Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Exam #2 Physiology Review > Muscle Physiology > Flashcards

Muscle Physiology Flashcards

1
Q

Define motor unit

A

Motor Unit: single motor neuron & all of the muscle fibers that it innervates. When the motor unit fires an AP all of the muscle fibers that it innervates will contract simultaneously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define motor recruitment

A

Motor Unit Recruitment: Number of muscle fibers contracting within a muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define tetanus

A

Smooth, sustained contraction of maximal strength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What proteins make up thick filaments?

A

Myosin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are proteins make up thin filaments?

A

Actin
Troponin
Tropomyosin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the functions of thin filaments?

A

Actin: shaft of thin filament/has myosin binding sites
Troponin: regulatory complex/stabilizes tropomyosin in the “blocking” position/interacts with Calcium
Tropomyosin: regulatory complex/covers or blocks the myosin binding sites on actin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is myosin ATPase located? What is its function?

A

Myosin Heads
It hydrolyzes ATP and turns it into ADP +Pi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where would you find dihydropyridine receptors?

A

Attached to the foot proteins on the T-tubule membrane side are voltage-sensitive receptors.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the function of the ryanodine receptors/channel?

A

Connects lateral sacs & the T-tubules
Also serve the calcium channels for calcium release from the lateral sacs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is creatine kinase?

A

Transfer of the phosphate between is reversible & catalyzed by creatine kinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is creatine phosphate?

A

Transfer of a high energy phosphate to ADP from creatine phosphate/ When ATP utilization is below production, the phosphate is transferred from ATP to creatine, creating creatine phosphate which can be stored in great quantities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the difference between neuromuscular fatigue & psychological fatigue?

A

Neuromuscular fatigue: Acetylcholine synthesis cannot keep up with demand

Psychological fatigue: Motor neuron activity decreases below desired contractile site

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the difference between hypertrophy & hyperplasia?

A

Hypertrophy: Increase diameter due to an increase in myosin and actin synthesis – only fast, glycolytic fibers

Hyperplasia: Increase in the number of cells – no MITOSIS; cells increase in size and then split lengthwise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What lines mark the end of the sarcomere?

A

Z-discs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a sarcomere?

A

Smallest functional contractile unit of skeletal muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the neurotransmitter used at the neuromuscular junction?

A

Acetylcholine (ACH)

17
Q

Why is ATP needed for relaxation?

A

ATP binds to myosin head à Myosin detaches from actin = Relaxation

18
Q

What is the function of the sarcoplasmic reticulum

A

Store intracellular calcium
Release calcium ions
Regulate calcium concentration

19
Q

What is the function of magnesium cross-bridging?

A

Magnesium ions must be attached to the ATP before hydrolysis of myosin head can occur

20
Q

What is rigor mortis?

A

Death induces an increase in calcium concentration which induces cross-bridge cycling

Once ATP is depleted the myosin & actin are unable to disengage = “stiffness of death”

21
Q

What is the function of the calcium ATPase pump?

A

Returns calcium to lateral sacs

22
Q

Define latent period

A

The period between the beginning of the stimulus & the onset of the contraction. The muscle AP has completed its cycle of depolarization & repolarization

23
Q

How can muscle contraction be varied in strength?

A

The number of muscle fibers contracting within a muscle (motor unit recruitment)

The tension developed by each contracting fiber

24
Q

How can tension be developed in individual fibers

A

Frequency of stimulation
Length of the fiber at the onset of concentration
Extent of fatigue
Thickness of the fiber

25
Q

Twitch summation

A

Frequency based increase summation
Occurrence of additional twitch contractions before pervious twitch has completely relaxed

26
Q

What does it mean by optimal muscle length?

A

The development of the tension in a muscle fiber is related to length or more importantly the number of actin and myosin cross-bridge that can form

In normal resting muscle, the muscle length is at or near their optimal length. Meaning that there is a maximum number of actin and myosin cross-bridge can be formed

27
Q

Why is tension development less in a shortened or lengthened sarcomere?

