Transcript Digestion in intestine and colon

• DIGESTION IN INTESTINE AND
COLON
Role of pancreas in the digestive
system
• There are two secretor functions of
pancreas – external and internal. The
external secretor function of pancreas
means that exsogenic cells of pancreas
and ducts cells produce pancreatic
juice. It helps to hydrolyzed protein to
peptides
and
amino
acids,
carbohydrates to monosaccharide, lipids
to the fat acids and glycerin. It
neutralizes acidic chyme, which come
from stomach.
• Internal secretor function of pancreas is
production
of
hormones
(insulin,
glucagon, somatostatin).
Composition and properties of
pancreatic juice
• Quantity of pancreatic juice per day is
1,5-2,0 L, pH is 8,0-8,5. It consists of a
big quantity of hydro carbonates. It has
near 10 % of protein – enzymes, which
are act on protein, lipids and
carbohydrates. According to that there are
3 groups of enzymes: proteolytic
•
lipolytic
•
amylolytic
Proteolytic enzymes
• Proteolytic enzymes: trypsinogen,
chymotrypsinogen, and
procarboxypolypeptidase, proelastase.
• Trypsinogen activated by enzymes
enterokinase (produces by the mucous
cells of duodenum).
• In pancreatic juice presents proteolytic
enzymes – elastases, nucleases etc. They
hydrolyzed protein to peptides and amino
acids.
Lipolytic enzymes
• The main enzymes for fat digestion (lipolytic
enzymes) are pancreatic lipase, which is capable of
hydrolyzing neutral fat into fatty acids and
monoglycerides; cholesterol esterase, which
causes hydrolysis of cholesterol esters; and
phospholipase, which splits fatty acids from
phospholipids.
• Lipolytic enzymes ejected in active (pancreatic
lipase,
muntinase)
and
inactive
conditions
(prophospholipase A).
Amylolytic enzymes
• The pancreatic digestive enzyme for
carbohydrates (amylolytic enzyme) is
alpha-amylase, which hydrolyzes
starches, glycogen, and most other
carbohydrates (except cellulose) to
form disaccharides, a few three
saccharides and very small glucose
polymers.
Regulation of pancreas secretion
• There are 3 phases of pancreatic secretion:
cephalic, stomach and intestine.
• The 1 stage caused by nervous influences.
N. vagus realizes this effect by helps of
conditioned and unconditioned reflexes.
Secretion begins after 1-2 minutes of food.
Juice consists of enzymes, small quantity of
water and ions. Sympathetic influences have
a trophy role.
• During the 2 phase there are two kinds of
influences: nervous and humoral (gastrin
from stomach).
• The 3 phase caused by chyme contents. The
main
is
humoral
factors
(secretin,
cholecystokinin-pancreasemin).
• Secretin stimulates production of a big
quantity of juice with a high concentration of
hydro carbonates and a small quantity of
enzymes in ducts cells. CKP stimulates
production of a less quantity of juice with a
big concentration of enzymes in acinars cells.
• Secretion of pancreatic juice stimulates also
by vaso-intestinal polypeptide, serotonin,
insulin, bombesin, substance P, calcium ions,
and salts of bile acids.
• Secretion of pancreatic juice inhibits by
glucagon, calcitonin, somatostatin. During
dreams, hart physical and mental activity,
pain secretion inhibits too.
Bile production and bile
secretion
• Secretion of bile occur all time and
increase by influences of bile acids,
cholecystokinin-pancreasemin, secretin.
• Bile secretion in the duodenum depends
from take food (minerals water, HCl, fatty
acids increase bile formation).
• It depends of nerves vagus (increase bile
formation) and humoral influences –
concentration of cholecystokininpancreasemin (increase bile formation and
ejection), secretin, gastrin.
Composition of bile:
• bilirubin,
• bile acids,
• cholesterol,
• leukocytes,
• some epitheliocytes,
• crystals of bilirubin,
• calcium.
Composition of bile
Indexes
Duodenal (А)
Bladder
(В)
Liver (С)
Color
Light-yellow
Duckbrown
Gold-yellow
15-20
30-60
Determined
of zond time
1,008-1,012
1,0281,032
1,008-1,012
рН
7,0-7,5
6,5-7,5
7,5-8,5
Bilirubin
mlmol/l
0,5-1,0
1,7-3,4
0,5-1,0
4-5
18-22
4-5
1,3-2,8
5,2-15,6
1,3-2,8
Volume, ml
Density g/сm3
Bile acids g/l
Cholesterol
mlmol/l
The role of bile
• 1. Neutralize the stomach acid;
• 2. Inhibit the act of stomach proteases;
• 3. Increase the activity of pancreatic lipase;
• 4. Emulsifiers the lipids by help of bile acids
actions;
• 5. Bile acids help stabilizing of emulsion;
• 6. Increase the absorption of fatty acids,
carrotin, vitamins K, D, E;
• 7. Increase tone and motor function of intestines
(more duodenum and large intestine);
• 8. Decrease the activity of intestine micro flora;
• 9. Take place of enzymes fixation on the
intestines surface.
Composition and properties of intestine
juice
• Composition of intestine juice:
• mucine, enzymes – peptidase, saccharase,
maltase, lactase, lipase, phosphatase,
nuclease; immunoglobulins; ions;
leukocytes; epitheliocytes (200 g per day).
• pH of intestine juice is 7,5-8,0; production
per day – near 1,8-2,5 L.
• Functions:
ending hydrolyses of all
nutritive substances; protective of mucus
wall; support of chyme in fluid condition;
formed of base reaction of intestine contents.
Increase secretion: parasympathetic
nerves, secretine, and glucagons.
Large intestines
colon ascendens
colon transversum
colon descendens
colon
sigmoideum
caecum
rectum
Digestion in the large
intestine
• Composition of intestine juice: mucus,
epithelial cells, and small quantity of
enzymes (peptidase, lipase, nuclease,
phosphatase).
• Functions:
protective from
mechanical,
• chemical irritations;
• formed of base reaction of intestine
contents.
Role of the micro flora of
large intestine
• 1. Ending decompose of all nutritive substances,
which are do not digested in small intestines.
• 2. Synthesis of some vitamins – of B group,
vitamin K.
• 3. Take place in metabolic processes.
• 4. Stimulates absorption of water and amino
acids.
• 5. Inactivate enzymes of small intestines.
• 6. Forms normal reaction in large intestine.
• 7. Decompose organic substances of chyme.
• 8. Have protective role to the pathogenic
microorganisms.