Test 4


What are the types of muscle tissues


Skeletal, cardiac, and smooth


What does the skeletal muscle do


attaches to bones and skin, its striated, voluntary, and powerful


What is the cardiac muscle


Its only in the heart, striated and involuntary


What is the smooth muscle


In the walls of hollow organs, stomach, urinary bladder, blood vessels, and airways, not striated, involuntary


What are the muscle functions


The movement of bones of fluids, mainting posture and body positions, stabilizing joints, and heat generation


What happens in the skeletal muscle


each muscle is served one artery, one nerve, and one or more veins


The Epimysium does what


surrounds the entire muscle, covered by what makes up tendons


What does Perimysium do


surrounds fascicles


What surrounds each muscle fiber


Endomysium


Muscles attach


Directly and indirectly


What happens Directly


epimysium of muscle is fused to the periosteum of bone or perichondrium of cartilage


What happens Indirectly


connective tissue wrappings extend beyond the muscle as a ropelike tendon or sheetlike aponeurosis


What are myofibrils


densely packed, rodlike elements, 80% of cell volume


Exhibit striations are what


perfectly aligned repeating series of dark A bands and light I bands


What is the smallest contractile unit muscle fiber, region of a myofibril between two successive Z discs, thick & thin myofilaments made of contractile proteins


Sarcomere


what are the features of sarcomere


thick filaments, thin filaments, and z discs


What do thick filaments do


run the entire length of an A band


What do thin filaments do


run the length of the I band and partway into the A band


What do Z discs do


Connect myofibrils to one another


What is contraction


The generation of force, does not cause shortening of the fiber, shortening occurs tension generated by cross bridges thin filaments exceeds forces opposing shortening


What are the requirements for skeletal muscle contaction


activation and excitation


What is activation


neural stimulation at a neuromuscular junction


What is excitation


Contraction coupling, generation and propagation of an action potential along the sarcolemma, final trigger a brief rise in intracellular Ca2+ levels


What are the cross bridge cyle


cross bridge formation, working stroke, cross bridge detachment, cocking of the myosin head


high energy myosin head attaches to thin filaments


cross bridge formation


myosin head pivots and pulls thin filament toward M line


Working stroke


ATP attaches to myosin head and cross bridge detaches


cross bridge detachment


Energy from hydolysis of ATP cooks the myosin head into the high-energy state


cocking of the muscle head


What is an isometric contraction


no shortening, muscle tension increases but does not exceed the load


What is a Isotonic contraction


muscle shortens because muscle tension exceeds the load


What is a motor unit


a motor neuron and all muscle fibers it supplies


What is a large motor unit


In large weight bearing muscles(thighs, hip)


What is a small motor unit


units in muscles that control fine movements