Download Immune System

Integumentary System
• Structure – mostly epithelial tissue
– 3 layers
• Epidermis – dead cells
• Dermis – living cells
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Hair follicles
Sweat and oil glands
Nerves
Muscle fibers
Blood vessels
• Subcutaneous layer (hypodermis) – adipose (fat) cells –
connective tissue
Immune System
Chapter 43
175
“Generic” Thinking on immune
system
• Antigen/pathogen: Anything trying to enter
and destroy cell
• Macrophage: Cell that “eats” and destroys
antigen
Immune System
• Functions
– Protection from pathogens and cancer
–
–
–
–
Viruses
Bacteria
Parasites
Toxins
– Innate Immunity – nonspecific defenses
• 1st line of defense
• 2nd line of defense
– Acquired immunity – specific defenses
• 3rd line of defense
– Humoral immune response
» B-cell response
– Cell mediated immune response
» T-cell response
INNATE IMMUNITY
Rapid responses to a
broad range of microbes
External defenses
Skin
Mucous membranes
Secretions
Invading
microbes
(pathogens)
ACQUIRED IMMUNITY
Slower responses to
specific microbes
Internal defenses
Phagocytic cells
Antimicrobial proteins
Humoral response
(antibodies)
Inflammatory response
Natural killer cells
Cell-mediated response
(cytotoxic
lymphocytes)
Immune System
• Structures
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–
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Skin
Mucous Membranes
Bone Marrow
WBC’s - leukocytes
• Neutrophils – attack pathogens in the blood and tissues
• Monocytes  macrophages – in body tissues
• Dendritic cells  Lymphocytes
– B-cells
– T-cells
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–
–
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Lymph nodes
Spleen
Lymph vessels
Thymus
Innate Immunity – Non Specific Defense 177
• 1st lines of defense
• Skin
– Barrier to pathogens
– Sebaceous (oil) and sweat glands secrete lysozyme
which destroys bacteria
• pH of 3-5 – acidic
• Mucous Membranes
– Line the respiratory, digestive, and urinary tracts
– Mucus and cilia trap and expel pathogens
• Secretions
– Stomach – gastric juice – pH 2
– Saliva, tears, and mucous all contain lysozyme
proteins
Innate Immunity – Non Specific Defenses
• 2nd lines of defense
– Only activated if the 1st line fails
• Phagocytes – Phagocytic WBC’s
– Attach to microbes (pathogens)  ingest them  lysosome destroys them
• Nitric oxide and lysozyme in lysosomes
• Tuberculosis is resistant to lysosome destruction
– Neutrophils
• Engulf pathogens traveling in the blood and self destruct  killing the
pathogen
– Macrophages (monocytes)
• Reside in tissues and organs and attack pathogens that enter or begin to
infect
– Dendritic cells
• Attack like macrophages and stimulate acquired immunity (3rd line of
defense)
– lymphocytes
176
• IQ 43.1
Innate Immunity – Non Specific Defenses
• Antimicrobial proteins – impede pathogen
reproduction
– Complement system
• Lyses microbes and triggers inflammation (inflammatory
response)
– Interferon
• Inhibit viral reproduction
• Natural Killer Cells
– Attack virus infected body cells and cancer cells 
apoptosis
• Programmed cell death
• Fever
– Stimulate WBC production and tissue repair
Blood clot
Pin
Pathogen
Macrophage
Chemical signals
Phagocytic cells
Capillary
Blood
clotting
elements
Phagocytosis
Red blood cell
1 Chemical signals released
by activated macrophages
and mast cells at the injury
site cause nearby capillaries
to widen and become more
permeable.
2 Fluid, antimicrobial proteins,
and clotting elements move
from the blood to the site.
Clotting begins.
3 Chemokines released by various
kinds of cells attract more
phagocytic cells from the blood
to the injury site.
4 Neutrophils and macrophages
phagocytose pathogens and
cell debris at the site, and the
tissue heals.
