Innate Immunity:
The immune system is the body system that fights infection and keeps our body from pathogens. There are types of immunity: Innate and Adaptive Immunities.
Innate Immunity: The innate immune system is the cells and physical barriers that you are born with. They target all types of pathogens; not specific pathogens. The innate immune system consists of two lines.
The 1st line consists of physical barriers including skin, nose, stomach, and other mucosae. Keratin on the skin makes the skin resistant to bacteria. Secretions such as sebum and sweat make the skin slightly acidic. The stomach contains gastric juice which destroy pathogens in the stomach. Tears and saliva contain lysozymes which kill pathogens in the oral cavity (mouth) and eyes.
The 2nd line consists of phagocytes (cells that engulf pathogens), natural killer cells (cells that kill our own body cells that are cancerous or virally infected), antimicrobial proteins, and causes fever and inflammation. Phagocytes engulf pathogens through phagocytosis. Phagocytosis has 5 steps: Adherence-occurs when the phagocyte binds to the pathogen. Endocytosis-the cell membrane reaches around pathogen to enclose which forms a phagosome or food vacuole. Fusion-lysosome fuses with the phagosome. Digestion-the lysozymes from the lysosomes digest and breakdown the pathogen. Exocytosis-the unneeded material is ejected from the cell. Opsonization occurs when complement proteins or antibodies bind to the pathogen and makes adherence easier. Respiratory Bursts occurs when the lysosome is not enough so the T-cells release free radicals.
Natural Killer cells kill out own human cells that have already been infected or have become cancerous. They function using perforins and granzymes. The perforins create a hole in cell membrane and the granzymes enter and breakdown cell material.
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