Chapter 9 & 10

Question 1

Action potential

Answer 1

A rapid change in a cell’s electrical charge that reverses the plasma membrane’s electrical polarity.

Question 2

Muscle fiber

Answer 2

Muscle cell

Question 3

neuromuscular junction

Answer 3

The junction between nerve endings and muscle fibers.

Question 4

Axon

Answer 4

A nerve fiber that sends nerve impulses.

Question 5

Synaptic knob

Answer 5

The enlargement at the end of an axon that secretes a neurotransmitter.

Question 6

Neurotransmitter

Answer 6

A chemical in the neuromuscular junction that aids in stimulating or inhibiting muscle contraction.

Question 7

Protein

Answer 7

An organic substance composed of linked amino acid molecules.

Question 8

Ligand gated ion channel

Answer 8

A channel that opens or closes when a ligand is bound to the receptor site.

Question 9

Resting Membrane Potential

Answer 9

The difference between the electric charge inside the membrane and just outside the membrane.

Question 10

End Plate Potential

Answer 10

A rapid change in membrane voltage.

Question 11

Sarcolemma

Answer 11

The cell membrane of a muscle fiber.

Question 12

T Tubules

Answer 12

Tube-like canals in the sarcolemma that deliver action potentials into the muscle fiber.

Question 13

Cytosol

Answer 13

The fluid matrix of the cytoplasm.

Question 14

Troponin

Answer 14

The protein component of the actin filament that helps block myosin from binding until calcium is present.

Question 15

Tropomyosin

Answer 15

The protein of the actin filament that blocks myosin from binding until calcium is present.

Question 16

Myosin

Answer 16

A thick myofilament in the sarcomere that acts with actin to contract and relax muscles.

Question 17

Actin

Answer 17

A thin myofilament in the sarcomere that is responsible for contraction and relaxation.

Question 18

Cross-bridge

Answer 18

The connection between the actin and myosin filaments where myosin heads bind.

Question 19

Myosin head

Answer 19

Globular protrusions on a myosin filament that bind to actin filaments to form cross-bridges.

Question 20

Ligand

Answer 20

A molecule that binds to a receptor site or enzyme.

Question 21

Cisternae

Answer 21

The interior space of the sarcoplasmic reticulum where calcium is stored.

Question 22

Antagonistic muscles

Answer 22

The other force is an opposite muscle that is paired with the first. This opposing muscle contracts to relieve the first muscle.

Question 23

Sliding filament theory

Answer 23

A theory that explains that muscles contract when thick and thin filaments slide past each other.

H zones and I bands of skeletal muscle fibers get narrower because of overlap and the Z lines compress closer to one another.

Question 24

contractility

Answer 24

(shortens forcefully),

Question 24

Myasthenia gravis

Answer 24

is a common disorder that inhibits action potentials that occur at the neuromuscular junction.

Question 25

excitability

Answer 25

(responds to stimuli),

Question 26

extensibility

Answer 26

(can be stretched and still contract),

Question 27

elasticity

Answer 27

(recoils to resting length).

Question 28

Myofibrils

Answer 28

are composed of two major protein fibers: actin and myosin.

Question 29

Depolarization

Answer 29

results from an increase in the permeability of the plasma membrane to Na+.

Question 30

The repolarization phase

Answer 30

of the action potential occurs when the Na+ channels close and the K+ channels open briefly.

Question 31

Isometric contractions

Answer 31

cause a change in muscle tension but no change in muscle length.

Question 32

Isotonic contractions

Answer 32

cause a change in muscle length but no change in muscle tension.

Question 33

Treppe

Answer 33

is an increase in the force of contraction during the first few contractions of a rested muscle.

Question 34

Incomplete tetanus

Answer 34

is partial relaxation between contractions;

Question 35

complete tetanus

Answer 35

is no relaxation between contractions.

Question 36

Multiple-motor-unit recruitment Muscle tone is the maintenance of steady tension for long periods.

Answer 36

results in more motor units responding to greater stimuli.

Question 37

Concentric contractions

Answer 37

cause muscles to shorten and tension to increase.

Question 38

Eccentric contractions

Answer 38

cause muscles to lengthen and tension to decrease gradually.

Question 39

Asynchronous contractions of motor units

Answer 39

produce smooth, steady muscle contractions.

Question 40

Slow twitch muscle fibers

Answer 40

Slow-twitch muscle fibers break down ATP slowly and have a well-developed blood supply, many mitochondria, and myoglobin. Long distance runners. Slow-twitch muscle fibers contract slowly and can remain contracted for longer amounts of time without becoming fatigued.

Question 41

Fast-Twitch Muscle Fibers

Answer 41

Fast-twitch muscle fibers break down ATP rapidly. Sprinters. Human muscle fibers that contract rapidly; become tired quickly when contracted.

Question 42

Visceral smooth muscle fibers - Smooth muscle

Answer 42

contract slowly, have gap junctions (and thus function as a single unit), and can be autorhythmic. More common in the body; works throughout the entire body

Question 43

Multiunit smooth muscle fibers - Smooth muscle

Answer 43

contract rapidly in response to stimulation by neurons and function independently. Contracts only when told to by nerves and hormones

Question 44

Smooth muscles

Answer 44

Fine and randomly organized, smooth muscles are short and have only one nucleus per fiber. Like cardiac muscles, smooth muscle movement is involuntary. They assist with digestion.

Question 45

Cardiac muscle

Answer 45

Your heart contains powerful cardiac muscles composed of cylindrical cells that branch. They pump involuntarily to send blood to every cell in your body.

Question 46

Skeletal

Answer 46

This muscle usually connects two bones, spanning between the bones to hold a joint together. When you contract skeletal muscle, it moves one bone in relation to another. Its fibers are long and thin.

Question 47

Electrical signal

Answer 47

A signal sent by the nervous system when there is a change in electrical charge between two points.

Question 48

Aerobic exercise

Answer 48

Aerobic exercise (like running) helps increase strength in slow-twitch muscles. It can also help convert fast-twitch fatigable muscle fibers into fast-twitch-fatigue-resistant fibers, allowing the muscle to become stronger and work longer.

Question 49

Anaerobic exercise

Answer 49

Anaerobic exercise (like weight-lifting) increases muscle mass and strength and also strengthens fast-twitch muscles.

Question 50

origin

Answer 50

The less movable end of a muscle attachment

Question 51

insertion

Answer 51

the more movable end is the

Question 52

An agonist

Answer 52

causes a certain movement

Question 53

Antagonist

Answer 53

acts in opposition to the agonist.

Question 54

Synergists

Answer 54

are muscles that function together to produce movement.

Question 55

Prime movers

Answer 55

are mainly responsible for a movement.

Question 56

Fixators

Answer 56

stabilize the action of prime movers.

Question 57

fulcrum

Answer 57

is located between the pull and the weight.

Question 58

weight

Answer 58

is located between the fulcrum and the pull.

Question 59

pull

Answer 59

is located between the fulcrum and the weight.