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: 2nd 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. Rabies1. 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
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.
http://www.bbc.co.uk/health/images/300/asthma_inhaler.jpg
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 animalsa. Ticks, mosquitoes
5. Sexual contact
http://www.img.uni-karlsruhe.de/download/aqul05_02.jpg
1. Viruses a. Contain RNA, and can be enclosed in a membrane
b. Are able to invade almost any type of livingorganism.
http://www.armageddononline.net/image/virus1.JPG
B. Types of Pathogens
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).
http://www.uwosh.edu/departments/biology/shors/textbook/images/smallpox.jpg
2. Bacteriaa. Most are harmless
to humans.
b. Treatment: antibiotics
c. Ex. Strep throat
d. Lyme Disease
1. Caused by ticks that carry a bacterium.
http://www.nlm.nih.gov/medlineplus/ency/images/ency/fullsize/19617.jpg
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
Lyme Disease cont.
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
a. More than 30 different species.
b. Most serious infections are caused by those found in tropical regions(warm and moist).
http://ebiomedia.com/stock/images/ciliarray.jpg
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
a. Tapeworm: pg. 5751) Parasitic flatworm. (What phylum?) 2) Absorbs digested food from the host’s intestine.3) Adult can be up to 18 meters long.
http://www.dogbreedinfo.com/images14/TapewormImg_1395.jpg
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
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.
http://www.humanillnesses.com/original/images/hdc_0001_0002_0_img0135.jpg