Muscle Physiology Flashcards Preview

Physiology 1 > Muscle Physiology > Flashcards

Flashcards in Muscle Physiology Deck (55):
1

List some functions of muscles.

• Locomotion
• Respiration
• Digestion
• Parturition
• Blood and lymph circulation
• Swallowing
• Generation of body heat

2

What are 4 specific properties of muscles?

1. Contractility
2. Excitability
3. Extensibility
4. Elasticity

3

Which type of muscle is present in 40% of the body?

Skeletal muscle

4

Which type of muscle is present in 10% of the body?

Smooth and cardiac muscles

5

Describe skeletal muscle.

Striated, voluntary, found in trunk, extremities, head and neck, fast contraction, peripheral nuclei

6

Describe smooth muscle.

No striations, involuntary, found in viscera and blood vessels, slow contraction, central nucleus

7

Describe cardiac muscles.

Striated, involuntary, fast contraction, central nuclei

8

What is the result of contraction of skeletal muscles?

Movement of the body

9

Sheath of connective tissue surrounding the muscle

Epimysium

10

Fascicle

A small bundle or cluster of muscle fibers (cells)

11

Perimysium

Connective tissue extensions from the epimysium that surround each fascicle

12

Connective tissue extensions from the
perimysium that surround the muscle fibers
and are attached to the sarcolemma

Endomysium

13

Sarcolemma

Thin cell membrane enclosing skeletal muscle fiber

14

Muscle Fiber

Elongated, the contractile unit. Pull transmitted by endomysium, perimysium and epimysium to tendon or
aponeurosis that is attached to bone

15

What are the 2 types of muscle fibers?

1. Red fibers, type 1 or slow twitch
2. White fibers, type 2 or fast twitch

16

Which type of muscle fatigues easily, and is larger in diameter?

Type 2

17

What is each myofibril composed of?

Repeating sarcomeres in a linear sequence

18

What is the basic contractile unit of striated muscle fibers?

Sarcomere

19

Where are sarcomeres found?

Between Z lines or Z disks

20

What do sarcomeres contain?

Protein myofilaments actin and myosin

21

What are responsible for actual muscle contraction?

Actin (thin) and myosin (thick)

22

T/F: Actin and myosin filaments partially interdigitate.

True

23

I Band

Light band, Isotropic to polarized light

24

A Band

Dark band, Anisotropic to polarized light

25

What are the ends of actin filaments attached to?

Z disk or Z line (forms periphery of sarcomere)

26

H Zone

Light zone in the center made of thick filaments

27

M Line

Found inside the H Zone, forms middle of sarcomere, made of thick filaments and accessory proteins

28

Why is the sarcoplasmic reticulum important for muscle contraction?

Regulates calcium storage, release and re-uptake

29

What is an organelle in the muscle fiber present in large numbers and provides energy?

Mitochondria

30

Where are T-tubules arranged?

Transverse to myofibril as invaginations of the sarcolemma

31

T/F: T-tubules allow the PM of the muscle fiber to carry the depolarization of the action potential to the interior of the fiber.

True

32

T/F: Membrane potential exists across the membrane of virtually all cells.

True

33

What are membrane potentials generated by?

Ionic differences between ICF and ECF

34

What do muscle and nerve cells generate at their membranes?

Rapidly changing electrochemical impulses

35

What do impulses transmit?

Signals along the nerve or muscle membranes

36

What type of muscle cells are controlled by a motor neuron?

Skeletal muscle

37

What are the different effects of membrane potential on diffusion of ions?

Net diffusion rate, nerst potential, pressure difference

38

What is Nerst potential?

The diffusion potential level across a membrane that exactly opposes the net diffusion of a particular ion through the membrane

39

T/F: If a higher pressure is applied in one side of the membrane, more molecules will diffuse to the other side.

True

40

Give an example of pressure difference.

Capillary exchange

41

Which ion is present in larger amounts in the cytosol?

Potassium

42

What is the resting membrane potential of nerve fibers when not transmitting nerve signals?

-70 millivolts

43

What are factors that determine the resting potential?

1. Diffusion of potassium thru nerve cell membrane
2. Diffusion of sodium thru nerve cell membrane
3. Contribution of Na-K pump

44

In the "leak channels", which way do sodium and potassium want to go?

More potassium going out than sodium going in

45

What is the most important contributor for resting potential?

Potassium diffusion

46

How are nerve signals transmitted by?

Action potentials

47

What are action potentials?

Rapid changes in the membrane potential that spread rapidly along the nerve fiber membrane

48

What does each action potential begin with?

Sudden change from the normal resting negative membrane potential, to a positive potential

49

What is the resting stage?

• Is the resting membrane potential
• Moment before AP begins
• Membrane is said to be “polarized” b/c of the negative MP

50

Depolarization state

A threshold for the initiation of the action potential is achieved, the membrane suddenly becomes permeable to sodium ions, Membrane Potential rising in the positive direction is called DEPOLARIZATION

51

How does sodium influx occur during depolarization state?

Voltage-gated sodium channels

52

Repolarization state

After the membrane becomes highly permeable to Na+, Na channels begin to close. Voltage-gated K channels open to a greater degree than normal. Rapid diffusion of K+ out of the cell. Re-establishment of normal negative resting potential is repolarization.

53

Where does the action potential travel?

In all directions away from the stimulus until the membrane has become depolarized.

54

T/F: A new action potential cannot occur in an excitable fiber as long as the membrane is still depolarized from the preceding AP.

True

55

What is the absolute refractory period?

The period when a second AP cannot be elicited