Disease and the Immune System

Disease is any change, other than an injury, that

disrupts the normal functioning of the body. It is the inability to maintain homeostasis.

Causes

1. Inheritance: sickle-cell anemia, hemophilia

2. Toxic Substances: cigarette smoke, alcohol

3. Poor Nutrition: ricketts, anorexia, scurvy4. Organ Malfunction: heart disease,

diabetes5. Personal Behavior: drug addiction,

alcoholism

Causes continued

6. Pathogens: organisms that enter the body and cause infectious diseases

Antigens Toxins that pathogens produce that cause

harm to an organism.

a) Virus Protein shell DNA or RNA

Examples of Viruses

Virus uses the host cell to reproduce

Examples of diseases caused by viruses:mono, flu, common cold, chicken

pox, small pox, pertussis, AIDS

AIDSsmall pox

chicken pox

6. Pathogens continued:b) Bacteria: Tuberculosis, E. coli, cholera,

tetanus

tuberculosis

E. coli

cholera

tetanus

c) Fungi: ringworm, athlete’s foot, jock itch

ringworm athlete’s foot

d) Parasites: lice, malaria, dysentery, tapeworm, schistosomiasis

lice

malaria in red blood cells

Amoebic dysentery

tapeworm

schistosomiasis

What is Immunity?

Immunity Immunity

The ability of the body to fight infection and/or foreign invaders by producing antibodies or killing infected cells.

Immune System The system in the body responsible for maintaining

homeostasis by recognizing harmful from nonharmful organisms and produces an appropriate response.

Parts of the Immune System

1. Blood - White Blood Cells in particular.

2. Lymph nodes

3. Thymus Gland – Produces T Lymphocytes

4. Bone Marrow – Produces B Lymphocytes

How does the body fight infection/foreign invaders?

The Body’s THREE lines of Defense

First Line of Defense – The Skin• Provides Physical and Chemical barriers

Physical – hard to penetrate, made of indigestible keratin Chemical – tears, sweat

Second Line of Defense – Nonspecific Immune Response

These are defenses the body uses no matter what the invader may be. These defenses include: Phagocytosis – done by Macrophages Natural Cell Killers Inflammation - caused by release of Histamine from leukocytes Fever – caused by histamines. The fever (high temp) kills invaders by

denaturing their proteins.

Macrophage: A phagocytic cell found in the liver, spleen, brain and lungs. Travels

to all areas of the body to find and eat pathogens.

This is a specific response to a specific pathogen/antigen.

The response involves the creation of Antibodies.

Third Line of Defense – Specific Immune Response

Antibodies

Y-shaped protein molecule.

Made up of variable and constant regions.

Made up of Heavy and Light chains.

Produced by B-Lymphocytes

Function: Recognize antigens, bind to and deactivate them. Note: Variable region

recognizes the anitgens.

How an antibody operates/works?Deactivation of a bacterium by an antibody.

The Pathway of Specific Immune Response

Pathogens

Pathogens eaten by Macrophage

Displays portion of Pathogen on surface

Helper-T cell recognizes Pathogen

Step 1

Step 2

Step 3

Activates B- CellActivates Cytotoxic

T- Cell

Memory B-CellMemory T-Cell

Kills Infected CellsAntibodies

Cellular Immunity .vs. Antibody Immunity

Carried out by T-Cells Infected cells are

killed by Cytotoxic T –Cells.

Carried out by B-cells Antibodies are

produced and dumped into blood stream.

Antibodies bind to antigens and deactivate them.

Cellular Immunity Antibody or Humoral Immunity

Immune Response Explained

1. Antigen infects cells.2. Macrophage ingests antigen and displays portion on its surface.3. Helper T- Cell recognizes antigen on the surface of the

macrophage and becomes active.4. Active Helper T-Cell activates Cytotoxic T-Cells and B-Cells.5. Cytotoxic T-Cells divide into Active Cytotoxic T-cells and Memory

T – Cells.6. Active Cytotoxic T-Cells kill infected cells.7. At the same time, B-Cells divide into Plasma Cells and Memory

B- Cells.8. Plasma cells produce antibodies that deactivate pathogen.9. Memory T and Memory B cells remain in the body to speed up the

response if the same antigen reappears.10. Suppressor T-Cells stop the immune response when all antigens

have been destroyed.

Immune Response Summary

Antigen

Macrophage

Helper T - Cell

Active Cytotoxic T-Cell Active B - Cell

Kills Infected Cells Memory T- Cell Plasma Cell Memory B-Cell

Antibodies

Deactivates Antigens

Displays copy of antigen on surface of cell

Cellular ImmunityAntibody Immunity

Primary .vs. Secondary Immune Response

Primary Immune Response This is a response to an invader the First time the

invader infects the body. No measurable immune response for first few days. Next 10 – 15 days antibody production grows

steadily

Secondary Immune Response A more rapid response to an invader the 2nd time it

invades the body. Antibody production increases dramatically and in a

much shorter time period..

