Functions of the Immune SystemWhat is the primary function? To maintain good health and to protect the body from harmful substances including:

• Pathogens disease-producing microorganisms ex. Bacteria, viruses, parasites

• Allergenssubstances that produce allergic reactions ex. Pollen, dust, animal dander

• Toxins poisonous or harmful substances ex. Venom

• Malignant cells potentially life-threatening cancer cells

Structures of the Immune System:The 1st Lines of Defense

• Intact Skin – wraps the body in a physical barrier that prevents invading organisms from entering the body. Open sores, burns, etc…offer a portal of entry for pathogens

• Respiratory system – traps inhaled foreign matter with the nose hairs and the moist mucous membranes lining the respiratory system. The tonsils (lymphatic system) also form a protective ring around the throat. If foreign matter gets past these barriers, coughing and sneezing help to expel it from the respiratory system.

• Digestive System- acids and enzymes produced by the stomach destroy invaders that are swallowed and consumed with food

• Lymphatic System – work with specialized white blood cells to attack and destroy pathogens that have succeeded in entering the body

The Antigen-Antibody Reactionthe immune reaction

• Involves binding antigens to antibodies• Labels a potentially dangerous antigen so it can

be recognized, and destroyed by the cells of the immune systemAntigen any substance that the body regards as being foreign (ex. Viruses, bacteria, toxins, & transplanted tissues)Antibody a disease-fighting protein created by the immune system in response to the presence of a specific antigen (often used interchangeably with Immunoglobulin)

Antigen-Antibody Reaction Model

Immunoglobulins

• Bind with specific antigens in the antigen-antibody response

• 5 primary types of immunoglobulins (AKA antibodies), which are secreted by plasma cells – Plasma cells – specialized WBC’s that produce

antibodies coded to destroy specific antigens

(See Table 6.1 for the 5 immunoglobulins)

Specialized Cells of the Antigen-Antibody Reaction

• Lymphocytes• B Cells• Dendritic Cells• T Cells

Lymphocytes

• WBC’s that are formed in the bone marrow as stem cells

• Undergo further maturation and differentiation in lymphoid tissues throughout the body (ex. Thymus)

• These changes allow the lymphocytes to act as specialized antibodies that are able to attack specific antigens

B Cells

• Specialized lymphocytes that produce and secrete antibodies

• Each lymphocyte makes a specific antibody that is capable of destroying a specific antigen– most effective against bacteria and viruses

circulating in the blood

Dendritic Cells

• Specialized WBC’s that patrol the body searching for antigens that produce infections

• When antigens are found, they grab, swallow, and internally break apart the captured antigen

• After destruction of the antigen, the dendritic cell “displays” fragments of the antigen on tentilce-like extensions of the cell, which activates the T Cells

Dendritic Cells and T Cell Relationship

T Cells

• Small lymphocytes that mature in the (?) as a result of being exposed to the hormone thymosin, which is secreted by the (?)

• Kill the infected cells on contact– Produce interferon, which are proteins that fight viruses by slowing

or stopping their multiplication memory Jogger: interferon interferes with viral multiplication

– Produce lymphokines, which attract macrophages to the infected site and prepare them to attack the invaders

Complement…not Compliment

• Group of proteins that normally circulate in the blood in an inactive form and are activated by contact with nonspecific antigens such as foreign blood cells or bacteria

• Marks foreign invaders and attracts phagocytes to destroy these antigens

Immunity

What is Immunity?The state of being resistant to a specific disease

Types of ImmunityNaturalPassiveAcquired

Natural Immunity

• Passed from the mother to her fetus before birth via the placenta and colostrum

• Only lasts for a short time (usually 6-8 weeks)

Passive Immunity

• Antibodies are passed from the mother to her child after birth through breast milk

Acquired Immunity

• Also known as active immunity, this is the production of antibodies against a specific antigen by the immune system either by contracting an infectious disease such as chickenpox, or by vaccinating against a disease such as poliomyelitis (polio).

Factors that Affect the Immune System

• General Health – if the immune system is compromised by poor health, it cannot be fully effective

What factors can you think of that will affect your general health?

Factors that Affect the Immune System

Age Who’s the most at risk?

older individuals usually have more acquired immunity, but their immune systems tend to respond less quickly and effectively to new challenges. Babies and very young children do not yet have as much acquired immunity, and their bodies

Factors that Affect the Immune System

Heredity – genes and genetic disorders affect the individual’s general health and functioning of their immune system

Do Allergies run in your family?

Which cells produce interferon?a. B cellsb. T cells c. dendritic cells

ANSWERT cells

When you get a flu shot, what type of immunity are you utilizing?a. Passiveb. Naturalc. Acquired

ANSWERAcquired

What is a substance that produces an allergic response called?

ANSWERAllergen

Which word means bleeding from the spleen?

ANSWERSplenorrhagia

Which cluster of lymph nodes are located in the armpit?ANSWERAxillary

Which organ is responsible for maturing the T cells?ANSWERThymus

Which organ is responsible for maturing the T cells?ANSWERThymus

Which type of immunity does a baby get from drinking breast milk containing antibodies?ANSWERPassive

Allergic Reactionsoccur when the body’s immune system reacts to a harmless allergen such as pollen, food, or animal

dander as if it were a dangerous invader.

