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Lymphatic and Immune system
• Chapter 17
Lymphatic
System
• System consists of
– Lymph fluid
– Lymphatic vessels
– Structures and organs
consisting of
lymphatic tissue
– Red bone marrow
– Lymphocytes
Tortora
Pages 454-455
Functions of
Lymphatic System
• Draining interstitial
fluid
• Transporting lipids
and lipid soluble
vitamins A,D, E, and
K
• Carries out immune
responses
Tortora
Page 456
Lymphatic and Interstitial fluid
• Same fluid - different areas.
– Interstitial fluid bathes cells.
– Lymphatic fluid is I.F. in lymphatic vessels.
• Contains same materials as plasma except no proteins
Lymphatic capillaries
– Lie between cells
– Open
– Collect interstitial
fluid.
– Fluid moves due to
pressure.
– Flaps open, allow fluid
in, then close
Tortora 456
Lymphatic Vessels
• Lymphatic vessels
– Carry lymph fluid
– Similar structure as
veins with
– Thinner walls & more
valves.
– Skeletal and muscular
pumps move it
towards the heart.
Tortora pg 457
Return to veins
• Lymphatic fluid is
returned to
circulatory system
via the jugular &
subclavian veins
• 20 L of plasma
become IF every day
• 17 L goes back to
heart via the veins
• 3 L becomes lymph
Tortora
456-457
Lymph Nodes
– Located along
lymphatic vessels.
– Arranged in groups.
– Afferent vessel leads
to node.
– Efferent leads away.
– Valves do not let
lymph fluid move
backwards.
Tortora pg 458-459
Lymphatic nodes
– 600 located in the body
– Concentrated at axillae,
mammary glands, throat
and groin
– Foreign materials are
filtered and destroyed in
nodes.
– Macrophages destroy by
phagocytosis
– Lymphocytes destroy by a
variety of immune
responses
Tortora pg 458
Macrophages
Two cross sections of a lymph node: macrophages, which appear
as red in the top image, are sticky cells that act like flypaper,
trapping viruses and bacteria when they enter the lymph node.
Green and blue show other structural elements of the node. In the
bottom picture, B cells are red and the structural elements of the
node are in green and blue
Swollen lymph nodes
Tonsils & spleen
• Tonsils:
– Large nodules grouped
together.
– Contains T and B
lymphocytes.
• Spleen
– Largest mass of lymphatic
tissue.
– Stores blood.
– Stores 1/3rd of the body’s
platelets
– Destroys broken RBCs &
platelets.
Thymus gland
– Contains T cells, dendritic
cells, and macrophages.
– Immature T cells arrive
here from the red bone
marrow.
– 2% “graduate” to be
mature T cells.
– Mature T cells leave the
thymus via the blood, are
carried to the lymph
nodes, spleen, and other
lymphatic tissues.
Tortora 458
Lymph Circulation
• Fluid from plasma of
blood.
• Interstitial fluid.
• Lymph Vessels and nodes
– Lymphatic capillaries
– Lymphatic vessels.
– Lymph nodes.
• Back to plasma.
Thursday 5/8/03
Pages 383-388
Lymph Circulation
• Lymph fluid is moved by;
– Skeletal muscles compressing
vessels.
– Valves insure one way flow.
• Edema
– Fluid gain in the interstitial
spaces.
– Can be due to blocked
lymphatic vessels or nodes.
Thursday 5/8/03
Pages 383-388
Innate Resistance to
Disease
• Pathogens are disease
causing organisms.
• Pathogens produce
toxins or toxic waste
products.
• Your ability to ward off
pathogens is resistance.
• Lack of resistance is
susceptibility.
Skin & Mucous
Membranes
• Skin is 1st defense
against pathogens.
• Mechanical factors
– Many layers of epithelial
cells.
– Role of keratin.
– Role of Mucus membranes.
– Mucus
– Cilia
– Role of lacrimal apparatus
– Role of Saliva
Skin & Mucous
Membranes
• Chemical Factors in
skin and mucous
membranes:
– Oil glands secrete
sebum.
– Perspiration
– Lysozymes
– Gastric juice
– Vaginal Secretions.
Defenses Against
Microbes
• Second line of defense:
– Interferon
• Proteins produced by
cells infected by
viruses.