A

If the muscle is shortened too much, then the actin filaments overlap, and the number of potential cross-bridging forming is also reduced (also thick filaments forced into z lines, prevents further shortening, calcium release is somehow inhibited via an unknown mechanism, and the ability of calcium to bind to troponin and remove tropomyosin is also inhibited in an unknown manner

All of these factors with a shortened muscle decrease tension develop

28
Q

Define Isotonic and Isometric contractions

A

Isotionic: Muscle tension remains constant while the muscle length changes
Isometric: Muscle tension develops at constant muscle length (length does not change)

29
Q

Why does lactic acid induce fatigue?

A

Lactic acid accumulation which inhibits enzymes in the energy-producing pathways or excitation-contraction coupling processes

30
Q

What are the 3 types of skeletal muscle fibers?

A

Slow Oxidative Type 1 fibers
Fast Oxidative Type 2 fibers
Fast Glycolytic Type 3 fibers

31
Q

What is the function of myoglobin?

A

Increases the rate of oxygen transfer from the blood and imparts a red color to these fibers

32
Q

What is disuse atrophy? What is denervation atrophy?

A

Disuse atrophy: decrease in muscle mass due to inactivity.

Denervation atrophy: nerve supply to muscle is lost

33
Q

How can the ATP synthesizing capacity of muscle be changed?

A

Increase mitochondria content

Increase vascularization

34
Q

What is the function of muscle spindles?

A

Muscle spindles monitor changes in muscle length and tension so that it can regulate both aspects to keep muscles at its optimal length

35
Q

Describe the internal architecture of a smooth muscle cell.

A

A) Dense bodies are anchored in position throughout the cell & attached to
the cell membrane by the intermediate filaments
B) Actin filaments are anchored to the dense bodies
C) Thick myosin filaments interact with the thin actin filaments
D) As the thin & thick filaments slide across each other, the cell collapses or
shrinks due to a pulling effect on the dense bodies and their connection to the
intermediate filaments (cytoskeleton)
E) No T-tubules, poorly developed sarcoplasmic reticulum

36
Q

Describe how a smooth muscle cell undergoes contraction.

A
  1. Dense bodies are dispersed throughout the sarcoplasm & also attached to the
    sarcolemma
  2. Intermediate filaments form a scaffold & maintain the dense bodies in their positions
  3. Actin filaments are connected to the dense bodies, with myosin filaments interacting
    with the actin filaments attached to two dense bodies
  4. Upon stimulation, there is a rise in intracellular calcium, which binds to an
    intracellular protein called calmodulin.
  5. This calcium-calmodulin complex binds to & activates myosin light chain kinase
  6. Activated myosin light chain kinase phosphorylates (adds a phosphate group to the
    myosin) the myosin light chains which allows it to interact with actin & allow
    filament sliding
  7. The actin & myosin slide across one another, causing the cell to “scrunch up” &
    contraction
  8. Relaxation occurs by a combination of Ca2+ removal (which de-activates the kinase)
    and the activity of phosphatases which remove the phosphate from the myosin
37
Q

What is the difference between pacemaker activity & a slow wave potential?

A

Pace maker activity: membrane potential gradually depolarizes due to shifts in passive ionic influxes, resulting in an action potential

Slow wave potentials: alternating depolarizations and hyperpolarization of the membrane potentials – if depolarization is significant – action potential generation is achieved

38
Q

What are the anatomical differences between skeletal, smooth, & cardiac muscle?

A

Skeletal muscle: Striated, tubular, multinucleated fiber; voluntary

Smooth muscle: Small and unstriated; involuntary

Cardiac muscles: Striated with thick and thin filaments; involuntary

39
Q

What are varicosities?

A

Release neurotransmitters in a “broad” fashion; not a distinct one-to-one connection like skeletal muscles

Exam #2 Physiology Review (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions