ZOL 03-31-08 - ZOL 328 03/31/08 MUSCLE - most responses...

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ZOL 328 03/31/08 MUSCLE - most responses muscle contraction - muscles are major effectors; they are the things that allow us to respond to whatever it is that’s going on around us - they move an animal or part of an animal through the environment - also move material such as food, air, and blood through the animal - they provide support by bracing our joints (such as the body wall) - heat production – endothermy - electric organs in rays and electric eels are modified muscle Development – cellular - muscle nearly always comes from mesodermal mesenchyme (mesenchyme: wandering cells) - the mesenchyme cells elongate and at that point are called myoblasts - they start to synthesize contactile (contractile???) proteins – actin, myosin The mature muscle “cells” are called muscle cells, myocytes, or muscle fibers. There are three different types of muscle based on their histology: 1) Skeletal muscle/striated muscle (in terms of histological tissue)/voluntary muscle - these are the muscles that move and support the skeleton - during development, many myoblasts fuse end to end - each fiber is a syncytium (there are many nuclei within one cell membrane) - this is why they are not really muscle cells , but muscle fibers - each fiber may be several centimeters long - they can either extend the full length of the muscle - or they can terminate in the connective tissue in the muscle Striated – actin and myosin are lined up; you can see the pattern under a microscope
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This note was uploaded on 06/29/2008 for the course ZOL 328 taught by Professor Hill during the Spring '08 term at Michigan State University.

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ZOL 03-31-08 - ZOL 328 03/31/08 MUSCLE - most responses...

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