The immune system is a system of biological structures and processes within an organism that protects against disease. To function properly, an immune system must detect a wide variety of agents, from viruses to parasitic worms, and distinguish them from the organism's own healthy tissue. Pathogens can rapidly evolve and adapt to avoid detection and neutralization by the immune system. As a result, multiple defense mechanisms have also evolved to recognize and neutralize pathogens

1. The Components of the Immune system
Author: Dr. Robert D. Craig, Ph.D
Aim: What are the components of the Immune system?
Learning objective: to investigate components and primary functions of the
human body’s immune system? (i.e. the 1st (first), 2nd (second) and 3rd
(third)line of defense that the Immune system uses?)
Learning standards:
1. Cite examples of how bacteria cause disease to the human body.
2. Cite examples of how viruses cause disease to the human body.
3. Identify examples of how the human body uses barrier defenses such as skin, tears and
saliva to protect itself against disease.
4. Identify examples of how the human body uses the cellular immune system to protect
itself against disease.
Materials: Handouts, Colored Markers, Ballons,(pathogens), Large White Bag
(Macrophage)
Post its (Antigens), Pins (Killer T cells)
Procedure:
Teacher will Handout K-W-L charts. Teacher will illicit student response. A vocabulary
sheet as well as a worksheet will be completed by students. Teacher will carry out demo
using ballons, pins, and Post-its to demonstrate third line of defense.
Assessment:
Students will have a discussion and complete the KWL chart for Lesson on the immune
system.

2. Name________________________ Period:________________
Date______________
Do Now: What is a disease(s)you have been immunized for?
1.____________________________________
2.____________________________________
3.____________________________________
Teacher guide:
Before: (15 minutes)
Today we are going to discuss the immune system. (Handout K-W-L charts.)
Do you know what the immune system is, or what it does?

3. Think about your responses and write them under “K” on your own charts.
Can I have a few volunteers to write their ideas on the board?
Now we are going to explore the immune system.
During: (45 minutes)
(Pass out vocabulary definitions and ideas including: white blood cells, antibodies,
lymphocytes, B and T lymphocytes, antigens, microbes, natural killer cells, and how
immune system functions)
Name________________________ Period:________________
Date______________

4. K W L
First Line: Surface Barriers or Mucus Immunity

5. 1. The first and, arguably, most important barrier is the skin. The skin cannot be
penetrated by most organisms unless it already has an opening, such as a nick,
scratch, or cut.
2. Mechanically, pathogens are expelled from the lungs by ciliary action as the tiny
hairs move in an upward motion; coughing and sneezing abruptly eject both living
and nonliving things from the respiratory system; the flushing action of tears,
saliva, and urine also force out pathogens, as does the sloughing off of skin.
3. Sticky mucus in respiratory and gastrointestinal tracts traps many
microorganisms.
4. Acid pH (< 7.0) of skin secretions inhibits bacterial growth. Hair follicles secrete
sebum that contains lactic acid and fatty acids both of which inhibit the growth of
some pathogenic bacteria and fungi. Areas of the skin not covered with hair, such
as the palms and soles of the feet, are most susceptible to fungal infections. Think
athlete's foot.
5. Saliva, tears, nasal secretions, and perspiration contain lysozyme, an enzyme that
destroys Gram positive bacterial cell walls causing cell lysis. Vaginal secretions
are also slightly acidic (after the onset of menses). Spermine and zinc in semen
destroy some pathogens. Lactoperoxidase is a powerful enzyme found in mother's
milk.
6. The stomach is a formidable obstacle insofar as its mucosa secrete hydrochloric
acid (0.9 < pH < 3.0, very acidic) and protein-digesting enzymes that kill many
pathogens. The stomach can even destroy drugs and other chemicals
SHARP Skin – largest organ
S - Swelling
H – Heat
A – Ache
R – Redness
P - Pain

