Immunity

Learning Targets 2-11

Disease BasicsDisease – any change that disrupts the normal

function of an organism

Caused by…– Bacteria– Viruses– Fungi– The environment

Pathogen – any disease causing agent

LT 3

Disease BasicsHow are Diseases Spread:1. Physical contact between members of the species2. Contaminated food or water3. Infected animals

How to Fight Diseases:4. Preventative Behaviors - hand washing, wastewater treatment

plants, sewers5. Drugs

a. Antibiotics-destroy bacteria, NOT VIRUSES, without harming host cells…some are naturally occurring (penicillin) or man-made

b. Antivirals- drugs made to inhibit or prevent viruses in cells or from entering cells (ex: flu vaccine)

6. Immunity- an organism’s own natural defenses that recognize, attack, destroy and “remember” pathogens using specialized cells or barriers.

LT 3

ImmunityThere are two kinds of immunity

1. Natural Immunity- cells, tissues or products naturally occurring in an organism that fight against pathogens; non-specific and specific

2. Acquired Immunity-developed by exposure to a vaccine or exposure to another animal’s antibodies; active and passive

LT 4

Natural ImmunityNon-Specific Defenses

“Castle Wall”• Physical or chemical barriers

that attempt to keep pathogens out.

First Line – • Includes the skin, mucous,

sweat, tears or salivaSecond Line --• White Blood Cells (WBC)• Fever• Interferons

Specific Defenses“The Soldiers”

• Specialized cells that track down and attempt to destroy pathogens that have managed to get in

Third Line - B Lymphocytes/Humoral Immunity- • protection of body’s liquids

T Lymphocytes/Cell-Mediated Immunity –

• protects against abnormal cells or pathogens in cells

Non-Specific Natural Immunity• Keeps most pathogens out• Does not discriminate between one threat or another1. First Line-Skin, mucous, sweat, tears

-Contain a protein enzyme called Lysozyme that breaks down the cells of pathogens

2. Second Line-Inflammatory Responsea. A response to injury or infectionb. If the pathogen does get in WBC are made in the millions and engulf and

destroy the pathogen-called phagocytesc. The body will also release chemicals to increase the core body

temperature-called a fever; high temperatures can kill most pathogens and increase heart rate to get WBC to site faster

3. Interferons- (watch this)-proteins made by virus-infected cells -slow down the reproduction of viruses to

allow the specific defenses time to respond.

LT 5

& 6

White Blood Cells (WBC)Blood contains…1. Red Blood Cells-carry O2

2. Platelets-help with clotting3. White Blood Cells-involved in IMMUNITY

Other Facts• Also called leukocytes• Do not carry O2

• 1000x less common than RBC• Produced from unspecialized cells in the bone marrow• Can live for days or years• Guard against infection, fight parasites, and attack bacteria• A high number of WBC indicates some sort of infection• Three kinds of WBC

1. Phagocytes – engulf and digest pathogens2. Histamine Producers – increase blood flow as an inflammatory response3. Lymphocytes – B and T-Cells

LT 7

Phagocyte - type of cell capable of engulfing and absorbing bacteria, small cells and particles; EX: WBC

Phagocytosis – ingestion of bacteria or other material by phagocytes

Pseudopodia- a protrusion of the cell membrane caused by cytoplasmic streaming; used for movement or “feeding”

Phagosome- a vacuole/sac in the cytoplasm of a cell containing any materials ingested during phagocytosis

Lysosome - an organelle in eukaryotic cells that have enzymes that digest worn out organelles, cell parts or food particles

WBC

Phagocyte

Phagocytosis

Pseudopodia

Phagosome

Lysosome

Specific Natural Immunity• Utilized when pathogens get past the non-specific

defenses• The immune response is triggeredAntigen- a substance (protein) that triggers an immune

response (ex: virus, bacteria, protists)

Cells in the Immune System that recognize antigens:1. B-Lymphocytes (B-Cells) 2. T-Lymphocytes (T-Cells)

LT 8

Humoral Immunity (B-Cells)

1. A pathogen enters the body2. The pathogen’s antigens are

recognized by B Cells (specialized cells-lymphocytes-that produce antibodies to attack pathogens)

3. This prompts the B-Cells to start dividing rapidly into Plasma and Memory cells

4. The plasma cells make antibodies. Antibodies are special proteins that recognize and bind to the antigens to try to destroy them.

The ends of the Y-shape

of the antibody

matches the shape of the

antigen

LT 8

Humoral Immunity (B-Cells)

5. Memory cells are also produced from the B-Cells. These cells remember pathogens encountered and can quickly reproduce antibodies if exposed to that antigen again. They are not active during the first exposure.

6. If the antigen comes back the Memory cells will divide into plasma cells and more memory cells to produce the specific antibodies needed again.

Cell-Mediated Immunity (T-Cells)

! NOT ASSOCIATED WITH ANTIBODIES !

1. T-Cells are specialized cells that defend against our own bad cells (like cancer cells) or cells infected with viruses.

2. If a pathogen is in a cell, antibodies cannot get into the cell to fight it.

3. Infected cells will have antigens of the pathogen on their surface that T-Cells can recognize and bind to.

4. T-Cells will divide into four kinds of cells to do this

a. Helper T-Cells-produce memory T-cells and activate B-Cells

b. Killer T-Cells-track down and destroy pathogens with antigens

c. Memory T-Cells-if a second exposure to the same antigen occurs they are involved (like Memory B-Cells)

d. Suppressor T-Cells-turn off Killer T-Cells

LT 9

T-cells are also important because

they activate B-Cells!!1. Phage cells can put can

put the pathogen’s antigens on their cell surface to be recognized by T-Cells.

2. Helper T-Cells specifically bind to the antigens.

3. Chemicals are sent out and signal Helper T-Cells to become killer T-cells and to activate B-Cells

4. Killer T-Cells will bind to antigens and destroy the cell, thus destroying the pathogen.

5. B-Cells differentiate and make plasma cells with antibodies.

Cell-Mediated Immunity (T-Cells)

Acquired ImmunityActive Acquire Immunity

-immunity produced by a body’s response to a vaccination or natural exposure to an antigen

Vaccine – the injection of a weakened form of a pathogen to produce an immune response

• Appears after an exposure to a pathogen

• Body produces antibodies against the pathogen

Passive Acquire Immunity-immunity gained temporarily

by being injected with another organisms antibodies

• Short lasting because foreign antibodies are eventually destroyed

• Developed naturally (from mother as a fetus or from breast-feeding) or deliberately (injections)

LT 11

Acquired Immunity Questions

Vaccinations1. I got chicken pox as a child.

Why haven’t I gotten it again. Explain.

2. Since I have had the chicken pox virus, I will be protected against the measles virus, right? Why or why not?

3. Why is a vaccine like a sneaky little trick to your immune system?

4. Why do I only need a tetanus virus every so often but a flu virus every year? I hate shots! Explain

Mother to Baby1. During which trimester of

pregnancy are antibodies passed from mother to baby?

2. If a baby is born prematurely, how does this affect their immunity? Why?

3. A mother’s milk takes a few days to be produced. Should a mother even bother nursing her baby in the hospital or wait until she gets home? Why?

4. My doctor recommended my husband and I get the Pertussis or Whooping Cough vaccine before my baby was born. Why?