Muscle

Question 1

actin

Answer 1

A thin myofilament contained in muscle cell which, with myosin, is involved in the sliding filament model of muscle contraction.

Question 2

myosin

Answer 2

A thick myofilament contained in muscle cell which, with actin, is involved in the sliding filament model of muscle contraction.

Question 3

troponin

Answer 3

A protein in muscle cells which, when it binds to calcium, is responsible for muscle contraction by shifting the position of tropomyosin which allows the binding of actin and myosin.

Question 4

tropomyosin

Answer 4

Together with troponin, it covers the actin-myosin binding sites in muscle cells during relaxation.

Question 5

muscle fiber

Answer 5

Muscle cells

Question 6

sarcomere

Answer 6

The smallest unit of muscle contraction

Question 7

sarcoplasmic reticulum

Answer 7

a form of smooth endoplasmic reticulum found in muscle cells which stores calcium ions

Question 8

rigor mortis

Answer 8

The phenomenon in which calcium ions leak out of the sarcoplasmic reticulum after death, stiffening the body with muscle contractions, which stop after all the available ATP has been used

Question 9

antagonistic muscle pairs

Answer 9

A set of two muscles which produce movement when one muscle contracts and the other relaxes. Example: bicep/tricep

Question 10

extensor

Answer 10

The muscle in an antagonistic muscle pair which contracts during extension.

Question 11

flexor

Answer 11

The muscle in an antagonistic muscle pair which contracts during flexion.

Question 12

tendon

Answer 12

A band of connective tissue which attaches muscle to bone.

Question 13

ligament

Answer 13

A band of connective tissue which connects bone to bone.

Question 14

bicep

Answer 14

The flexor in the antagonistic muscle pair with the tricep.

Question 15

tricep

Answer 15

The extensor in the antagonistic muscle pair with the bicep.

Question 16

fast twitch muscles

Answer 16

type of muscle which contracts quickly when stimulate with little endurance.

Question 17

slow twitch muscles

Answer 17

type of muscle which contracts slowly when stimulated with great endurance.

Question 18

neuromuscular junction

Answer 18

The junction between a motor neuron and a skeletal muscle cell.

Question 19

motor unit

Answer 19

One motor neuron and all the muscle cells it stimulates.

Question 20

motor neuron

Answer 20

A neuron which carries information away from the brain and spinal cord to a muscle

Question 21

summation and tetanus

Answer 21

The phenomenon of successive muscle action potentials (twitches) allowing sustained movement. Tetanus results when there is no time for relaxation in between muscle twitches, and can only last until ATP runs out, resulting in fatigue.

Question 22

ATP

Answer 22

Energy source for cells. Stored ATP is the primary source of energy for muscle contractions

Question 23

creatine phosphate

Answer 23

A high energy compound stored in muscle tissue that converts ADP to ATP when ATP stores in the muscle have been depleted.

Question 24

anaerobic respiration

Answer 24

The process of converting glycogen stored in the muscles into glucose, used when creatine phosphate stores are depleted. Used for burst activities.

Question 25

aerobic respiration

Answer 25

The process of utilizing oxygen in hemoglobin or myoglobin to produce ATP during prolonged activity.

Question 26

List three different types of muscle.

Answer 26

Skeletal
Smooth
Cardiac

Question 27

What do the three muscle types have in common?

Answer 27

All are excitable (respond to stimuli)
All are contractile (ability to shorten)
All are extensible (stretchy)
All are elastic (return to their original shape after stretching)

Question 28

How is skeletal muscle different from smooth and cardiac muscle?

Answer 28

Skeletal muscle is large, long, and contains multiple nuclei per cell.

Question 29

Describe the sliding filament model of muscle contraction.

Answer 29

Actin filaments slide along myosin filaments, shortening the sarcomere without the filaments themselves shortening.

Question 30

What role does calcium play in muscle contraction?

Answer 30

Calcium binds to the troponin, causing it to change shape, move the tropomyosin, and allow the actin and myosin to bind.

Question 31

What triggers the release of calcium into the cytoplasm?

Answer 31

A nerve impulse from a motor neuron

Question 32

Which fatigues faster: fast twitch or slow twitch muscle?

Answer 32

fast twitch

Question 33

Why are drugs like steroids and testosterone attractive to body builders?

Answer 33

Because they stimulate the body’s ability to build muscle

Question 34

What are the side effects of using drugs like steroids and testosterone?

Answer 34

Damage to liver, cardiovascular damage, decreased testicle size, potential sterility, masculine traits in females.

Question 35

What are the four necessary steps of muscle contraction in the sliding filament model?

Answer 35

1) Cross-bridge attachment: myosin heads attach to nearest actin
2) Power stroke: binding causes release of energy, which causes myosin head to jerk back to bent position
3) Cross-bridge detachment: ATP molecules bind to the myosin head, causing myosin head to disengage from actin.
4) Myosin reactivation: Myosin head splits ATP into ADP and inorganic phosphate, which restarts the contraction cycle.

Question 36

Each time a muscle cell contracts (myosin and actin bind), two ATP molecules are used. List four sources for these ATP molecules.

Answer 36

1) stored ATP
2) creatine phosphate
3) anaerobic metabolic pathways
4) aerobic respiration