Gastrointestinal System Instructor: Ge Shun Office: 0850 physiological sciences Jining medical college Department of Physiology.

Slides:



Advertisements
Similar presentations
Lecture 1 Gastrointestinal Physiology
Advertisements

Digestive system I.
GASTROINTESTINAL PHYSIOLOGY Chapter-I (Gastrointestinal Secretions) Ass. Prof. Dr. Emre Hamurtekin EMU Faculty of Pharmacy.
Digestive System Chapter 23.
Chapter 21c The Digestive System.
Gastrointestinal Motility, Propulsion and Digestion
Chapter 3: The Human Body. Body Cells  Form tissues  Tissues form Organs  Organs form Systems (e.g., digestive)  Turnover  Require nutrients.
Smooth muscle surrounds the major hollow organs - including: blood vessels, bronchi, gut, uterus, bladder. Responsive to a variety of stimuli: neural input.
Electrical Activity of Gastrointestinal Smooth Muscle
GASTROINTESTINAL PHYSIOLOGY Chapter-III (Gastrointestinal Motility) Ass. Prof. Dr. Emre Hamurtekin EMU Faculty of Pharmacy.
Digestive Hormones Gastrin family Secretin family Others
Gastrointestinal Physiology
Physiological functions of the stomach
Gastric secretions Gastric secretion is a colorless, watery, acidic, digestive fluid produced in the stomach. Physical properties; It is a watery fluid,
Digestion in the Stomach
Gastric Motility Functions of gastric motility Store food
Chapter 21a The Digestive System. About this Chapter Digestion function and processes Anatomy of the digestive system Motility Secretion Regulation of.
Digestive System Chapter 18.
Functions of the digestive system
Lecture 3 Dr. Zahoor Ali Shaikh
Physiology of Gastrointestinal System (L6) Physiology of The Pancreas
Gastrointestinal function secretion, regulation Daniel Hodyc Department of Physiology Pictures and schemes – L. R. Johnson – Essential Medical Physiology,
The Digestive System. Organ groups of digestion Alimentary organs – Mouth – Pharynx – Esophagus – Stomach – Small and large intestine Accessory digestive.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings CV Quiz.
Human Anatomy and Physiology Transport and mixing of food in the alimentary tract.
General principles of gastrointestinal system function
Human Anatomy and Physiology Secretory functions of the alimentary tract.
Pancreatic secretion: In addition to secreting insulin by the islet cell of langerhans. Digestive enzymes are secreted by pancreatic acini, &large volume.
Digestive System Gastrointestinal Tract 1. Mouth Accessory Structures
Seeley Essentials of Anatomy and Physiology 6th Edition Chapter 16
Physiology Gastrointestinal System
Digestion Overview. salivary α-amylase, mucins - parotid, submandibular, sublingual glands lingual lipase - lingual serous bicarbonate ion, mucus - mucosal.
Physiology of the Digestive System
Chapter 3: Digestion. The Digestive System (also known as the Gastrointestinal System) A collection of organs whose purpose is to break down foods into.
School of Nursing & Midwifery Studies UWCM©
Gastrointestinal Physiology Xia Qiang, PhD Department of Physiology Zhejiang University School of Medicine
1 Chapter 31 Gastrointestinal Regulation and Motility.
1 III GASTRIC MOTILITY. 2 Major Function of Gastric Motility  To serve as a reservoir  To break food into small particles and mix food with gastric.
Digestive System.
GIT HORMONES DR. AMEL EASSAWI DR. SHAIKH MUJEEB AHMED 1.
 Both chemical (via salivary amylase) and mechanical digestion (teeth) take place in the mouth (chewing is mastication)  Salivary amylase breaks down.
Functions of the digestive system Ingestion- bringing in food/nutrients Mechanical processing- mechanically breaking food down, chewing, etc. Digestion-
Chapter 14: Functions of the Digestive System What activities occur within the GI Tract?
Regulation of the Digestive System The digestive system is regulated by the nervous and endocrine systems – Nervous System In the presence of food, a message.
- The cardiac region is located lust inside the cardiac sphincter. - The fundus is the superior most portion located above the cardiac sphincter. - The.
The Digestive System By Khaled Na3im. The Digestive System.
1 III GASTRIC MOTILITY. 2 Major Function of Gastric Motility  To serve as a reservoir  To break food into small particles and mix food with gastric.
Regulation of Digestion. ?? If you are like most people, you rarely think about the number of tasks that must be performed by your digestive system to.
Gastrointestinal physiology 2 M.Bayat Ph.D Principles of GI secretion,salivary, esophageal & gastric secretion.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Gastric Phase  Storage  Stomach stores food and controls its passage into.
Digestive, Excretory & Urinary Systems Digestive, Excretory & Urinary Systems DIGESTION & ITS ORGANS.
消化和吸收 -2 ( Digestion & Absorption ) 蒋 正 尧 青岛大学医学院 生理学教研室
Gastrointestinal System
© 2018 Pearson Education, Inc..
Digestive System Physiology of the pancreas
Gastro-intestinal Tract (GIT)
GASTRO-INTESTINAL HORMONES
Functions of stomach.
Chapter 3 Digestions and Absorption
Gastrointestinal Physiology
The Digestive System.
The Digestive System.
Digestion, Absorption and Transport
Gastrointestinal system
Chapter 17 Digestive System
Human digestion.
Pancreatic Secretions
Lecture 2b- 17 January 2019 Lecture based largely on chapter 1 of
Gastrointestinal Physiology
Presentation transcript:

