Muscle Contraction Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What does tropomyosin cover when muscles are relaxed?

A

binding sites on actin

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

Where are Ca2+ ions released from?

A

sarcoplasmic reticulum

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

What do the Ca2+ ions cause?

A

causes tropomyosin to move and expose the binding sites on actin (by binding to troponin)

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

What can happen when the binding sites are exposed?

A

myosin heads can bind to the binding sites on actin, forming a crossbridge

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

What happens after a crossbridge is formed?

A

tension occurs as a result of the angle, which leads to the actin being pulled and sliding along the myosin

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

What can happen when the binding sites are exposed?

A

myosin heads can bind to the binding sites on actin, forming a crossbridge

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

What does the sliding movement of actin result in?

A

the release of ADP and Pi

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

What happens when a new ATP molecule binds to the myosin head?

A

the myosin head changes shape slightly, meaning the binding site is no longer complementary so myosin detaches from the actin

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

What enzyme is found in the sarcoplasm?

A

ATPase

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

What does the ATPase do in the context of muscle contraction?

A

hydrolyses the ATP on the myosin head causing the shape to return to normal, therefore it is once again complementary to actin

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

What activates ATPase?

A

Ca2+ ions

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

What is the role of phosphocreatine?

A

provides phosphates to help regenerate ATP from ADP

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

What happens to the length of the sarcomere when the muscle contracts?

A

sarcomere shortens

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

What happens to the H-zone and I band as the muscle contracts?

A

it shortens

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

What happens to the length of the A-band as the muscle contracts?

A

stays constant

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

How does a muscle contract?

A
  • Ca2+ diffuse in to myofibrils
  • cause movement of tropomyosin
  • exposing binding sites on actin
  • myosin head binds to binding site on actin
  • hydrolysis of ATP on myosin heads causes them to bend
  • pulling actin molecules
  • as a new ATP attaches, myosin will detach
17
Q

What is the role of ATP in muscle contraction?

A
  • provides energy for the myosin heads to change angle
  • hydrolysed to release energy which allows myosin heads to return to original position
  • provides energy for the active transport of Ca2+ ions into the sarcoplasmic reticulum
18
Q

What is the role of Ca2+ in muscle contraction?

A
  • binds to tropomyosin causing a conformational change which exposes actin-myosin binding sites
  • activates ATPase