- concentrate urine if animal is dehydrated
- produce a higher volume of more dilute urine to excrete excess water
3 of 15
Which hormone regulates sensible water loss?
ADH (Antidiuretic Hormone)
4 of 15
How is secretion of ADH regulated?
- osmolarity monitored by osmoreceptors in the hypothalamus- increase firing in response to increased osmolarity
- increased osmolarity = increased ADH release
5 of 15
Describe ADH
- made in hypothalamus
- secreted from posterior pituitary gland
- regulates sensible water loss
- increases permeability of collecting duct to water by promoting the insertion of aquaporins into principle cells to allow more reabsorption of water
- regul
6 of 15
Apart from detecting plasma osmolarity, what else do osmoreceptors do?
control thirst
- when osmolarity is increased by approx. 3% the thirst centre is stimulated
7 of 15
What is ADH stimulated by?
- small changes in plasma osmolarity
- large changes in blood volume
8 of 15
Name the major ion in ECF
Na+
9 of 15
How is the concentration of Na+ regulated?
- no receptor for Na+ concentration
- all ingested Na+ is absorbed
- kidneys regulate ECF volume by adjusting excretion of Na+ (water follows Na)
- regulation for Na+ is dependent upon receptors for BP + blood volume
10 of 15
How is blood volume monitored?
stretch sensitive nerve endings in atria + veins
11 of 15
How is blood pressure monitored?
baroreceptors detect changes in arterial pressure
12 of 15
Name the 3 hormones that regulate renal Na+ and Cl- reabsorption/ excretion
Describe the homeostatic mechanisms that work together to correct dehydration
- reduced blood pressure activates ANS = release of angiotensin II
- reduced GFR
- increase ADH
- increase in concentration of urine
- increase in reabsorption of Na+
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