BIOL373L Study Guide - Quiz Guide: Ileum, Duodenum, Membrane Potential
2 Mar 2018
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Biol 373l study questions experiment 4: orientation of smooth muscle and contraction. Inner circular layer contracts and decreases diameter, forms bolus, mixes food. Outer longitudinal layer relaxes and shortens the tube, moves along the gi tract: functional characteristics and anatomical features. Smooth muscles have gap junctions that allow coordinated action. All fibres of the single unit are connected to one another: locations of sphincters. At the anus/rectum: entry of ca2+ into smooth muscle. Voltage gated channels open; opens according to membrane potential. Ligand gated channels; influenced by binding of chemical messengers to receptors on cell surface. Stretch gated channels; open when cell is elongated: aerate liquid that surrounds intestine. Allows mixture of ion contents in water. Provides oxygen to allow muscle segment to continue contractions: hormone for inhibition of motility. Secretin is secreted by the mucosa of the duodenum in the lower gi tract. Specialized cells lining the upper small intestine detect acidic contents and are the stimulus of secretin.
