Chapter5 Digestion and Absorption Section 1 Introduction Section2 Ingestion Section3 Digestion in Mouth Section4 Digestion in Stomach Section5 Digestion in Small Intestine Section6 Digestion in Large Intestine Section7 Absorption
Chapter5 Digestion and Absorption Section 1 Introduction Section2 Ingestion Section3 Digestion in Mouth Section4 Digestion in Stomach Section5 Digestion in Small Intestine Section6 Digestion in Large Intestine Section7 Absorption
Section 1 Introduction
Section 1 Introduction
GI tract mouth,pharynx(咽)， Parotid salivary gland esophagus(食管)， Mouth Sublingual salivary gland- Pharynx stomach, Trachea small intestine Submandibular salivary gland Esophagus large intestine Accessory Glandular Liver- Stomach Gallbladder Pancreas Organs salivary glands(唾液腺) Small intestine liver, Colon Cecum Large Gallbladder(胆囊) intestine Rectum Anus pancreas(胰腺)
GI tract mouth, pharynx(咽), esophagus(食管), stomach, small intestine, large intestine Accessory Glandular Organs salivary glands(唾液腺) liver, Gallbladder(胆囊) pancreas(胰腺)
The conception of digestion and absorption Digestion:Process by which food and large molecules are degraded to produce smaller molecules that can be absorbed across the wall of the gastrointestinal tract. Absorption:Process by which nutrient molecules are absorbed by cell that 人類的消化系统 @束只大学版检石 line the gastrointestinal tract and enter the bloodstream
The conception of digestion and absorption Digestion: Process by which food and large molecules are degraded to produce smaller molecules that can be absorbed across the wall of the gastrointestinal tract. Absorption: Process by which nutrient molecules are absorbed by cell that line the gastrointestinal tract and enter the bloodstream
Patterns of digestion (1)Mechanical Digestion (2)Chemical digestion (3)Microbial digestion
(1)Mechanical Digestion (2)Chemical digestion (3)Microbial digestion Patterns of digestion
碳水化合物 物理消化 消化 化学消化 微生物消化 蛋白质 吸收 废物排出 脂肪 水、维生素和无机盐：直接吸收
水、维生素和无机盐: 直接吸收 蛋白质 碳水化合物 脂肪 消化 吸收 废物排出 物理消化 化学消化 微生物消化
General properties of gastrointestinal smooth muscle 1.Lower excitability,slower contraction and relaxation 2.Autorhythmicity 3.Higher extensibility 4.Tonic contraction(紧张性收缩) 5.More sensitive to stretch,chemicals,cold and warm stimulation but not to electric stimulation
General properties of gastrointestinal smooth muscle 1. Lower excitability, slower contraction and relaxation 2. Autorhythmicity 3. Higher extensibility 4. 5. More sensitive to stretch, chemicals, cold and warm stimulation but not to electric stimulation Tonic contraction(紧张性收缩)
Electrical activity of GI smooth muscle 1.Resting potential 2.Slow wave or basic electric rhythm (BER) Basic electrical rhythm is the spontaneous rhythmic,subthreshold depolarization of the cell membrane in the gastrointestinal tract
Electrical activity of GI smooth muscle 1. Resting potential 2.Slow wave or basic electric rhythm (BER) Basic electrical rhythm is the spontaneous rhythmic, subthreshold depolarization of the cell membrane in the gastrointestinal tract
Slow waves are changes in resting membrane potential > 3-12 cycles per minute depending on area of GI tract -3/min in stomach,12/min small intestine Always present but do not always cause contractions Frequency of contractions dictated by frequency of slow waves
➢ Slow waves are changes in resting membrane potential ➢ 3-12 cycles per minute depending on area of GI tract - 3/min in stomach, 12/min small intestine ➢ Always present but do not always cause contractions ➢ Frequency of contractions dictated by frequency of slow waves
3.Action potentional 当慢波电位超过一定临界值时，可触发一个或多个 动作电位。 动作电位的数目越多，肌肉收缩的幅度就越大。 刺激迷走神经可引起肠平滑肌发生较大和多个动作 电位并引发较强的收缩；刺激交感神经则降低动作电 位 Rp一BER一阈电位一Ap 去极化：Ca2+内流 人风A 1.5 Action potentials 复极化：K+外流 Slow waves 5 sec
3.Action potentional 当慢波电位超过一定临界值时，可触发一个或多个 动作电位。 动作电位的数目越多，肌肉收缩的幅度就越大。 刺激迷走神经可引起肠平滑肌发生较大和多个动作 电位并引发较强的收缩；刺激交感神经则降低动作电 位。 Rp —BER — 阈电位— Ap 去极化:Ca 2+内流 复极化:K+外流