Question

SA node physiology:

Compare and contrast these two conditions on heart rate: (1) decrease permeability of Funny-Na+ channels and (2) partially blocks SA node Voltage gated- K+ channels

Answer 1

Decreased permeability of Funny-Na+ channels	Partially blockade of SA node Voltage gated- K+ channels
It leads to activation of cAMP and hyperpolarization	It leads to depolarization and prolongation of action potential
The channels revert to resting state.	There is repetitive firing of neurons
There is responsiveness towards neurotransmitter.	There is increased transmitter release
There is no glandular activity	There is an increased endocrine activity

The inward current mediated partly by potassium and partly by sodium is important for pacemaker cells (hyperpolarized cells).