16 Homeostasis Control Of Water Potential

Question 1

Where are kidneys found

Answer 1

Two kidneys found at back of abdominal cavity

Question 2

Section thru kidney shows it’s made up of

Answer 2

Fibrous capsule: outer membrane that protects the kidney
Cortex: lighter coloured outer region made up of renal (Bowman’s) capsules, convoluted tubules and blood vessels
Medulla: darker coloured inner region made up of loops of Henle, collecting ducts and blood vessels
Renal pelvis: funnel shaped cavity that collects urine into ureter
Ureter: tube that carries urine to the bladder
Renal artery: supplies the kidney with blood from the heart via the aorta
Renal vein: returns blood to the heart via the vena cava

Question 3

Structure or kidney

Answer 3

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SEE TXTBOOK PG 131

Question 4

Region of nephron and blood vessels

Answer 4

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SEE TEXTBOOK PG 133

Question 5

Where are podocytes found

Answer 5

Inner layer of renal capsule

Question 6

Podiatry and ultrafiltration

Answer 6

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SEE TXTBOOK PG 136

Question 7

Concentration of urine produced directly related to…

Answer 7

Length of loop of henle

Question 8

Region of medulla between the two limbs

Answer 8

Interstitial region

Question 9

Channel proteins specific to water

Answer 9

Aquaporins

Question 10

Counter current multiplier of loop of henle

Answer 10

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SEE TXTBOOK PG 138

Question 11

Continuation of fall in water potential

Answer 11

ADH increases the permeability of the collecting duct to urea, which therefore passes out, further lowering water pot of fluid around duct.
Combined effect is more H2O leaves collecting duct by osmosis down water pot gradient and re-enters blood.
As reabsorbed H2O came from blood in 1st place, this will prevent water pot getting lower. Osmoreceptors send nerve impulses to thirst centre of brain, to encourage the individ to seek out and drink more water
Osmoreceptors in hypothalamus detect rise in H2O pot and send fewer impulses to pituitary gland
Pituitary gland reduces release of ADH and permeability of collecting ducts to H20 and urea reverts to its former state

Question 12

Fall in solute conc of blood raises it water pot caused by

Answer 12

Large vol of water consumed

Salts used in metabolism or excreted not ring replaced in diet

Question 13

Fall in solute conc of blood and rise in water potential response

Answer 13

Osmoreceptors in hypothalamus detect rise in H2O pot and increases the freq of nerve impulses to the pituitary gland to reduce its release of ADH
Less ADH via blood leads to decrease in permeability of collecting ducts to water and urea
Less water is reabsorbed into blood from collecting duct
More dilute urine is produced and water pot of blood falls
When water pot of blood has returned to norm osmoreceptors in hypothalamus cause pituitary to raise its ADH release back to normal levels
Negative feedback

Question 14

Regulation of water pot of blood by ADH diagram

Answer 14

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SEE TXTBOOK PG 405