Muscular System

Question 1

What are the basic functions of muscle?

Answer 1

1. Voluntary body movement
2. Stability of support
3. Movement of blood, food, urine
4. Control of body openings and passages

Question 2

What are the 4 properties of muscle tissue and why are they important?

Answer 2

1. Excitability - change electrical state
2. Contractility - to shorten in length
3. Extensibility - to stretch in length
4. Elasticity - to return to original shape

Question 3

What is action potential?

Answer 3

The change in voltage of a cell membrane in response to a stimulus that allows it to do something

Question 4

What does a relaxed muscles have?

Answer 4

Resting membrane potential

Question 5

List the layers of connective tissue around a muscle from deep to superficial

Answer 5

1. Endomysium - loose CT covering that surrounds each muscle fiber
2. Perimysium - CT covering that bundles skeletal muscle fibers into fasicles
3. Epimysium - Outer CT layer that surrounds skeletal muscle
4. Fascia - dense CT layer that covers and separates groups of muscles

Question 6

At least how many attachment sites does a muscle have?

Answer 6

Two: origin and insertion

Question 7

Origin

Answer 7

Anchoring end of a muscle, usually proximal-most. Doesn’t move, pulls muscle toward it.

Question 8

Where do muscles pull toward?

Answer 8

The origin

Question 9

Belly (of a muscle)

Answer 9

Midsection, central bulky body of muscle that contracts

Question 10

Insertion

Answer 10

Opposite end of origin, the end that pulls

Question 11

Tendon

Answer 11

Dense cord-like CT structure that anchors muscle to a bone

Question 12

Aponeurosis

Answer 12

A sheet of CT that anchors muscles to each other or to bone

Question 13

What is true about muscles that span a joint?

Answer 13

The origin is on one side and the insertion is on the other

Question 14

Prime Mover (Agonist)

Answer 14

Produces the most force during a joint action

Question 15

Synergist

Answer 15

Adds force to a movement with the prime mover

Question 16

Antagonist

Answer 16

Opposes or reverse motion of the prime mover

Question 17

Fixator

Answer 17

Synergist that immobilizes bone at muscle’s origin

Question 18

List the criteria for naming a muscle

Answer 18

Associated bone or body region
Shape
Muscle action
Relative size
Number of origina
Direction of muscle fibers
Location of origin or insertion

Question 19

Sacrolemma

Answer 19

Plasma membrane of muscle cell

Question 20

Sarcoplasm

Answer 20

Cytoplasm of the muscle cell
glycogen storage form of glucose
myoglobin protein to store oxygen

Question 21

Myofibrilis

Answer 21

Long cylindrical strands of connective proteins

Question 22

Sarcoplasmic reticulum

Answer 22

A smooth ER that stores Ca ions

Question 23

T-tubules

Answer 23

Inward projections of sarcolemma that tunnel into a cell, carries the electrical signal from the neuromuscular junction to sarcolemma, causing release of Ca from sarcoplasmic reticulum

Question 24

Terminal Cisternae

Answer 24

Enlarges areas of SR around the T-tubules

Question 25

Triad

Answer 25

One T-tubule bordered by two terminal cisternae

Question 26

Myosin

Answer 26

Protein if a thick filament, grabs actin to shorten sarcolemma and **contract** the muscle

Question 27

Actin

Answer 27

Protein of thin filament that contains binding sites for myosin

Question 28

Troponin

Answer 28

Regulatory protein that binds actin, tropomyosin and calcium

Question 29

Tropomyosin

Answer 29

Regulatory protein that covers myosin-binding sites on actin

Question 30

What are the contractile proteins that make sarcomere?

Answer 30

**z-disc** anchors thin filaments at the ends of the sarcomere **thick filament** the center **thin filamenrs** attach at z-disc and extend toward the center

Question 31

Sarcomere

Answer 31

Longitudinally repeating contractile units of skeletal muscle

Question 32

Motor Unit

Answer 32

A motor neuron and the group of muscle fibers that it innervates

Question 33

Somatic motor neurons

Answer 33

Control skeletal muscular contractions

Question 34

What does a muscle need to contract?

Answer 34

A signal

Question 35

Neurotransmitter

Answer 35

A chemical released by a neuron to control target cells

Question 36

What is the neurotransmitter that stimulates a muscle contraction?

Answer 36

Acetylcholine (ACh)

Question 37

What breaks down ACh?

Answer 37

A-cetyl-cho-lin-este-rase

Question 38

What is the relationship between motor unit size and muscle force?

Answer 38

Size matters: it determines the amount of control. It is possible to recruit more units for stronger muscle contractions