Lecture 1 - Organs

Question 1

What is heart rate controlled by?

Answer 1

Pacemaker cells in the Sinoatrial (SA) node mainly and then secondly by pacemaker cells in the atrioventricular node

Question 2

Noradrenaline causing PKA to be activated

Answer 2

Attaches to the β1-adrenergic receptor in the cell, which causes adenylyl cyclase to be active, which reacts with ATP to form cAMP, and then cyclic AMP activates protein kinase A (PKA)

Question 3

PKA’s effect on increasing Ca²⁺ movement and therefore muscle contraction

Answer 3

PKA increases the L-type Ca²⁺ channels’ tendency to open.

The increase in Ca²⁺ movement affects muscle contraction and this is how noradrenaline allows for higher muscle movement.