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


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


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