Gastrointestinal System Instructor: Ge Shun Office: 0850 physiological sciences Jining medical college Department of Physiology

Gastrointestinal System 1. G.I. Physiology: general organization of G.I. tract 2. Mastication and deglutition 3. Gastric secretion 4. Regulation of gastric secretion 5. Pathophysiology of peptic ulcer 6. Biliary and pancreatic secretions 7. Physiology of colon 8. Pathophysiology of diarrhea disease

Gastrointestinal System includes GI tract plus the accessory organs.

Four processes carried out by the GI tract

Digestive secretions from the liver and the pancreas are delivered into the duodenum of the small intestine through the sphincter of Oddi.

Functions of small intenstine movements Mixes the luminal contents with secretions Brings the contents nto contact with the epithelial surface Slowly advances the luminal material toward the large intenstine

Structure of the GI Tract Wall

(I) Physiological properties of gastrointestinal smooth muscle (1) General properties - Low excitability - High extensibility - Tonic contraction - Autorhythmicity - High sensitivity to temperature, stretch & chemical stimulation

(2) Electrophysiological properties (a) Resting potential: - between -50 and -60 Mv - Ionic basis -Em (selective membrane permeability to K+) -Electrogenic Na+-K+ pump

(b) Slow wave (basic electrical rhythm,BER) - The spontaneous rhythmic, subthreshold depolarizations of the cell membrane (slow wave) of the gastrointestinal tract - Initiated in the interstitial cells of Cajal (ICC) (pacemaker cell)

Slow wave (basic electrical rhythm) - Intensity: 5~15 mV - Frequency: 3~12 cpm - Ionic mechanism spontaneous rhythmic changes in Na+-K+ pump activity

Frequencies: 3-12 per minute

(c) Spike potentials (action potentials) only at the peaks of slow waves Threshold: -40 mV

Spike potential (Action potential) -Duration: 10~20 ms -Ionic mechanism: Depolarization: Ca 2+ influx Repolarization: K + efflux

The higher the slow wave potential rises, the greater the frequency of the spike potentials

(II) Neural control of gastrointestinal function Enteric nervous system Extrinsic nervous system

Myenteric plexus : control over GI motility Submucous plexus: regulate gastrointestinal blood flow and control GI secretion

(III) Hormonal Regulation --GI hormones The hormones synthesized by a large number of endocrine cells within the gastrointestinal tract Brain-gut peptides: a number of the classical GI hormones are also synthesized in the brain

Four main types Gastrin Cholecystokinin Secretin Gastric inhibitory polypeptide (GIP)

