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CHAPTER 24
24.1
Nonspecific Defenses:
Innate Immunity
Components: skin, sweat, saliva, tears,
mucous membranes lining organ
systems that open to the external
environment—digestive/respiratory/
genitourinary, stomach acid, nose hair,
cilia
Innate defensive cells:
Phagocytes: white blood cells that eat
bacteria & foreign materials that enter the
body
•Neutrophils: engulf microbes in infected
tissue
•Macrophages: develop from monocytes &
phagocytize bacteria & virus-infected
cells,…they wander actively in interstitial
fluid
Natural Killer Cells: attack cancer cells
& virus infected cells by releasing
chemicals that promote apoptosis
(AKA-programmed cell death)
[Not phagocytic]
NOTE: All types of
these white blood
cells leave the blood
& scavenge invading
cells in the interstitial
fluid & body tissues
Innate defense by proteins: either
attack microbes directly or impede their
production
Interferons: proteins produced by virusinfected cells that help other cells resist
viruses (Fig. 24.1B p. 486)
Complement system: about 30 proteins that
circulate in the blood plasma and work with
other defense mechanisms
Inflammatory Response:
24.2
•Any damage to tissue (microorganisms or
physical injury) triggers this response,…
injured cells release histamine – this causes
the blood vessels in vicinity to dilate &
become leakier
WBC’s that rushed to the area engulf
microorganisms & clean up debris
pus = dead WBCs that accumulate in
area, along w/fluids
Response to an infection may be
localized or systemic
systemic – infection is widespread so
more WBCs will circulate,…fever (good
and/or bad) may result
THE LYMPHATIC
SYSTEM
Components:
Lymphatic system
consists of branching
network of vessels,
lymph nodes, thymus,
tonsils, appendix,
spleen, bone marrow
24.3
Lymphatic vessels carry a fluid
called lymph.
Lymphatic system has 2 main
functions:
1return
tissue fluid to circulatory
system
2fight infections
Circulation of Lymph:
•Lymph enters system through open
lymphatic capillaries
•Largest lymph ducts (R lymphatic duct
& thoracic duct) empty into circulatory
system’s veins in shoulders
•As lymph circulates, microbes from
infected sites & cancer cells can be
phagocytized by macrophages
The Immune Response
The Immune System:
• When the nonspecific defense
mechanisms fail, the immune
system provides another line of
defense
- usually more effective than
nonspecific
- can amplify certain nonspecific
responses
The immune system recognizes foreign
materials in the body:
- foreign invaders are called antigens
- can include certain molecules on the
surfaces of
viruses, bacteria,
mold spores,
cancer cells,
pollen
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Bacteria Bad Boys
Bacillus anthracis :
Bordetella petussis :
Clostridium botulinum :
Clostridium tetani :
Escherichia coli :
Lactobacillus acidophilus :
Neisseria gonorrhoeae :
Salmonella typhimurium :
Streptococcus mutans :
Streptococcus pneumoniae
Treponema pallidum :
Vibrio cholerae :
anthrax
whooping cough
botulism
tetanus
acute pyelonephritis
cavities
gonorrhoea
food poisoning
cavities
: pneumonia
syphilis
cholera
•Antibody - a protein found in
blood plasma that attaches to one
particular kind of antigen & helps
counter its effects
- antibodies do not recognize the
whole antigen, only the localized
region on the surface known as the
antigenic determinant
-binding sites on the antibody &
antigenic determinant have
complementary
shapes
(lock & key)
Immunity means resistance to specific
invaders:
- acquired by natural infection, or
- acquired by vaccination
(weakened or inactive form of the
pathogen)
2 TYPES
1. Active
immunity achieved either
naturally or
artificially when
foreign materials
enter the body
2. Passive immunity - achieved
when antibodies pass from mom to
fetus or to a nursing newborn or
when travelling (GG shots)
The Immune Response
Cells of the Immune System:
Lymphocytes - WBCs that produce
the immune response,…they come
from stem cells in bone marrow.
