IMMUNE SYSTEM

Parts of Human Blood PARTS OF HUMAN BLOOD: 1.Plasma – non-living, yellow liquid part of blood - 92% water - 8% blood proteins, nutrients, salts and waste chemicals

2.Red Blood Cells – cells in the blood that carry oxygen to the body tissues - Make up most of the blood - Part of the living portion of blood - Give blood its red color - Primarily in your bone marrow ( the soft center part of the bone) - Main job is to deliver oxygen to all body cells

3. White Blood Cells – the cells in the blood that destroy harmful microbes, remove dead cells and make proteins that help prevent disease - are made in bone marrow and organs such as the spleen, thymus gland and tonsils - move to an infection and destroy the bacteria causing it

4. Platelets are cell parts that aid in forming blood clots

IMMUNITY Immune system is made of proteins, cells and tissues that identify and defend the body against foreign invaders Disease – condition in which a system organ or part of an organ is not functioning properly Infectious disease – one that can be spread from one host to another Pathogen – any agent that causes diseases (bacteria, viruses, protists, fungi and inverts.)

Parts of the immune system Parts of the immune system: teardrops, mucus and skin

How the Immune System Works Antibodies are chemicals that help destroy bacteria or viruses Antigen – foreign substances usually proteins that invade the body and cause diseases Antibiotics – chemicals capable of inhibiting growth of some bacteria - destroy harmful and helpful bacteria (should eat yogurt to replace the helpful ones) - Develop resistance to antibiotics

Beneficial to Man Decomposers Processing food 1. Vinegar making = yeast + bacteria 2. Sauerkraut – anaerobic bacteria ferment sugar in leaves 3. milk products – cheese, yogurt Pasteurization

Conditions for Growth Suitable temperature Moisture Darkness (for most) Suitable food source

Methods of Infection 1.Airborne – sneeze or cough may discharge thousands of droplets into the air (cold, sore throat) 2.Waterborne – spread most rapidly a. Viruses and bacteria associated with human wastes b. If underground water becomes contaminated from seepage from septic tanks, disease can be spread for many miles 3.Contact infections- spread slowly a. Eating utensils, hands, sexual contact 4. Arthropods – lice, mosquitoes, fleas ticks

Defense against Disease Defense against disease A.Non – specific 1. Skin and mucous membranes a. Skin stops bacteria from entering living tissue b. Cut or scrape-blood clot barrier against bacteria c. Infection results when break into skin is too large d. Puncture wounds introduce bacteria deep into muscle e. Bacteria swallowed with food you eat: acid secretions in stomach destroy most of the bacteria f. Tears – bacteria entering the eyes are swept along with the tears into tear ducts which lead into nasal cavity. Lysozyme –enzyme which protects against bacteria g. Cilia – line nose and trachea i. Trap bacteria and dust particles ii. Cigarette smoke – damage mucous layer, cilia and underlying cells

2. Phagocytes – white blood cells Break in skin and bacteria or microorganisms invade, white blood cells rush to destroy them Macrophage – white blood cells engulf 100 or more bacteria. Also damage and dead host cells. When tissue invaded b bacteria, blood supply increases- flushed and red and warmer Inflammation – fluid from blood enters spaces between injured tissue – swelling Pus – mixture of living and dead white blood cell, living and dead bacteria and dead tissue cells

3.Fever – some parts of the immune system function better at higher temps. Some viruses and bacteria do not do well at higher temps. 4.Interferon – Defense against virus - Chemical defense against virus a. Cell invaded by virus – cell makes interferon b. interferon released into intercellular spaces and taken into other cells c. These cells produce an anti-virus protein protects cell by preventing virus from making viral proteins d. Approx. 3 days after onset of viral infection Specific antiviral antibodies attack

B. Specific Defense – attack a specific pathogen Antigen – any substance that causes a specific immune response (Ex.: Chicken pox) Lymphocyte – special white blood cell (T-cells & B- cells ) 1.Primary immune response – 1 st exposure to antigen a. T- Cells made attack antigens directly b. B-Cells made produce chemicals that render antigens harmless-antibodies 2. Secondary immune response-future exposures when body encounters the same pathogen in the future, memory T & B cells divide quickly fight the infection before it over whelms the system

Immunity Against Disease Immunity – resistance of the body against infections 1.Species (inborn) general immunity of all people to pathogens of other species Some exceptions: Tuberculosis, West Nile, Anthrax 2.Active acquired a. Natural – as one recovered from certain infectious diseases usually permanent. Example: diptheria, scarlet fever, measles, mumps b. Artificial – Vaccines 3. Passive acquired a. Natural – transfer of antibodies from mother to infant through placenta or breast feeding 6months – 1 yr b. artificial – injecting serum with antibodies lasts 3weeks -3month