Lect 6 - Block 3 - Tubuloglomerular Feedback Flashcards
The macula dense is found in the _______ and is part of the juxtaglomerular apparatus
Distal tubule
If distal tubule NaCl delivery fails (lower GFR), 3 things happen to compensate
Dilate afferent
Constrict efferent
Release renin
Nephron GFR is regulated by what
It’s own juxtaglomerular apparatus. Each nephron regulates it’s own function
Renin release causes intrarenal formation of ________. This acts more on the ______ arteriole.
Angiotensin II
Efferent arteriole
GFR decreases, flow through tubule decreases, flow past macula dense decreases…
This causes 2 things that increase GFR
Release of renin, forming angiotensin II, by macula densa (JG cells) constricting efferent arteriole
Paracrine signals from macula dense to dilate afferent arteriole
Increased Na intake results in increased blood flow to this part of huge kidney
Cortex
________ preferentially dilates juxtamedullary nephrons. In diseased kidneys with low blood flow, this is important to ________ salt and water.
Prostaglandins
Blocking prostaglandin production in individuals with impaired renal function may cause a further decrease in renal function
Blocking prostaglandin production in individuals with impaired renal function may cause a further decrease in renal function.
What drug class does this?NSAIDs
Almost all Na in the body is in the ______ cellular space
Urinary Na regulation is where most of an control happens for body Na levels
120mmol/day (intake & excretion)
Extracellular space
2/3 of Na is reabsorbed in huge PT, more is reabsorbed in huge _____ by _______. The rest is reabsorbed by the DT and CD, dropping excreted amount to 1%
Thick ascending limb of hone loop of Henle, by NaK2Cl transporters
_______ cells (Lacis cells) can contract, causing a ______ in GFR, reducing amount of Na excreted.
2 agents that increase permeability _____ and _____
2 agents that decrease permeability _____ and _____
Mesangial cells contract, decreasing GFR
Increase permeability: ANP, NO (increase GFR)
Decrease permeability: norepi, epi, ADH
An increase in GFR causes an increase in protein concentration in the peritubular capillaries, increasing the reabsorption of fluid. This is called __________ _______
Glomerulotubular balance
Renal sympathetic nerves:
- directly contract _______, _____ GFR
- Cause release of renin, leading to formation of angiotensin II
- Norepi and angiotensin II increase Na reabsorption at the _______ _______. They act synergistically.
- _____ causes contraction of the glomerular capillary cells, which decreases permeability of glomerular capillaries and decreases GFR
- Contract afferent arteriole.e, decreasing GFR
2. - Proximal tubule cells
- Norepi
_______ increases Na reabsorption in the distal tubule
Its release is stimulated by an increase in plasma ______ levels and also by the hormone _____
Aldosterone
K levels and angiotensin II causes release of aldosterone
It acts on the electrogenic reabsorption channels in the distal tubule on the apical surface
ANP/urodilatin acts on ____ (part of nephron) to _____ Na reabsorption
It works through cyclic _____
Collecting duct, to decrease Na reabsorption
Cyclic GMP to decrease the entry of Na through channels in the medullary collecting duct
Angiotensin II increases Na reabsorption by:
- It is one of the stimuli causing release of ________
- A2 ________ the glomerular cap. cells, _______ glomerular cap. permeability, causing a ____ in GFR
- Constricts the ____ arteriole, and ________ the filtration fraction, enhancing the reabsorption of Na and water in the ________ capillaries, which decreases Na excretion
- aldosterone (Na retaining hormone)
- A2 contracts the glomerular cap cells, decreases glomerular cap perm, causing a decrease in GFR