The Lymphatic System

Chapter 22

Immune System

• Defends body against pathogens (bacteria, viruses, some protists & fungi) • Distinguishes between self and non-self •

Infectious Diseases

pathogens inhalation – result from the presence of • Transmission includes contact with infected individuals/organism, water, food, or airborne •

Contagious (Communicable) Diseases

infectious diseases capable of being transmitted from one person to another

1. First line of defense (non-specific)

• • • •

Skin Lysozyme

= enzyme in saliva, sweat, tears; attacks bacterial cell walls

Mucus

= traps pathogens

Cilia

= help clear mucus (and pathogens) from respiratory tract

2. Second line of defense (non-specific)

A. Phagocytic white blood cells

(mainly neutrophils and monocytes) destroy pathogens (phago= eat, cyte=cell) • Attracted to a site of infection by chemicals released by injured cells ( chemotaxis )

B. Inflammation -

infected cells release histamine which is a vasodilator, this causes swelling, redness, pain, fever, and it brings WBCs to the area of infection

antibody immunity; specific attack on foreign particles

Antigen

- foreign protein that triggers immune response

Antibodies (immunoglobulins)

proteins made by lymphocytes; bind to antigens and mark them for macrophage destruction

3

rd

Line of Defense (specific)

Lymphocytes

- WBCs; two types: B (mature in bone marrow) and T (mature in thymus); both are made in bone marrow

Look at this picture – p. 801

3

rd

Line of Defense Cont.

1. Primary Immune Response

• First appearance of antigen in the body; memory cells are formed

2. Secondary Immune Response

• Second appearance of antigen; higher levels of antibodies are formed in shorter time; you do not experience sickness due to antibody production from memory cells

Treatment of Infectious Diseases

1.

Three lines of defense of the Immune System 2.

Antibiotics

(

ONLY FOR BACTERIAL INFECTIONS!!!

) • First antibiotic – penicillin – Alexander Flemming • • •

3. Vaccines

Activate the primary immune response and formation of memory cells without causing severe disease symptoms Typically made from dead/inactive virus or bacteria or their proteins First vaccine – smallpox – Edward Jenner

Disorders of the Immune System

•

Autoimmune Disorders

– body produces antibodies against its own tissue, e.g. Grave’s disease (hyperthyroidism) and rheumatoid arthritis •

Allergies

occur when the body reacts to materials which should not be antigenic, e.g. peanuts

Immunity Active immunity

Production of a person’s own antibodies; long lasting

Passive immunity

An individual is given antibodies by another ; short-term (weeks- 6 months)

Natural Active

When pathogen enters body in the normal way, we make antibodies

Artificial Active Vaccination

– person makes antibodies without becoming ill

Natural Passive

From mother in uterus & breast milk

Artificial Passive

Immunoglobulin injection; extremely fast, but short lived (e.g. snake venom) Edward Jenner