| Factors that
increase excitability: |
| |
- Sympathetic stimulation - Lowers
the resting membrane potential - becoming more
positive.
- Mild Hyperkaleamia (increase in
potassium concentration) - partial depolarisation
- Hypocalcaemia (decrease in calcium
concentration) - partial depolarisation
- Adrenaline - similar to
sympathetic stimulation
- Digitalis - increase atrial muscle
excitability
- Mild Hypoxia - Partial
depolarisation
- Ischaemia - Partial depolarisation
|
| Factors that
decrease excitability: |
| |
- Parasympathetic Stimulation -
decreases excitability only of the atrial muscle
cells
- Hyponatreamia (decrease in sodium
concentration)
- Marked Hyperkaleamia - Marked
depolarisation
- Hypokaleamia - Hyperpolarisation
- Hypercalceamia - decreases
permeability to sodium
- Acetyl choline - same as
parasympthetic stimulation
- Digitalis - decreases ventricular
muscle excitability
- Marked Hypoxia - marked
depolarisation
|
