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
Laying down all day results in what to water balance in the body?
Body secretes water because blood that is normally pooled in the legs from gravity is now circulating. This results in the body getting rid of the excess. The person is at risk of passing out if standing up suddenly.
K+ intake is 100mmol/day
The major compartment in the body where K is found is _______
3 things cause K to move into the compartment from the previous blank
Intracellular Fluid
Insulin (quickest way to drop K), epi, aldosterone
90% of K is secreted in urine, 10% in feces
2/3 of K is reabsorbed in the PT, nothing in the descending limb, most in the ______, with essentially none excreted. ______ causes some secretion of K in the DT
Thin ascending
______ and ______ stimulate K secretion in the DT, by acting on ______ cells
Aldosterone and K+ increase K+ secretion in the DT
Principal cells
Aldosterone causes an increase in the expression of apical Na channels and an increase in expression and activity of basolateral Na/K-ATPase. Transepithelial reabsorption of Na creates a luman negative transepithelial potential, and this is what promotes secretion of K into the lumen.
Acute renal regulation of plasma Na
Increase concentration: 4 things
Decrease concentration: 2 things
Chronic regulation of plasma Na:
Increase: 1 thing
Decrease: 1 thing
Acute increase in plasma Na: Aldosterone, Angiotensin II, SNS, Blood Pressure
Acute decrease in plasma Na: ANP, Urodilatin
Chronic increase in plasma Na: aldosterone
Chronic decrease in plasma Na: ADH (major control - dilutional)
Acute renal regulation of plasma volume
increase: 1 thing
decrease: nothing
Chronic renal regulation of plasma volume
increase: nothing
decrease: 1 thing
Acute renal regulation of plasma volume
increase: ADH
decrease: nothing
Chronic renal regulation of plasma volume
increase: nothing
decrease: increased renal perfusion pressure
_____ causes release of Ca from bone
Parathyroid hormone
50-60% of plasma Ca is filtered, the rest is bound to albumin and other plasma proteins.
2/3 reabsorbed in PT via the ____ route.
Some reabsorbed in the TAL via ____ route
Distal tubule reabsorption of Ca is regulated by _____
Paracellular
Paracellular
PTH
PTH acutely and chronically ______ Ca reabsorption
_________ on _________ surface of the _____
_____ on the _________ surface of the ______
PTH also causes a decrease in _____ reabsorption
increases
Ca-ATPase on basolateral surface of DT
Na/Ca exchange on the basolateral surface of DT
PTH causes a decrease in PO4 reabsorption
Normal PCO2
Normal Bicarb
Every ____mmHg CO2 increase results in an increase of bicarb by ____mEq/L
40mmHg
26mEq/L
The first thing to help buffer pH is _______, then ______, then ______
body proteins, respiratory CO2 changes (minutes), Renal HCO3 excretion (days)
85% of bicarbonate reabsorption occurs in the ______ by ______ and _______ transporters and ______ enzyme
Proximal Tubule
Na/HCO3 symport
________ cells of the DT regulates H+ excretion
Intercalated cells, some H ATPase facing lumen, some facing blood, depending on if blood is acidic or basic
Hydrogen ATPase is on the apical surface of the ___ and ___
Urine pH can drop to _____
DT and CD
4.5 (1000 fold greater from cell to lumen - it is why you need H-ATPase)
Ammonium trapping is when NH3 leaves the DT and CD cells as NH3 and becomes NH4+ in the lumen. The charged particle can’t cross back. The NH3 in the cell is made from _______
Glutamine
3 renal responses to metabolic acidosis
- Decrease filtered load of bicarbonate (plasma bicarb low)
- Increase H secretion
- Increase NH3 production (from glutamine) to absorb H+ secreted
What % of filtered bicarbonate is excreted in a normal kidney?
0% is secreted
2 types of acids produced by the human body
volatile (co2 —> HCO3)
non-volatile (fixed acids) H + SO4 + PO4
The negative feedback process of tubuloglomerular feedback helps maintain constant delivery of ______ to the distal tubule
NaCl
