Homeostasis:

= a set of fast, controlled, localised responses that prevent significant blood loss when there is a breach in the vessel wall

3 stages - Vascular spasm
- Platelet plug formation
- Coagulation

Vascular spasm
- VC of the blood vessels to minimise blood loss
- 20-30mins
- buys time for platelet plug formation
- Triggered by: - damage to the vascular smooth muscle
- chemicals released from the damaged endothelium
- pain reflexes

Platelet plug formation
- Platelets aggregate and attach to each other and the exposed collagen from the vessel wall
- They become sticky, swollen and spikey.
- They then release chemicals: SEROTONIN - enhances vascular spasm
ADP - attracts platelets
THROMBOXANE A2 - both
- Platelets release these chemicals, attracting more platelets which release more chemicals - postive feedback cycle.

Coagulation
- Changing from a liquid state to a gel-like state

	Created by jasminejohnson09 about 13 years ago

Cardiac Physiology Note on Homeostasis, created by jasminejohnson09 on 24/04/2013.