The document discusses the physiology of digestion. It begins by describing the digestive tract as an open system that exchanges energy, substances, and information with the external environment. It then discusses the breakdown of foods through mechanical and chemical processes in the mouth, stomach, and intestines. This includes the roles of enzymes, hormones, and intestinal bacteria. The summary concludes by noting the digestive tract has several functions, including secretion, motility, absorption, and protection.

1. PHYSIOLOGY OF
DIGESTION

2. ORGANISM IS AN
OPENED SYSTEM
Types of exchange with
external environment:
Energy exchange
Substance exchange
Information exchange

3. SUBSTANCES from the
external environment
HIGH MOLECULAR SUBSTANCES,
which have species specificity :
proteins,
fats,
carbohydrates,
Microelements, vitamins, water,
cellulose

4. Trophic homeostasis
content of nutrients in the
internal medium of the body
Kept up due to constant food
intake

5. Sponsored
Medical Lecture Notes – All Subjects
USMLE Exam (America) – Practice

6. DIGESTION is
physical and chemical food proccesing
in the result of which its components
preserve their energy and plasticity,
but lose species specificity and
are converted to absorbable particles
which are included in normal
metabolism.

7. food
Меchanical
processes
Fragmentation,
mixing,
movement
Chemical
processes
Enzymatic hydrolysis
to monomeres
Transport
Monomeres delivery to blood
Motor
function
Secretory
function
Absorbtive function

8. DIGESTIVE TRACT
FUNCTIONS

9. DIGESTIVE TRACT
FUNCTIONS
Secretory– secretion of digestive juices by
the digestive glands
Motor – is performed by the muscle layer of
the GIT, results in the changes of food from
solid to liquid
Absorbtive – transport of end products of
digestion, salts, water and vitamins from
the cavity to blood and lymph

10. PARTAKING IN BODY
METABOLISM
WATER, NUTRIENTS, MICROELEMENTS,
VITAMINS AND BILE ACIDS CIRCULATION
CIRCULATION SAVES SUBSTANSES AND
ENERGY FOR THE BODY

11. 2 L Н2О
8L juices 10 L
0,1L
blood
lungs
sweatvapour
kidney
urine
2 L

12. EXCRETION
Excretion of metabolites or toxic
substances from blood into the GIT
cavity:
bile pigments, metabolites, toxic
salts, drugs

13. Incretory function
Intestinal hormones, which regulate
functions of digestive tract are secreted by
the cells of APUD-system, located in the
mucous membrane of digestive tract and
in pancreas

14. PROTECTIVE FUNCTION
Mucous membrane of GIT is an immune
barrier between external and internal
environment:
 Lymphoid nodes
 Lymphocytes and tissue macrophages –
Ig А
 intraepithelial Т-lymphocytes.
Bacteriocidic, bacteriostatic and
desintoxicative function

15. RECEPTIVE FUNCTION
chemo- and mechanoreceptive fields
of digestive tract may be common for
reflex arcs of visceral systems
(excretory, cardio-vascular) and
somatic reflexes

16. ROLE IN HAEMOPOESIS
SECRETION of gastromucoproteid-
HEMAMIN (intrinsic Castle factor),
necessary for vitamin В-12 absorption.
Mucous membrane of stomach and small
intestines аnd liver (along with bone
marrow and spleen) are ferritin depots

17. INTESTINAL BACTERIAL FLORA
FUNCTIONS:
1. Final break down of non-digested food:
a) Fermentation of carbohydrates to lactic
and acetic acid, аlcohol, СО2 and Н2О;
b) Proteins decay and formation of indol,
skatol, biologicaly active amines,
hydrogen sulphate and methane.

18. 2. Inactivation of digestive juices
components.
3. synthesis of vitamin K and vitamins of the
B complex .
4. Constant stimulus for natural immunity
5. suppresses pathogenic microorganisms
and prevents infection

19. Basic types of digestion
INTRACELLULAR
•CAVITY
•MEMBRANE

20. MOTOR FUNCTION OF
DIGESTIVE TRACT
1. STRIATED MUSCLES:
 mouth cavity, larynx and upper part of
oesophagus (mastication and
swallowing);
 External anus sphincter (tonic
contractions).
2. Smooth muscles (mixing and moving).

