A&P Ch. 6 part. 1

What structure is the functional unit of contraction in a skeletal muscle fiber?

The sarcomere

Which neurotransmitter is released by motor neurons at the neuromuscular junction?

acetylcholine

What initiates an action potential on a muscle cell?

acetylcholine binding to receptors on the sarcolemma within the neuromuscular junction

What mineral is released within muscle cells to trigger contraction?

calcium

Striated involuntary muscle tissue is classified as ________ muscle

cardiac

Striated involuntary muscle tissue found in the heart is ________.

cardiac muscle

What type of muscle tissue is both striated and involuntary?

cardiac muscle

The heads of the myosin myofilaments are called ________ when they link the thick and thin filaments together during skeletal muscle contraction.

cross bridges

Which layer of connective tissue surrounds each skeletal muscle fiber?

endomysium

The prefix ____ means "above," "upon" or "over."

epi-

The connective tissue covering on the outside of a whole muscle is the _________

epimysium

What term describes the ability of a muscle to vary its degree of shortening to generate the strength needed to lift a 5 lb weight, a 7 lb weight, and finally a 10 lb weight?

graded responses

Which of these characteristics applies only to cardiac muscle tissue?

intercalated discs

the prefix ___ means "equal" or "same."

iso-

A type of muscle contraction that generates force, but does not shorten the muscle is called ________

isometric

Which chemical is produced during vigorous exercise when the supply of oxygen is limited or inadequate?

lactic acid

The prefix _____ means "muscle."

myo-

The part of a muscle fiber that contracts is called a/an _________

myofibril

The prefix _____ means "around."

peri-

The connective tissue covering around a fascicle is the _________

perimysium

Which connective tissue bundles muscle fibers into fascicles?

perimysium

The prefix ______ means "flesh."

sarco-

The plasma membrane of a skeletal muscle cell is called the ________.

sarcolemma

The structural and functional unit of skeletal muscle is called a/an _________

sarcomere

What organelle wraps and surrounds the myofibril and stores calcium?

sarcoplasmic reticulum

A sarcomere is ________.

the contractile unit between two Z discs

After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment?

ATP binds to the myosin head.

Which method of regenerating ATP during muscle contraction can produce lactic acid?

Anaerobic glycolysis

Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber?

Calcium ions are stored in the sarcoplasmic reticulum.

What specific event triggers the uncovering of the myosin binding site on actin?

Calcium ions bind to troponin and change its shape

What creates the alternating light and dark bands that provides the striation pattern on skeletal muscle tissue?

A bands and I bands

The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge?

A myosin head bound to actin

When does cross bridge cycling end?

Cross bridge cycling ends when sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin.

How does the myosin head obtain the energy required for activation?

The energy comes from the hydrolysis of ATP.