Ch20 Flashcards
What is diuresis?
Urination
What is nocturnal enuresis indicative of?
Insufficient ADH
What part of the nephron does ADH act on?
Collecting duct
In the absence of ADH is urine dilute or concentrated?
Dilute
How does vasopressin elicit a response?
Binds to membrane receptor on basolateral side of collecting duct epithelium. Receptor activates cAMP second messenger system and AQP2 is inserted into apical membrane
Does increasing plasma OsM induce or inhibit ADH secretion?
Induce
What ion transporter is in the ascending loop of Henle?
NKCC
Transports Na+, K+, 2Cl-
What is the primary action of aldosterone?
Renal sodium reabsorption
How does aldosterone elicit a response? In what cell type?
After binding to the intracellular receptor in the P cell, new protein channels and pumps are made and inserted into the membrane. On the apical side these channels and pumps reabsorb Na+ and secrete K+. On the basolateral side new Na+,K+ ATPases push Na+ into the blood and pull K+ from the blood.
On existing channels and pumps aldosterone increases efficiency
What 3 stimuli regulate aldosterone release? Which is the primary?
- Hyperkalemia stimulate aldosterone secretion
- Increased osmolarity inhibits aldosterone secretion
- Tropic effect of ANG II (primary control)
Where is angiotensinogen produced? What stimulates it?
Made in the liver
No stimulus needed, constitutively produces
What enzyme converts angiotensinogen into ANG I? Where is it made and what stimulates it?
Low BP stimulates the JG cells to make the enzyme renin
What converts ANG I into ANG II? Where is it made?
ACE (angiotensin converting enzyme) is made by the endothelium in the lungs
What is the effect of ANG II on the arterioles?
Vasoconstriction
What is the effect of ANG II on the CVCC?
Increased cardiac response (higher CO)
What is the effect of ANG II on the hypothalamus?
Release of vasopressin
Increase in thirst
What is the effect of ANG II on the adrenal cortex?
Release of aldosterone to increase Na+ resorption (and hence water resorption)
What cardiac hormone is antagonistic to the RAAS pathway?
Atrial natriuretic peptide (ANP)
What stimulates ANP secretion and from where?
Stretch receptors in the atria when BP is too high
What does ANP do and how?
It lowers BP by
1. Increasing GFR by making more available surface area for filtration (idk how)
2. Decreases NaCl and water reabsorption in the collecting duct
3. ANP inhibits renin, aldosterone, and ADH release
4. Stimulates parasympathetic system
Net result is increase naturesis and diuresis
Does acidosis result in neuron hyperexcitability or hypoexcitability? Alkalosis?
Acidosis: Hypoexcitability
Alkalosis: hyperexcitability
What is the first line of defense against pH changes?
Buffers (HCO3-)
What 2 ways is HCO3- reabsorption regulated in the proximal tubule?
- H+ is combined with HCO3- in the lumen, forming CO2 that diffuses into the epithelial cell. The CO2 is again separated into H+ and HCO3-. The luminal Na+ and cellular H+ are exchanged. The ceullar Na+ and cellular HCO3- are both delivered to the blood.
- Glutamine is metabolized in the epithelium into NH4+ and aKG. The NH4+ is exchanged for luminal Na+. The cellular HCO3- gradient is used to pump HCO3- and Na+ into the blood
What cell type functions in resolving acidosis?
Type A
