7

Question 1

Bile juice ………normally secrete…………

Answer 1

The liver cells normally secrete 600-1000 ml/day of
bile.

Question 2

Functions of bile:

Answer 2

1. Bile plays an important role in fat digestion and
   absorption, because the bile acids in the bile:
   (i) help to emulsify the large fat particles of the food
   into many minute particles (detergent action), the surface of which can then be attacked by lipase enzymes secreted in pancreatic juice.
   (ii) aid in absorption of the digested fat end products
   through the intestinal mucosal membrane by forming
   micelles.
2. Bile serves as a means for excretion of several important
   waste products from the blood. These especially include bilirubin, and excesses of cholesterol.

Question 3

Bile is secreted in two stages by the liver:

Answer 3

(1) The initial portion is secreted by the hepatocytes.
It contains large amounts of bile acids, cholesterol, and other organic constituents. This secretion is stimulated by parasympathetic nervous system (via vagus nerve) and also by bile salts.

(2) In its course through the bile ducts, a second portion of liver secretion is added to the initial bile. This secretion is a watery solution of Na+ and HCO ions secreted by secretory epithelial cells that line the ductules and ducts
• The second secretion is stimulated especially by
secretin hormone, release of additional
quantities of HCO 3 - ions to supplement the HCO
ions in pancreatic secretion

Question 4

Storing and Concentrating Bile in the Gallbladder (GB).

Answer 4

The maximum volume of bile that the GB can hold
is only 30-60 ml.
Water, Na+, cl-, and most other small electrolytes
are continually absorbed through the GB mucosa,
concentrating the remaining bile constituents that
contain the bile salts, cholesterol, lecithin and
bilirubin. -N.B. Bile is concentrated Up to 15 times in GB.

Question 5

Enterohepatic Circulation of Bile Salts

Answer 5

About 94 % of the bile salts are reabsorbed into the
blood from the small intestine.
 They then enter the portal blood and pass back to
the liver.

Question 6

i. Bile salts are the best ………….. substance

Answer 6

choleretic substance
(stimulate hepatocytes).

Question 7

Secretin hormone stimulate the

Answer 7

ductular secretion
of bile.

Question 8

The bile acids are mainly

Answer 8

cholic acid &
chenodeoxycholic acid. They are synthesized from
cholesterol (either from diet or synthesized in the
liver cells).

Question 9

Emptying of the Gallbladder

Answer 9

1-Nervous:
Vagal stimulation causes weak contraction of GB
& relaxation of sphincter of Oddi.
The intestinal enteric nervous system (like vagus
2. Hormonal (CCK):
 Causes contraction of the GB & relaxation of the
sphincter of Oddi.
 CCK is secreted from the duodenal mucosa in
response to the presence of fatty foods in the
duodenum.