DIGESTIVE SYSTEM anatomy healthcare And medicine

Anatomy

1. DIGESTIVE SYSTEMDIGESTIVE SYSTEM
Adelina Torgomyan MD., PhD.Adelina Torgomyan MD., PhD.
Physiology departmentPhysiology department

2. Digestive
system
Digestive tract
Secretory
organs
Esophagus
Salivary glandsPancreas
Stomach
Liver
Small bowelLarge bowel

4. I- mucosaI- mucosa
II-II-
submucosasubmucosa
III- III-
muscular muscular
layerlayer
IV- serosaIV- serosa

5. Digestive: secretor, motor, absorptionDigestive: secretor, motor, absorption
Non digestive: Non digestive:
regulation of water- salt balance,regulation of water- salt balance,
excretory, excretory,
endocrine, endocrine,
hemopoiesis regulation, hemopoiesis regulation,
defensedefense
FunctionsFunctions

6. According to the origin of digestive According to the origin of digestive
enzymes: proper, enzymes: proper,
autolytic, autolytic,
symbiotic symbiotic
Depending on the place: Depending on the place:
intracellular, intracellular,
extracellular (cavital, membranous) extracellular (cavital, membranous)

7. Oral cavityOral cavity

8. Mechanical processing (mastication, mixing Mechanical processing (mastication, mixing
with saliva)with saliva)
Bolus formation Bolus formation
Food chemical processing (carbs) Food chemical processing (carbs)
Defense (lysozyme)Defense (lysozyme)
Taste perceptionTaste perception
Deglutition : Deglutition :
oral (buccal) phase – voluntary oral (buccal) phase – voluntary
pharyngeal pharyngeal
esophageal esophageal

9. Salivary glandsSalivary glands
Saliva contentSaliva content
0.5-2 l0.5-2 l
Water 99.5%Water 99.5%
Ph = 5.8- 7.4Ph = 5.8- 7.4
Organic: mucin, Organic: mucin,
αα- amylase, maltase,- amylase, maltase,
lysozime, kallikrein lysozime, kallikrein
Urea, uric acid, Urea, uric acid,
creatinine creatinine
Inorganic: Na, K, Ca Inorganic: Na, K, Ca
chlorides, carbonates, chlorides, carbonates,
phosphates…phosphates…

10. Salivary glands Salivary glands
Parotid is serous glandParotid is serous gland
Sublingual, Sublingual,
submandibullar- mixedsubmandibullar- mixed
Secretory parts- serous Secretory parts- serous
(acinar), sero-mucous (acinar), sero-mucous
(mixed, tubulo-acinar), (mixed, tubulo-acinar),
mucous (tubular)mucous (tubular)
Ducts- intralobular Ducts- intralobular
(1-intercalated, (1-intercalated,
2-striated), 2-striated),
3- interlobular3- interlobular

11. Control of salivationControl of salivation
Cephalic phase:Cephalic phase:
1. conditioned reflexes (from visual, 1. conditioned reflexes (from visual,
smell, hearing receptors)smell, hearing receptors)
2. unconditional reflexes (from taste 2. unconditional reflexes (from taste
receptors in oral cavity):receptors in oral cavity):
parasympathetic n.s. parasympathetic n.s.
sympathetic n.s.sympathetic n.s.

12. Afferent stimulation: trigeminal, facial, Afferent stimulation: trigeminal, facial,
glossofaringeal, vagus nn.glossofaringeal, vagus nn.
Salivation center in medulla oblongataSalivation center in medulla oblongata
Efferent impulses: chorda tympani Efferent impulses: chorda tympani
(submandibular, sublingual glands)(submandibular, sublingual glands)
glossofaringeal n. (parotid gland)glossofaringeal n. (parotid gland)
Parasympathetic Parasympathetic innervation center in innervation center in
medullamedulla oblongata ( oblongata ( AchAch- ↑ secretion of - ↑ secretion of
watery saliva rich in enzymes)watery saliva rich in enzymes)
Sympathetic Sympathetic center in center in T2-T4 T2-T4 segments of segments of
spinal cord, lateral horns (spinal cord, lateral horns (NANA- secretion of - secretion of
thick saliva rich in mucin)thick saliva rich in mucin)

