Blood Clotting and Inflammation

• What are the non-specific defenses against pathogens mentioned?

  Skin, mucous membranes, and lysozyme
• What happens when the skin is damaged?

  Pathogens can enter the blood and tissue
• What is the role of blood clotting when the skin is damaged?

  To prevent or reduce pathogen entry
• What are platelets?

  Tiny cell fragments with no nucleus
• Where are platelets formed?

  In the bone marrow
• What activates platelets during blood clotting?

  Exposure to proteins outside the endothelium
• What do activated platelets form over a damaged area?

  A plug to stop bleeding
• What is thromboplastin's role in blood clotting?

  It converts prothrombin into thrombin
• What does fibrin do in blood clotting?

  Forms a mesh trapping red blood cells
• What does thrombin act on to form fibrin?

  Soluble fibrinogen
• What chemical do activated platelets release to cause blood vessel contraction?

  Serotonin
• What is the effect of serotonin on blood vessels?

  Narrows the blood vessel, reducing blood flow
• What forms on the surface of the skin as the clot dries?

  A scab
• What protects underlying tissue from pathogens during healing?

  The scab
• What activates mast cells during tissue damage?

  Damaged tissue
• What chemical do mast cells release?

  Histamine
• What is vasodilation?

  Dilation of blood vessels
• What effect does increased temperature have on pathogens?

  Reduces their ability to reproduce
• What is edema?

  Swelling of nearby tissues
• What do cytokines attract to the damaged tissue?

  Phagocytes
• What is the role of cytokines in response to infection?

  Trigger an increase in body temperature
• What is the next topic to be covered in the following video?

  Phagocytosis