unit 2: Homeostasis

Question 1

Homeostasis in the blood

Answer 1

reduction and stoppage of blood loss from damaged blood vessels

three mechanisms:
1. vascular spasm
2. platelet plug formation
3. blood clotting

Question 2

Vascular spasm

Answer 2

helps until the other longer term mechanisms have effect
caused by substances released by damaged muscle

the vascular spasm: helps the muscle in the vessel wall contracts near the injury point to reduce blood loss

Question 3

Platelet plug formation

Answer 3

1. Adhesion: adhere to exposed collagen of connective tissue (basement membrane) of the damaged vessel
2. Release reaction: Platelets extend processes and release substances ( ex. vasoconstrictors, clotting factors)
3. Aggregation: platelets stick to each other and form a plug

Question 4

coagulation

Answer 4

Fibrinogen is converted to fibrin
- occurs in 3 phases
fibrin forms a mesh that traps red blood cells and platelets, forming the clot