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Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology, Elsevier, 2003
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Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Dec 25, 2015

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Page 1: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Gastrointestinal function

secretion, regulation

Daniel HodycDepartment of Physiology

Pictures and schemes – L. R. Johnson – Essential Medical Physiology, Elsevier, 2003

Page 2: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

1. Salivary secretion

2. Gastric secretion

3. Pancreatic secretion

GIT secretion

Page 3: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Salivary

secretion

Page 4: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Anatomy, Inervation

Page 5: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Functions of saliva Digestion

- ptyalin (α-amylase) - identical to pancreatic amylase

- cleaves α-1,4-glycosidic bonds of carbohydrates - 75 % of starch, pH optimum 7- functionally replaceable by pancreatic enzyme

- lingual lipase- triglycerides- lower acidic optimum – remains active throughout the stomach and into the proximal duodenum

- dissolves dietary constituents

- increases the sensitivity of taste buds

Page 6: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Functions of saliva Lubrication

- mucus content- facilitates swallowing- necessary for speech

Protection

- dilution and buffering of harmful substances- salivation before vomiting- xerostomia chronic infections- lysozym, IgA binding protein, lactoferin- take-up of Ca and phosphate - concentration

Page 7: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Composition of saliva

Major characteristics of saliva:

- relatively large volume

- high potassium concentration

- low osmolarity

- two stages in secretion acini x salivary duct

- specialized organic materials

Page 8: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Composition of saliva

Page 9: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Composition of saliva

Page 10: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Composition of saliva

Organic composition:

- ptyalin, lipase

- lysozym, IgA binding protein, lactoferin

α-globulin bradykinin

kallikrein

vasodilation

Page 11: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Neural regulation of secretion

Page 12: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Gastric

secretion

Page 13: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Gastric secretionGastric juice

- hydrochloric acid- conversion of pepsinogen to pepsine- bacteriostatic effect

- pepsin- protein digestion- replaceable by pancreatic enzymes

- mucus- protective coating, lubricant- part of gastric mucosal barrier

- intrinsic factor- binds B12 vitamin, absorption in the ileum- the only indispensable substance in gastric juice

Page 14: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Gastric secretion

Secretory regions

Oxyntic gland

Page 15: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Gastric juice electrolytes

Page 16: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Hydrochloric acid secretion

alkaline tide

Page 17: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Stimulation of acid secretion

Parasympathetics (Ach)

Gastrin

Histamine

Potentiation of agents

Page 18: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Hydrochloric acid secretion – perietal cell

Nonsecreting cell Secreting cell

Page 19: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Stimulation of acid secretion – cephalic

phase blocked by vagotomy

sham feeding

hypoglycemia

role of GRP(bombesin)

Page 20: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Gastric phase

60 % of acid response

distension

peptides

calcium alcohol caffeine

Page 21: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Stimulation of gastric acid secretion

Page 22: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Regulation of gastrin release

Gastrin Cell Somatostatin Cell

Acetylcholine

-

Page 23: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Intragastric pH after a meal

Stomach – somatostatinDuodenum – secretin, hyperosmotic chyme fatty acids

Inhibition of acid secretion

Page 24: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Production of Pepsin

Ach H+

Pepsinogen

Pepsin

Page 25: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Pancreatic

secretion

Page 26: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Secretion of water and electrolytes

Na, K – the same as in plasma

Bicarbonate concentration – up to 5 times higher than in plasma

Page 27: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Mechanism of water and electrolytes secretion

Na-K-ATPase

Bicarbonatein plasma

High extracellular Cl- concentration

Carbonic anhydrase

Page 28: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Mechanism of enzymes secretion

Proteolytic enzymes – secreted as inactive precursors

trypsinogen trypsinenterokinase

chymotrypsinogenprokarboxypeptidase

chymotrypsinkarboxypeptidase

Page 29: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Mechanism of enzymes secretion

Inhibition of pancreatic autodigestion

trypsinogen trypsinenterokinase

chymotrypsinogenprokarboxypeptidase

chymotrypsinkarboxypeptidase

Trypsin inhibitor

Page 30: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Mechanism of enzymes secretion

Inhibition of pancreatic autodigestion

trypsinogen trypsinenterokinase

chymotrypsinogenprokarboxypeptidase

chymotrypsinkarboxypeptidase

Trypsin inhibitor

Failure PANCREATITIS

Page 31: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Mechanism of enzymes secretion

Glycolytic enzymes- secreted as active enzymes- pancreatic α-amylase- cleaves starch and glycogen into di- and

trisacharides

Lypolytic enzymes - secreted as active enzymes - pancreatic lipase - glycerol + fatty acids

Page 32: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Regulation of pancreatic secretionCephalic and gastric phase

Acetylcholine

CCK

Secretin

waterbicarbonate

enzymes

Page 33: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Regulation of pancreatic secretionIntestinal phase

Acetylcholine

CCK

Secretin

waterbicarbonate

enzymes

Fat

H+

Page 34: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

Response to a meal

neutralization- pancreatic

bicarbonate

changes in diet

changes in enzyme

secretion

Page 35: Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,

The effect of potentiation of enzyme secretion in pancreas

Phenylalanin + Secretin (CCK)

Secretin 1unit / kg.hr

Phenylalanin (CCK)