What do platelets do in blood?

Answer 1

Platelets are cell fragments which are an important part of blood clotting. Similarly to red blood cells, they don't have a nucleus, but they are a lot smaller than red blood cells. When there are too few platelets, wounds don't close as well and you bleed more. Conversely, when there are too many, your blood clots too easily and blood clots might form without there being a wound - leading to thrombosis. However, the range of platelet counts that are healthy is very large, unlike for other blood cells. If you're on the lower end, somebody with five times as many platelets as you might still be perfectly healthy.

How they work: When a blood vessel is injured, blood comes into contact with the protein mesh underneath the vessel wall. This mesh contains collagen. Blood contains platelets, but also a protein called Von Willebrand Factor (VWF), which sticks to collagen. Once it is stuck down, VWF itself becomes sticky for platelets which are also in the blood. This way, VWF becomes like glue stripts for platelets to stick onto an injury. This causes platelets to activate and stick to each other, forming a plug over the injury. There are more details to what platelets do, but this is their main function.

Answer 2

Whenever a blood vessel is damaged, platelets form a clot by clumping together at the edges of the wound. The platelets also cause the blood vessels to reduce bleeding by constriction, attract more platelets to enlarge the clot, and start the work of the plasma protein fibrinogen at the wound site. Fibrinogen in the blood is transformed into threads of fibrin that combine with the platelets to form a sort of mesh that helps the clot seal the wounded blood vessel.

Answer 3

They stop you from bleeding. When you cut yourself, the platelets form a plug (or clot) by sticking together - this slows down and eventually stops the bleeding. The scab left over a cut is simply dried-out platelets that have merged to form a protective cover, while your body repairs the skin underneath.

Answer 4

Platelets form blood clots and 'scabs' when we cut ourselves - to reduce or stop us bleeding.

Answer 5

Platelets form blood clots when we bleed - to seal a cut or wound.