The mechanism that protects normal pancreas from autodigestion is: (LQ)
|A||Secretion of biocarbonate|
|B||Protease inhibitors present in plasma.|
|C||Proteolytic enzymes secreted in inactive form.|
|D||The resistance of pancreatic cells.|
- The pancreatic enzymes have the capability of digesting the pancreas itself (mainly proteases) (Auto digestion of pancreas is considered to be the main pathogenic mechanism for pancreatitis).
- Normally, auto digestion of pancreas is prevented by several means:
a. The enzymes are synthesized as inactive pro enzymes (with the exception of amylase and lipase)
b. They are sequestered in membrane bound zymogen granules in acinar cells
c. Activation of pro enzymes requires conversion of inactive trypsinogen to active trypsin by duodenal enteropeptidase.
d. Trypsin inhibitors are present within acinar and ductal secretions.
e. Intra pancreatic release of trypsin activates an enzyme or enzymes that degrades other enzymes to inert products.
f. (t) Lysosomal enzymes are capable of degrading zymogen granules when normal acinar secretion is impaired or blocked.
g. Acinar cells are remarkably resistant to the action of trypsin, chymotrypsin and phospholipase A2 .
- Regarding option 'a' pancreatic enzymes require alkaline medium for their activity so bicarbonate secretion will help in their activity.
1. Adrenal glands two parts ~Adrenal cortex and Adrenal medulla
2. Adrenal Medulla: →
a. It constitutes 28% of the mass of the Adrenal gland
b. Secretes catecholamines→eg. Epinephrine, Nor-epinephrine and Dopamine.
c. 90% of cells are epinephrine secreting type, and 10% are the norepinephrine secreting type. The type cell that secretes dopamine is unknown.
3. Adrenal cortex: -dividing into three zones (outer to inner side)
a. Zonaglomerula→15% mass of Adrenal gland, secrete Aldosterone, and not appreciably controlled by ACTH.
b. Zonafasiculata→50% mass of Adrenal gland, secrete glucocorticosteroids (cortisol), and controlled appreciably by ACTH.
c. Zonareticuaris→7% mass of Adrenal gland, secreted sex hormones [Testosterone (Andrognes) Estrogens + progestin] and controlled by ACTH. .
4. Clinical Aspect of Adrenal Glands:
a. In human, the ratio of secreted cortisol to corticosterone is approx. 7: 1
b. M.C. cause of CAR (virilization) is 21 α-hydroxylase deficiency
c. Circadian rhythm →for corticol (ACTH)
The biological clock responsible for the diurnal (circadian) ACTH rhythm is located in the suprachiasmatic nuclei of hypothalmus.→Highest cortisol (ACTH) level is in the early morning (ie. 4 to 10 AM)→Leastcortisal (ACTH) level is in the evening
d. Cushing's syndrome ~due excess of glucocorticoids (cortisol)
e. Addison's disease ~due to Adrenocortical insufficiency.