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.