The digestive system ii
Download
1 / 31

THE DIGESTIVE SYSTEM II - PowerPoint PPT Presentation


  • 132 Views
  • Uploaded on
  • Presentation posted in: General

THE DIGESTIVE SYSTEM II. D. C. Mikulecky Professor of Physiology Virginia Commonwealth University. PANCREATIC SECRETIONS. THE PANCREAS IS BOTH ENDOCRINE AND EXOCRINE THE EXOCRINE PANCREAS SECRETES DIGESTIVE ENZYMES AND AN AQUEOUS ALKALINE FLUID PANCREATIC SECRETION IS HORMONALLY REGULATED

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha

Download Presentation

THE DIGESTIVE SYSTEM II

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


The digestive system ii
THE DIGESTIVE SYSTEM II

D. C. Mikulecky

Professor of Physiology

Virginia Commonwealth University


Pancreatic secretions
PANCREATIC SECRETIONS

  • THE PANCREAS IS BOTH ENDOCRINE AND EXOCRINE

  • THE EXOCRINE PANCREAS SECRETES DIGESTIVE ENZYMES AND AN AQUEOUS ALKALINE FLUID

  • PANCREATIC SECRETION IS HORMONALLY REGULATED

  • PANCREATIC SECRETIONS REACH THE SMALL INTESTINE VIA THE COMMON BILE DUCT


The endocrine pancreas
THE ENDOCRINE PANCREAS

  • INSULIN AND GLUCAGON

  • IMPORTANT IN THE CONTROL OF GLUCOSE, FAT AND PROTEIN METABOLISM

  • ACT IN OPPOSITE WAYS



Aqueous component of pancreatic secretion
AQUEOUS COMPONENT OF PANCREATIC SECRETION

  • COMPOSITION CHANGES WITH SECRETION RATE (TRANSIT TIME)

  • DUCTILE CELLS SECRETE BICARBONATE AND WATER

  • CHLORIDE AND BICARBONATE VARY RECIPROCALLY

  • SODIUM AND POTASSIUM ARE LIKE IN PLASMA


Hormonal control of pancreatic secretion
HORMONAL CONTROL OF PANCREATIC SECRETION

  • ACID IN DUODENAL LUMEN >SECRETIN: STIMULATES PANCREATIC DUCT CELLS TO PRODUCE SIGNIFICANT QUANTITES OF AQUEOUS ALKALINE SECRETION

  • FAT AND PROTEIN IN DUODENAL LUMEN>CHOLECYSTOKININ (CCK):STIMULATES PANCREATIC ACINAR CELLS TO SECRETE DIGESTIVE ENZYMES


Hormones secreted in duodenum signal the composition of the incoming chyme
HORMONES SECRETED IN DUODENUM SIGNAL THE COMPOSITION OF THE INCOMING CHYME

  • SECRETIN

  • CHOLECYSTOKININ


Secretin
SECRETIN INCOMING CHYME

  • ENDOCRINE CELLS IN DUODENAL MUCOSA

  • ACID IN DUODENAL LUMEN

  • INHIBITS GASTRIC EMPTYING

  • INHIBITS GASTRIC SECRETION

  • STIMULATES AQUEOUS BICARBONATE SECRETION BY PANCREAS

  • STIMULATES BICARBONATE RICH BILE SECRETION BYLIVER


Cholecystokinin
CHOLECYSTOKININ INCOMING CHYME

  • ENDOCRINE CELLS IN DUODENAL MUCOSA

  • FAT AND PROTEIN IN DUODENAL LUMEN

  • INHIBITS GASTRIC EMPTYING

  • INHIBITS GASTRIC SECRETION

  • CAUSES GALL BLADDER CONTRACTION

  • CAUSES RELAXATION OF THE SPHINCTER OF ODDI

  • CONTRIBUTES TO SATIETY


Functions of the liver
FUNCTIONS OF THE LIVER INCOMING CHYME

  • METABILIC PROCESSING OF ABSORBED FOOD

  • DETOXIFICATION2

  • SYNTHESIS OF PLASMA PROTEINS

  • STORAGE OF GLYCOGEN AND FAT, ETC.

  • REMOVAL OF BACTERIA AND WORN-OUT RBC

  • EXCRETION OF CHOLESTEROL AND BILIRUBIN


Bile secretion storage and circulation
BILE SECRETION, STORAGE, AND CIRCULATION INCOMING CHYME

