The Immune System

Function responsible for destroying disease-causing agents antigens White blood cells

various organs chemicals numerous cells Composition Composition facilitate immune processes

Infectious Disease illness Organisms/virus enter and reproduce inside the body

Transmission of Disease a. direct contact - contact through air, sexual contact b. indirect contact – requires a carrier 1. contaminated food and water due to poor sanitation and untreated sewage 2. bites of infected animals

3 Lines of Defense Immune System Nonspecific 1 st stage: Skin 2 nd stage: Inflammation Specific 3 rd stage: Immune Response

Nonspecific  Line of defense that destroys all types of pathogens disregarding type Specific  Line of defense that destroys only one particular kind of pathogen  Micromanagement of stopping particular diseases TYPES OF IMMUNE RESPONSES

NONSPECIFIC DEFENSES: 1 st & 2nd External body covering, including the skin and mucous membrane Lymphatic system and other organs Chemicals that kill or prevent the entry of microorganisms (lysozyme, sebum, mucus, sweat) Chemicals that promote inflammation and phagocytosis Phagocytic and inflammation- inducer white blood cells

Types of Leukocytes (white blood cells) TypeFunction Neutrophils Phagocytosis of bacteria Eosinophils Destruction of parasitic worms Inactivation of allergic reactions Basophils Releasing histamines that cause inflammation and allergy

Types of Leukocytes TypeFunction Lymphocytes antibodies (fight disease and destruction of infected cells) Monocytes Phagocytosis (Destruction of bacteria, infected cells, and dead red blood cells)

Leukocytes

A Macrophage engulfing bacteria

Monocytes Granulocytes

3 Lines of Defense: 2 nd Line: Inflammation When pathogens invade body tissue, the inflammatory response occurs. skin is punctured histamine trigger inflammatory response.

2 nd Line: Inflammation Capillaries expand increasing blood flow expand and redden white blood cells enter and engulf pathogens

2 nd Line: Inflammation phagocytes to increase activity and stop bacterial growth. Inflammatory response fever pyrogen brain increase body temperature

2 nd Line: Inflammation Other components of the 2 nd line: Interferon – protein that interferes with replication of viruses - released by cells that have been invaded by viruses - warn healthy cells Natural Killer Cells – attack infected body cells causing them to burst

3rd Line of Defense: The Specific Immune Response

3 rd Line: the Immune Response Antigens – a molecule that elicits the immune response Antibody – a disease fighting protein produced in response to a specific antigen

3 rd Line: the Immune Response Upon recognizing the antigen, the body responds through two processes: 1. Humoral Immunity 2. Cell-mediated Immunity

Humoral Immunity Antibodies: Antibodies are produced by WBCs called B Lymphocytes, or B Cells. produced to mark a specific pathogen for destruction but not actually destroy them.

Humoral Immunity Antibodies cause pathogens to clump together, in order for macrophages to engulf them. When a B cell recognizes an antigen, it responds by dividing numerous times, in order to create an army of B cells.

Humoral Immunity

Cell-Mediated Immunity T Lymphocytes, or T Cells, come from the bone marrow, and mature in the thymus glands. Molecules on each T Cell recognize a specific antigen. fight diseases up front

Cell-Mediated Immunity Kinds of T Cells: 1. Killer T Cell – ( cytotoxic T Cell) produces a protein that ruptures infected cell membranes 2. Helper T Cell – stimulates Killer T Cells to divide when the need arises; also stimulates B Cells. 3. Suppressor T Cell – inhibit the activity of T Cells when they are no longer needed

* Acquired Immunity The body’s resistance to previously encountered pathogens. Memory Cells

A Summary of Cells Involved in the Immune Responses

Immune System Disorders

Allergies allergens exaggerated actions counteract a harmless thing

Auto-immune Disorders immune system mistakes normal, functioning body cells as pathogens. Multiple Sclerosis  T Cells attack the myelin sheath surrounding cells near the central nervous system.

Auto-immune Disorders Type I Diabetes WBC attacking insulin-producing cells in the pancreas. Arthritis WBC attack and destroy bone joint cells. Addison’s Disease WBC attack adrenal glands, causing fluctuations in the body’s functions in physical or mental exertion.

Auto-immune Disorders Arthritis Multiple Sclerosis

AIDS AIDS stands for Acquired Immune Deficiency Syndrome. body’s immune system cannot protect itself against pathogens because it is attacked by HIV, Human immunodeficiency virus.

AIDS HIV is spread: - through 1. direct contact of body fluids, like blood, semen, or breast milk. 2. intercourse, needles, or blood transfusion - not through casual contact nor insect bites