21. LAYERS OF THE DIGESTIVE
TRACT WALL
Serose
Longitudinal muscle layer
Intramuscular nervous plexus
Circular muscle layer
Submucous nervous plexus
Submucous muscle layer
Mucous
брыжейка

22. TYPES OF MOTOR
ACTIVITY

23. Peristalsis
Propulsive – movement of chyme from oral to
anal end of digestive channel
Non-propulsive– mixing of chyme in a certain
part of digestive channel
oesophagus,
stomach,
Small intestine

25. RYTHMIC SEGMENTATION
SMALL AND LARGE INTESTINE
MIXING

27. Pendulum movements
SMALL AND LARGE INTESTINE
Longitudinal movement of
the intestinal wall with regards to chyme

28. TONIC CONTRACTION
SPHINCTERS
FUNCTIONAL DIVISION
OF DEPARTMENTS

29. INTRAMURAL PERISTALSIS
REFLEX
chyme
1
2 3
2
3
CONTRACTION-
cholinergic
RELAXATION-
pyrinergic

30. Secretory function

31. SECRETION is
Intracellular process during which
the cell:
Gets necessary substances from
blood plasma
Synthesises the secret
Excretes the secreted substances
along with water and electrolites

32. Basilar
membrane
Apical
membrane

33. Secretory cycle
1. Поступление исходных веществ (вода,
ионы, АК, моносахара) путем диффузии
и пиноцитоза через базальную
мембрану.
2. Синтез фермента (белкового секрета) на
рибосомах и слизистого компонента на
пластинчатом комплексе Гольджи с
использованием АТФ (митохондрии).
3. Дозревание – образование и накопление
гранул секрета в апикальной части
клетки.
4. Экструзия – мерокриновый, апокрино-
вый и голокриновый механизм.

35. Primary saliva
Solution rich in electrolites & enzymes.
Types of enzymes:
 Amylazes
 Lipazes
 Proteazes
 nucleazes

36. Secondary saliva
Is formed in the ducts due to ionic
exchange, as the result Рh is
changed & can be regulated.

37. Types of regulation
nervous
Conditioned &
Unconditioned reflexes
Intraorganal reflexes
(local)
Humoral
endocrine paracrine

38. Unconditioned & conditioned
reflexes
Extero- or intero
receptors
CNS
Secretory cell Endocrine cell
Hormon in blood

39. Intraorganic
(local reflexes)
interoreceptors
Metasympathetic
intraorganic
ganglia
Secretory cell

40. Endocrine mechanism
Chyme
Endocrine cell
Secretory cell
Hormons of APUD system
Blood vessel

41. Paracrine mechanism
Chyme
Endocrine
cell
Secretory cell
Tissue hormone

42. Methods of studying
digestive system
functions

43. Acute experiment
Advantages:
1. Direct influence on the studied organs &
their elements;
2. Information on the elementary reactions ;
Disadvantages:
1. Breaking down the anatomical integrity of
the body;
2. Organ’s function disturbances (narcosis);
3. One time observation only.

44. Chronic experiment
Advantages:
1. Observation of organ functioning in
physiological conditions;
2. Observation of functions changed with
time.
Disadvantages:
1. Experiment’s results show summarized
activity of many organs or the system on
the whole.

45. Methods of studying
digestion in the mouth
cavity

46. Fistula - a hollow organ
connection with the
external
environment
Fistula of a salivatory gland is a salivatory
gland duct on the external buccal surface
First operation was performed by Basov in
1942

47. Leshli-Krasnogorskiy capsule

49. myoelectromasticatziography

50. Methods of studying
digestion in the
stomach

51. Stomach nervous supply

52. Stomach fistula

53. Pavlov’s pouch

54. Hendenhain’s pouch

55. «Sham» feeding experiment

57. Methods of studying
digestion in the guts

58. Fistulas of pancreatic &
common bile ducts
pancreas
pancreas
SKIN
DUODENUM DUODENUM
liver
SKIN
liver

59. Acute methods
Studying lymphatic vessels
VIVIDIFFUSION
v. portae
liver
solution

60. chronic
ISOLATED INTESTINE
Tiry method Tiry-Vella method

61. 1.Polyfistule method
INTESTINE
SKIN
FISTULAS
2.
London’s
angiostomia
-V. portae
fistula
-formation

