Brainscape's Knowledge GenomeTM

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


See full index

Physiology > Muscle Contraction > Flashcards

Muscle Contraction Flashcards

1
Q

What does each muscle fiber contain?

A

Myofibrils

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

What two myofibrils make up a muscle fiber?

A

Actin and myosin

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

What myofibril is a globular protein consisting of two alpha-helical twisted strands?

A

Actin

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

Which myofibril is made up of a heavy chain pair of alpha-helical tails and two light chain pairs of “heads”?

A

Myosin

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

Which component of myosin has an actin binding site that binds and hydrolyzes ATP?

A

The “Heads” (Light chains)

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

What is the basic contractile unit of a muscle fiber?

A

Sarcomere

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

Which myofibril is covered in tropomyosin?

A

Actin

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

What does tropomyosin function to do?

A

Covers Actin-myosin binding site at rest, moves from that site at AP

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

Which myofibril is associated with troponin?

A

Actin

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

What does troponin function to do?

A

Release Ca2+ for binding to tropomyosin allowing it move for Cross-Bridge cycling

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

What structure is the middle of the sarcomere?

A

M line

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

What structure is surrounding each side of the M line until actin site?

A

Bare zone (no overlap)

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

What structure is on each side of the actin?

A

Z disks

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

What makes up the I band of a sarcomere?

A

Actin lines

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

What makes up the A band of a sarcomere?

A

Actin and myosin lines

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

What actin-binding protein anchors the myofibrillar array to the CM?

A

Dystrophin

17
Q

What large protein extends from the M line to Z disks, partly passing through the myosin?

A

Titin

18
Q

What protein extends from one end of actin to the other, setting the length?

A

Nebulin

19
Q

What protein anchors actin to Z disk?

A

Alpha Actinin

20
Q

What structure does a contraction reach the muscle fiber via?

A

Transverse tubules

21
Q

Through what structure does the contraction get to the SR from the Transverse Tubules?

A

Dihydropyridine receptors

22
Q

What structure is the storage and release site of Ca2+ for E-C Coupling?

A

SR

23
Q

What structure on the SR does Ca2+ flow through to get to muscle?

A

Ryanodine Receptors

24
Q

What substance pumps calcium back to the SR?

A

Ca2+ ATPase (SERCA)

25
Q

Summarize the mechanism of Excitation-contraction coupling of Skeletal Muscle. (seven steps)

A
  1. AP -> T-tubules for depolarization from the surface to interior of muscle fiber. 2. Depolarization of t-tubule causes dihydropyridine receptors to open Ryanodine receptors for Ca@+ release. 3. Ca2+ is releases from SR to muscle fiber. 4. Ca2+ binds to troponin, 5. That bind causes tropmyosin to unbind and move to allow for actin-myosin cross bridge. 6. Myosin and actin bind. ATP binds to myosin head. ATP is hydrolyzed to ADP+P providing the energy to walk along the actin filament. ADP is releases and myosin is returned to OG state and continue walking until Ca2+ unbinds to troponin. 7. Relaxation occurs when Ca2+ unbinds and is reaccumulated in SR by SERCA. Tropomyosin returns to binding sites to stop cross bridge cycling for relaxation.
26
Q

Summarize the mechanism of Smooth Muscle E-C Coupling. (6 steps)

A
  1. depolarization opens Ca2+ channels in SR. Influx increases concentration and if threshold is reached, AP can occur and further depolarization occurs opening Ca2+ channels. 2. Neurotransmitters open Ca2+ channels = influx. 3. Ca2+ binds to calmodulin which binds to and activate myosin-light-chain kinase. 4. MLCK phosphorylates myosin light chain increasing ATPase for cross bridge coupling. 5. Calponin and caldesmon inhibit/excite myosin ATPase. 6. When [Ca2+] decreases to low enough levels, relaxation occurs by either hyperpolarization, direct inhibition of Ca2+ channels, or decreased release of Ca2+ from SR.
27
Q

What is a sustained contraction of muscle twitch due to insufficient tome for SR to accumulate Ca2+?

A

Tetanus

28
Q

What is the relationship between the length and tension of a muscle?

A

A full length, there is zero tension. As length decreases, produces overlap, producing tension

29
Q

What is the relationship between force and velocity of a muscle contraction?

A

At initial length, as contraction occurs, velocity slows. (An isometric contraction initially @ 3 lengths has 0 velocity until added force.

30
Q

What type of muscle fiber has rapid cross bridge cycling and rapid rate of shortening?

A

Fast twitch (Type II)

31
Q

What type of muscle Fibers have slow cross bridge cycling and slow rate of shortening?

A

Slow Twitch (Type I)

32
Q

What type of fibers withstand better fatigue?

A

Slow twitch (Type I) due to oxidative nature vs glycolytic nature of Type II

33
Q

True/False: Fibers can be different within a given motor unit.

A

False, thy are all the same.

34
Q

What is the relationship between control and size of fibers?

A

Small fibers have better control over large fibers

35
Q

What is the relationship between reaction and size of fibers?

A

Small fibers are rapid reacting while large fibers are slower reacting

36
Q

Hypertrophy (increase in size) does what to the stimulation of a muscle?

A

Increase force but not speed

37
Q

Hyperplasia (increase in # of fibers) does what to the stimulation of a muscle?

A

Increase force but no change in velocity

38
Q

Lengthening a fiber has what effect on the stimulation of a muscle?

A

No change in force but increase speed of contraction

39
Q

Atrophy (decrease in size) does what to the stimulation of a muscle?

A

Decreases load, decreasing size, decreasing force

Physiology (11 decks)

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