15. Stomach Stomach

16. Stomach Stomach

17. Gastric secretionGastric secretion2- 2.5 l daily2- 2.5 l daily
Water 99-99.5 % Water 99-99.5 %
Ph =1.5- 1.8Ph =1.5- 1.8
HCl 0.3- 0.5%HCl 0.3- 0.5%
Mucin Mucin
Intrinsic factor of Castle Intrinsic factor of Castle (B12 absorption)(B12 absorption)
Urea, uric acid, creatinineUrea, uric acid, creatinine
EnzymesEnzymes::
Pepsinogens: Pepsinogens: pepsins A,B pepsins A,B (proper, Ph 1.5- 2)(proper, Ph 1.5- 2)
pepsins Cpepsins C (gastricsins, Ph 3.2- 3.5) (gastricsins, Ph 3.2- 3.5)
LipaseLipase (Ph 5.9-7.9) (Ph 5.9-7.9)

18. Under the action of carbonic anhydrase, blood CO2 produces carbonic acid. Carbonic
acid dissociates into a bicarbonate ion and a proton H+, which is pumped into the
stomach lumen in exchange for K+. A high concentration of intracellular K+ is
maintained by the Na+,K+ ATPase, while HCO3— is exchanged for Cl— by an antiport.
The tubulovesicles of the cell apex are seen to be related to hydrochloric acid secretion,
because their number decreases after parietal cell stimulation. The bicarbonate ion
returns to the blood and is responsible for a measurable increase in blood pH during
digestion.

19. HCl functionsHCl functionsDenaturing of proteinsDenaturing of proteins
Activation of pepsinogensActivation of pepsinogens
Acidic PhAcidic Ph
AntibacterialAntibacterial
Regulation of motilityRegulation of motility
Gastrin secretion regulationGastrin secretion regulation
Activation of secretin, enterokinase in Activation of secretin, enterokinase in
duodenumduodenum

26. Regulation of gastric Regulation of gastric
secretionsecretion

29. Stimulators: Stimulators:
gastrin, histamine, bombesin, gastrin, histamine, bombesin,
motilinmotilin
Parasympathetic n.s., AChParasympathetic n.s., ACh
Inhibitors: Inhibitors:
secretin, cholecystokinin, secretin, cholecystokinin,
somatostatin, glucagon, somatostatin, glucagon,
calcitonin, adrenaline calcitonin, adrenaline
Sympathetic n.s., NASympathetic n.s., NA

34. Small bowelSmall bowel

35. Small bowelSmall bowel

36. Small intestineSmall intestine

37. Small intestineSmall intestine
duodenum jejunum duodenum jejunum

38. Intestinal secretionIntestinal secretion
(of morphonecrotic type)(of morphonecrotic type)
pH 7.2-7.5pH 7.2-7.5
Liquid portion: water, inorganic and organicLiquid portion: water, inorganic and organic
Solid portion: epithelial cells containing Solid portion: epithelial cells containing
enzymes associated with brush border enzymes associated with brush border
(enterokinase, dipetidases, lactase, maltase, (enterokinase, dipetidases, lactase, maltase,
sucrase) sucrase)
Regulation: Regulation: Peripheral (local) mechanismsPeripheral (local) mechanisms

39. PancreasPancreas
mixed gland:mixed gland:
exocrine-exocrine-
enzymesenzymes
endocrine- endocrine-
hormoneshormones

40. Pancreas Pancreas

41. Pancreatic secretionPancreatic secretion
1.5- 2 l 1.5- 2 l
Ph 7.8- 8.4Ph 7.8- 8.4
WaterWater
Inorganic (Inorganic (bicarbonatesbicarbonates))
Organic (Organic (enzymesenzymes: proteases, lipases, : proteases, lipases,
carbohydrases) carbohydrases)

42. ProteolyticProteolytic – –
endopeptidases (endopeptidases (trypsin, chymotrypsin, trypsin, chymotrypsin,
elastase)elastase)
exopeptidases (exopeptidases (carboxypeptidase, carboxypeptidase,
aminopeptidase, dipeptidasesaminopeptidase, dipeptidases))
Carbolytic –Carbolytic –
amylaseamylase, disaccharidases (lactase, maltase, , disaccharidases (lactase, maltase,
sucrase)sucrase)
Lipolytic – Lipolytic –
LipaseLipase, phospholipase, esterase, phospholipase, esterase
Nucleases-Nucleases-
DNase, RNaseDNase, RNase

44. Regulation of secretionRegulation of secretion
Cephalic phase: conditional, unconditional Cephalic phase: conditional, unconditional
reflexes reflexes
Gastric phaseGastric phase
Intestinal phase: neuronal mechanisms,Intestinal phase: neuronal mechanisms,
humoral mechanismshumoral mechanisms: stimulated by : stimulated by
cholecystokinin, secretin, gastrin, bombesin, cholecystokinin, secretin, gastrin, bombesin,
Parasympathetic n.s., AChParasympathetic n.s., ACh
inhibited by glucagon, calcitonin, inhibited by glucagon, calcitonin,
somatostatin, adrenaline somatostatin, adrenaline
Sympathetic n.s., NASympathetic n.s., NA

47. Liver Liver

48. Liver Liver

49. Sinusoidal
surface
Canalicullar
surface
Intercellular
surface
Hepatocyte Hepatocyte

50. BileBile
0.5- 1.5 l daily0.5- 1.5 l daily
Water- 97.5%Water- 97.5%
Ph 7.8-8.6 (gall bladder pH 6.0-7.0)Ph 7.8-8.6 (gall bladder pH 6.0-7.0)
Mineral salts (Mineral salts (bicarbonatesbicarbonates))
Proteins, aminoacidsProteins, aminoacids
VitaminsVitamins
Bile acids Bile acids (80% glycocholic, 20% taurocholic)(80% glycocholic, 20% taurocholic)
Bile pigments (Bile pigments (biliverdin, bilirubinbiliverdin, bilirubin) )
CholesterolCholesterol
Mucin Mucin
Urea, uric acid, creatinine Urea, uric acid, creatinine

51. Bile functionsBile functions
Fats emulsificationFats emulsification
Forms micelles Forms micelles
Facilitates absorptionFacilitates absorption
Activates enzymes (lipase)Activates enzymes (lipase)
Alkaline PhAlkaline Ph
Neutralizes HClNeutralizes HCl
Controls bile production and ejectionControls bile production and ejection
Regulates motor and secretory activitiesRegulates motor and secretory activities
BactericidalBactericidal
Absorption of fat soluble vitamins A,D,E,K Absorption of fat soluble vitamins A,D,E,K
and cholesterol and cholesterol

52. Control of bile release Control of bile release
Cephalic phase: conditional, unconditional Cephalic phase: conditional, unconditional
reflexes reflexes
Gastric phaseGastric phase
Intestinal phase: neuronal mechanisms,Intestinal phase: neuronal mechanisms,
humoral mechanismshumoral mechanisms: stimulated by : stimulated by
cholecystokinin, gastrin, secretin, bombesincholecystokinin, gastrin, secretin, bombesin
Parasympathetic n.s., AChParasympathetic n.s., ACh
inhibited by glucagon, calcitonin, VIP inhibited by glucagon, calcitonin, VIP
somatostatin, adrenaline somatostatin, adrenaline
Sympathetic n.s., NASympathetic n.s., NA

57. Large bowel Large bowel

58. Large intestine, appendixLarge intestine, appendix

59. SecretionSecretion
(of morphonecrotic type) (of morphonecrotic type)
Ph 8.5- 9.0Ph 8.5- 9.0
Liquid portion (water, mucus, salts)Liquid portion (water, mucus, salts)
Solid portion (shed cells containing Solid portion (shed cells containing
enzymes, mainly alkaline phosphatase)enzymes, mainly alkaline phosphatase)
Regulation Regulation
Local (peripheral) neuronal mechanismsLocal (peripheral) neuronal mechanisms

60. Microflora Microflora
Final breakdown of food: cellulose Final breakdown of food: cellulose
digestion, proteins decay digestion, proteins decay
Immune barrier (suppression of Immune barrier (suppression of
pathogens)pathogens)
Synthesis of Vit. Synthesis of Vit. K K and and B B complexcomplex
Enzymes inactivationEnzymes inactivation
Participation in metabolism Participation in metabolism

61. Motor activityMotor activity
Stomach Small intestineLarge
intestine
Peristalsis
(tonic)
Propulsive
contractions
(phasic)
Rhythmic
segmentation
Peristalsis
Pendular
Villi
contraction
Rhythmic
segmentation
Peristalsis
Pendular
Antiperistalsis

63. Oral
cavity
Stomach Small int.
cavity
Small int.
brush bor
Larg
e int
Carbs Ph=5.8-
7.4
Salivary
amylase
Ph=7.8-8.4
Pancreatic
amylase
Sucrase
Maltase
Lactase
Ph=8
.5-
9.0
Protei
ns
Pepsin
Ph=1.5-2
HCl(0.3-
0.5%)
Trypsin
Chemotripsin
Elastase
Carboxipeptid
ase
Aminopeptida
se
Dipeptidases
Micr
ophl
ora
Lipids Milk
lipase
Emulsification
By bile
Lipase
Nuclei
cacid
RNAse
DNAse
Nucleosidase

64. Regulation Regulation
Central
reflexes
Humoral Peripheral
reflexes
Salivary
glands
+++ - -
Stomach +++ +++ +++
Pancreas,
bile
excretion
++ +++ ++
Small , large
bowel
+ + +++