Lecture 12 - Renal Part 2 Flashcards
Where is 65% of all filtrate reabsorbed?
Proximal convoluted tubule
Where is most sodium actively reabsorbed?
Thick ascending limb
Where is most sodium passively reabsorbed?
Thin loop of henle
What is the macula densa?
Part pressed against the afferent and efferent arteriole
- connects them to determine regulation
- creates the juxtaglomerular apparatus
What is the juxtaglomerular apparatus?
detects how much sodium is being reabsorbed and how much is being excreted
How is Angiotensin 2 created?
Angiotensinogen (Renin substrate) binds with renin which is a key regulatory step
- this turns into angiotensin 1 which is the inactive form. and combines with a converting enzyme to become angiotensin 2 which is the active form
What does Angiotensin 2 do?
Stimulates sodium reabsorption and vasoconstriction
- also stimulates the release of aldosterone
- also controls potassium excretion
What is the effect of Angiotensin 2 on the body?
Raises BP by increasing the total peripheral resistance
- Regulated by the release of renin from the kidneys
Where do steroids come from?
Cholesterol molecules
What does aldosterone control?
Plasma potassium concentration and increases sodium reabsorption through the use of channels
How does countercurrent exchange control sodium chloride excretion?
Blood flows in one direction while the tubular fluid flows in the opposite direction
- this increases the excretion of NaCl
How is bicarbonate reabsorbed in the B-cells of the kidney?
Bicarbonate is exchanged for Cl-
- helps to maintain the acid-base balance
How does ADH regulate the total body water?
ADH is secreted from the posterior pituitary which increases water permeability into the collecting duct
- V2 receptors are stimulated which increases water absorption
If free water clearance is a negative value…
then the kidneys are returning “free” water to the plasma
If free water clearance is a positive value…
then the kidneys are removing “free” water from the plasma
