Physiology 2130 Lecture Notes - Lecture 8: Afferent Arterioles, Juxtaglomerular Cell, Renin
30 Apr 2018
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Sodium Handling
-Kidney responsible for maintaining sodium balance & can alter excretion to maintain
homeostasis
-output mostly through urine
-increased sodium = increased ECF volume = Increased BP
1. Two Hormonal systems that Regulate Na Balance
• Renin-Angiotensin Aldosterone system (RAAS)
-for when Na is low
-increases Na reabsorption
-does this by producing enzyme (renin) & two diff hormones (angiotensin 2 and
aldosterone)
➢ Renin
-made by juxtaglomerular cells of afferent arteriole when Na low
-renin cleaves angiotension (released by liver) to the non active angiotensin 1
-angiotensin 1 then cleaved again by the enzyme ACE
-ACE made in lung capillary endothelium
-once, angiotensin 1 is cleaved it is now in the active form of angiotensin 2
once we have Angiotensin2, we can react to low
NA
-Renin is the rate limiting step
-is iportat eause /o it, e o’t eer
make angiotensin 1
• Atrial Natriuretic Peptide (ANP)
-for when Na high
-functions to decrease Na reabsorption
Made by: cardiac atrial cells
Properties: peptide hormone
Stimulus: high BP
Sensors: stretch receptors (in atria)
Action: decrease Na reabsorption
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Document Summary
Kidney responsible for maintaining sodium balance & can alter excretion to maintain homeostasis. Increased sodium = increased ecf volume = increased bp: two hormonal systems that regulate na balance, renin-angiotensin aldosterone system (raas) Does this by producing enzyme (renin) & two diff hormones (angiotensin 2 and aldosterone) Made by juxtaglomerular cells of afferent arteriole when na low. Renin cleaves angiotension (released by liver) to the non active angiotensin 1. Angiotensin 1 then cleaved again by the enzyme ace. Once, angiotensin 1 is cleaved it is now in the active form of angiotensin 2. Ace made in lung capillary endothelium once we have angiotensin2, we can react to low. Is i(cid:373)porta(cid:374)t (cid:271)e(cid:272)ause (cid:449)/o it, (cid:449)e (cid:449)o(cid:374)"t e(cid:448)er make angiotensin 1: atrial natriuretic peptide (anp) Therefore, faster flow through tubule, less na can be reabsorbed. & slows filtrate travelling through fluid and allows more na to be reabsorbed.
