2020 unified

Question 1

describe how the endocrine and nervous system work together to increase water reabsorption from the collecting duct

Aldosterone:
* sodium ions pumped out of collecting duct cells (into
tissue fluid) (and potassium ions pumped in)
* lowers water potential in tissue fluid
* concentration gradient established
* sodium ions reabsorbed from the collecting duct lumen
* water diffuses into collecting duct cells / out of lumen via
osmosis.

Answer 1

endocrine system:
-hypothalamus causes release of ADH from pituitary
-aldosterone released from adrenal cortex
-ADH binds to receptors on the cell membranes of collecting ducts, this increases the permeability to water (regulated by aquaporins)

Nervous system
- hypothalamus is part of the nervous system
-osmoreceptors in the hypothalamus detect a low water potential in the blood
-ADH is produced in the hypothalamus
-posterior pituitary is an extension of the hypothalamus
-negative feedback

Aldosterone
- sodium ions pumped out of the collecting duct cells into tissue fluid and potassium ions are pumped in
-lowers water potential in tissue fluid
-conc grad estblished
-sodium ions reabsorbed
-water diffuses into collecting duct cells
-osmosis

Question 2

what is the function of distal convoluted tubules

Answer 2

reabsorption of ions