HUMB1000 Study Guide - Final Guide: Gastric Acid, Extracellular Fluid, Earwax
10 Jun 2018
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The immune system
The Lymphatic system
Function:
• Fluid balance - Excess interstitial fluid enters lymphatic capillaries and becomes lymph
• Fat absorption – Absorbs fat and other substance from digestive tracts through lacteals
• Defence – Fights infection. Lymph by lymph nodes and blood by spleen filters foreign
substances and microorganisms
Physical/external defences (First line of defence)
• Skin
• External layers keratin acts as a good barrier against pathogens
• Sebum of skin, sweat and vaginal fluid are acidic and can kill bacteria
• Gastric juice
• In the stomach and the various digestive enzymes kill bacteria
• Mucus membrane of respiratory tracts
• Secrete mucus to trap micro-organisms, pollen, and dust particles and sweep them out
by cilia
• Saliva and tears
• Contain lysozyme that can kill bacteria by digesting their cell walls
• Clotting of blood
• Seals wound to prevent excessive loss of blood and entry of pathogen
• Lysozyme
• An enzyme that kills bacteria which is found in saliva, sweat, secretions of the nose and
tissue fluid
• Cerumen
• Ear wax which is slightly acidic and protects the outer ear against infection
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Document Summary
Function: fluid balance - excess interstitial fluid enters lymphatic capillaries and becomes lymph, fat absorption absorbs fat and other substance from digestive tracts through lacteals, defence fights infection. Lymph by lymph nodes and blood by spleen filters foreign substances and microorganisms. Inflammation (second line of defence: fever inhibits bacterial growth and increases the rate of tissue repair during an infection, inflammation is the body"s immediate response to damage caused by wounds, insect bites etc. The injured site becomes red, hot, swollen and painful: when stimulated by mechanical damage or by local chemical changes, mast cells release histamine, heparin and other substances into the tissue fluid. It also enhances the migration of phagocytic cells and delivery of clotting chemicals to the injured site. A clot of the fluid around the damaged area does form and this slows the spread of pathogen into healthy tissues: the chemicals released by the mast cells attract phagocytes.
