5.1 Plasma Osmolarity

Question 1

What is the normal urinary osmolarity?

Answer 1

500-700 mOsm/L

Question 2

What detects osmolarity in the blood?

Answer 2

Hypothalamic osmoreceptors

Question 3

What two ways does the body start osmolarity change?

Answer 3

Thirst receptors

ADH

Question 4

Where are osmoreceptors found?

Answer 4

OVLT in hypothalamus

Anterior and ventral to third ventricle

Question 5

What are the actions of ADH?

Answer 5

Increases permeability of the collecting duct to urea and water
Inhibits reabsorption of Na+ in the late DCT

Question 6

How is osmolarity increased?

Answer 6

Limit water uptake
Loss of large amount of hyposmotic urine
Reabsorb Na+ ions

Question 7

What channels does ADH stimulate to be added into the collecting duct membrane?

Answer 7

Aquaporin 2

Question 8

What is diabetes insipidus?

Answer 8

Not enough ADH produced in the pituitary so water is inadequately reabsorbed. Large volumes of urine

Question 9

What is SIADH?

Answer 9

Significant release of ADH from the pituitary