  • SECRETED BY THE LIVER

  • RECYCLED THROUGH ENTEROHEPATIC CIRCULATION

  • STORED IN GALL BLADDER


Liver blood flow
LIVER BLOOD FLOW INCOMING CHYME

INFERIOR

VENA CAVA

AORTA

HEART

HEPATIC

VEIN

HEPATIC

ARTERY

LIVER

HEPATIC

PORTAL

VEIN

ARTERIES TO

DIGESTIVE TRACT

STOMACH

AND

SMALL

INTESTINE


Bile salt circulation
BILE SALT CIRCULATION INCOMING CHYME

LIVER

GALL BLADDER

SPHINCTER

OF ODDI

DUODENUM


S i motility
S.I. MOTILITY INCOMING CHYME

  • SEGMENTATION CONTRACTIONS

  • PACEMAKER CELLS

  • MIXING AND PROPULSION


Segmentation contractions
SEGMENTATION CONTRACTIONS INCOMING CHYME

  • INITIATED BY PACEMAKER CELLS

  • MIXING ACTION

  • MOVES CHYME DOWNWARD

  • ILEOCECAL VALVE


S i secretions
S.I. SECRETIONS INCOMING CHYME

  • MANLY MUCOUS

  • NO DIGESTIVE ENZYMES


Digestion
DIGESTION INCOMING CHYME

  • MAINLY IN THE SMALL INTESTINE

  • PANCREATIC ENZYMES

  • BRUSH BORDER ENZYMES


Mainly in the small intestine
MAINLY IN THE SMALL INTESTINE INCOMING CHYME

  • SALIVARY AMYLASE

  • ACID AND PEPSIN IN THE STOMACH

  • ENZYMES COME FROM PANCREAS


Pancreatic enzymes
PANCREATIC ENZYMES INCOMING CHYME

  • PROTEOLYTIC: BREAK PROTEINS DOWN TO SMALLER PEPTIDE FRAGMENTS AND/OR AMINO ACIDS

  • PANCREATIC AMYLASE BREAKS STARCH DOWN TO OLIGOSACHHARIDES AND DISACCHARIDES

  • PANCREATIC LIPASE, PHOSPHOLIPASE AND OTHERS

  • OTHERS


Enzyme precursors are a way of protecting the gut from self digestion
ENZYME PRECURSORS ARE A WAY OF PROTECTING THE GUT FROM SELF-DIGESTION

  • PEPSIN IN THE SOMACH AND PROTEOLYTIC ENZYMES IN THEM PANCREAS

  • SECRETED IN AN INACTIVE FORM, LONGER MOLECULE

  • REMOVAL OF A SEGMENT ACTIVATES THEM


Brush border enzymes
BRUSH BORDER ENZYMES SELF-DIGESTION

  • CARBOHYDRATES: DISACCARIDASES IN BRUSH BORDER MEMBRANE FINISH THE JOB

  • PROTEINS: ALSO POLY AND DI-PEPTIDASES

  • TRANSPORT SYSTEMS ARE NEAR-LESSENS THE OSMOTIC EFFECT?


Absorption the small intestine is the absorbing organ
ABSORPTION: THE SMALL INTESTINE IS THE ABSORBING ORGAN SELF-DIGESTION

  • LARGE SURFACE AREA

  • ACTIVE SODIUM TRANSPORT

  • FLUID AND ELECTROLYTES

  • SUGARS AND AA BY SECONDARY ACTIVE TRANSPORT

  • FAT

  • VITAMINS AND MINERALS


Fluid and electrolyte absorption is by a special process isotonic transport
FLUID AND ELECTROLYTE ABSORPTION IS BY A SPECIAL PROCESS: ISOTONIC TRANSPORT

  • THE WHOLE TISSUE (SODIUM TRANSPORTING EPITHELIUM) IS INVOLVED

  • SODIUM/POTASSIUM ATPASE PUMPS ONLY ON BASOLATERAL CELL MEMBRANES

  • TIGHT JUNCTIONS VS LOOSE SEROSAL SIDE (6-PACK ANALOGY)



A network model of coupled salt and volume flow through an epithelium
A Network Model of Coupled Salt and Volume Flow Through an Epithelium

CL

PL

LUMEN

AM

TJ

BL

CELL

BM

BLOOD

PB

CB


Sodium reabsorption
Sodium Reabsorption Epithelium

PUMP: Na/K ATPase

Plasma

Sodium

Lumen

Cells

Potassium

Chloride

Water


Sodium reabsorption1
Sodium Reabsorption Epithelium

PUMP: Na/K ATPase

Plasma

Sodium

Lumen

Cells

Potassium

Chloride

Water


Potassium secretion
Potassium Secretion Epithelium

PUMP: Na/K ATPase

Plasma

Sodium

Lumen

Cells

Potassium

Chloride

Water


The curran macintosh model
THE CURRAN-MACINTOSH MODEL Epithelium

HYPERTONIC FLUID

INJECTED

FLUID MOVES

R ---> L

B

A

C

MEMBRANES: TIGHT LOOSE


Sources of water and electrolytes in gut ml day excluding intestinal secretions
SOURCES OF WATER AND ELECTROLYTES IN GUT(ML/DAY), EXCLUDING INTESTINAL SECRETIONS

  • IMBIBED:2,000

  • SECRETIONS:

  • SALIVA1,500

  • GASTRIC JUICE2,000

  • PANCREATIC JUICE1,500

  • BILE 500

  • INTESTINAL1,500

  • -----------------------------------------------------------TOTAL: SECRETED + IMBIBED9,000


Sites of absorption
SITES OF ABSORPTION INTESTINAL SECRETIONS

SMALL INTESTINE8,500

COLON 400

--------------------------------------------------------------TOTAL ABSORBED8,900

(IN FECES 100)


ad
  • Login