医学生理学3PPT课件
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repolarization: K+ outward flow
1. General physiological characteristics
➢low excitibility
➢slow contractility
➢high extensibility
➢tonicity ➢Sensitive for chemical,thermal and mechanical stretch stimulation
Chapter 6 Digestion and absorption
Introduction
Concepts of digestion and absorption Characteristics of the smooth muscle of gastrointestinal tract Secretory function of digestive gland
Characteristics: single or mutiple spikes which
Action: the number of spike potential determine contraction
Mechanism: depolarization: slow Ca2+-Na+channels Ca2+ inward flow , Na+ inward flow
Neural control of gastrointestinal tract
Endocrine function of gastrointestinal tract
Ⅰ. Concepts of digestion and absorption
The main types of foods Carbohydrads, fat , protein large molecules Vitamine, inorganic salt, water small
2. Electrophysiological characteristics Resting potential Slow wave potential Action potential
Fra Baidu bibliotek
Resting potential of smooth muscle IN GI
Value: -50 -60mV Formation:
Mechanism: cyclic changes of the activity of Na+ -K+ pump
Function: the base of AP formation
Action Potential
Inducing: the depolarization of slow wave reaches TP by stimulation
Mechanical Digestion:
The motility of smooth muscle in gastrointestinal tract grinds food and mixes it with digestive juice to prepare it for chemical digestion and absorption, and then propels the food along the gastrointestinal tract.
molecules
fiber
Digestion:
The breakdown of proteins, fats and carbohydrates into absorbable molecules in the gastrointestinal tract.
Protein amino acid Carbohydrate monosaccharide Fat fatty acid and glycerol
out flow of K+ ; Na+ Cl- Ca2+ electrogenic Na+ -K+ pump
Factors affecting RP: depolarization: stretch; Acetylcholine(Ach); Parasympathetic N. some gut hormone hyper depolarization: Epinephrine(E) Norepinephrine(NE) sympathetic N.
Chemical Digestion:
Nutrients in the food are broken down by the digestive juice secreted by the secretory glands.
Ⅱ.Characteristics of Gastrointestinal Smooth Muscle
Absorption:
The movement of the digested products ,water and electrolytes from the lumen of digestive tract into the
lymph or the blood.
closed relationship between digestion and absorption
Slow wave or basic electric rhythm (BER)
Definition: Spontaneous, slow and rhythmic fluctuation ( depolarization and repolarization) on resting potential in gastrointestinal smooth muscle cells.
Size: 5-15mV (from –65 to-45mV)
Frequency: 3-12/min stomach--- 3; duodenum---12; ileum---8，9
Origin: interstitial Cajal cells, which serve as pacemaker for GI smooth muscle
1. General physiological characteristics
➢low excitibility
➢slow contractility
➢high extensibility
➢tonicity ➢Sensitive for chemical,thermal and mechanical stretch stimulation
Chapter 6 Digestion and absorption
Introduction
Concepts of digestion and absorption Characteristics of the smooth muscle of gastrointestinal tract Secretory function of digestive gland
Characteristics: single or mutiple spikes which
Action: the number of spike potential determine contraction
Mechanism: depolarization: slow Ca2+-Na+channels Ca2+ inward flow , Na+ inward flow
Neural control of gastrointestinal tract
Endocrine function of gastrointestinal tract
Ⅰ. Concepts of digestion and absorption
The main types of foods Carbohydrads, fat , protein large molecules Vitamine, inorganic salt, water small
2. Electrophysiological characteristics Resting potential Slow wave potential Action potential
Fra Baidu bibliotek
Resting potential of smooth muscle IN GI
Value: -50 -60mV Formation:
Mechanism: cyclic changes of the activity of Na+ -K+ pump
Function: the base of AP formation
Action Potential
Inducing: the depolarization of slow wave reaches TP by stimulation
Mechanical Digestion:
The motility of smooth muscle in gastrointestinal tract grinds food and mixes it with digestive juice to prepare it for chemical digestion and absorption, and then propels the food along the gastrointestinal tract.
molecules
fiber
Digestion:
The breakdown of proteins, fats and carbohydrates into absorbable molecules in the gastrointestinal tract.
Protein amino acid Carbohydrate monosaccharide Fat fatty acid and glycerol
out flow of K+ ; Na+ Cl- Ca2+ electrogenic Na+ -K+ pump
Factors affecting RP: depolarization: stretch; Acetylcholine(Ach); Parasympathetic N. some gut hormone hyper depolarization: Epinephrine(E) Norepinephrine(NE) sympathetic N.
Chemical Digestion:
Nutrients in the food are broken down by the digestive juice secreted by the secretory glands.
Ⅱ.Characteristics of Gastrointestinal Smooth Muscle
Absorption:
The movement of the digested products ,water and electrolytes from the lumen of digestive tract into the
lymph or the blood.
closed relationship between digestion and absorption
Slow wave or basic electric rhythm (BER)
Definition: Spontaneous, slow and rhythmic fluctuation ( depolarization and repolarization) on resting potential in gastrointestinal smooth muscle cells.
Size: 5-15mV (from –65 to-45mV)
Frequency: 3-12/min stomach--- 3; duodenum---12; ileum---8，9
Origin: interstitial Cajal cells, which serve as pacemaker for GI smooth muscle