Some renal phys Flashcards
How much C.O. do the kidneys receive?
20-25%
What is the functional unit of the kidney?
nephron
(1 million/kidney)
What are the main parts of a nephron?
Glomerulus / bowman’s capsule
Proximal convoluted tubule (PCT)
Loop of Henle - Ascending and descending
Distal convoluted tubule (DCT)
Collecting duct
Which type of nephron has the most control in regulating the concentration of urine?
juxtamedullary
After the renal artery, what arteries does the blood flow through?
Renal A –> lobar A –> segmental A –> interlobar A –> Arcuate A –> Interlobular A –> Afferent arterioles
What do afferent arterioles lead to?
Glomerulus
How does blood leave the glomerulus?
Efferent artery –> peritubular capillaries –> vasa recta
Which vessels have the greatest control over glomerular pressure?
afferent/efferent arterioles
Do glomerular capillaries have high or low pressure?
high
do peritubular capillaries have high or low pressure?
low
what happens at the glomerulus?
(options for these questions: filtration, H20 reabsorption, solute reabsorption, secretion)
filtration
Is there active or passive transport at the glomerulus?
passive
At the glomerulus, can cells and proteins get through?
No - too big
How much does the glomerulus filter per day? per minute?
180 L/day
1.2 L/min
How is GFR regulated extrinsically? (2 mechanisms)
- by sympathetic nerves in eff/aff arterioles
(e. g. baroreceptor reflex - if blood pressure is low, afferent arteriole will constrict to increase renal pressure) - by hormonal control of RAA axis
(e. g. if blood pressure is low, renin is released to increase pressure)
There are 3 other hormones that regulate GFR. What are they and what do they do? (“the 3 A’s”)
ADH: retains h20
Aldosterone: reasborbs Na
ANP: the opposite. inhibits Na/H20 reabsorption but promotes their secretion; inhibits ADH secretion
How if GFR regulated intrinsically? (2 mechanisms)
-
myogenic mechanism
(e. g. aff/eff arterioles measure passive stretch and adjust BP to maintain their normal stretch) -
tubuloglomerular feedback
(e. g. macula densa senses total solute concentration, and adjusts afferent arteriole constriction/dilation to all more/less filtrate to pass)
Where is renin released from?
granular cells
What structure tells granular cells to release renin?
macula densa
(tubuloglomerular feedback)
Renin causes vasoconstriction, but what other hormone does it signal?
What does that hormone do?
aldosterone
retains Na in the body (to also retain H20)
What other chemical can the macula densa have released?
What do these do?
releases PGE2, NO
these tell afferent arteriole to dilate
(would be released with low solute concentration)
If GFR is low, will you have constriction or dilation
1) at the afferent arteriole
2) at the efferent arteriole
afferent: constricts
efferent: dilates