How are the foodstuffs digested
How are the foodstuffs digested ?
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. Chemical Digestion: Nutrients in the food are broken down by the enzymes in digestive juice secreted by the secretory glands
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. Chemical Digestion: Nutrients in the food are broken down by the enzymes in digestive juice secreted by the secretory glands
I. Characteristics of Gastrointestinal Smooth muscle 1. General physiological characteristics >low excitibility >slow contractility > high extensibility >tonicity >Sensitive for chemical, thermal and mechanical stretch stimulation
1. General physiological characteristics Ⅱ.Characteristics of Gastrointestinal Smooth Muscle ➢low excitibility ➢high extensibility ➢tonicity ➢Sensitive for chemical, thermal and mechanical stretch stimulation ➢slow contractility
2. Electrophysiological characteristics +Resting potential +Slow wave potential rAction potential Relationship between Electrical Activity and Contractile Activity SPIKES Electrical Threshold Threshold for contraction SLOW WAVES
2. Electrophysiological characteristics Slow wave potential Action potential Resting potential
Resting potential of smooth muscle In gi Value:-50---60mV Formation out flow of K+: Nat ca2+ electrogenic Nat-K pump
Resting potential of smooth muscle IN GI Value: -50 -60mV Formation: out flow of K+ ; Na+ Ca2+ electrogenic Na+ -K+ pump