Innate Immunity

Immunity Body’s mechanisms to prevent and fight foreign invaders Pathogens – anything that can cause disease – includes bacteria, viruses, parasites, toxins, etc.

Innate Immunity Innate = born with it, always present Non-specific Does not improve after exposure

Physical Barriers Skin – Layers of epithelial cells Contains sebaceous glands which secrete sebum (oil) which is slightly acidic to kill bacteria and other invaders Hair – helps trap invaders Sweat – high salt content kills many types of invaders

Mucous membranes – line areas inside the body that are directly exposed to things from the exterior environment (digestive tract, respiratory tract, urinary tract) Mucous traps invaders

Chemical defenses Acidity – low pH found on skin, mucous membranes, stomach acid, urine Lysozymes – enzymes that break down bacterial cell walls, found in tears, saliva, sweat, mucus

Natural Bacteria Non-pathogenic Out-compete pathogens – better at getting available space and nutrients so there’s not enough left over for invaders

Fever Relates to ideal temperatures for enzyme function Pathogens replicate more slowly, immune cells work faster Can be dangerous if it gets too high

Phagocytes Specific types of white blood cells recognize, engulf, and destroy pathogens Macrophages most common https://www.youtube.com/watch?v=rPLfnZHcICA

Natural killer cells Destroy infected cells and cancerous cells Release granules by exocytosis near the infected cell to kill them

Inflammation Response to tissue damage Signs include pain, redness, heat, and swelling Tissue damage causes a release of many chemical signals, including histamines, which triggers nearby capillaries to dilate, increasing blood supply to help deliver clotting factors and phagocytes