jimtrue.com : school : BSC2011 : CH 49: Animal Systems - Muscles (pp 1080-1086)

Posted by Jim True on November 4, 2004 5:57 PM. Last Updated October 22, 2006 9:23 PM

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CH 49: Animal Systems - Muscles (pp 1080-1086)

Functions

• Movement - Virtually all locomotoin and physial movement of body involves muscle activity of some type.
• Internal Transport - Processes of digestion, circulation, gas exchange (with respiratory system).
• Temperature Maintenance - The major source of internal heat production is the release of waste heat by muscle activity.
• Protection - Muscles often overlie and protect delicate internal organs, e.g., abdominal muscles.

Muscles by Phyla

• P. Porifera - Remember these have NO systems of any kind! Cells can use expansion and contraction of cytoplasm to open/close pores, but no real muscles.
• P. Cnidaria - Possess epitheliomuscular cells, columnar epithelium with myofibrils (contractile proteins). Help animal to move and expand and contract gastrovascular cavity (gut).
• P.Platyhelminthes - Muscle groups usually work in antagonistic pairs (as one set contracts, antagonists relax and vice versa).
• Well supplied with longitudinal and circular skeletal muscles, especially in C.Turbellaria
• P. Nematoda - Unique among animals, possess ONLY logitudinal muscles.
• Results in very wide side-to-side thrashing, which is dampened by surroundings (soil, flesh, etc.).
• P.Mollusca - Muscles include fast contracting skeletal muscles for rapid movement.
• In many cases, fast muscle is mixed with slow contracting muscles, for example, to close a shell quickly (fast) and then hold it closed (slow).
• P.Annelida - Well developed circular and longitudinal skeletal muscles.
• Body is moved in many species by peristalsis, a wavelike series of progressive contractions that move down the length of the body (same thing that occurs in digestive and circulatory systems).
• P.Arthropoda - Well developed striated musculature, allows rapid, dextrous movement.
• In insects, myofibrillar muscles for wings are present. These contract over very short distances extremely rapidly to allow the wings to beat fast enough to lift the body.
• P.Echinodermata - Skeletal muscles weakly developed in all but the C.Ophiuroidea (brittle stars).
• Most echinoderms use a unique water vascular system (will discuss later) to move, ophiuroids use muscles (fastest moving of the echinoderms).
• P.Chordata - Muscles and muscle system well developed.
• In larval Urochordata, Cephalochordata and fishes, body musculature is arranged in mytotomes, V or W shaped blocks of muscle somites arranged for body flexibility and side-to-side undulatory motion (s or wave like pattern).

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