Arteries and veins are blood vessels. Here platelets fulfill their hemostatic function by recognizing wounds. If the wall of a blood vessel is injured platelets adhere, aggregate and release granule content.

• Collagen of the vessel wall is usually covered by the endothelium.

• Platelets recognize unusual substances such as subendothelial collagen exposed in a wound.

• The layer of the blood vessel wall that faces the blood.

• Resting platelets don't normally adhere to intact endothelium.

• Hemostasis means to stop bleeding.

• Platelets are specialized to recognize wounds, adhere, aggregate and release intracellular content.

• When platelets interact with pathogens they activate.

• Plasma proteins like complement factors or immunoglobulins bind to their surface.

• This "opsonization" signals to macrophages to remove these platelets.

• A wound is the prime site for pathogen entry.

• Since platelets are the first cells at the site of a wound they are best suited as fist line of defense against infection.

• Platelets can take up viruses and interact with bacteria.

• Platelets contain bactericidal substances in their granules.

• Platelets are part of the innate immune system and connect the innate and the adaptive immune system.

• Thrombosis is the formation of a blood clot.

• Platelets respond to damage in a blood vessel wall in the absence of bleeding.

• Overdosing of anti‐thrombotic drugs can cause bleeding.