welcome back next up we're going to learn about how electrolytes are essential for maintaining fluid balance I'd like to start off this section by showing you a short clip from our textbook which by the way our book has some excellent animations in this chapter so the one that we're going to watch is the role of electrolytes and water balance and then we'll talk a little bit more about this the body maintains a healthy balance of fluid and electrolytes by keeping an appropriate movement of electrolytes in and out of the cells water follows solutes down the concentration gradient cells control fluid Movement by directing the movement of electrolytes or charged particles such as sodium and pottassium diffusion is the process where substances will naturally move from an area of high concentration to an area of lower concentration such as when a cube of salt or sugar is added to water over time the water and substance molecules will mix evenly as they each move to areas of lowest concentration our bodies use this natural phenomenon to maintain a healthy fluid balance changing the concentration of Water by pumping electrolytes in and out of cells cells control the movement of sodium and pottassium through special proteins that pump sodium in and out of the cell cell membranes are permeable to water as the concentration of sodium becomes greater on the inside of the cell membrane water flows to the side of greatest concentration until equilibrium is reached when the electrolite concentration is much greater outside the cell water is drawn outside the cell causing the cell to shrink possibly resulting in death of the cell this is what happens when you become dehydrated the role of elect electrolytes in the body is to maintain water balance simply put water follows electrolytes okay very good so that's a nice overview into these electrolytes so a couple of things I wanted to comment upon electrolites are solutes that are helpful with fluid balance the cations ions that we learn about in this class as well as chemistry are sodium and potassium primarily whereas the anion are the negatively charged electrolytes to to be chloride and phosphate and those are bound to the sodium and the potassium so any kind of change in concentration of these cat ions or anion will cause shifts in fluid from inside the cell to outside of the cell the movement of water across the cell membrane is also known as osmosis so ultimately going from an area of low concentration to an area of high concentration and then as alluded to in the video clip the sodium potassium pump becomes very essential at maintaining fluid balance I'd like you to pause me for a second and read over the figure figure 117 here on the slide so you have a basic understanding of the pump and then I'll talk about a few things related to it okay so the sodium potassium pump as youve read helps to maintain electrolyte balance and what we have occurring at all times in the body is sodium slowly leaking into the cells okay so it's leaking into the cells water we know follows sodium and as a result the inside of the cell can become too full too full of water so this is when the sodium potassium pump kicks in it's going to start pushing sodium out of the cells potassium comes into the cell as a result and when that sodium is pushed out of the cell water will also follow it so in this example that I'm walking you through we have water following sodium inside the cell it starts to get too too much in there it will push sodium out which then water will follow and get to a better point of balance just as a side note with the sodium potassium pump uh you've probably learned in other courses this also is a way that we create electrical charges in the body for ultimately muscle contractions and movements plus the pump also helps with nutrient absorption so if you remember back to chapter 3 where we discuss digestion and absorption of nutrients without the sodium potassium pump we're not going to absorb sodium I'm sorry we're not going to absorb glucose and amino acids into the cells as efficiently so it has some other functions in relation to its structure here we're just overviewing its role in the fluid balance the last item on the slide is uh the protein albumin uh so albumin is a protein that's found within our bloodstream and and actually I'm going to go to my previous slide where we've got the The Vessel here so imagine that alongside these red blood cells we've got a protein molecule in there so just a globule of protein it's called albumin albumin is essential for maintaining appropriate fluid balance within the bloodstream if we start dropping in our albumin levels due to sickness or not eating enough protein whatever it might be then we have fewer albumin particles or deciliter of blood and that's going to trigger the body hey caution we have not enough of this we need to get that concentration corrected and what the body will do is push extra fluid from the blood into these intial spaces what that will do for albumin is it will make it look good in the bloodstream so we get back up to that volume that we need however it can create a scenario where we've got too much water between our cells which then can cause swalling so appropriate fluid balance within the blood is also essential and albu plays a big role with this you might remember back to the protein chapter where we talked about quashi or cor and how long-term protein Mal nutrition can lead to swelling in the midsection this is due to albumin so those kids no longer have enough protein in their bodies to make albumin in the bloodstream happen as a result the volume in the blood is being sent into the interal or between the cells spaces okay I've got one more slide here that's more physiology related and then we'll switch gears and talk more about uh the last last few topics related to water so fluid balance is linked with our blood pressure uh closely right and we need to maintain appropriate blood pressure so that we are transporting nutrients efficiently to the bloodstream through the bloodstream excuse me to to our cells and tissues there are two hormones that play very key roles in regulating our blood volume and this is directly tied to blood pressure so I'm going to walk you through both of these scenarios uh the first hormone is anti-diuretic hormone or ADH so on the figure that you see on the right hand side the ADH pathway is the top one this is a scenario in which actually in your brain there's going to be a sensor on your hypothalamus that detects that we have a little too much sodium in the blood so not enough water to balance out that sodium that will lead to the scenario where the pituitary gland is stimulated to release the hormone ADH anti-diuretic hormone and just by its name you can get an idea of its function anti-diuretic so diuretic is something that's going to cause someone to lose fluid diuresis anti-diuretic is something that's going to cause us to retain fluid and that's what ADH does it will act upon the kidneys to basically hang on to more water so to reabsorb more water in the blood which will then balance out the sodium increase the blood volume and therefore blood pressure is maintained okay so less urine as a result on my slide here I've got some blanks so let's walk through those so anti-diuretic hormone is going to increase thirst it's going to tell your body hey you're thirsty you need to drink more to offset the low volume in the blood it is going to decrease urine output the kidneys retain more fluid and as a result it's going to restore blood volume to normal okay so this is one key pathway the other pathway that's Illustrated on the slide starts in the kidneys and ends in the kidneys and let let's walk through this one so starting in the kidneys uh we have a the can you sense a drop in blood volume so they're filtering out our water and waste throughout the day they're now sensing there's not enough volume coming through so the kidneys will release a hormone I'm sorry an enzyme called renin and this enzyme runin it goes through a series of steps basically it activates a compound called Angiotensin one the lungs then help activate that or convert that compound into Angiotensin 2 and I'll stop here for a second Angiotensin 2 is a good Vaso constrictor meaning it's going to act upon the blood vessels to contract harder uh this is going to increase blood volume and blood pressure and remember our Ro our initial trigger here is not enough blood volume so the vessels will start constricting more from Angiotensin 2 to try to get that blood pressure back up Angiotensin 2 also here in our image will act upon the adrenal glands which sit on top of our kidneys and they will be triggered to release aldosterone this is the second key hormone aldosterone is a hormone that's going to trigger the kidneys to hang on to more sodium and how this works to increase our blood pressure is well we know water follows sodium so if we're going to hang on to more sodium then more water will be retained and as a result we have that blood vessel or I'm sorry that blood pressure correction occur ing so both of these hormones ADH and aldosterone have key roles in maintaining the appropriate volume and blood pressure the blank here on the the left hand side so I've got just a summary of the the pathways here aldosterone is going to reabsorb sodium right so sodium is the blank here to help increase blood volume and blood pressure all right so that's it on the physiology I hope that was interesting to you next and finally we're going to cover our needs of water as well as what can occur with d and overhydration