Cardiac muscle

Question 1

How does cardiac muscle differ from skeletal muscle?

Answer 1

• Calcium source is extracellular
• Single unit muscle
• Force length curve

Question 2

How can calcium be increased?

Answer 2

Via phosphorylation - increase in stimulus and adrenaline

Question 3

What kind of junction allows the heart to work as a unit?

Answer 3

Gap junctions via diffusion

Question 4

How can we increase the strength of contraction?

Answer 4

1) Increased nerve stimulation: calcium goes back to 0 after contraction which sensitises muscle to calcium, so the next burst of calcium will have a stronger effect
2) Increase calcium via nerves and gap junctions: Adrenaline and noradrenaline are released, adrenaline activates GS coupled receptors which increase cAMP, activating protein kinase A which phosphorylation calcium channels so they open for longer

Question 5

How does smooth muscle differ from skeletal muscle?

Answer 5

• Calcium source is extracellular
• Single unit
• Control of contraction - MICS prevent binding of actin and myosin

Question 6

Outline smooth muscle structure

Answer 6

Irregular organisation of actin and myosin means smooth muscles ‘round up’ when contracting which creates a greater degree of shortening and a broader range of maximum tension