Lecture: Blood platelets #2

What are platelets

platelets are fragments of incomplete cells with a normal count ranging from 130,000-360,000 per mm².

What is the purpose of platelets?

Platelets plug breaks in blood vessels and start the clot formation process.

What is the process the body takes to stop bleeding called?

Hemostasis

What are the steps in hemostasis?

1. blood vessel spasm, 2. Platelet plug formation, 3.Blood coagulation

Blood vessel spasm

Vessel walls contract, reducing blood flow. Platelets release serotonin to prolong the spasm.

Platelet plug formation

Platelets stick to exposed collagen and to each other, forming a protective plug.

Blood coagulation

Fibrinogen is broken down into fibrin by thrombin, creating a weblike structure that catches platelets and cells to form a clot.

What protein forms a web-like structure during blood coagulation?

Fibrin (derived from fibrinogen, broken down by thrombin).

What is an abnormal blood clot called, and what is it called if it travels through the vascular system?

An abnormal blood clot is a thrombus. If it travels through the vascular system, it is called an embolus

What are the potential dangers of an embolus?

It can lodge in narrow arteries, altering blood flow, leading to:

• A coronary artery blockage (heart attack).

• A cerebral artery blockage (stroke).