The Immune System: Your Defense Against Disease
Terms: Immune System: body s primary defense against disease-causing microorganisms. Immune: condition in which a body is able to permanently fight a disease. Disease: any change, other than an injury, that interferes with the normal functioning of the body.
Pathogen: disease-causing microorganisms viruses, bacteria, fungi, & protozoans. Infection: condition that results when the body is successfully invaded by a pathogen.
I. Two parts of the Immune System: A. Nonspecific defenses 1. Generalized; not directed at a specific pathogen, but all pathogens. http://www.ehponline.org/members/2004/112-1/pathogens.jpg
2. First line of defense against pathogens: a. Skin: Pathogens must penetrate the layers of dead skin cells in order to get inside the body. 1) Oil & sweat glands, produce an acidic environment killing many microorganisms. 2) When cut; microorganisms can penetrate causing infection.
b. Respiratory Defenses: cilia, mucous, & hairs c. Mouth: Saliva d. Stomach: gastric fluids (acidic) http://www.mypharmacy.co.uk/health_information/topics/m/mouth_problem/mouth.jpg
3. Inflammatory response: 2 nd line of defense a. Bacteria in a wound are attacked by white blood cells (leukocytes). http://www.affordablehousinginstitute.org/blogs/us/white_blood_cell_among_red_small.jpg
b. If the infection remains small and in one place, a reddish swollen area develops ( inflamed ). c. Fever is sometimes produced, which often slows or stops the growth of such microorganisms. http://www.nuigalway.ie/postgrad/go4th/images/mhe_070.jpg
B. Specific Defenses: 1. If the nonspecific defense fails, a series of specific defenses attack the disease-causing agent. (A specific antibody will only attack a specific antigen.) http://www.hepatitis-c.de/bilder/antigen.jpg
2. Examples: antibodies, T & B cells (specialized leukocytes). 3. Leads to permanent immunity. http://www.lbl.gov/publications/currents/archive/view-assets/oct-03-2003/t-cell2.jpg
II. Vaccinations: A. The injection of a weakened or mild pathogen to produce immunity. B. Rabies 1. Fatal virus. 2. Transmitted through the bite of an animal. http://www.amarilloanimalcontrol.com/images/dog_bite.jpg
C. Polio (1955) 1. Caused by 3 different viruses that attacks the nervous system, specifically the motor neurons. 2. Most common among children. http://www.immune.org.nz/site_resources/professionals/diseases/polio/polio.jpg
III. Immune System Disorders: A. Allergies: 1. Overreaction of the immune system. 2. Antigens cause the release of histamines. http://www.guysandstthomas.nhs.uk/resources/image/p/paediactricallergy/paedallergy_sneeze.jpg
http://www.bbc.co.uk/health/images/300/asthma_inhaler.jpg 3. Histamines: increase flow of blood & fluids to infected area, resulting in sneezing, runny nose, itchy eyes, etc B. Asthma: respiratory disease; often arises b/c of allergies; smooth muscle in airways contract, limiting airflow, thus breathing becomes difficult.
IV. Transmission and Agents of Disease: A. Disease Transmission: 1. Entrance into the body (cut, wound). a. Tetanus or lockjaw-- caused by bacterium Clostridium tetani, present in soil. b. Symptoms: fever, muscle spasms, even death. http://www1.peterson.scu.k12.ca.us/~babad/thermometer.jpg
2. Coughing/sneezing a. Cold, measles, mumps, influenza 3. Contaminated water or food 4. Infected animals a. Ticks, mosquitoes 5. Sexual contact http://www.img.uni-karlsruhe.de/download/aqul05_02.jpg
B. Types of Pathogens 1. Viruses a. Contain RNA, and can be enclosed in a membrane b. Are able to invade almost any type of living organism. http://www.armageddononline.net/image/virus1.jpg
http://www.uwosh.edu/departments/biology/shors/textbook/images/smallpox.jpg c. Must invade a living cell by attaching to the cell s surface, then inserting its genetic material into the cell, enabling the virus to replicate or reproduce (i.e. HIV, smallpox, measles, polio).
2. Bacteria http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/19617.jpg a. Most are harmless to humans. b. Treatment: antibiotics c. Ex. Strep throat d. Lyme Disease 1. Caused by ticks that carry a bacterium.
Lyme Disease cont. 2. Rash will develop near tick bite (bulls eye) 3. Symptoms: headache, fever, fatigue, pain in joints and muscles. 4. Spread most commonly by deer, but found in the outdoors 5. Present in Michigan http://www.eurekaspringswest.com/images/deer%20&%20fawns,small.jpg
3. Fungi a. Most do not cause disease. b. Most common fungal infections are those of the skin (i.e. types of ringworm; such as athlete s foot-rough, irritable patches on the toes. http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/2468.jpg
4. Protozoans http://ebiomedia.com/stock/images/ciliarray.jpg a. More than 30 different species. b. Most serious infections are caused by those found in tropical regions (warm and moist).
c. Infections caused by protozoans: 1) Malaria (Diagram on page 388) 2) Caused by protozoan Plasmodium, which lives in the blood. 3) Spread by mosquitoes. http://content.answers.com/main/content/wp/en/thumb/e/e9/400px-anopheles_albimanus_mosquito.jpg
5. Other Infections http://www.dogbreedinfo.com/images14/tapewormimg_1395.jpg a. Tapeworm: pg. 575 1) Parasitic flatworm. (What phylum?) 2) Absorbs digested food from the host s intestine. 3) Adult can be up to 18 meters long.
4. We get them from eating raw or incompletely cooked meat (beef). 5. Almost never kills the host, but do use up a lot of food hosts may lose weight and become weak. http://images.inmagine.com/168nwm/mixa/mx031/mx031013.jpg
b. Hookworm: pg. 577 http://www.humanillnesses.com/original/images/hdc_0001_0002_0_img0135.jpg 1) Serious human intestinal parasite. 2) Burrow into human skin and enter the bloodstream through an unprotected foot. 3) Travel through the bloodstream, lungs, throat, and attach to our intestines. 4) ¼ of the world may be infected.