11 renal - WEEKLY THOUGHTS-MODULE 11 RENAL The kidney is my...

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WEEKLY THOUGHTS-MODULE 11 RENAL The kidney is my favourite organ. It is quite complex, which is involved in many different functions important for homeostasis (know these). Each kidney is approximately the size of your fist and can actually filter 180 L of fluid a day! This is pretty impressive for two organs that are fairly small. Maybe even more interestingly, we can actually lose almost ¾ of our kidney function and still live - which is why it’s possible to donate a kidney. 1. Anatomy of the kidney : You will notice that there are 2 basic regions to the kidney, the outer cortex (don’t get this confused with the cerebral cortex) and the inner medulla (once again, not the medulla oblongata). I am most interested in you understanding and knowing the functional part of the kidney … the nephron. You probably want to know also what the ureter is, and that we have only 1 bladder but 2 kidneys. 2. Anatomy and Function of the nephron - this is important so know this (its anatomy, structure, blood supply including the afferent, efferent arterioles, glomerulus, peritubular capillaries). The nephron is the functional unit of the kidney … meaning this is where it all happens! We have over 1 million of these nephrons per kidney, and if you think about it, this is pretty necessary since we are filtering 180 L per day. You can think of the nephron as a big snake. The mouth area is where Bowman’s capsule is found. You can pretend that your snake has its mouth wrapped around a little sieve. That is really what the glomerulus acts like. The glomerulus is a ball of really leaky capillaries that receives blood from the afferent arteriole and after some things are filtered, the blood leaves via the efferent arteriole. Things that are too big can’t enter Bowman’s capsule. These include plasma proteins and red blood cells. The presence of either one of these in the filtrate is a clear sign that the kidney is not happy since in the healthy kidney, these are simply too big to pass through. A lot of fluid (but not all) is filtered out of the capillaries first through little holes in the capillaries, and then has to bypass another special cell type (the podocytes) that have little “feet” that wrap around the capillaries and act kind of like another layer of sieve. If the fluid makes it through these … it ends up in Bowman’s capsule and will start its journey through the nephron. The important thing to remember is that the fluid in Bowman’s capsule isn’t just water, but rather it has lots of “goodies” dissolved in it like glucose, Na + , K + , waste products, and many others. We will only discuss the movement of a select few substances through the nephron tubule. 3. How does filtration happen?
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This note was uploaded on 05/17/2010 for the course PHYSIOLOGY Phys 2130 taught by Professor Anitawoods during the Spring '10 term at University of Guelph.

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11 renal - WEEKLY THOUGHTS-MODULE 11 RENAL The kidney is my...

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