Transcript 1. Describe the first non-specific line of defense the

Chapter 43 Reading Quiz
1.
Which group of cells make up 60 – 70% of
all WBCs?
2. Prostaglandins & ____ are released by
injured tissue to promote blood flow to
the area.
3. The two main types of lymphocytes are
the __ cells & the __ cells.
4. Which type(s) of blood could a Type B
person receive?
1. Describe the first non-specific line of
defense the body has against infection.
• The skin, mucous membranes, and
secretions (saliva, tears)
• Act as:
1. Physical barriers
2. Chemical defenses (sweat pH 3 – 5)
- acidic stomach 
Lining of the trachea
2. Describe the second non-specific line of
defense, including the “killer cells”,
inflammatory response, and antimicrobial
proteins.
• Phagocytic WBC’s (neutrophils)
- engulf and destroy microbes
- NK (natural killer) cells lyse infected cells
• Inflammatory response
- increase in local blood supply
- histamine: triggers dilation (allergic reactions)
- enhance migration of phagocytic cells
• Antimicrobial proteins
- interferons: limit cell to cell spread 
3. What is the importance of specific
immunity? What provides this specificity and
diversity?
• Lymphocytes provide the specificity and diversity
of the immune system
• B & T cells circulate throughout the blood & lymph
- these recognize and respond to particular
microbes and foreign molecules (antigens)
• B cells secrete antibodies
• With the diversity that exists, the immune system
has the capacity to respond to millions of
different antigenic molecules & pathogens 
4. How are immune responses induced, and
describe immunological memory.
• Response induced  when antigens
interact with specific lymphocytes
• Each selected lymphocyte is activated to
divide & differentiate, forming 2 clones of
cells
A  effector cells to combat antigen
B  memory cells which bear receptors
specific for that antigen for a long time
- called “cloning selection” 
Immunological memory
5. How does the immune system distinguish
self from nonself? Why is this important?
• T cells are developed in the thymus
• B cells are developed in the bone marrow
• As development occurs they are tested for
self-reactivity
- if positive, they become nonfunctional or
a victim to apoptosis
• Failure of self-tolerance can lead to
autoimmune diseases like multiple sclerosis

6. Describe the various cell surface markers
and their functions.
• MHC  major histocompatibility complex
- marks body cells as “self”
- class I  found on all nucleated cells
- class II  only macrophages, B & T cells
- job is “antigen presentation”  present antigen
proteins to T cells (2 types)
1. Cytotoxic T cells  antigen receptors bind to
fragments (I MHC)
2. Helper T cells  bind to fragments from II MHC

7. Describe humoral immunity and cellmediated immunity.
Humoral Immunity
• Involves B cell
activation and results
from the production
of antibodies that
circulate in the blood
plasma & lymph
Cell-mediated
Immunity
• Depends on the action
of T cells – immunity
to some infections
passed along when T
lymphocytes are
transferred 
8. Overview the function of helper T
lymphocytes in immunity.
• II MHC molecules are recognized by helper
T cells
- serve as antigen-presenting cells
• Help mobilize both humoral and cellmediated branches of the immune response

9. How do cytotoxic T cells counter
intracellular pathogens? Which response is
this associated with?
•
Is associated with the cell-mediated
response
1. The T cell receptor of a cytotoxic T cell
recognizes a class I MHC antigen complex
on the surface of an infected cell
2. Discharge of perforin protein, which
lyses the antigen-presenting cell 
10. Describe the process by which B cells
make antibodies to fight against
extracellular pathogens. Which response is
this associated with?
• Associated with the humoral response
• Response is initiated when B cells bearing
antigen receptors are selected by specific
antigens
- antibody initiated to known pathogen 
11. Describe antibody structure and function.
• Antibody molecule
 2 identical antigenbinding sites, each
molecule consists of
four polypeptide
chains (2 light, 2
heavy) 
12. Describe the antibody-mediated disposal
of antigen.
• The binding of antibodies to antigens to
form antigen-antibody complexes is the
basis of several antigen disposal
mechanisms
• Ex: neutralization (blocks viral binding
sites), agglutination, precipitation 
13. Describe the immune system in
invertebrates.
• It is rudimentary and little is known
• One well-developed aspect is the
distinguishing between self and non-self
• Have immunological memory 
14. Describe the two ways in which immunity
can be achieved.
1. Active 
• Natural: depends on the response of the
immune system
• Artificial: immunization/vaccines
(inactivated toxins)
2. Passive 
• Antibodies transferred from one
individual to another*
• Pregnancy or injecting antibodies from
other people 
15. Why are blood transfusions and tissue
transplants limited? Describe the problems
associated with organ transplants.
• The immune system’s capacity to
distinguish self from nonself is what limits
the possibilities
• ABO blood groups, antigens, Rh factors
• Graft vs. host reaction is due to the MHC
(major histocompatibility complex)
• The same mechanisms that help a body
fight off invaders fights off the new
transplant 
16. Briefly discuss allergies.
• Allergies are hypersensitive (exaggerated)
responses to certain environmental antigens
(allergens)
• Most common allergies involve the antibodies of
the IgE class (one of the 5 classes of
Immunoglobins)
• Most serious consequence is anaphylactic shock
- drop in blood pressure and death
- must carry a syringe with epinephrine
- common  bee venom, penicillin, peanuts, fish 
17. What are autoimmune diseases?
• When the immune system loses tolerance
for self and turns against certain molecules
of the body
• Ex: lupus  antibodies generated against
all molecules
• Ex: rheumatoid arthritis  cartilage and
joints are damaged
• Ex: multiple sclerosis  T cells reactive
against myelin sheath in nervous system 
18. What are immunodeficiency diseases?
• It is an immune dysfunction
• Mostly genetic, the worst is SCID (severe
combined immunodeficiency) where both
branches of the immune system fail
• Must have a bone marrow transplant
• Ex: Hodgkin’s disease, suppresses the
lymphatic system 
19. Describe AIDS and the history and
treatment of this disease.
• In 1981, a particular type of sarcoma (cancer of
skin & blood vessels) was noticed  rare except in
immunosuppressed individuals
• AIDS  acquired immuno-deficiency syndrome
- susceptible to opportunistic diseases, infections,
and cancers
• In 1983, HIV (retrovirus human immunodeficiency
virus) was identified as the causative agent of
AIDS

AIDS continued…
• Mortality is about 100%, it is the most lethal pathogen ever
encountered
• Probably evolved from an HIV-like virus (SIV) in Africa
• Seen as early as 1959 in blood samples
• AIDS cannot be cured at this time and the progression of
HIV  AIDS cannot be stopped
• Treatment is very expensive and includes:
1. DNA inhibitors
2. Reverse transcriptase inhibitors
3. Protease inhibitors
• HIV is transmitted via infected body fluids (blood/semen);
is NOT contracted by casual contact
• In 1997, 6 million people acquired HIV 