Question

1) On what receptors does adrenaline act to produce this effect, and how is the subsequent increase in contraction strength brought about?

and

2) What other action does adrenaline have in the intact heart?

Answer 1

Question. 1

The effect in the question is not mention what is the effect.

• Adrenaline mainly act on heart on the Beta 1 receptors.
• Sympathetic adrenaline and Noradrenaline has a positive inotropic effect on heart.
• It increase the strength of contraction by making more calcium ion ( Ca2+) available to sarcomeres.
• Increase in the intracellular free calcium ion that regulates the troponin - tropomyosin system.
• Calcium ion s act on tropomyosin that affect both the extent and rate of force development result in increased contractility.

Question 2.

1. It shortens the ismoeteric contraction phase .

2. It increases the speed of contraction.

3. It increases the systolic emptying of left ventricle.

4. It lowers the diatolic pressure.

5. It increases the amplitude of pulse pressure.

6. It also increases the heart rate.