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The Immune & Lymphatic System, Ch.22
Types of Defense
________________________: Innate defenses
Present at birth and provide immediate protection
1st line of defense: skin and mucous membranes
2nd line of defense: internal defenses
________________________: Immunity
______________
______________
Nonspecific Defense Mechanisms
 Physical barriers
 Chemical barriers
 Increase in body temperature
 Production of antimicrobial proteins
 Inflammatory response
First line: skin & mucous membranes
 Physical and chemical barriers:
Epidermis
 Skin =barrier, & when sheds will remove microbes
 Invade adjacent tissues & circulation thru cuts
Mucus- traps microbes
Hair, cilia
Lacrimal apparatus- tears contain lysozyme
 Lysozyme found in: tears, perspiration, nasal secretions, &
tissue fluids
Urine, vaginal secretions, defecation, vomit
Acidic: sebum, perspiration, gastric juice, vaginal
secretions
Second line: Internal defenses
 Antimicrobial proteins:
Interferons (IFN)- virus infected cells produce antiviral proteins, communicate to uninfected cells
Complement system- enhance immune, cytolysis,
phagocytosis, inflammation
Transferrins- inhibit bacterial growth
 Natural Killer Cells & phagocytes
 Inflammation
 Fever:
↑ temp due to reset hypothalamic thermostat
Intensifies IFN, microbes, speed up repair
Natural Killer Cells
NKC = 5-10% of lymphocytes in blood
Spleen, lymph nodes, RBM
Lack molecules to identify T & B cells
Ability to kill variety of infected & tumor cells
Attack cell w/abnormal MHC
Bind
Release granules of toxic substance
• Perforin  cytolysis
• Granzymes induce apoptosis or self-destruction
Kills cell but NOT MICROBES inside cell
• Microbes need to be phagocytized
Phagocytes
 Phagocytosis (part of Specific Immunity):
Neutrophils
__________________  wandering macrophages
 Fixed macrophages stay put
• Histiocytes, Kupffer cells, alveolar, microglia, and tissue
macrophages in spleen, lymph nodes, & RBM
5 phases:
 _________________
 Adherence
 Ingestion
 Digestion
 Killing
Inflammatory response
fig 22.10
 Causes: pathogens (bacteria, virus), abrasions,
chemical irritations, disturbances of cells,
extreme temperatures, burns, radiation
 4 signs & symptoms:
______________
______________
______________
______________
 Can also cause loss of function depending upon
site and extent of injury:
Inflammatory response (2)
Purpose: attempt to dispose of microbes,
toxins, foreign substances
Prevents spread of above
Prepare for repair and restoration
3 Stages of inflammation:
Vasodilation & ↑ bv permeability
Emigration of phagocytes
Tissue repair
Vasodilation & ↑ permeability
Vasodilation  ↑ blood flow to area
Remove microbial toxins, dead cells
↑ permeability  proteins & clotting factors
Substances responsible:
Histamine
Kinins
Prostaglandins
Leukotrienes
Complement
1. When a localized area exhibits
increased capillary filtration and
swelling, this is an indication that
A.
B.
C.
D.
E.
an immune response is underway
fever is developing
inflammation is occurring
Ab are phagocytizing target cells
fever is ending
2. Which type of molecule is produced
by viral-infected cells to communicate
to non-infected cells of the presence of
a virus?
A.
B.
C.
D.
E.
Complement
Interferon
Pyrogen
Antigen
Antibodies
3. Saliva and tears contain this enzyme
that destroys bacteria.
A.
B.
C.
D.
E.
Trypsin
Amylase
Lysozyme
Salivase
Kinase
Specific resistance: Immunity
Specificity and memory
Humoral or antibody-mediated (AMI)
_________________ into plasma cells 
synthesize & ___________ or immunoglobulins
Antibody bind and inactivates its antigen
Cell- mediated (CMI)
_______________ proliferate into cytotoxic T
cells that ______________ the invading antigen
T cell populations
 Cytotoxic T cells:
Kill infected cells and cancer cells
 Helper T cells:
Secrete __________________- help regulate B cells
and T cells,  play a pivotal role in BOTH humoral & cell
mediated responses
Secrete protein factors and molecules secreted to
regulate neighboring cells
 Memory T cells:
Remain from proliferated clone after CM response
Cell mediated immunity
Activation of T cells by specific antigen
T cell proliferation & differentiation into clone of
effector cells
Elimination – ________________  cytolysis
Specific to specific antigens
Can leave lymph tissue to seek and destroy
foreign antigens
Antibody-mediated response
_______________________
________ responds to _____________ antigen
Stay in lymph tissue: nodes,spleen,MALT
Activated upon presence of foreign antigen
Differentiate into plasma cells
Produce antibodies
Ab circulate in lymph and blood to reach invasion site
Some B cells become ____________________
Ab-mediated response
 Inactive B cell
receptor binds
antigen, can stimulate
T cell to intensify
response
 Plasma cells develop
and produce Ab
 Memory cells develop
and remain to
respond to antigen in
the future
Production of antibodies
4. A "foreign" molecule which can invoke
the immune response is called a(n)
A.
B.
C.
D.
E.
Antigen
Immunoglobulin
Hapten
Antibody
Histamine
5. The immune cell that allows for
subsequent recognition of an antigen
resulting in a secondary response is called
a(n)
A.
