Chapter_35

Chapter_35 - Chapter 35 BIO 1002 Chapter 35 Action and...

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Unformatted text preview: Chapter 35 BIO 1002 4/22/2008 Chapter 35 : Action and Support: The Muscles and Skeletons A. 3 Types of Muscles : 1. Skeletal: moves the skeleton 2. Cardiac: forms the heart 3. Smooth: surrounds many organs (particularly of the digestive system) and blood vessels B. Skeletal Muscles : Structure : muscle muscle fiber (run the entire length of the muscle [up to 35 cm] and stripped in appearance ) myofibril (contractile units) aligned lengthwise sarcomere (contractile subunits) which are cross- wise sections of the myofibril thick and thin filaments are connected by a myosin cross-bridge Figure Muscle contractions : 1) Thin filament binding sites must be exposed 2) cross-bridges attach to the binging sites 3) Using energy from ATP, cross-bridges release and reattach farther up (like climbing hand over hand) 4) Pulls thin filament past the thick filament shortening sarcomere and contracting muscle Muscle control : Muscle fibers produce action potential: 1. Motor neuron releases neurotransmitters 2. Muscle fibers forms a postsynaptic action potential 3. Accessory proteins expose binding sites 4. Action potential ends, accessory proteins cover binding sites ending contraction 3 Types of Skeletons: 1. Hydrostatic skeleton : consists of a fluid filled sac: fluid can’t compress, so when the sac is squeezed narrower it lengthens the body, and when it is squeezed shorter it widens the body Examples: worm moving, tongue 2. Exoskeleton : (arthropods, hard outer shell, must be shed to grow, “molting”) Example: crawfish, lobsters, crab 1 Chapter 35 BIO 1002 4/22/2008 3. Endoskeleton : internal skeleton find in vertebrates 5 Functions of Vertebrate Skeleton: a. Support and protect internal organs b. Movement c. Produce blood cells (in bone marrow) d. Store calcium and phosphorous e. Hearing (3 small bones in the inner ear, vibrate and respond to sound) Vertebrate Skeletal Tissues : 1. Cartilage : living cells that secrete a flexible, elastic, nonliving collagen matrix. Matrix makes up most of the cartilage. No blood vessels (but still receive oxygen by diffusion) Functions: 1) Forms embryonic skeleton 2) Covers bone ends 3) Outer ear and nose tip are flexible...
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Chapter_35 - Chapter 35 BIO 1002 Chapter 35 Action and...

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