The
Lymphatic
System
Chapter 22
Immune System
• Defends body against pathogens (bacteria, viruses,
some protists & fungi)
• Distinguishes between self and non-self
• Infectious Diseases – result from the presence of
pathogens
• Transmission includes contact with infected
individuals/organism, water, food, or airborne
inhalation
• 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
rd Line of
3
attack on foreign particles
Defense (specific)
Antigen - foreign protein that
triggers immune response
Antibodies (immunoglobulins) proteins made by lymphocytes;
bind to antigens and mark them
for macrophage destruction
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
3rd 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
Natural Active
When pathogen
enters body in the
normal way, we
make antibodies
Passive immunity
An individual is given antibodies by
another ; short-term (weeks- 6 months)
Artificial Active
Natural Passive
Vaccination –
From mother in
person makes
uterus & breast milk
antibodies without
becoming ill
Edward Jenner
Artificial Passive
Immunoglobulin
injection;
extremely fast, but
short lived (e.g.
snake venom)