illustrating it or on on the board so there is a if we look at the equation co2 plus h2o goes to h2 co3 then which then goes to hydrogen ions plus bicarbonate so we know that co2 is a carbon dioxide is a waste product of cellular metabolism and when we add water to co2 we make carbonic acid which is h2 co3 and then this will dissociate into hydrogen ions and bicarbonate hco3 negative so and the way chemical reactions occur the left side of the equation here would be the reactants that we start with and the right side of the equation would be the products so if we start with more reactants if we had a lot of co2 we’re going to create more products on the right side so with increasing co2 we’re going to eventually result in creating more hydrogen ions and more bicarbonate so this is where the relationship is between carbon dioxide and pH so as we have more co2 it results in more hydrogen ions being produced which means it’s increasing acidity so if we look at these this reaction will result in hydrogen ions which are acids and bicarbonate ions which are bases so in effect we can use we can use those hydrogen ions to increase acidity of fluid if necessary and we can use those bicarbonate ions hco3 negative to decrease acidity if we require so the bicarbonate can bind to hydrogen ions to neutralize or the hydrogen ions can be used alone as as a source of increasing acidity once again we’re trying to achieve a homeostatic range of 7.35 to 7.45 pH the bottom reaction HB refers to the protein hemoglobin which is the protein that binds oxygen inside the red blood cell and we know that with increasing concentration of hydrogen ions in the area at the hemoglobin oxygen complex it causes the hemoglobin to release the oxygen which makes sense and we’ll do more detail on this process again in class and as a result the hemoglobin will then bind hemoglobin is a protein it will bind the hydrogen ions and take it out of circulation so to speak and in effect neutralize the acidity that’s created by that hydrogen ion the final component of the chemical buffer systems in blood is the phosphate buffer system and this is located mostly in the intracellular fluid and these phosphate structures will bind hydrogen ions so in our first example hydrogen ion h+ is a strong acid and if we combine it with hydrogen phosphate hpo4 to negative we create a weak acid so in doing this going from a strong acid to a weak acid we are decreasing the acidity of the fluids on the other hand if we have a situation where the float is too basic to alkaline so we have these hydroxyl ions o h- which are strong bases we can combine it now with the weak acid h2 po4 and as a result we make water and we create again hpo4 hydrogen phosphate which is a weak base so we’ve

gone from a strong base to a weak base so in this case we’ve made the fluids more acidic so in this way we’re trying to again get that homeostatic range of 7.35 to 7.45 whether we have to make it more acidic or more basic to get to that range so we’ve seen that chemical buffers can tie up excess acids or bases but they don’t eliminate them from the body they just neutralize them while they’re still in the fluids the lungs we’ll see can also decrease acidity by getting rid of carbon dioxide so by increasing our respiratory rate or depth of respiration we can blow off more carbon dioxide and that in effect will create a less acidic blood but only the kidneys can rid the body of the metabolic acids so phosphoric uric lactic acids keto ketones these all these structures that are made from metabolic reactions in the cells can actually get rid of be rid of through the kidneys and this is important because if we can get rid of these structures these assets it eventually results in a condition known as metabolic acidosis where the entire body becomes all fluids in the body are becoming more and more acidic and it can eventually become life-threatening so only the kidneys have the power to actually excrete or get rid of these acids from the body so the ultimate acid based regulatory organs are the kidneys the mechanisms that the kidneys have for neutralizing acids getting rid of acids is extremely powerful when we look at the kidneys abilities to regulate acid-base balance the most important renal or kidney mechanisms for regulating Essbase balance is dealing with bicarbonate ions so bicarbonate is HCl three- and if we want to increase the acidity of our fluids in our body we can get rid of bicarbonate ions so we can put bicarbonate in the urine to pee it out so in effect that’s going to raise the acidity of the blood and conversely if we want to decrease the acidity of the blood we can reabsorb or take bicarbonate out of the urine filtrate and bring it back into the blood to try to create a less acidic environment within the blood so in either case you’re you’re manipulating the concentration of bicarbonate ions either you’re keeping more in the blood or you’re getting rid of more in the urine if we look at this diagram here this figure so this is a representation of cells tissue within the kidney the peritubular capillary that you see there will be that’s going to be the blood that is part of our systemic circulation so we see there by car ion’s in brackets new hco3 negative so if the blood in the peritoneal capillary which represents our circulatory system if the blood is too acidic there we can bring more bicarbonate ions hco3 negative into the peritubular capillaries to make that blood less acidic on the other hand we can also excrete more hydrogen ions out and on the left side of that image you see the filtrate in the tube you’ll lumen so that represents the what’s going to become urine and so again if it were too acidic in the blood these chemical reactions can result in hydrogen ions being put into the urine filtrate so that we can pee that out in our urine and an in effect cause decreasing acidity of the blood we look at the state of respiratory acidosis or respiratory alkalosis it’s important to understand what this refers to so this has to do with the concentration of carbon dioxide in the blood and it’s the going to result from the inability of the respiratory system to get rid of enough co2 or to balance the pH in the blood by the respiratory rate so you’re going to see problems very commonly in people who have lung disorders things like bronchitis emphysema lung cancer