62. Ekk-Pavlov anastomose
Is formed between v. portae & v. cava
inferior so that blood from the
intestine would go directly into the
circulatory system without passing
through the liver.
The experiment shows the role of
liver in detoxication

63. CLINICAL METHODS
OF STUDYING
DIGESTION

64. PROBING
1.Background secretion
2.Stimulated secretion:
GASTRIC SECRETION IS STIMULATED BY DRY
BREAD, CABBAGE JUICE,ALKOHOL OR I/V
INJECTION OF HYSTAMINE
PANCREATIC SECRETION IS STIMULATED BY
0,2-,5% HCl solution
BILE EXCRETION IS STIMULATED BY 20-30 ml of
magnesium sulphate

65. OTHER METHODS
ENDOSCOPY
INDICATORS INTRODUCTION
BLOOD, LYMPH & FECES CHEMICAL
ANALYSIS
TELERADIO PILLS

66. DIGESTION IN THE
MOUTH CAVITY.
GUSTATORY SENSORY
SYSTEM.

67. MOUTH CAVITY
Peripheral PART OF GUSTATORY
SENSORY SYSTEM:
1. Defines eatable & non-eatable
substances;
2. Is a receptory field for the non-
conditioned reflexes in all the gastro-
intestinal tract.

68. Mouth cavity functions:
1. Mastication & formation of foog
bolus;
2. Primary hydrolysis of some
substances – carbohydrates (α-
amylase, maximum activity at рН
6,9)

69. Salivatory glands are paired
structures
1. Parotid– serous – 25% of saliva
2. Submandibular – mixed – 70% of saliva
3. Sublingual – mixed – 5% of saliva
4. Small, scatered in the mouth cavity -
слизистые

70. Saliva composition
99% of water
Main mineral components:
 sodium, potassium, chlorine,
hydrocarbonates.
Macromolecules:
 Enzymes – α-amylaze, Lizotzim,
proteinases, callicrein.
 Glicoproteins, mucopolisaccarides
(mucin)
 Immunoglobulines

71. Phases of secretory
cycle.
Entering of initial substances (water, ions,
aminoacids, monosaccarides) by the way of
diffusion and pinocytosis.
Synthesis of enzymes on rybosomes and mucous
(mucopolysaccarides and mucoproteins) in Golgi
– complex.
Maturition – formation and storage of secretory
granules.
Extrusion – merocrine, apocrine and holocrine
mechanism.

72. Mechanism
of secondary
saliva
secretion
0,5 to 2,0 l per day
рН of saliva at rest –
5,45-6,06
At stimulation –
7,8

73. Parasympathetic influence
on saliva secretion
Efferent fibres:
Chorda tympani – sublingual &
submandibular glands
N. glossopharyngeus –parotid
gland

74. Ach
m-cholinoreceptors
Increased potassium permeability
Calmodulin activation
Stimulation of saliva extrusion
A lot of watery saliva is secreted
Vessels
dilation

75. Sympathetic influence on
saliva secretion
Sympathetic fibres of II-IV thoracis segments
Constant influence on synthesis & maturation
of secrete (enzimes & mucin).
On stimulation of sympathetic fibres:
 Little amount of viscous, rich in enzimes &
mucin saliva is secreted;
 Vessels & ducts constriction

76. adrenalin
β-adrenoreceptors
Adenylate-cyclase activation
АТP C-АМP
ENZIMES & MUCIN SECRETION
DUCTS & VESSELS
CONSTRICTION
Little AMOUNT OF SALIVA RICH IN
ENZIMES & MUCIN

77. Reflex regulation of saliva
secretion
cortex
Cond.
Ref.
food
N/cond.
Ref.
Med. Obl.

78. SALIVA FUNCTIONS
Serves as a solvent for chemoreception
(H2O).
Formation of food bolus.
Provision of swallowing act.
Provision of formation of speech.
Protective function ( lizotzim, nucleases).
Hydrolysis of carbohydrates.
Hermetization of mouth cavity during
sucking ( in newborn).
Nutritive medium for teeth enamel

79. Gustatory analyser
scheme
Taste receptors
Nucleus tractus solitarii
VII, XI
Of cranium nerves
n. Arcuatus of
thalamus
Lemniscus
medialis
Postcentral gyrus
Taste of sweet,
Bitter,
Salty,
sour