BIOL-242 Lecture Notes - Lecture 20: Mucous Membrane, Immune System, Sebaceous Gland
16 May 2020
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Chapter 21 part 1 | the immune system: innate and. Body"s first line of defense // skin and the mucous membranes. Surface barriers // anything that separates us from the outside environment, warding off invading pathogens. Keratin resistant to weak acids and bases, bacterial enzymes, and toxins. Low ph / acidity of skin and secretions - acid mantle - inhibits growth. Enzymes - lysozyme of saliva, respiratory mucus, and lacrimal fluid - kill many microorganisms. Defensins - antimicrobial peptides - inhibit growth. Other chemicals - lipids in sebum, dermcidin in sweat - toxic. Cilia of upper respiratory tract sweet dust and bacteria-laden mucus toward mouth. Surface barriers breached by nicks or cuts. Second line of defense must protect deeper tissues. Phagocytes (cells that chase bacteria/viruses to internalize & destroy them) Inflammation (macrophages, mast cells, wbcs, and inflammatory chemicals) Fever (to slow down the replication of these pathogens) Third line of defense attacks particular foreign substances.
