Physiology - Endocrine Control of Body Fluid Volume and Composition Flashcards
Where in the nephron do hormones act?
Distal tubule and distal collecting duct
What are the 4 hormones that act on the distal tubule and collecting duct?
- ADH
- Aldosterone
- Atrial natriuretic hormone
- PTH
How does ADH work to increase water reabsorption?
What kind of urine does this result in?
Increases permeability of distal tubule/distal collecting duct to water
Hypertonic urine
What effect does dehydration have on ADH secretion?
How does this impact the urine volume and osmolarity?
What impact does ADH have on salt excretion?
Increase
Urine volume is small
Osmolarity is high
No impact
What does ADH bind to in the collecting duct/distal tubule?
Type 2-vasopressin receptor on the basal membrane of the tubular cell
Cranial DI is caused by increase/decrease of ADH?
What causes nephrogenic DI?
Decrease in ADH
Failure of kidneys to respond to ADH
When is aldosterone released?
- in what system?
- in response of increase/decrease of what ions?
In RAAS system
Increase in K+ -> acts directly on adrenal cortex to produce aldosterone
Decrease in Na+ -> causes the secretion of renin -> RAAS triggers release of aldosterone
What does aldosterone do?
What effect does this have?
Increases Na+ reabsorption and K+ secretion
Increase BP
What 3 ways can renin be triggered to be released?
- Reduced pressure in afferent arteriole
- Macula dense cells sense the NaCl in distal tubule
- Increased sympathetic activity as a result of reduced arterial BP (generally as a result of shock)
What effect does ANP (atrial natrireutic peptide) have on the kidneys?
In what circumstances is it released and where from?
Increases Na+ excretion -> decrease BP
High BP - released by atrial cells
What is the scientific name for urination?
Micturation
How does erythropoietin stimulate RBC production?
Stimulates bone marrow to produce RBC
