Topics:
Animal Physiology, Animal Refresher
Factors Responsible for Platelet Activation During Blood Clotting
During blood clotting, factors responsible for platelet activation include:
- All the above — Correct Answer
- Collagen only
- Thrombin & Platelet activation factor (PAF) only
- ADP & Ca²⁺ only
Explanation:
Correct Answer: All the above
Platelet activation during primary hemostasis is triggered by multiple factors simultaneously:
Factors That Activate Platelets
- Collagen: Exposed when the vascular endothelium is damaged; collagen directly activates platelets via surface receptors (glycoprotein Ia/IIa), triggering adhesion and shape change.
- Thrombin: Generated during the coagulation cascade; a potent platelet activator via PAR (protease-activated receptors) on the platelet surface.
- Platelet Activating Factor (PAF): A phospholipid mediator released by damaged endothelium and leukocytes; activates platelets via specific G-protein coupled receptors.
- ADP (Adenosine Diphosphate): Released from damaged red blood cells and from platelet dense granules; activates additional platelets via P2Y1 and P2Y12 receptors, amplifying the platelet response.
- Ca²⁺ (Calcium): Required for platelet shape change, granule secretion, and activation of phospholipase — essential intracellular messenger for platelet activation.
Summary of Haemostasis
Primary haemostasis (platelet plug): Vascular injury → Collagen exposure → Platelet adhesion (via vWF) → Platelet activation (ADP, Thrombin, PAF, Ca²⁺) → Platelet aggregation → Platelet plug formation.
📚 About this Topic — Animal Physiology
This multiple choice question is from Animal Physiology, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Physiology to strengthen your preparation.
