Lecture 12: Renal Endocrinology Flashcards
ADH is critical for which function?
Water reabsorption
What is the pathway of ADH release?
paraventricular/supraoptic nuclei synthesizes ADH > travels though the hypothalamic hypophyseal tract > released as vesicles by the posterior pituitary > targets kidneys and arterioles
What is the pathway of ADH synthesis?
Prepropressophysin cleaved to propressophysin in hypothalamus
Travel to posterior lobe where it is cleaved to ADH > released
Very simply, what is osmolarity and how does ADH relate to it?
What is blood volume and how does ADH relate to it?
- How concentrated the ECF is. ADH wants to “dilute” concentrated blood
- How much fluid is in the ECF. Directly proportional to BP. ADH reabsorbs water to add to the blood volume if it is low
How does the hypothalamus detect body osmolarity?
How does the hypothalamus detect blood pressure?
Osmoreceptors (relays info to PVN and SON
Baroreceptors (relays info to PVN and SON via CN Ix/x
____ blood pressure, _____ arterial stretch, ______ osmolarity trigger ADH release
Low; low (due to blood volume), high
ADH secretion is most sensitive to _______ changes
Plasma osmolality (small changes affects regulation a lot compared to other variables)
What receptors does ADH bind in the arterioles?
In the kidneys?
V1
V2
What does ADH specifically do in the collecting duct that allows water reabsorption?
Increase in aq2 expression on the luminal side to let more water through
During dehydration/hyperosmolarity, what happens to …
BV
Osmolarity
Urine
Low
High, can lead to hypernatremia
Low volume and more concentrated urine (body attempts to keep as much water in)
During hypervolemia/hypoosmolarity, what happens to …
BV
Osmolarity
Urine
High
Low
High volume, diluted (body gets rid of excess water)
What is the characterizing symptom of diabetes insipidus?
Losing water/low water (polyuria, polydipsia)
Central DI vs Nephrogenic DI (causes, treatments)
- Central: no ADH so you can’t keep the water. Damage to pituitary or hypothalamus. Tx with desmopressin which inhibits water excretion
- Nephrogenic: kidney not responding to ADH so you can’t keep water. Kidney disease/damage.
How does the water deprivation test for DI work?
Patient stops drinking water but still makes high urine volume/diluted urine.
Syndrome of inappropriate ADH secretion (SIADH)
Cause
What disease is this associated with usually?
High ADH secretion leading to water retention and diluted blood
Small lung cell carcinoma
What is the main purpose of aldosterone?
Na+ reabsorption and K+ excretion (direct) Water reabsorption (indirect, water follows the salt)
What does aldosterone specifically control at the nephron tubule?
Increases expression of ATPases/channels that change the passage of K+ and Na+
What is the RAAS?
Renin-angiotensin-II-aldosterone system
Activated during conditions of low BP and BV > Na+ resorption
What does primary adrenal gland insufficiency mean?
What does secondary or tertiary adrenal gland insufficiency mean?
- Defect at Adrenal cortex leading to low aldosterone and cortisol
- Defect at pituitary or hypothalamus leading to low cortisol (area responsible for aldosterone not affected)
Myocytes produce ______ which _________
ANP and BNP; reduce workload on the heart by decreasing blood volume
What is urodilatin?
Released by the kidney at the distal tubule and collecting duct. Similar functions to ANP and BNP by inhibiting resorption at the nephron > decrease blood volume
How do natriuretic peptides regulate renal vasculature?
Goal is to excrete Na+ so increases GFR by vasodilation of afferent arterioles and vasoconstriction of efferent arterioles
What other processes control salt and water regulation?
SNS > renin > promote resorption
What effect does sodium intake have on the body?
More sodium intake = water is reabsorbed as it follows it = increases blood volume
And vice versa
