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Flashcards in Muscle Tissue Deck (48):
1

What is acetylcholine?

ACh - The neurotransmitter released at a neuromuscular junction.

2

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

contractility

3

How does muscle contraction occur?

The overlapping of myofilaments increases, shortening the overall sarcomere.

4

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

Smooth

5

What does the sliding filament theory describe?

Muscle contraction

6

Name three characteristics of cardiac muscle cells.

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

7

What is acetylcholinesterase?

The enzyme that breaks down acetylcholine.

8

What is the enzyme that breaks down acetylcholine?

acetylcholinesterase

9

What is a motor unit?

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

10

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

Cardiac: involuntary; smooth: involuntary; skeletal: voluntary

11

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

Elasticity.

12

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

Isometric

13

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

Isotonic

14

How do smooth muscle myocytes differ from cardiocytes?

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

15

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

Sarcomere

16

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

Contraction

17

List the steps of muscle relaxation in order:

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.

18

Describe some characteristics of smooth muscle.

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

19

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

electrical potential

20

What is a feature unique to cardiac muscle?

intercalated discs

21

What occurs during the relaxation phase of muscle contraction?

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

22

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

Complete tetanus

23

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

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

24

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

T-tubules

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?

end-plate potential

26

What affects twitch strength?

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

27

What is myosin ATPase?

An enzyme located in the myosin head that hydrolyzes ATP

28

How do resistance exercises cause muscle growth?

They increase the size of myofibrils.

29

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

Smooth muscle

30

Which muscle tissue resists fatigue and frequently exhibits tetanus?

Smooth Muscle

31

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

Slow twitch

32

What is a thick filament composed of in myofibril?

pairs of myosin molecules intertwined together

33

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

Motor end plate

34

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

myoglobin

35

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

Electrolyte loss, fuel depletion, and central fatigue

36

Where is calcium stored in a skeletal muscle cell?

sarcoplasmic reticulum

37

An overstretched or over contracted muscle will result in what?

A weak contraction

38

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

Concentric

39

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

Eccentric

40

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

Tropomyosin

41

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

latent period

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?

Sodium

43

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

Depolarization

44

Which fibers are adapted for a quick response?

Fast glycolytic

45

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

T-tubules

46

Which structures coordinate contractions in cardiac muscle cells

Gap junctions

47

Pockets within the sarcolemma of smooth muscle that contain calcium channels

caveolae

48

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

contraction