6. The Second Line: Passive immunity
Passive immunity is the transfer of active humoral immunity in the form of readymade
antibodies, from one individual to another. Passive immunity can occur naturally, when
maternal antibodies are transferred to the fetus through the placenta,
1.Naturally acquired passive immunity:
Maternal passive immunity is a type of naturally acquired passive immunity, and refers to
antibody-mediated immunity conveyed to a fetus by its mother during pregnancy
2. Artificially acquired passive immunity
Artificially acquired passive immunity is a short-term immunization achieved by the
transfer of antibodies, which can be administered in several forms; as human or animal
blood plasma or serum, as pooled human immunoglobulin for intravenous (IVIG) or
intramuscular (IG)
A phagocyte is a cell that attracts (by chemotaxis), adheres to, engulfs, and ingests
foreign bodies. They are released into the blood and eventually mature into macrophages
(meaning "big eaters", see below). They are made in the bone marrow.
Carry out Demo here!
1. Use balloons as air bourne pathogens.
2. Use large white bag as Macrophage
3. Use post-its as antigens
4. Use pins to pop balloons, they are the Killer T Cells
Adaptive or Acquired Immunity
Lymphocytes come in two major types: B cells and T cells. The blood contains 20–50%
of circulating lymphocytes; the rest move in the lymph system. Roughly 80% of them are
T cells, 15% B cells. Lymphocytes constitute 20–40% of the body's WBCs. Their total
mass is about the same as that of the brain or liver. (Heavy stuff!)
B cells are produced in the stem cells of the bone marrow; they produce antibody and
oversee humoral immunity. T cells are nonantibody-producing lymphocytes which are

7. also produced in the bone marrow but sensitized in the thymus and constitute the basis of
cell-mediated immunity. The production of these cells is diagrammed below.
Parts of the immune system are changeable and can adapt to better attack the invading
antigen. There are two fundamental adaptive mechanisms: cell-mediated immunity and
humoral immunity.
T cells are primed in the thymus, where they undergo two selection processes. The first
positive selection process weeds out only those T cells with the correct set of receptors
that can recognize the MHC molecules responsible for self-recognition. Then a negative
selection process begins whereby T cells that can recognize MHC molecules complexed
with foreign peptides are allowed to pass out of the thymus.
Third Line of Defense: Helper T and Killer T
The process by which T cells and B cells interact with antigens is summarized in the
diagram below.

9. Killer T cells directly attack other cells carrying foreign or abnormal antigens on their
surfaces
Killer T cell are a sub-group of T cells that kill cells infected with viruses (and other
pathogens), or are otherwise damaged or dysfunctional. As with B cells, each type of T
cell recognises a different antigen. Killer T cells are activated when their T cell receptor
(TCR) binds to this specific antigen
Helper T cells regulate both the innate and adaptive immune responses and help
determine which types of immune responses the body will make to a particular pathogen
A person who is HIV positive has to check their viral load, or T-cell count. If it is above
500, this persons immune system is injeporty.

10. Name_____________________________ Period:____________Date: ____________
Vocabulary- Immune System
1. Immune System
_________________________________________________________________
_______
____________________________________________________________
2. Microbes
_________________________________________________________________
_______
____________________________________________________________
3. White Blood Cells
_________________________________________________________________
_______
____________________________________________________________
4. Antibodies
_________________________________________________________________
_______
____________________________________________________________
5. Phagocytes
_________________________________________________________________
_______
____________________________________________________________

11. 6. B-lymphocytes
_________________________________________________________________
_______
____________________________________________________________
7. Memory Cells
_________________________________________________________________
_______
____________________________________________________________
8. Natural Killer Cells
_________________________________________________________________
_______
____________________________________________________________
9. Antigens
_________________________________________________________________
_______
____________________________________________________________
10. T-Cells
_________________________________________________________________
_______
____________________________________________________________

12. Name ____________________ Period: Date__________________
Type (Comm
Disease Causes Symptoms Treatments or
Noncomm)
Flu
Asthma
HIV/AIDS
Cancer
Diabetes
Common
Cold

13. B Cell
Bone Marrow