its all about gastroiuntestinal

1. Digestive physiology (2)
Topic name: Digestion in the stomach, the value of
gastric acid hydrochloric acid. Digestion in the
intestines. Motility of the gastrointestinal tract.
Lecture plan:
1. Digestion in the stomach. Composition and properties of gastric juice.
2. Regulation of gastric secretion. Phases of gastric secretion.
3. Digestion in the small intestine:
a) pancreatic juice, composition and properties
b) secretion of pancreatic juice, its phases.
c) bile, composition, importance in digestion processes.
d) digestion in the small intestine. Intestinal juice and composition
e) cavity and parietal digestion.
4. Intestinal motility. Types of movements. Regulation of motility.
Translated by Darya Goryacheva, assistant of the Department of Physiology norms

2. Digestion in the stomach
• Food mixed with saliva is
retained in the stomach
from 3 to 10 hours for
mechanical and chemical
processing
Food in the
stomach
Prepyloric
sphincter
Food lump
Pyloric
sphincter
Food is in
the pyloric
part
Passage of food
into the
duodenum
Food is in the
duodenum
Further food
promotion

3. Stomach functions
1. Secretory.
2. Motor.
3. Suction.
4. Excretory: the release of metabolites into the gastric cavity.
5. Endocrine: the formation of gastrointestinal hormones (GIH).
6. Protective.

4. • Secretory activity is carried out by the glands of the stomach,
represented by 3 types of cells:
1) the main glandulocytes, producing the enzymes pepsinogen;
2) lining (parietal) - hydrochloric acid;
3) additional - mucin.

5. • A person secretes 2.0-2.5 liters of gastric juice per day - it is a
colorless transparent liquid.
• The specific gravity is 1.002-1.007.
• Osmotic pressure - 300 mosm / l (7.5 atm).
• pH - 0.8 - 1.5, contains hydrochloric acid - 0.3-0.5%

6. Н2О – 99,0-99,5% Dry residue - 1.0-0.5%
Organic substances Inorganic substances
1. Enzymes: Actions Chlorides, sulfates,
phosphates,
bicarbonates: sodium,
potassium, calcium,
magnesium.
- pepsin A Protein hydrolysis at pH 1.5-2
- gastrixin (pepsin C) Optimum action at pH 3.2-3.5
- pepsin B (parapepsin or
gelatinase)
Breaks down connective tissue
proteins
- rennin (pepsin D or chymosin) Convert milk caseinogen to casein in
the presence of Ca ++ ions
- gastric lipase Break down emulsified fats (milk fats)
into glycerin and fatty acids
Gastric juice composition

7. Organic substances
Actions
2. Lysozyme (muramidase) Antibacterial action
3. Castle factor - gastromucoprotein (mucin) 1. Protects the mucous membrane from
mechanical and chemical irritants (HCl action).
2. Essential for the absorption of vitamin B12.
4. Ureaza Breaks down urea
5. Uric acid, urea, lactic acid, amino acids,
polypeptides

8. Regulation of gastric secretion
• Nervous and humoral mechanisms
are involved in the regulation of the
secretory activity of the gastric
glands.
• The functions of the stomach are
stimulated by the vagus nerve. The
sympathetic nerves have an
inhibitory effect.

9. Humoral factors are:
1. Gastrin.
2. Histamine.
3. Bombesin.
4. Motilin et al. GIG.
5. Hydrolysis products of proteins, fats, etc.

10. Phases of gastric secretion
III. Intestinal: when food passes into the intestines. Stimulants
of gastric secretion: enterogastrin, bombesin, protein hydrolysis
products, extractive substances.
I. Complex reflex - cerebral
Conditioned reflex Unconditioned reflex
II. Gastric (neurohumoral)
Mechanical Humoral (gastrin, histamine,
bombesin, "fed blood“)

11. The function of the stomach is inhibited by:
1. Gastron, enterogastron.
2. Somatostatin.
3. VIP is a vasoactive intestinal peptide.
4. Cholecystokinin-pancreozymin.
5. GCP is a gastrointestinal peptide.
6. Glucagon.
7. Fat metabolism products.

12. Digestion in the small intestine
1. The small intestine exceeds the length of the human body by 4-5 times
and is divided into 3 sections:
1) 1 duodenum,
2) jejunum,
3) ileum.
2. In the small intestine, cavity and parietal digestion are distinguished.
3. The hydrolysis of nutrients in the duodenum occurs under the influence
of enzymes contained in pancreatic juice, intestinal juice and bile.
• The residence time of food chyme in the intestine is 10-12 hours.