(IV) Phases of Gastrointenstinal Control Cephalic phase Gastric phase Intenstinal phase Three phase of gastric secretion.swf

Summary Terms: - Basic electrical rhythm (BER) or slow waves - Gastrointestinal (GI) hormones Three phase of gastric secretion

Mouth, Pharynx, and Esophagus Secretion of saliva The Salivary Glands Parotid gland Mandibular gland Sublingual gland

Saliva 1000 ml/d pH 6.0~7.0 Composition of saliva -H 2 O -Na +, Cl -, K +, HCO 3 - -Mucus (containing mucin) -Amylase, lysozyme, …

Swallowing

Digestion in the Stomach

Chief cells synthesize and secrete the protease precursor known as pepsinogen. Parietal cells synthesize and secrete the hydrochloric acid responsible for the acidic pH in the gastric lumen.

(I) Gastric juice (1) Hydrochloric acid Secreted by the parietal cells Output - Basal: 0~5 mmol/h - Maximal: 20~25 mmol/h

Acid production by the parietal cells in the stomach depends on the generation of carbonic acid; subsequent movement of hydrogen ions into the gastric lumen results from primary active transport.

Four chemical messengers regulate HCl secretion

Role of HCl - Acid sterilization - Activation of pepsinogen - Promotion of secretin secretion - Assisted effect of iron and calcium absorption

(2) Pepsinogen

(3) Mucus-HCO 3 - barrier

If the mucus-HCO3- barrier is weak?

(4) Intrinsic factor A high molecular weight glycoprotein, synthesized and secreted by the parietal cells The intrinsic factor binds to Vit B 12 and facilitates its absorption

(II) Regulation of gastric secretion (1) Basic factors that stimulate gastric secretion - Acetylcholine (+ all secretory cells) - Gastrin (+ parietal cells) - Histamine (+ parietal cells)

(2) Nervous regulation - ‘Short’ reflex pathways - ‘Long’ autonomic pathways

(3) Humoral regulation

(4) Phases of gastric secretion Cephalic phase Gastric phase Intestinal phase

Motor Function of the Stomach

Receptive relaxation - Storage function (1.0~1.5 L) - Vago-vagal reflex Peristalsis - BER in the stomach

Motor Function of the Stomach

Emptying of the stomach Emptying rate - Fluid > viscous - Small particle > large particle - Isosmotic > hyper- & hypo-osmotic - Carbohydrates > Protein > Fat - Regular meal 4 ~ 6 hrs

Summary Terms: - Receptive relaxation (Storage function of the stomach) - Mucus-HCO3- barrier - Intrinsic factor Gastric secretion (including the composition and physiological function of the gastric juice, the regulation of gastric secretion)

Pancreatic Secretion

(I) Pancreatic juice pH 7.8~8.4 ~1500 ml/day Isosmotic Components: - Pancreatic digestive enzymes: secreted by pancreatic acini - Sodium bicarbonate: secreted by small ductules and larger ducts

Secretion of bicarbonate ions

Secretion of pancreatic digestive enzymes

(II) Regulation of pancreatic secretion Basic stimuli that cause pancreatic secretion - Ach - Cholecystokinin: Secreted by I cells Stimulates the acinar cells to secrete large amounts of enzymes - Secretin: Released by S cells Acts primarily on the duct cells to stimulate the secretion of a large volume of solution with a high HCO3- concentration

Bile Secretion and Liver Function

Composition of bile

Function of bile

Enterohepatic circulation

Regulation of bile secretion

Small Intestine

Absorption in the gastrointestinal tract (I) Basic principle of absorption

Absorption in the gastrointestinal tract

3. Absorption mechanisms Active transport Diffusion Solvent drag

(II) Absorption of major nutrients

2. Carbohydrates

3. Proteins

4. Fats

(1) Absorption through lymph duct to the circulatory blood (2) Direct absorption into the portal blood

Summary Pancreatic secretion (including the composition and physiological function of the pancreatic juice, the regulation of pancreatic secretion) Biliary secretion (including the composition and physiological function of the bile) Absorption in the small intestine Describe the digestion of carbohydrates, proteins and fat