ATRIAL NATRIURETIC PEPTIDE
Which of the following inhibits aldosterone synthesis in the adrenal cortex?
| A |
Adrenocorticotropin (ACTH) |
|
| B |
Atrial natriuretic peptide (ANP) |
|
| C |
Angiotensin I |
|
| D |
Angiotensin II |
Which of the following inhibits aldosterone synthesis in the adrenal cortex?
| A |
Adrenocorticotropin (ACTH) |
|
| B |
Atrial natriuretic peptide (ANP) |
|
| C |
Angiotensin I |
|
| D |
Angiotensin II |
Cyclic GMP act on :
| A |
Insulin |
|
| B |
Thyroxin |
|
| C |
Atrial natriuretic peptide |
|
| D |
Growth harmone |
Cyclic GMP act on :
| A |
Insulin |
|
| B |
Thyroxin |
|
| C |
Atrial natriuretic peptide |
|
| D |
Growth harmone |
C i.e. Atrial natriuretic peptide
ANF is mediated by (ANF: Atrial natriuretic factor):
| A |
Inositol phosphate |
|
| B |
DAG |
|
| C |
CyAMP |
|
| D |
CyGMP |
ANF is mediated by (ANF: Atrial natriuretic factor):
| A |
Inositol phosphate |
|
| B |
DAG |
|
| C |
CyAMP |
|
| D |
CyGMP |
D i.e. CyGMP
ANP acts at the:
September 2009
| A |
Proximal tubule |
|
| B |
Distal tubule |
|
| C |
Collecting tubule |
|
| D |
Henle loop |
ANP acts at the:
September 2009
| A |
Proximal tubule |
|
| B |
Distal tubule |
|
| C |
Collecting tubule |
|
| D |
Henle loop |
Ans. C: Collecting tubule
ANP act on the collecting tubule and duct to increase Na+ excretion.
It produce this effect by dilating afferent arterioles and relaxing mesangial cells. Both of these actions increase glomerular filtration. In addition, it act on the renal tubules to inhibit Na+ reabsorption. Other actions include an increase in capillary permeability, leading to extravasation of fluid and a decline in blood pressure. In addition, it relax vascular smooth muscle in arterioles and venules. These peptides also inhibit renin secretion and counteract the pressor effects of catecholamines and angiotensin II.
In the brain, ANP is present in neurons, and an ANP-containing neural pathway projects from the anteromedial part of the hypothalamus to the areas in the lower brainstem that are concerned with neural regulation of the cardiovascular system. In general, the effects of ANP in the brain are opposite to those of angiotensin II, and ANP-containing neural circuits appear to be involved in lowering blood pressure and promoting natriuresis.
