Infectious Disease• Disease – any change, other than an

injury, that disrupts the normal functions of the body

• Germ theory of Disease – Pasteur & Koch conclude that disease

caused by germs & not curses /evil spirits– Diseases are caused by pathogens including

bacteria, viruses, fungi, protists, worms, materials in the environment, and genetic disorders

Spreading Disease• Physical Contact

– Direct or indirect

• Contaminated food or water

• Infected animals– Animals that carry pathogens from person to

person are called vectors

Fighting Diseases

• Antibiotics are compounds that interfere with the cellular processes of pathogenic organisms without harming the cells of the human or animal host– Naturally occurring: Penicillin

– Synthetic: Cipro

First Line of Defense

• The skin provides a barrier to most pathogens– If the skin is broken, pathogens can enter &

multiply

– Bodily secretions including mucus, saliva, and tears contain lysozyme which destroys bacterial cell walls

Second Line of Defense• The inflammatory response is activated

when tissue is damaged by injury or infection.

• White blood cells (WBC’s) enter the infected tissues and engulf and destroy bacteria.– Increase in body temperature (fever)– Increase in heart rate and blood flow

• Interferon fights viral infections

After the nonspecific defenses fail, the antigen that has entered the body trigger an immune response• B lymphocytes (B cells) provide humoral immunity by

attacking antigens and pathogens in body fluids using antibodies that recognize and bind to pathogens.

• T lymphocytes (T cells) provide cell mediated immunity by attacking abnormal cells and pathogens living inside living cells– Killer T cells destroy bacteria, fungi, protists, & foreign tissue– Memory T cells cause a response if the same antigen enters

the body again– Supressor T cells shut down killer T cells once the pathogen

is under control

Types of Immunity• Active immunity appears after exposure to

an antigen as a result of the immune response and can develop as a result of natural exposure or from a vaccine

• Passive immunity occurs when antibodies produced by other animals against a pathogen are injected into the bloodstream and lasts only a short time.

Immune Response Summary

Antigen

Macrophage

Helper T - Cell

Active Cytotoxic T-Cell Active B - Cell

Kills Infected Cells Memory T- Cell Plasma Cell Memory B-Cell

Antibodies

Deactivates Antigens

Allergies

1. Allergy causing antigens enter the body.

2. Antigens attach to mast cells and trigger the inflammatory response

3. Histamine is releaseda) Blood flow to area increases

b) Mucus production in the respiratory tract increases

Asthma• A chronic respiratory disease in which the

air passages become narrower causing wheezing, coughing, and difficulty breathing

• Triggered by allergies, respiratory infections, exercise, stress, cold air, and certain medications.

Autoimmune Diseases• The body mistakenly attacks its own cells.

• Examples of autoimmune diseases include Type I diabetes, rheumatoid arthritis, myasthenia gravis, and multiple schlerosis.

• Can be treated with medications to relieve symptoms or supress the immune response.

Immunodeficiency Diseases

• Can be caused by viral infections or result from errors during development.– AIDS is caused by HIV (a retrovirus) that

evades the defenses of the immune system and destroys helper T cells.

• http://www.roche-hiv.com/portal/eipf/pb/hiv/Roche-HIV/demonstrationoffusioninhibition

Environment and Health• Factors including air quality, water quality,

poisonous wastes, and solar radiation exposure can affect health.

• When environmental factors cause changes in DNA, tumors which may be malignant form.

• Carcinogens are chemical compounds known to cause cancer.

Immune system Animations

• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter24/animation__the_immune_response.html

• http://pennhealth.com/health_info/animationplayer/immune_response.html

• http://science.nhmccd.edu/biol/inflam.html

Vaccinations

• http://resources.schoolscience.co.uk/ABPI/immune/immAnim3.htm