The Immune System By Isabella de Jesus, Sarah Dillon, and

Moriah Becker

Nonspecific Defenses Against InfectionFirst line of defense-

skin; physical barrier against pathogensMucous, saliva, and tears contain lysozyme that breaks

down bacterial cell wallsSecond 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 bacteriaInterferon: interfere with viral growth by slowing down

the production of new virusesFever: releases chemicals that increase body

temperature which slows down or stops the growth of some pathogens

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

pathogenSpecific immune

defenses are triggered by molecules called antigens

Two Types of ImmunityHumoral 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

Acquired immunityActive 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

VaccinationInjection of weakened or similar but less dangerous pathogen to produce immunity

Immune System Disorders

Allergies- antigens that cause allergic

reactions are called allergensThey 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

HIV and AIDSHuman Immunodeficiency Virus-

Causes AIDSDeadly 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 AIDSHIV mutates and evolves rapidly

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