-some lymphocytes continue to
develop in bone marrow & become
specialized B cells
-others are carried by blood to thymus
& become specialized as T cells
-humans can have 100 million to 100
billion different B cells & T cells
B cells provide humoral immunity
-B cells secrete antibodies that are
carried by blood & lymph to the site
of infection
-this system defends against bacteria
& viruses present in body fluids
-can be transferred passively by
plasma donation
T cells provide cell-mediated immunity
-defends against bacteria, viruses,
fungi, protozoans, & cancer cells
inside body cells
-circulate in blood & mount a cellular
attack on repeated foreign invaders
•Both T & B cells must mature
before they are able to function in
defense of the body
- must be able to recognize &
respond to a specific antigen
-must have specialized regions on their
surface known as antigen receptors
•Both T & B cells will make memory
cells in response to an antigen
- they are activated by a second
exposure to an antigen
- seem to confer life immunity
(measles, chicken pox)
The Immune Response
Humoral Immunity:
•response is mediated by the
production of antibodies made by B
cells
•each antibody is made of 4
polypeptide chains: 2 heavy & 2
light chains (this gives it a Y shape)
•Each of the 4 chains of the
antibody has a constant (C) region:
- constant role in destroying
invading cells is to mark them for
destruction (opsonization)
- phagocytes will then destroy the
antigen
•Variable region (V) is at the tip of
each arm of the Y
•forms an antigen-binding site
Cell-mediated Immunity:
•this defense mechanism is
produced by T cells & battles
pathogens that have already
entered body cells
•T cells do not make antibodies they make proteins known as T cell
Receptors
•When a T cell recognizes foreign
antigens, they differentiate into effector
cells
- cytotoxic T cells kill target cells
directly
* receptors on the T cells recognize
antigenic determinants on the target
* target cell will then be lysed
* T cells may also attack cancer cells &
prevent them from spreading
•Helper T cells: (many roles)
- help activate cytotoxic T cells &
macrophages
- help stimulate B
cells to make antibodies
- interact w/other WBCs that function
as antigen-presenting cells (APCs) these cells present a foreign antigen
to the helper T cell
Self from Nonself
(Blood Types)
• For each blood type there is an
antigen present on the surface
of the RBC
- Type O has no antigens
- Type A has antigen A
- Type B has antigen B
- Type AB has antigens A & B
•Blood types w/antigens on the
surface do not have antibodies
against that antigen
•another blood group
antigen is the Rh factor
- antibodies produced by mom can
react w/blood of fetus
- problems when Rh(-) mom produces
antibodies against Rh(+) fetus
1.Platelets are
joined
w/fibrinogen
2.Fibrin forms
3. Clots form
(Our bodies respond
to antigens)
Major Histocompatibility Complex
•Ability to distinguish self from
nonself (MHC)
•acts as your biochemical fingerprint: it is 2 sets of self proteins on
surfaces of our cells
•this complex must be considered
before any kind of transplant is
done
Immunological Malfunction
• Autoimmune disease - when the
immune system turns against its own
body
- lupus, rheumatoid arthritis,
scleroderma
Lupus,…people develop immune reactions
against their own nucleic acids; deposits of
antibody-nucleic acid complexes accumulate
causing inflamed joints & kidney
Immunodeficiency diseases cause part
or all of the immune system to be
lacking
-Hodgkin’s Disease is a lymphocyte
cancer
-Severe Combined Immunodeficiency
(SCID) is when both B & T cells are
lacking or inactive (sensitivity to minor
infections)
•Allergies are overreactions to
certain environmental antigens
- these antigens are called
allergens (dust, pollen, insect
toxins, cat saliva)
- allergic reactions are usually
rapid & occur in nasal passages,
skin, bronchi
-antibodies trigger allergic reactions
by binding to,…
mast cells: noncirculating cells located
in connective tissue
-the antibody & mast cell combo
binds to
an antigen
Mast cells
Histamine
Tryptase
Basophils
T lymphocytes Neutrophils
Prostoglandins
Leukotrienes
Eosinophils
Cytokines
Chemokines
* mast cells release histamine (causes
sneezing, itchiness of skin, tearing of
eyes)
* this process is called degranulation
* an antihistamine is a drug that
interferes w/the actions of the
histamine
Anaphylactic shock is a dangerous
type of allergic reaction
-extremely allergic to things like bee
stings, mosquitoes,etc.
-blood vessel will dilate abruptly,
causing a drop in blood pressure
(shock)
What do you know about AIDS?
1.When was it first diagnosed in the
U.S.? 1981
2. What do AIDS patients die from?
Secondary infections,…ExPneumonia, cancer, etc.
3. What is HIV?
Human Immunodeficiency Virus
4. What does the acronym AIDS
stand for? Acquired ImmunoDeficiency Syndrome
5. When does HIV become AIDS?
When the body is no longer able
to fight off infections that a normal
immune system could defend
against.
6. True or False: Blood transfusion
patients are at high risk of
acquiring HIV. FALSE
7. Who is predominantly diagnosed
with AIDS?
Anyone having
promiscuous sex
is at risk. IV needles
with drug use.
(HIV virus)
8. Which countries are at high risk
for AIDS? Africa as a whole,…and
Haiti, Thailand,…poorer, uneducated
9. True or False: The number of new
HIV diagnosed patients in Illinois
has decreased. FALSE
10. What is the best way to decrease
or eliminate HIV? Don’t have sex
AIDS
• Acquired Immune Deficiency Syndrome
• since 1981, more than 60 million people
worldwide have been infected w/the
AIDS virus HIV
• since 1981, more than 25 million people
worldwide have died from AIDS related
causes
• 33.4 million people worldwide are living
with HIV
• 5 million new cases of HIV were reported
in 2004
Your Area
• New cases of HIV in Illinois:
* 2004 – 1,410
* 2005 – 1,366
• St. Louis area:
*2003: 2,312 HIV
4,717 AIDS
People living with HIV/AIDS in 2008
Adults living with HIV/AIDS in 2008
Women living with HIV/AIDS in 2008
Children living with HIV/AIDS in 2008
People newly infected with HIV in 2008
Children newly infected with HIV in
2008
AIDS deaths in 2008
Child AIDS deaths in 2008
Estimate
Range
33.4
million
31.3
million
15.7
million
2.1 million
31.1-35.8
million
29.2-33.7
million
14.2-17.2
million
1.2-2.9 million
2.7 million 2.4-3.0 million
0.43
0.24-0.61
million
million
2.0 million 1.7-2.4 million
0.28
million
0.15-0.41
million
http://www.avert.org/worldstats.htm
http://www.until.org/statistics
http://www.idph.state.il.us/aids
• Affects a variety of cells preferring the helper T cells,
causing no cell-mediated or
humoral response
• death usually results, not from
AIDS, but another infectious
agent or cancer