• Localized allergic response – also known as a cellular response, includes redness, itching, and burning where the skin has come into contact with an allergen. Ex. Poison ivy can cause a localized allergic response

Although the body reacts mildly to the 1st exposure, sensitivity is established and future contacts can cause much more

severe symptoms!

• Systemic reaction (anaphylaxis) – a severe reaction to an allergen. Symptoms of this response develop quickly. Without medical aid, the patient can die.

Patients experiencing anaphylactic shock may present with:• Wheezing• Sensation of choking/shortness of breath• Rash and pruritus (hives) • swelling of the lips and faces• hypotension

• Scratch test – a diagnostic test to identify common allergens such as tree pollen and ragweed. Swelling and itching indicate and allergic reaction

Antihistamines medications that relieve or prevent the symptoms

of allergiesWork by preventing the effect of histamines,

which is a substance produced by the body that causes itching, sneezing, runny nose, and watery eyes of an allergic reaction

• Appears to be genetically transmitted• Occurs mostly in women during childbearing yearsExamples:– Rheumatoid Arthritis– Myasthenia Gravis– Pernicious Anemia– Crohn’s Disease– Multiple Sclerosis– Scleroderma– Graves Disease

Autoimmune Disordersany disease characterized by a condition in which the immune system produces antibodies against its own

tissues

Immunodeficiency Disordersoccur when the immune system is compromised

(weakened, reduced, absent)

• Human immunodeficiency virus (HIV) – bloodborne infection in which the virus damages or kills the cells of the immune system causing it to progressively fail, which leaves the body at risk for developing many life-threating opportunistic infections

• Acquired immunodeficiency syndrome (AIDS)- the most advanced, and fatal stage of an HIV infection

What is an opportunistic infection?

An infection cause by a pathogen that does not normally produce an illness in healthy humans but does when the host is already weakened (debilitated) by another condition

Example:Karposi’s Sarcoma – can be an opportunistic infection

frequently associated with HIV, this cancer causes patches of abnormal tissue to grow under the skin, in the lining of the mouth, nose, and throat or in other organs.

Karposi’s Sarcoma

Before the AIDS epidemic, Kaposi's sarcoma was seen mainly in elderly Italian and Jewish men, and rarely, in elderly women. Among this group, the tumors developed slowly. In AIDS patients, the cancer can develop quickly. The cancer may also involve the skin, lungs, gastrointestinal tract, and other organs.

Screening Tests for HIV

• ELISA (enzyme linked immunosorben assay) blood test used to screen for the presence of HIV antibodies

• Western blot test – blood test that produces more accurate results than the ELISA test. – Performed to confirm the diagnosis when the

results of the ELISA test are postive– ELISA sometimes produces false positive results

Treatments of the Immune System

• Immunotherapy – involves either stimulating or repressing the immune response– Ex: in the treatment of cancer, it is used to

stimulate the immune system to fight the malignancy

– Ex: in the treatment of allergies, it is used to repress the body’s sensitivity to a particular antigen

Treatments of the Immune System

• Antibody Therapy – synthetic immunoglobulins are used as post-exposure preventative measures against certain viruses, including rabies and some types of hepatitis

• Immunosupression – treatment to repress or interfere with the ability of the immune system to respond to stimulation by antigens– Ex: Immunosuppressants are given to recipients of

organ donations to prevent the rejection of the donor tissue and also to depress autoimmune disorders

Which “bug” am I?

I am a rod shaped spore-forming bacteria. Tetanus (commonly known as lockjaw) is part of my family and is transmitted through a cut or wound and causes severe muscle spasms.

Answer:

Bacilli

Which “bug” am I?I am a spiral-shaped bacteria that has flexible walls and am capable of movement. Lyme disease is caused by a member of my family and is transmitted to humans by the bite of an infected deer tick. Symptoms may include fever, headache, fatigue and a skin rash. If left untreated, Lyme disease can spread to the joints, heart and nervous system.

Answer:

Spirochete

Lyme Disease

Which “bug” am I?I am a small bacterium that lives in lice, fleas, ticks, and mites. Someone in my family causes Rocky Mountain Spotted Fever, which is transmitted to humans by the bite of an infected tick. The signs and symptoms of this disease include fever of sudden onset, headache, and muscle pain followed by the development of a rash

Answer:

Rickettsia

Rocky Mountain Spotted Fever

Which “bug” am I?I am a group of about 30 species of bacteria that form irregular groups or clusters resembling grapes. Most of my family are harmless and live normally on your skin and mucous membranes however my aureus cousin commonly infects wounds and can cause toxic shock syndrome or food poisoning!

Answer:

Staphylococcus

Which “bug” am I?I am a family of bacteria that form a chain. Many members of my family are harmless, but some members are responsible for illnesses including strep throat, meningitis, endocarditis, and necrotizing fasciitis!!!

Answer:

Streptococci