• Bind to receptor sites
of other cells.
– Complement
• Group of about 20
proteins.
• Found in the plasma of
blood.
• Inhance immune system.
Monday 5/12/03
Pages 388-388
Defenses Against
Microbes
• Natural killer cells
– Type of lymphocyte.
– Ability to kill microbes and
some cancer cells.
– Located in spleen, lymph
nodes, bone marrow, and
blood.
• Phagocytes
– Macrophages are
monocytes that morph.
• Wandering and fixed.
– Neutrophils
• Hi
Monday 5/12/03
Pages 388-388
Phagocytosis
• Chemotaxis
– Phagocytes move towards
higher concentration of
chemicals.
• Adherence
– Phagocytes attach to
microbe.
– Role of complement.
• Ingestion
– Pseudopod surrounds
microbe.
– Phagocytic vesicle is formed.
– Vesicle fuses to lysosome.
– Microbe is digested.
– Wastes are released by
exocytosis.
Inflammation
• Caused by pathogens,
abrasions, chemical
irritations.
• Symptoms
– Redness
– Pain
– Heat
– Swelling
Inflammation
• Stages of
inflammation
– Vasodilation &
increased
permeability of
blood vessels.
– Phagocyte
migration.
• Usually within
an hour.
• Chemotaxis &
emigration
• Repair
Fever
• The hypothalamic
thermostat resets
to raise body temp.
• Reason: higher
temps inhibit
antigen replication,
but speeds up
interferon and
body repair
Innate and Adaptive Immunity
• Innate immunity is a generalized response
• Adaptive immunity refers to “specific”
response to certain pathogens.
• An antigen is any substance that triggers an
immune response.
• The immune system carries out immune
responses to antigens
• Self-tolerance is when a body does not attack
its own tissues and chemicals. Lack of self
tolerance results in autoimmune diseases.
2 forms of adaptive immunity
– Cell mediated immunity:
• Cells directly attack a specific antigen
(pathogens)
– Antibody mediated immunity:
• Antibodies are produced to attack specific
antigen.
– Both use mature T and B cells
– 2 types work together to remove infection
T Cells and Cell Mediated Immunity
•
Recognizing self from
nonself :MHCs
–
•
–
Major histocompatibility
complex proteins recognize
non-self antigens
Role of MHCs in transplants
T Cells destroy
antigens:
–
–
–
–
Macrophages present
antigen to T cells.
T cells sensitize.
T cells clone.
Lyse infected cells
Antibodies and antigens
•
•
•
•
Antigens can be
– Whole pathogens
– Toxins
– Parts of pathogens
Antigens + interleukin2 induce plasma cells
to secrete proteins
called antibodies
(immunoglobulins)
Shaped like a “Y”
One arm is always the
same.
Other 2 arms are
specifically shaped to
antigen.
Tortora
Pages 465-467
Antibody action
• Antibodies travel
to the infection
site, bind to the
antigen, and
inactivate it.
How Antibodies affect antigens
• Neutralize the
antigen toxins
• Immobilize
bacteria.
• Agglutinationantigens are stuck
together
Memory cells
–
–
–
–
Converted B
lymphocytes
B lymphocytes
were shown the
antigen by
macrophages.
B cells now
recognize antigen.
Some B cells
become memory
cells
B Cells and AntibodyMediated immunity
• Long-lasting
antibodies and
lymphocytes
“remember” the
invading antigen
• If the body is ever
re-exposed, it will
launch a swift
attack
Tortora
Pages 428-437
Primary and secondary response
Vaccines and immunological
memory
• Vaccines contain weakened,
killed microbes or parts of
microbes.
• Without getting sick, your
body launches an immune
response, activating B and T
cells
• If you are ever exposed, your
body will quickly remove the
antigen.
• Some vaccines need “booster
shots” to remain effective
• ( tetanus)
Types of Immunity
1. Naturally acquired active immunity.
•
Response to pathogens in every day life.
•
Natural transfer of resistance. Nursing baby.
•
Acquired through vaccinations.
•
Intravenous injection of antibodies.
2. Naturally acquired passive immunity.
3. Artificially acquired active immunity.
4. Artificially acquired passive immunity.