Renin-Angiotensin-Aldosterone System

one of the many important functions of our endocrine system is to control blood asmol is to control the amount of blood volume and the blood pressure inside our vessels now one mechanism by which our body can basically increase the blood pressure when the blood pressure drops and our body is by following a pathway known as the reenan andio intens and aldosterone pathway or system and what this system basically does is it increases the blood volume it increases the blood pressure inside our blood vessels so let's discuss how this pathway actually works and let's begin by discussing a portion of the kidney known as the juxa glamer apparatus so this is basically a structure that consists of three different types of cells now two of these different types of cells are the macul densus cells and the jux GL glomerular cells and these two different types of cells basically have their own unique function so basically when our blood volume drops inside our vessels when our blood pressure drops and when the profusion rate inside our kidneys drops that simply means when the rate at which our fluid is passing through the kidneys drops this causes our macul densus cells to basically release a prostag glandon that travels to our jux the glomer cells and this causes those cells to release an enzyme called rinin now note that just the glal cells don't have to be activated they don't have to be stimulated by the macul densa to actually release rein that is they can release rein independently without being stimulated by the macula dens cells so basically this apparatus the ju the glome apparatus contain special types of cells that can sense a drop in blood volume A Drop in blood pressure and these cells release rinin into our blood system so if we take a look at the following diagram a low blood volume a low blood pressure and a low kidney profusion raate basically positively stimulates the kidneys to produce and release our rein enzyme into our bloodstream now at the same exact time the liver the cells inside the liver basically produce a zymogen enzyme known as angiotensinogen now this is released into our bloodstream and when this an angiotensinogen mixes with our rein the rein basically Cleaves this zyen at a specific location on that amino acid sequence quence and it activates the angiotensinogen into the Angiotensin one form so basically once the once in the bloodstream rein goes on to activate the zymogen angiotensinogen into Angiotensin one by cleaving it proteolytically at a specific position along the amino acid sequence angiotensinogen is produced inside our liver cells now once we activate the OT tensin one it basically goes on travels through our blood system and eventually ends up at lung cells as well as in our kidney cells and once it's found in those cells the cells basically contain a special type of enzyme known as Ace which stands for Angiotensin converting enzyme and what that enzyme basically does is it converts Angiotensin one into Angiotensin 2 by basically cleaving two residues on that particular enzyme so Angiotensin one hormone then travels to lung cells and kidney cells there an enzyme called Angiotensin converting enzyme or Ace basically transforms Angiotensin 1 into Angiotensin 2 now angion tensin 2 is basically one of the final products of this pathway because it itself can actually stimulate our blood vessels to constrict and it also stimulates the increase in our blood volume and blood pressure inside our blood vessels now the question is how exactly does it achieve this well once angot testin 2 is produced and released into our bloodstream what happens is it basically goes on to special cells inside our adrenal cortex known as the Zona glucosa and this Zone this region that contains these special types of cells basically releases our hormone known as aldosterone and aldosterone as we know from our discussion on the adrenal cortex basically causes our kidneys to become more permeable to certain ions so the rate at which sodium and the chloride increases so the rate at which these two ions travel back into the plasma increases and we excrete more pottassium and hydrogen ions and what this creates is a net movement of ions back into the blood and this forces more water to be reabsorbed by the blood so this increases the amount of blood volume inside our blood and this causes increase in our blood pressure now what the angot testin 2 also does is it basically goes on and stimulates the release of the anti diuretic hormone ADH that is stored inside the posterior pituitary gland and produced by the hypothalamus so uh ADH also known as vasopressin basically causes our kidneys to reabsorb more water it becomes more permeable to water the cell membrane and so water increases inside our blood plasma and this increases our blood pressure inside our blood vessel now Angiotensin 2 actually also constricts our blood vessels and that causes an increase inside our uh blood vessels so more specifically it causes the constriction of our arterials throughout the body as well as inside our kidneys now when our in when our blood pressure increases when our blood volume increases the increase in the blood volume can basically create a negative feedback loop and that will basically go on and cause ourin to stop being secreted by the kidneys so let's take a look at the following diagram that basically describes summarizes the reenan angot testine aldosterone system so let's suppose inside our blood we have a low volume of blood plasma we have low blood pressure and that means we have a low profusion rate inside our kidneys so this will basically cause special types of cells known as ju the glom cells inside the kidneys to release our enzyme known as rein and at the same time liver cells produce and release a zymogen known as angiotensinogen into the bloodstream and when these two mix the rein will basically cleave our angiotensinogen and form Angiotensin one now once we form Angiotensin one it will then travel into lung cells and also into kidney cells and it will be activated by using the Angiotensin converting enzyme into Angiotensin 2 and then Angiotensin 2 basically goes on to activate the ADH the vasopressin release by the posterior pituitary which causes our kidneys to become more permeable to water and reabsorb more water into our blood vessels now it also causes the release of aldosterone which basically causes our kidneys also to reabsorb more water by creating a net movement of ions back into the blood and it also constricts our arterials which increases our blood pressure so all these three effects result in an increase in blood volume increase in blood flow rate our profusion rate inside our kidney and also increase es our blood pressure and when our blood pressure increases that can basically react in a negative feedback Lube to cause our kidneys the jux the gloma cells to stop releasing renin and this is basically how we control our blood pressure inside our body this is the method by which the endocrine system can basically control the blood level the blood osmolarity as well as our blood pressure in inside our body

Channel: Andrey K

Views: 68,510

Keywords: renin-angiotensin system, renin-angiotensin-aldosterone system, renin-angiotensin pathway, renin-angiotensin-aldosterone pathway, renin, angiotensinogen, angiotensin I, angiotensin II, antidiuretic hormone, vasopressin, effects of angiotensin, blood pressure and blood volume, endocrine system, effect of renin, juxtraglomerular cells, macula densa cells, granular cells, Angiotensin

Id: NMWaKdO76NQ

Length: 9min 31sec (571 seconds)

Published: Thu Oct 09 2014