6

Question 1

Pancreatic secretion

Volume، pH، Composition

Answer 1

Volume : 1- 2 L /day.
pH : alkaline 8.3 (due to NaHco 3).
Composition:
1. Ductular secretion: consists of
- Water 98.3 %.
- Inorganic substance (HCO3-) 1 %.
2. Acinar secretion (organic) 0.5% consists of enzymes which are:

Question 2

Proteolytic enzymes of Acinar secretion

Answer 2

Trypsinogen endopeptidases
, II. Chymotrypsinogen: Endopeptidase
III. Proelastase endopeptidases
IV. Erypsins exopeptidases
V. Ribonucleases &Deoxyribonucleases

Question 3

Trypsinogen
- is activated to trypsin by …………….. secreted who from the intestinal mucosa.
- Trypsin also activates trypsinogen
(autoactivation). - It hydrolyses proteins into…………. ,………….,……..

Answer 3

enterokinase enzyme
hydrolyses proteins into proteoses,
peptones and polypeptides.

Question 4

Erypsins, Proelastase Chymotrypsinogen activated to by

Answer 4

trypsin

Question 5

Pancreatic amylase: Acts on……

Answer 5

Acts on cooked & uncooked
starch.

It acts in alkaline medium of the
small intestine.

Question 6

Lipolytic enzymes:

Answer 6

1. Pancreatic lipase:it hydrolyses fats into F.A. & glycerol.
   - Its action is increased by bile salts which:
   ~ Emulsificates fats.
   ~ Activates lipase enzyme.
   ~ Dissolve away the digested fats and
   helps its absorption (by forming micelles
2. Prophospholipase: Activated by trypsin into phospholipase A.
   - Changes lecithicin into lysolecithicin.
3. Esterase: - It hydrolyses cholesterol esters into free
   cholesterol

Question 7

Regulation of
pancreatic secretion:

Answer 7

1- Nervous regulation: Vagus nerve
- During the cephalic and gastric phase of gastric secretion.
2- Hormonal:
- Secretin (aqueous secretion ).
- Cholecystokinin (enzymatic
secretion)

Question 8

Mechanism of pancreatic secretion:

Answer 8

A. Nervous (vagus):
- Conditioned.
- Unconditioned The juice secreted is small in volume, poor in alkalies & rich in enzymes.
B. Hormonal: (more important)
1. Secretin H.
- Is released from the mucosa of
the upper part of the small intestine due to contact of HCl with it.
- It stimulates the ductular secretion
(increase cAMP)
- The juice secreted is large in
volume, poor in enzymes & rich in alkalies.

2. Pancreozymin cholecystokinin (CCK):
   
   • Is released from the mucosa of the upper part of the small intestine due to contact digestive products of protein & fats with it.
     - It increases the acinar secretion (increases cGMP & Ca2+).
     - The juice secreted (like vagus).

Question 9

Other functions of:

Secretin, CCK

Answer 9

A. Secretin:
1. Increase Bile flow.
2. Stimulation of insulin secretion.
3. Stimulation of intestinal movements.
4. Decrease Gastric acid secretion & motility.
CCK:
1. Contraction of G.B.
2. Stimulation of glucagon secretion
3. Stimulation of intestinal motility.
4. Inhibition of gastric acid secretion & motility.