The Immune System

1. The Immune System By Isabella de Jesus, Sarah Dillon, and Moriah Becker

2. Nonspecific Defenses Against Infection • First line of defense- • skin; physical barrier against pathogens • Mucous, saliva, and tears contain lysozyme that breaks down bacterial cell walls • Second line of defense- • Inflammatory response: begins when pathogen stimulate cells called mast cells to release chemicals known as histamines • white blood cells move from blood vessels to infected tissues and engulf and destroy bacteria • Interferon: interfere with viral growth by slowing down the production of new viruses • Fever: releases chemicals that increase body temperature which slows down or stops the growth of some pathogens

3. Specific Defenses Against infection • Third line of defense- • Immune system: inactivates or kills any foreign substances or cells that enter the body • Respond to a particular pathogen • Specific immune defenses are triggered by molecules called antigens

4. Two Types of Immunity • Humoral immunity- • Depends on the action of antibodies that circulate in the blood and lymph • Plasma cells produce and release antibodies that are carried through the bloodstream • Memory B cells react quickly if the same pathogen enters the body again • Cell- mediated immunity- • Depends on the action of macrophages and several types of T cells • Defends the body against some viruses, fungi, and single celled pathogens • T cells also protect the body from cells that become cancerous

5. Acquired immunity • Active immunity- • Vaccination that stimulates the immune system with an antigen • The immune system produces memory B cells and memory T cells that quicken and strengthen the body’s response to a repeated infection • Passive immunity- • Antibodies produced against a pathogen by other individuals or animals to produce temporary immunity • Lasts only a short time because the immune system eventually destroys the foreign antibodies

6. Vaccination Injection of weakened or similar but less dangerous pathogen to produce immunity

7. Immune System Disorders • Allergies- • antigens that cause allergic reactions are called allergens • They trigger inflammatory response by causing mast cells to release histamines • May cause sneezing, watery eyes, and runny nose, etc. • Asthma- • A chronic disease caused by allergic reactions in the respiratory system • Causes air passages to narrow causing wheezing and coughing and difficulty breathing

8. HIV and AIDS • Human Immunodeficiency Virus- • Causes AIDS • Deadly because it can hide from defenses of the immune system and attacks key cells in the immune system leaving it weak • AIDS- • No cure for AIDS • HIV mutates and evolves rapidly

9. Key Vocabulary • Vector- animal that transports a pathogen to a human • Inflammatory response- nonspecific defense reaction to tissue damage caused by injury or infection • Histamines- chemical released by mast cells that increases the flow of blood and fluids to the infected area during an inflammatory response • Fever- increase body temperature that occurs in response to infection • Pathogen- disease causing agent • Interferon- group of proteins that help cells resist viral infection • Immune response- the body’s specific recognition response in memory to a pathogen attack • Antigen- any substance that triggers an immune response • Antibody- protein that either attacks antigens directly or produces antigen binding proteins • Active immunity- immunity the develops as a result of natural or deliberate exposure to an antigen • Passive immunity- temporary immunity that develops as a result of natural or deliberate exposure to an antibody