DIGESTION IN INTESTINE AND COLON

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• DIGESTION IN INTESTINE AND COLON

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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).

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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

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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.

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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).

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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.

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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-pancrea
  semin).

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• 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.

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Bile production and bile secretion

• Secretion of bile occur all time and increase by
  influences of bile acids, cholecystokinin-pancreas
  emin, 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 cholecystokinin-pancreasemin (increase bile
  formation and ejection), secretin, gastrin.

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Composition of bile

• bilirubin,
• bile acids,
• cholesterol,
• leukocytes,
• some epitheliocytes,
• crystals of bilirubin,
• calcium.

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Composition of bile
Indexes Duodenal (?) Bladder (?) Liver (?)
Color Light-yellow Duck-brown Gold-yellow
Volume, ml 15-20 30-60 Determined of zond time
Density g/?m3 1,008-1,012 1,028-1,032 1,008-1,012
?? 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
Bile acids g/l 4-5 18-22 4-5
Cholesterol mlmol/l 1,3-2,8 5,2-15,6 1,3-2,8
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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.

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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.

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Large intestines
colon transversum
colon ascendens
colon descendens
colon sigmoideum
caecum
rectum
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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. 

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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.