Lecture Notes Chapter 49a

Lecture Notes Chapter 49a - Chapter 49: Motor Mechanisms...

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Chapter 49: Motor Mechanisms Animal skeletons function in support, protection, and movement The various types of animal movements all result from muscles working against some type of skeleton. The main functions of a skeleton are: support, protection, and movement Types of Skeletons Hydrostatic skeletons Exoskeletons endoskeletons Hydrostatic Skeletons A hydrostatic skeleton consists of fluid held under pressure in a closed body compartment This is the main type of skeleton in most cnidarians, flatworms, nematodes, and annelids o Annelids use their hydrostatic skeleton for peristalsis a type of movement on land produced by rhythmic waves of muscle contractions Exoskeletons An exoskeleton is a hard encasement deposited on the surface of an animal o Exoskeletons are found in most molluscs and arthropods Endoskeletons An endoskeleton consists of hard supporting elements such as bones, buried within the soft tissue of an animal o Endoskeletons are found in sponges, echinoderms, and chordates The mammalian skeleton is built from more than 200 bones o Some fused together and others connected at joints by ligaments that allow freedom of movement In addition to the skeleton muscles and tendons help support large land vertebrates Muscles move skeletal parts by contracting Skeletal muscles are attached to the skeleton in antagonistic pairs with each member of the pair working against each other Vertebrate Skeletal Muscle Skeletal muscle is also called striated muscle because the regular arrangement of the myofilaments creates a pattern of light and dark bands, particularly in polarized light Each repeating unit is a sarcomere – the smallest functional unit of striated muscle Bordered by Z lines The areas that contain the myofilments are the I band, A band, and H zone o Named after their appearance in polarized light ( isotropic band, anisotropic band)
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Vertebrate skeletal muscle is characterized by a hierarchy of smaller and smaller units A skeletal muscle consists of a bundle of long muscle fibers running parallel to the
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This note was uploaded on 09/28/2009 for the course BIOL 172 taught by Professor Staff during the Spring '08 term at Hawaii.

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Lecture Notes Chapter 49a - Chapter 49: Motor Mechanisms...

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