Innate Immunity – Non Specific Defenses
• Inflammatory Response
– 1. Skin is punctured and pathogens enter
– 2. Mast cells in connective tissue release histamine
increasing permeability and dilation of capillaries to
injured site
– 3. WBC’s and blood clotting factors move from the blood
to the infection
– 4. Clot forms a scab
– 5. Neutrophils and macrophages attack pathogens
– 6. WBC’s release chemokines which attract more
phagocytes to attack the pathogen
• Positive feedback
– 7. Redness, swelling, and soreness are side effects
Warm Up:
• Have Pogil ready to be checked
Antigen Binding to an Antibody
Specific Immune Response (3rd line of defense)
Antibody
has a specific binding
Site to bind antigen
Antigen Binding to an Antibody
• s
Acquired Immunity – Specific Defense
- 185
• 3rd line of defense
• Lymphocytes
Bone marrow
Lymphoid
stem cell
Thymus
– Humoral Immune Response
• B-Cells  Antibodies
• Made and matured in bone
marrow
– Cell Mediated Immune
Response
• T- Cells  attack infected
body cells
• Made in bone marrow and
matured in the thymus
T cell
B cell
Blood, lymph, and lymphoid tissues
(lymph nodes, spleen, and others)
Cell-mediated immune response
Humoral immune response
First exposure to antigen
Intact antigens
Antigens engulfed and
displayed by dendritic cells
Antigens displayed
by infected cells
Activate
Activate
Activate
Secreted
cytokines
activate
B cell
Helper
T cell
Gives rise to
Plasma
cells
Memory
B cells
Secrete antibodies that defend against
pathogens and toxins in extracellular fluid
Cytotoxic
T cell
Gives rise to
Gives rise to
Active and
memory
helper
T cells
Memory
cytotoxic
T cells
Active
cytotoxic
T cells
Defend against infected cells, cancer
cells, and transplanted tissues
Triggering a lymphocyte response
•
•
•
•
Humoral Response – B-Cell
B-Cells are also activated by
intact antigens on pathogens
B-Cells give rise to Plasma
cells and Memory Cells
Plasma Cells make antibodies
to trap pathogens and mark
them for destruction
Memory cells “remember”
antigens so antibodies can be
made quickly upon second
exposure.
Cell Mediated Response – T-Cell
• Cytotoxic T-Cells are also
activated by antigens displayed
on infected body cells
– Antigen displayed in Class I MHC
• Cytotoxic T-Cells give rise to
Active Cytotoxic T-Cells and
Memory Cytotoxic T-Cells
• Active Cytotoxic T-Cells kill
infected body cells, cancer
cells, and transplant tissues
• Memory Cytotoxoic T-Cell
“remember” the antigen so
infected cells can be killed
quickly upon second exposure.
Blood Groups
Antibodies
Produced
Blood Type
Antigen(s)
• A
• A antigens • Anti - B
• A and O Blood
• B
• B antigens • Anti - A
• B and O Blood
• AB
• A and B
antigens
• NONE
• A, B, AB, and O
Blood
• O
• NONE
Can Receive
– Universal recipient
• Anti – A and
• O only
Anti - B
– Universal donor
Rhesus Factor and Blood
• Rh factor – blood antigen
• Can be problematic in
pregnancy if the mom is Rh(lacks the antigen) and the
baby is Rh+ (has the
antigen)
• If blood mixes during
delivery mom will produce
antibodies for the Rh
antigen
• If mom has a 2nd child that
is Rh+ her antibodies will
attack the fetus during late
pregnancy and child birth
– Mom is injected with anti-Rh
antibodies to prevent this
Transplants
• No two people except identical twins have
identical MHC molecules
– % matches are made in a transplant to minimize
rejection
– Transplant recipients take medicine to suppress the
immune response to the transplant
• Leaves the recipient susceptible to other infections
• Bone Marrow Transplant
– Graft vs. Host
– Graft is bone marrow – unless matched carefully
could cause the new blood cells produced in the
bone marrow to reject the host
Autoimmune Diseases
• Immune system does not recognize body cells as
self and creates antibodies against them
• Lupus – attack histones and DNA
• Arthritis – attack cartilage and joints
• Insulin dependent Diabetes – attack beta cells of
the pancreas which secretes insulin
• Multiple Sclerosis – attacks myelin sheath on
neurons
AIDS
• People with AIDS are
susceptible to opportunistic
infections that the immune
system cannot fight off.
• HIV (RNA Virus)  AIDS
• Retrovirus – uses the enzyme
reverse transcriptase
• HIV invades and destroys
Helper T-Cells impairing both
the Humoral and Cell
Mediated Responses
• Summarize the immune system in a page. Use
all key terms and explain the difference
between 1st, 2nd, and 3rd line of defense.
Underline key terms and use pogil to help
guide your writing. Also, use a review book if
needed.
• Explain why blood types produce antibodies
for the opposing blood type. Explain why a
person with AB blood doesn’t produce
antibodies.