Immune System

What It’s All About – the BASICS Defend the body against pathogens Recognize self from non-self Specific and Non-specific “Bottom line”: Fight infection through the production of cells that inactivate foreign substances/cells

Protection Pathogens Infectious disease Toxic Reproduce in the host GERMS Koch’s postulate

Koch came up with these rules to identify a pathogen that causes a specific disease

4 ways of getting sick Contact an infected person directly

4 ways of getting sick Contact an infected person INdirectly

4 ways of getting sick Eat infected food or drink infected water

4 ways of getting sick Get bitten by an infected animal

Bubonic Plague Bubonic plague is an infectious disease, circulating mainly among small rodents and their fleas. Without treatment, the bubonic plague kills about two thirds of infected humans within 4 days. Swollen lymph glands are typical symptoms of the plague. During the 14th century, 25 million people in Europe were belived to have died (around 40% of the entire population).

Immune System Anatomy Lymphatic System Lymph (fluid with WBCs) Lymph nodes (store WBCs) Tonsils, thymus, spleen, appendix, red bone marrow, adenoids

Line up the Troops First line of defense is non-specific Blocks anything from entering body system

First Line of Defense Examples Skin: wall that blocks pathogens Sweat: acidic, salty, contains enzymes Mucus: coats openings to body Tears: wash out pathogens entering eye

If that didn’t work…. Second line of defense: Inflammatory Response When the pathogen enters the body Injured cells release HISTAMINE Capillaries expand so blood flow increases Fluid leaks out into space between cells Swelling, redness, pain, heat What can you do to relieve these symptoms? (Take an ANTI histamine)

SPECIFIC DEFENSE IMMUNE RESPONSE Specific for pathogen Most effective if you’ve been infected before Through entire body Triggered by substance in pathogen = antigen Can be defense in body fluids (humoral) OR defense against abnormal cells or pathogens (cell-mediated)

Cells Involved White Blood cells = LEUKOCYTES They are made in the bone marrow Some develop in bone marrow, others in the thymus The picture is of a phagocyte – a wbc that engulfs and digests a pathogen

Cells Specifics Non-specific: Phagocytes: engulf (eat) and digest pathogens Macrophages are the biggest Specific: Lymphocytes: B-cells and T-cells

Humoral Immunity – Immunity against pathogens in body fluids Some B cells recognize specific pathogen B cells mature in Bone marrow Antibodies from B-cells Some B cells remember specific antigens & will produce antibodies whenever the pathogen reappears (memory cells) Antibodies: Attach to antigen and attract macrophages

B cell immune response 10 to 17 days for full response B cells + antibodies Y invader (foreign antigen) tested by B cells (in blood & lymph) memory cells “reserves” Y Y recognition Y captured invaders Y clone 1000s of clone cells plasma cells release antibodies Y Y

Lymphocytes: B-cell

Cell-Mediated Immunity Cells directly attack and destroy Ag (antigen) Cancer cells, infected body cells, invading cells T cells involved Born in bone marrow but mature in Thymus 3 types: killer, helper, suppressor

T cells Killer T cells Helper T cells (aka T4) Suppressor T cells Attack Ag (puncture cell membrane) Helper T cells (aka T4) Stimulate Killer Ts to divide, stimulate B cells to divide and release Antibodies Suppressor T cells Stop the activity of other T cells

T cell response killer T cell activate killer T cells infected cell helper T cell helper T cell or stimulate B cells & antibodies Y activated macrophage helper T cell Y

Lymphocytes From Stem Cells

Lymphocytes: T-cell

Memory Cells Primary response: new pathogen, new response (5-10 days until max production of B and T cells) Secondary Response: same pathogen, old response (1-2 days, so you don’t even get sick!) Memory cells can last your entire life!! You get “booster” vaccines to reactivate the memory cells

Vaccinations Immune system exposed to harmless version of pathogen triggers active immunity stimulates immune system to produce antibodies to invader rapid response if future exposure Most successful against viral diseases

Immune response pathogen invasion antigen exposure skin skin free antigens in blood antigens on infected cells macrophages (APC) humoral response cellular response B cells helper T cells T cells plasma B cells memory B cells memory T cells cytotoxic T cells Y antibodies

HIV and AIDS HIV attacks T4 cells (Helper T cells) Body can’t defend against any Ags! Known as an STD: transported in semen, blood, breast milk Once T4 count is so low that body can’t fight disease, we say the person has AIDS Takes about 10 years to develop AIDS

AIDS Infection

Huge Outbreak in Africa African Children Orphaned by AIDS

Allergies

Allergies Histamine released even though antigen is harmless If blood vessels dilate too much: ANAPHYLACTIC SHOCK

Autoimmune Disorders Immune system attack SELF cells Multiple Sclerosis: T cells destroy nerve cells Maybe Type 1 Diabetes is attack on pancreas

Multiple Sclerosis