Muscle Tissue

Question 1

What is acetylcholine?

Answer 1

ACh - The neurotransmitter released at a neuromuscular junction.

Question 2

The characteristic that allows muscles to pull on bones and organs to create movement is called:

Answer 2

contractility

Question 3

How does muscle contraction occur?

Answer 3

The overlapping of myofilaments increases, shortening the overall sarcomere.

Question 4

What type of muscle cells have a fusiform shape and taper to a point at the end?

Answer 4

Smooth

Question 5

What does the sliding filament theory describe?

Answer 5

Muscle contraction

Question 6

Name three characteristics of cardiac muscle cells.

Answer 6

They contract with regular rhythm, they are resistant to fatigue, and they contract nearly in unison, it is rich in myoglobin, it has large stores of glycogen, it uses aerobic respiration almost exclusively

Question 7

What is acetylcholinesterase?

Answer 7

The enzyme that breaks down acetylcholine.

Question 8

What is the enzyme that breaks down acetylcholine?

Answer 8

acetylcholinesterase

Question 9

What is a motor unit?

Answer 9

All of the muscle fibers innervated by a single motor nerve fiber.

Question 10

Tell whether cardiac, smooth, and skeletal muscle are voluntary or involuntary

Answer 10

Cardiac: involuntary; smooth: involuntary; skeletal: voluntary

Question 11

When muscles stretch and recoil, they recoil to a shorter length. What is this property called?

Answer 11

Elasticity.

Question 12

What type of contraction involves the development of tension but no change in length?

Answer 12

Isometric

Question 13

What type of contraction involves the development of tension with a change in length

Answer 13

Isotonic

Question 14

How do smooth muscle myocytes differ from cardiocytes?

Answer 14

Smooth muscle myocytes have no T tubules while cardiac muscles do.

Question 15

What is the portion of a myofibril from one Z disc to another?

Answer 15

Sarcomere

Question 16

The step in which muscle fiber develops tension and may shorten is called what?

Answer 16

Contraction

Question 17

List the steps of muscle relaxation in order:

Answer 17

1: The nerve signal ceases. 2: AChE breaks ACh down. 3: Active transport pumps in the sarcoplasmic reticulum begin to pump calcium back into cisternae. 4: Calcium releases from troponin. 5: Tropomyosin covers the myosin binding sites.

Question 18

Describe some characteristics of smooth muscle.

Answer 18

Has no T-tubules, has little SR, is uninucleated, typically slow to contract and slow to relax

Question 19

What is the difference in electrical charge between one point and another?

Answer 19

electrical potential

Question 20

What is a feature unique to cardiac muscle?

Answer 20

intercalated discs

Question 21

What occurs during the relaxation phase of muscle contraction?

Answer 21

Myosin releases the thin filaments; calcium levels in the sarcoplasm fall; muscle tension declines

Question 22

What is the continuous, forceful contraction in a muscle with no relaxation between stimulii?

Answer 22

Complete tetanus

Question 23

What is the quick up-and-down voltage shift from negative to positive called, and what is it caused by?

Answer 23

Action potential, caused by the movement of Na and K across the cell membrane.

Question 24

Which membranous structures conduct impulses through the sarcoplasm to stimulate the release of calcium?

Answer 24

T-tubules

Question 25

What causes the opening of ion channels, resulting in the initial movement of Na and K across the plasma membrane at the neuromuscular junction? If continued, this can trigger an action potential at the neighboring sarcolemma?

Answer 25

end-plate potential

Question 26

What affects twitch strength?

Answer 26

How stretched the muscle was just before stimulation; temperature of the muscle; muscle fatigue; stimulation frequency

Question 27

What is myosin ATPase?

Answer 27

An enzyme located in the myosin head that hydrolyzes ATP

Question 28

How do resistance exercises cause muscle growth?

Answer 28

They increase the size of myofibrils.

Question 29

In which type of muscle can excitation be non-electrical?

Answer 29

Smooth muscle

Question 30

Which muscle tissue resists fatigue and frequently exhibits tetanus?

Answer 30

Smooth Muscle

Question 31

Fibers well adapted to aerobic respiration are called what -twitch fibers?

Answer 31

Slow twitch

Question 32

What is a thick filament composed of in myofibril?

Answer 32

pairs of myosin molecules intertwined together

Question 33

What is the indented region of a sarcolemma that participates in the neruomuscular junction called?

Answer 33

Motor end plate

Question 34

What is the name of the red pigment that stores oxygen needed for muscular activity?

Answer 34

myoglobin

Question 35

Which three situations lead to muscle fatigue in long-duration exercises?

Answer 35

Electrolyte loss, fuel depletion, and central fatigue

Question 36

Where is calcium stored in a skeletal muscle cell?

Answer 36

sarcoplasmic reticulum

Question 37

An overstretched or over contracted muscle will result in what?

Answer 37

A weak contraction

Question 38

In which type of contraction does a muscle shorten as it maintains tension?

Answer 38

Concentric

Question 39

In which type of contraction does a muscle lengthen as it maintains tension?

Answer 39

Eccentric

Question 40

When a muscle is at rest, which molecule blocks the active sites on the actin molecule?

Answer 40

Tropomyosin

Question 41

On a myogram, what is the time between the stimulus and the twitch?

Answer 41

latent period

Question 42

When acetylcholine binds to its receptors on the motor end plate, an ion channel opens, allowing which ions to diffuse quickly into the cell?

Answer 42

Sodium

Question 43

What is the change in membrane potential with the entry of sodium ions called?

Answer 43

Depolarization

Question 44

Which fibers are adapted for a quick response?

Answer 44

Fast glycolytic

Question 45

How does the action potential move deep into the muscle cell?

Answer 45

T-tubules

Question 46

Which structures coordinate contractions in cardiac muscle cells

Answer 46

Gap junctions

Question 47

Pockets within the sarcolemma of smooth muscle that contain calcium channels

Answer 47

caveolae

Question 48

During what period of a muscle twitch does a muscle fiber shorten and generate force?

Answer 48

contraction