B.
C.
D.
E.
helper T-cell
memory cell
antigen-presenting cell
plasma cell
macrophage
6. Active, artificially acquired immunity
is a result of
A. Vaccination
B. Ab passed from mother to fetus
through the placenta
C. Ab passed from mother to baby
through breast milk
D. injection of immune serum
E. Ab produced due to previous exposure
to an antigen
Clinical Connections
Organ transplants- rejection dependent
upon similarity of MHCs
Immunodeficiency- as in HIV, lose helper T
cells, opportunistic infections may occur
Autoimmune diseases- fail to display self
tolerance and attack own tissues
Hypersensitivity- allergic rxn to things that
most people tolerate (4 types)
7. Cytotoxic T cells kill target cells
A. through insertion of perforins into the
target's membrane
B. by secreting antibodies
C. by phagocytosis
D. through injection of tumor necrosis
factor
E. Causing an inflammatory response
8. Lymphocytes that develop
immunocompetence in the thymus are
A.
B.
C.
D.
E.
neutrophils
T lymphocytes
B lymphocytes
Basophils
Eosinophils
9. This type of disease results from the
inability of the immune system to
distinguish self from non-self antigens:
A.
B.
C.
D.
E.
Allergy
Immunodeficiency
Anaphylaxis
Autoimmune disease
Inflammatory response
The Lymphatic System
 Vessels
 Primary lymphatic organs
Red bone marrow
Thymus
 Secondary lymph organs and tissue
Lymph nodes
Spleen
Lymph nodules (tissue because lacks capsule)
Functions of the Lymphatic System
Draining excess interstitial fluid
______________ = interstitial fluid that has
passed into a lymph vessel
Transporting dietary lipids
Lacteals-- GI tract to blood
Protecting against invasion through
immune responses
Lymphatic tissue = specialized reticular CT with
many lymphocytes
Lymphatic vessels, fig 22.2
Lymphatic vessels
Begin as lymph capillaries
Spaces between cells, closed one end
Unite to form larger vessels
Lymph vessels resemble veins but
Are thinner
Have more valves
Intervals along vessels: lymph nodes
w/masses of T cells & B cells
Lymphatic vessels (2)
In skin: lie in subQ, follow same general
route as veins
Viscera: generally follow arteries forming
plexuses around them
Avascular tissue: often lack lymphatic
capillaries
Cartilage, epidermis, cornea, CNS, spleen,
RBM
Lymph capillaries
Slightly larger than blood capillaries
have a unique structure: interstitial fluid
can flow in but not out
endothelial cells in wall overlap BUT:
when pressure is greater in interstitial fluid than
in lymph, cells separate slightly
one-way valve opening, fluid enters
when pressure greater capillary, closed & lymph
cannot flow out
Lymph capillaries (2)
Anchoring filaments- contain elastic fibers,
attach lymphatic endothelial cells to
surrounding tissues
When excess interstitial fluid accumulates,
tissue swells filaments are pulled, opening
larger for fluid to enter
Lacteals- specialized lymph capillaries in
small intestine
Carry dietary lipids lymph vesselsblood
Chlye- lipids present in lymph
Lymph formation and flow
 Most components of plasma can filter freely to
form interstitial fluid
More out than back in  lymph returns this fluid
 Excess filtered fluid≈ 3L/day=lymph
Small amt of proteins (most plasma proteins too large)
Proteins don’t easily diffuse backlymph
important
 Valves for one way movement
 Skeletal and respiratory pumps (as veins)
Lymph nodes
 ≈ 600 scattered throughout body
superficial and deep, usually in groups
however, high concentration in
Mammary gland
Axillae
Groin
 Function as filters
Foreign substances trapped by reticular fibers within
sinuses
Macrophages destroy by phagocytosis
Lymphocytes destroy by immune responses
Flow thru nodes is unidirectional
Afferent lymphatic vessels 
valves of node 
subcapsular sinus 
trabecular sinuses (cortex) 
medullary sinuses 
one of 2 efferent lymph vessels 
valves 
hilum = also where bv enter and leave
Primary (1°) lymphatic organs
Where stem cells divide & become
immunocompetent
Red Bone Marrow
Thymus
Stem cells divide & mature into
B cells – red bone marrow
T cells - thymus
2° Lymphatic organs and tissue
Where most immune responses occur
Lymph nodes
Spleen
Lymphatic nodules
MALT – mucosa associated lymphatic tissue in
mucous membrane: GI, urinary, repro tracts and
respiratory airways
• GALT- gut associated lymphoid tissue
 Tonsils
 Peyer’s patches
Spleen is a lymphatic organ, fig 22.7
 Largest single mass of lymphatic tissue
 In fetus develops blood cells
 Phagocytosis of worn out blood cells
 2 types of tissue:
white pulp- mostly lymphatic tissue
Macrophages & lymphocytes arranged around
branches of splenic artery
red pulp – consists of venous sinuses filled with blood &
cords of splenic tissue
RBC, macrophages, lymphocytes, plasma cells,
& granulocytes
Functions of the red pulp of spleen
______________ by macrophages of
ruptured, worn out, or defective red blood
cells and platelets
_______________________ (up to 1/3 of
body’s supply)
_____________________ during fetal life