kidney 3 Hormonal control mechanisms

Question 1

What regulates water volume?

2) Rulates plasma Na+?

Answer 1

1) Vasopressin/ Antidiuretic Hormone (ADH)

2) Aldosterone

Question 2

describe direction of flow in vesa recta?

2) what is its function?

Answer 2

flows in opposite direciton to flow of loop of Henle

2) Stops concentration gradient made by loop of Henle being washed away

Question 3

results of loop of henle?

Answer 3

water lost but still dilute

Question 4

what occurs in collecting duct?

Answer 4

collecitng duct H2O permeable, water exits into interstitium = concentrated urine

Question 5

What produces ADH?

Answer 5

supraoptic and paraventricular nuclei of the hypothalamus

Question 6

Where is ADH released from?

Answer 6

posterior pituatry gland

Question 7

What causes releases of ADH?

Answer 7

increased plasma osmolarity (by even 1%) senscended by osmoreceptors in hypothalamus message sent to posterior pituatry

• decreased blood P
• decreased blood vol.

Question 8

What are the effects f ADH?

Answer 8

increases water permeability of collecting duct

• increases urea permeability in inner meddullary region of collecting duct
• increases NaCl reabsorbtion in TAL

Question 9

How does ADH act on collecting duct to produce hyperosmotic urine?

Answer 9

ADH binds to receptor on SA on basolateral SA of collecting duct

2) stimulates adenylyl cyclase = cAMP activate protein kinases
3) increases insertion of aquaporins into apical SA of CD
4) increases in water permeability thus there is more water reabsorbtion

Question 10

WHat does hyperosmotic urine mean?

Answer 10

cocentrated urine

lots of solute

Question 11

What is the effect of no ADH on collecting duct?

Answer 11

no aquaporins in apical surface thus urine is hyposmotic

Question 12

What are the effects of osmoreceptors when stimulated in their different locations + where are they ?

Answer 12

1) supraoptic & paraventricular nuclei - stimulate ADH release from posterior pituitary if water deprived , if excess fluid ingested causes ADH release suppression
2) lateral preoptic area- causes feeling of thrist

Question 13

Osmoreceptors are the main controllers of ADH, what else control them?

Answer 13

atrial natriuretic peptide (atrial stretch, ANP release = inhibits ADH)
nicotine (stimulates ADH)
alcohol (inihibits ADH)

Question 14

Where is aldosterone released from?

Answer 14

adrenal cortex

Question 15

aldosterone release is stimulated by

Answer 15

increased K+ - decreased blood pressure (via RAAS) (increased osmolarity inhibits)

Question 16

1) What are the effects of aldosterone?

2) What is the net effect?

Answer 16

• increases Na+ reabsorption in the distal tubule & CD
• increases K+ secretion in the distal tubule & CD
  2) increased blood volume and pressure

Question 17

What is the site of action of aldosterone?

Answer 17

collecting duct

Question 18

What effect does aldosterone have on the collecting duct?

Answer 18

1) binds to receptor in cytoplasm
2) initiates transcription
3) increase number of ENaCC channels in apical surface and more Na-K pumps
4) more Na+ uptaken , Cl- also as follows Na+

Question 19

What are the macula densa cells?

Answer 19

an area of closely packed specialized cells lining the wall of the distal tubule, in loop of henle, sense differences in blood flow and Na+

Question 20

What happens if there is an decrease in blood flow in afferent arteriole?
(due to hypovolemia of hypotension)

Answer 20

1) arteriole will relax as low blood pressure detected by baroreceptors leading to sympathetic stimulation= fall in tension
2) if this doesn’t increase blood flow enough macula densa cells will recognise low amounts of Na+ passing by and relase paracrine hormone to juxtaglomerular cells
3) stimulating them to release renin
4) influencing the renin-angiotensin pathway?

Question 21

What is the role of macula densa cells in the renin-angiotensin pathway?

Answer 21

1) macula densa cells detect low Na+
2) send paracrine hormone to juxtagulomerular cells
3) stimulating them to produce reninithat produce

Question 22

What is the effect of renin on the renin-angiotensin-aldosterone system?

Answer 22

activates andiotensinogen to angiotensin 1, converting enzyme in lung to angiotensin 2
stimulating release of aldosterone by adrenal cortex, increase Na+

Question 23

Why is release of ANP differenet ot aldosterone and ADH?

Answer 23

released when blood volume increases as atria stretch so release ANP

Question 24

ANP effects the hypothalamus how?

Answer 24

inhibits release of ADH

Question 25

WHat effects does ANP have on the kidney?

Answer 25

1) GFR
2) inihibition of renin
3) inhibition of NaCl and H20 reabsorbtion

Question 26

WHat is the result of ANP?

Answer 26

More NaCl- and water excreted in urine

Question 27

1) What inhibits renin release?

2) What activates renin release?

Answer 27

1)resoration of blood volume
lots of angiotensin 2
2) hypovolemia