lab_8-intestinal_motility

lab_8-intestinal_motility - Lab 8 Intestinal Motility...

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Unformatted text preview: Lab 8 Intestinal Motility Gastrointestinal System Mouth -> esophagus -> stomach -> small intestine -> large intestine Accessory Glands/organs: salivary glands, pancreas (enzymes & bicarb.), liver (bile) Gastrointestinal system works to deliver nutrients and water to the body by breaking down food (digestion) and absorbing these smaller solutes that are moved (motility) through the different sections of the GI tract GI Tract Anatomy GI tract varies along its length but has a common structure organization: Mucosa : epithelial layer, lamina propria (capillaries, enteric neurons & immune cells), and a smooth muscle layer (lamina muscularis mucosae) Submucosa : loose connective tissue & larger blood vessels and glands Muscle Layer : Muscularis externa has 2 layers of smooth muscle (SM) Inner layer of circular SM (changes diameter) and an outer layer of longitudinal SM (changes intestinal length) Serosa : Layer of connective tissue covered by epithelial Gastrointestinal Motility Segmentation : Segments along the small intestine contract for mixing Moves the intestinal content back and forth to provide mixing and increases the time for nutrient absorption Peristalsis: Propels the bolus forward Involves the contraction and shortening of the circular muscle and relaxation of the longitudinal muscle before the bolus and the shortening of the longitudinal muscle and relaxation of the circular muscle after the bolus Smooth Muscle Spindle shaped cells with a single nucleus Contain thick myosin filaments, thin actin filaments (contain tropomyosin, but no troponin) and intermediate filaments that help support the structure of the cell Actin and myosin in SM are not regularly arranged so there is no striated pattern (No sarcomeres or myofibrils) Actin filaments are anchored to dense bodies (same protein as in z- bands) that are found throughout the SM cell SM does not have T-tubules or lateral sacs and they have a poorly developed SR SM cells do not have a specialized motor end plate. Neurons synapse...
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This note was uploaded on 03/01/2010 for the course NPB101L 83009 taught by Professor Liets during the Spring '09 term at UC Davis.

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lab_8-intestinal_motility - Lab 8 Intestinal Motility...

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