Primary .vs. Secondary Immune Response

Passive .vs. Active Immunity1. Active Immunity

This is immunity where the body is “actively” producing antibodies to fight infection.

Ex: You have a throat infection and you are actively creating antibodies to fight it.

Vaccination: An injection of a weakened strain of an infectious microbe (pathogen) that causes the body to undergo active immunity (produce antibodies).

2. Passive ImmunityThis is immunity where antibodies are given to a person from the blood of another person or animal.This immunity only lasts for a short period of time.

ex: Breastfeeding mothers pass antibodies to their children through the milk.

ex: Vaccines against tropical diseases like cholera & typhoid

Man-made treatments for diseases

Antibiotics Produced by certain organisms that destroy

bacteria. Can slow down reproduction Ex. Penicillin, made from a kind of mold, interferes

with the production of the cell walls of the bacteria

Cannot be used against viruses. Some drugs can be used that interrupt the viruses life cycle, so prevents virus from entering the host cells.

Autoimmune Disease

Autoimmune diseases are diseases where the immune system begins to attack itself. Ex:

Rheumatoid Arthritis – crippling disease of the joints. Lupus – disease of blood and organs. Multiple Sclerosis – disease of nervous system

Cause(s): unknown Cures/Treatments: No known cures. Usually treated

with drugs.

Allergies

Allergy- An exaggerated response by the immune system to an allergen.

Allergen: a normally harmless substance that causes an allergic reaction.ex: dust, pollen, mould, food, insect stings

Types of Allergic reactionsThere are two types of allergic reactions.

a. Immediate – occurs within seconds and normally lasts for about 30 mins.b. Delayed – takes longer to react and can last for a much longer time.

What happens during an allergic reaction?

During an allergic reaction antibodies cause histamines to be released from certain cells.

Histamines cause:a. Swelling of tissuesb. Release of fluids (runny noses and eyes)c. muscle spasms (some cases)

Anaphylaxis or anaphylactic shock:This is the sudden and severe allergic reaction to a substance that can cause death.

Treatments for Allergies1. Avoidance of material – especially food.2. Epinephrine – “epi – pen”3. Antihistamines -- benadryl

HIV and AIDS

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HIV History• HIV is thought to have entered into humans

somewhere between 1914 and 1940.

• In 1983, a retrovirus, now called human immunodeficiency virus (HIV), had been identified as the cause of AIDS.

• The HIV antibody test has be used to screen all blood supplies in the U.S. since 1985.

• People receiving blood or blood products before 1985 may have been infected.

HIVHuman Immunodeficiency Virus

• HIV infects the immune system cell called the Helper T cells (-most important white blood cell involved in identifying infections.)

AIDSAcquired Immune Deficiency Syndrome

• The immune crippling disease caused by the HIV virus in which the body becomes unable to protect itself against any secondary infections.

Body Fluids with High Concentrations of HIV

BloodSemen/Vaginal fluids (as high as blood)Breast milkPus from sores

Low concentrations of HIV

It is highly unlikely you will be infected if you come into contact with:

SweatTearsUrineSaliva (-highly possible if blood from

mouth sores is present)

How is HIV Spread?

ANY type of sexual activity (highest risk)Sharing used drug needlesPregnancy-from mother to childSharing razors- if blood is presentKissing- if even the smallest amount of

blood is present. (-membranes of mouth are thin enough for HIV to enter straight into the body.)

Tattoos/body piercing if equipment is not clean.

How is HIV not spread?

Shaking handsHuggingSwimming poolsToilet seatsInsect bitesDonating blood

Can HIV be cured?

NO! Drugs are available to manage the disease, but HIV stays in the body forever!

PROBLEM: RNA viruses mutate at a very high rate. A person with HIV under control can evolve resistance to the drug treatments.

Some infected persons have several strains of HIV in their bodies.

What does HIV look like?

Initial infection- flu like symptoms a few weeks after infection.

Stage 1-HIV positive with no symptoms- can stay at this stage for up to 10 years, but still can pass on the virus.

Stage 2-HIV positive with symptoms- at this point the person is said to have AIDS. Symptoms include: swollen glands, chronic diarrhea, loss of weight

and appetite, fever, fatigue, skin rashes (lesions), night sweats, oral thrush. Life expectancy: 2 to 5 years.

Death and AIDS

Stage III-Full blown AIDS- Person dies of rare opportunistic infections that

take advantage the weakened immune system: Person dies in a matter of months. AIDS related illnesses include rare cancers and

Pneumonia.

Stages of HIV Infection