Brainscape's Knowledge GenomeTM

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


See full index

BIOM20002 - HSF > Lecture 15 - Cardiac and Smooth Muscle > Flashcards

Lecture 15 - Cardiac and Smooth Muscle Flashcards

0
Q

Do cardiac muscles fire action potentials?

A

Yes

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

Describe the structure of cardiac muscle

A

Branching cells interconnected by intercalated disks

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

How do contractile cell in the myocardium get the signal to contract?

A

Autorhythmic cells initiate the contraction, the action potentials spread from neighbouring cells

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

How is the action potential of the cardiac muscle and the skeletal muscle different?

A

In cardiac muscle, the AP lasts much longer, as is the refractory period. This means that there is an absolute upper limit to the speed of heart beats

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

Describe the action potential in cardiac contractile cells

A 
1. Depolarisation
• Na+ in, fast
2. Initial repolarisation
• K+ out, fast
3. Plateau
• Ca2+ in, slow
• Halt in K efflux
4. Repolarisation
• K+ out, fast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe Excitation-Contraction coupling in cardiac muscle cells

A
  1. Action potential arrives from neighbour, flows down T tubules
  2. L type Ca2+ channels on plasma membrane open; Ca rushes into cell
  3. Calcium induced calcium release; RyR channels on the SR open; more Ca comes out.
  4. Calcium binds to troponin
  5. Tropomyosin moved off the myosin binding site, myosin binds to actin
  6. Crossbridge cycling
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is meant by calcium induced calcium release?

A

Once calcium flow in throu the L type Ca channel, the RuR channel opens and more calcium flows into the cytosol from the SR

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

What are the two channel types that are important for cardiac muscle contraction?

A
  • L type Ca2+ channel on plasma membrane

* RyR channel on SR

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

Describe the conduction pathway in the heart

A
  1. Sinoatrial node
  2. Intermodal pathway
  3. Atrioventricular node
  4. Left and right branches of Bundle of His
  5. Purkinje fibres
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the action potential in cardiac autorhythmic cells

A
  1. Calcium in slowly
  2. Threshold reached –> calcium in fast
  3. K out fast
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

In cardiac muscle cells, most Ca comes from the …

A

Sarcoplasmic reticulum

More Ca from outside cell than in skeletal muscle, though.

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

Where is smooth muscle commonly found?

A

Wall of organs:

  • stomach
  • intestines
  • kidneys
  • blood vessels
  • bladder
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe the different layers of smooth muscle in organs such as the stomach

A

There are many layers, with the muscle arranged in different orientations.
When the different layers contract, the stomach restricts along the different planes

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

Describe the pathway leading to contraction in smooth muscle cells

A
  1. Muscle excited
  2. Calcium channel opens, calcium rushes into cytosol
  3. Calcium induced calcium release from SR
  4. Calcium in the cytosol binds to calmodulin, making a CaCaM complex
  5. This activates MLCK
  6. MLCK phosphorylates the myosin head
  7. Muscle contraction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the difference between single and multi unit smooth muscle cells?

A

Single unit smooth muscle cells are electrically linked by gap junctions.

These cells all contract together

Eg. In the small intestine

Multi unit smooth muscle cells must be excited individually
Eg. The eye muscle

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

What is different about the length of muscle contraction in smooth muscle?

A

In smooth muscle, the myosin heads remain bound in the rigor state. The muscle can remain contracted for hours

16
Q

What is the structure of arteries?

A

Endothelium
Elastic tissue
Lots of smooth muscle
Fibrous tissue

17
Q

What is the structure of arterioles?

A

Endothelium, smooth muscle

18
Q

What is the structure of capillaries?

A

Endothelium

19
Q

What is the structure of venules?

A

Endothelium

Fibrous tissue

21
Q

What is the structure of veins?

A

Endothelium
Elastic fibres
Smooth muscle
Fibrous tissue

22
Q

What allows electrical coupling of cardiac muscle cells?

A

Intercalated disks:

• gap junctions

23
Q

How is calcium removed from the cytosol once the contraction needs to be inhibited?

A

Pumped back into the SR by Ca-ATPase pump

24
Q

Compare the variability in force of contraction in heart and skeletal muscle

A

Skeletal: invariant
Cardiac: force production can be graded

25
Q

Describe grading of cardiac muscle force production

A 
Depends on Ca cytosolic concentration
• more calcium enters the cytosol
• more Ca bound to troponin
• more active contractile fibres
• increased force of contraction
26
Q

Why is it important for cardiac contractile cells have a longer action potential?

A

Prevents tetanus

Heart cannot function if it is continually contracted, because it can’t fill with blood

27
Q

What is the resting membrane potential of myocardial autorhythmic cells?

A

No resting membrane potential

Unstable membrane potential that fluctuates from -60 mV up to threshold

BIOM20002 - HSF (60 decks)

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