13. Composition and properties of pancreatic juice
• The juice is a colorless liquid.
• Specific gravity 1.007-1.009.
• pH - 7.8-8.4 (alkaline reaction - the presence of bicarbonates).
• 1.5-2.0 liters are allocated per day.
Water – 99% Dry residue - 1%
Organic substances Inorganic substances

14. Organic substances Inorganic substances
1.Protease enzymes break down proteins
• Trypsinogen enterokinase intestinal juice trypsin
• Chymotrypsinogen trypsin chymotrypsin
• Carboxypeptidase (A, B)
• Elastase
• Ribonuclease
Cations:
Na +, Ca 2+, K +, Mg2 +
Anions:
Cl -, HCO3-, HPO4
2. Lipase - hydrolysis of emulsified fats in the presence of bile acids, Ca
++ salts
3. Hydrolytic enzymes - hydrolysis of carbohydrates to di- and
monosaccharides.
-amylase
maltase
lactase
Mucous substances

15. Secretion of pancreatic juice, its phases
• The secretion of the pancreatic gland increases 2-3 minutes after eating and
lasts 6-14 hours.
2 phases of pancreatic secretion:
I. Complex reflex phase
Conditioned reflex
II. Humoral-chemical phase
Occurs under the influence of the GIH
Unconditioned reflex

16. • Enhances juice secretion:
Prosecretin HCl Secretin
Pancreoimin-cholecystokinin
Bombesin, gastrin, insulin
• These substances are inhibit the secretion:
Glucagon, calcitonin, gastric inhibitory peptide, vasoactive intestinal
peptide, somatostatin.

17. Bile, its meaning
• Bile is formed in the liver continuously, and enters the duodenum
during digestion. Outside of digestion, bile accumulates in the
gallbladder.
• Distinguish between cystic and hepatic bile.

18. Bile composition • 500-1500 ml of bile is formed per day.
• pH of gallbladder bile - 6.0-7.0
• pH - hepatic bile - 7.3-8.0
• Specific gravity - 1.008-1.015
• Water - 86.6-97.4%
• Dry residue:
Organic substances Inorganic
substances
1. Bile pigments: bilirubin, biliverdin
2. Bile acids and their salts: taurocholic - 20%,
glycocholic - 80%
3. Cholesterol.
4. Mucin.
5. Fatty acids, lipids.
Na+, Fe2+, Mg2+, K+,
Ca2+, anions Cl-,
HCO3
-.

19. The role of bile in digestion
1. Activates pancreatic, intestinal lipase, as well as other enzymes of
pancreatic juice, increases its secretion.
2. Emulsifies fats.
3. Promotes the absorption of fatty acids and glycerin in the form of
micelles.
4. Inactivates pepsin.
5. Strengthens intestinal motility.
6. Participates in the formation of feces.
7. Participates in the absorption of fat-soluble vitamins, cholesterol,
calcium salts.
8. Bactericidal action.

20. • Bile secretion occurs conditionally and unconditionally reflexively.
• Bile secretion is stimulated by: bile acids, gastrin, secretin, bombesin
• Bile secretion is Inhibited by: glucagon, calcitonin, vasoactive
intestinal peptide

21. Digestion in the small intestine
• Intestinal juice composition
 The color is yellowish with a specific odor.
 pH - 7.2-7.5, reaches 8.6-9.0
 Water - 98% Dry residue - 2%
• Organic substances, includes more than 20 enzymes that complete the
hydrolysis of food substances.
1. Proteases: enterokinase, polypeptidase, aminopeptidase, nucleidease.
2. Hydrolysis of disaccharides is carried out by maltase, lactase, sucrase - only in the
small intestine.
3. Lipase, phospholipase, phosphatase.
4. Mucin.
• Inorganic substances: 1% mineral salts K+, Na+, Ca2+, chlorides,
bicarbonates

22. Intestinal juice production
• In the intestinal secretion, the 1st phase is neurohumoral
• Food irritates mechano- and chemoreceptors and, with the
participation of the intramural nervous system, reflexively increases
the secretion of juice

23. Parietal digestion
Discovered by Ugolev A.
• In the small intestine, large-
molecular substances are
hydrolyzed by the type of cavity
digestion. As a result, oligomers
are formed, the hydrolysis of
which is completed in the zone of
the striated border of intestinal
enterocytes by enzymes adsorbed
on the microvilli and glycocalyx.
The end product of the hydrolysis
of oligomers - monomers - are
absorbed into the blood and
body.
Vascular network
Villi
Lymphatic network
Epithelium
Muscle
Nerve fibers

24. • The main intestinal enzymes involved in parietal digestion:
• hydrolysis of carbohydrates -  -glucosidase (maltase, trehalase),
lactase, invertase, etc.
• hydrolysis of oligo- and dipeptides - peptidases;
• Alkaline phosphatase, lipase

25. Intestinal motility
• It is carried out by contraction of the smooth muscles of the intestinal
wall (circular and longitudinal)

26. 5 types of movements
1. Tonic contraction.
2. Pendulum.
3. Rhythmic segmentation.
4. Peristaltic.
5. Antipersital (with the act of vomiting).

27. Regulation of motility
• The intestine is automatic; regulation is carried out by the autonomic
nervous system. The vagus nerve enhances motor skills, the
sympathetic nerves suppress it.
Humoral regulation
• These substances enhance motility: vasopressin, oxytocin, bradykinin,
serotonin, histamine, gastrin, cholecystokinin-pancreozymin, digestion
products of nutrients, especially fats, etc.
• These substances inhibit motility: adrenaline, norepinephrine

28. THANK YOU FOR YOUR ATTENTION!