can result in respiratory acidosis for example because they’re not able to effectively get rid of as much carbon dioxide as they should be able to because of these pathologies so respiratory acidosis and alkalosis refers to either increasing acidity or alkalinity of the blood but due to some process that’s occurring in the lungs so the result is the partial pressure of carbon dioxide or the amount of carbon dioxide in the blood is not being adequately regulated by the respiratory system okay so it’s important to know that respiratory acidosis is the most common cause of acid-base balance imbalance in the body so for example if we already mentioned pathologies like bronchitis pneumonia emphysema where there’s gas exchange as being impaired in the lungs it’s going to result in rising levels of carbon dioxide in the blood so this refers directly then to increasing acidity of the blood or what’s known as respiratory acidosis respiratory alkalosis happens when the carbon dioxide in the blood is too low so if you have not enough co2 in the blood remember that co2 correlates with acidity so if you have very low co2 it’s going to result in your blood being too alkaline your pH as risen above 7.45 so this is what you see when somebody is hyperventilating so if there’s a problem with not feeling like you’re getting enough oxygen maybe due to anxiety or even being in a high altitude situation and so in this case co2 is too low so this is when people will breathe into a bag so when you’re breathing into a bag to correct respiratory alkalosis what you’re doing is that you’re you’re breathing out carbon dioxide in a bag but now you’re also breathing carbon dioxide back in again and so in a short period of time you’re you’re raising the carbon dioxide levels in your blood because of this process of breathing in and out of a bag metabolic acidosis on the other hand has to do with bicarbonate ion concentrations in the blood so respiratory acidosis is correlated with carbon dioxide levels metabolic acidosis has to do with bicarbonate levels so if the bicarbonate ion if you don’t have enough bicarbonate ion in your blood it means that your blood is becoming more acidic which means that the pH is is going lower than the seven point three five so causes of metabolic acidosis either you’re losing too much bicarbonate ion so for example in cases of diarrhea or if you have a kidney disorder that’s causing you to pee Oh too much bicarbonate ion or on the other hand if you have a conditions where your body your cells are making too much acids so too many acids so you’re producing too much lactic acid or if you’re diabetic you’re using you’re breaking down proteins fats and creating these these acids that are making you metabolically acidic on the other hand metabolic alkalosis means that your blood pH is rising above the 7.45 homeostatic level and this can indicate that there are too much there’s too much bicarbonate in your blood so or not enough acid so for example if you’re vomiting and repeatedly vomiting and you’re vomiting the acid stomach contents are very acidic and if you’re vomiting that acid out of your stomach you’re decreasing the amount of acid available to your blood and so in effect causing the blood to become more alkaline people who take excessive numbers of antacids you know like tums those types of things or in a fluid form that’s trying to neutralize the acidity if people have problems with heartburn that kind of thing that if they take excessive amounts of these antacids it can put you into a state of metabolic alkalosis and conditions of constipation where people are not having regular bowel movements for and the waste materials staying inside the digestive too for prolonged periods of time and it gives your digestive system more time to be able to absorb more bicarbonate that’s in those digestive juices and it can potentially cause you to go into a state of metabolic acidosis important to understand that the the two systems a respiratory system and the urinary

system the kidneys will help to or will attempt to compensate for each other’s problems if it’s creating an acidosis or an alkalosis state in the body so for example the respiratory system will attempt to correct metabolic acid based balances by either causing you to hyperventilate or to hyperventilate so if you are becoming metabolically acidic due to some disorder your breathing rate tends to increase and either increase in frequency and in depth of respiration with the attempt to try to blow off more co2 and to try to compensate for that acidity that metabolic acidity by decreasing their level of carbon dioxide in your blood conversely if you’re becoming metabolically alkaline too basic your respiratory system will try to compensate by having you hyperventilate or respiratory rate down and your make your depth of respiration more shallow so you’re trying to retain more carbon dioxide in your blood to try to compensate for that metabolic alkalosis and the kidneys will do the same in the end the response to respiratory acidosis or alkalosis so if you have respiratory acidosis too much carbon dioxide in your blood the kidneys will try to reabsorb more bicarbonate out of the urine filtrate try to neutralize that acidity