Segmentation: mix contents to promote digestion absorption Segmental contractions are responsible for mixing No net forward movement Q
11 Segmentation: mix contents to promote digestion & absorption
Peristalsis Distinctive pattern of smooth muscle conttactiers that propels foodstuffs distally through the esophagus and intestines Mediated by Local, intrinsic nervous system Ex: peristalsis is not affect to any significant degree by vagotomy or sympathectomy
12 Peristalsis • Distinctive pattern of smooth muscle contractions that propels foodstuffs distally through the esophagus and intestines • Mediated by…. • Local, intrinsic nervous system • Ex: peristalsis is not affect to any significant degree by vagotomy or sympathectomy
Small Intestinal Motility Peristalsis: movement along the tract Peristaltic contractions are responsible for forward movement Contraction Bolus Receiving segment Time zero : , Bolus moves forward Seconds later::.'s Direction of movement
13 Small Intestinal Motility Peristalsis: movement along the tract
Peristalsis Longitudinal muscle Contraction Circular muscle STEP 1: From Contraction of circular muscles mouth- nus behind food STEP 2: Contraction Contraction of muscles ahead of food mass Contraction STEP 3: Contraction of circular muscle layer forces food mass
14 Peristalsis Figure 24.4
图1,14位相性收缩在十二指肠中传播较 图中符号后的数字指的是该传感器距幽门 允许,引自 Sarma SK, SG3-59 MF. Small inte Clin North Am 入八八^入 peristalsis m 八八八八八八八 s0Bn人人人人入^~八八入入 字指的是该传 ysiology and Clin North An,198918375-405 sG1233 八 图1,16远 运动以非推进性收缩 sG18395 gy. Gastroenterol 八八八 in North An,198918:375=405 sG224 sG24419 人八人 15
15 peristalsis