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Lymphatic and Immune System
Biology 12-Chapter 13
Overview/Objectives
• 13.1- The Lymph System
o Functions of the lymphatic system
o Lymphatic organs
• 13.2- Non-specific and Specific Defenses
o Immunity and the differences between non-specific and
specific defenses
o Examples of non-specific defenses
o Blood cells responsible for specific defences and their
functions
• 13.3- Induced Immunity
o Difference between active and passive immunity
• 13.4- Immunity Side Effects
o Complications and disorders with the immune system
13.1- The Lymphatic System
• Consists of lymphatic vessels and lymphatic
organs
• Closely associated with the cardiovascular
system
• 3 main functions:
1. Lymphatic capillaries take up excess tissue fluid
and return it to the blood
2. Lacteals absorb fats from the digestive tract &
transport them to the blood stream
3. Help Defend the body against disease
Lymphatic Vessels
• Form a one-way system beginning with
lymphatic capillaries
• Larger lymphatic vessels are similar to veins.
They have valves and depend on the
contraction of muscles for fluid (lymph)
movement
• This is why people who are less mobile tend to
have fluid retention in their feet and ankles
o Edema= localized swelling caused by tissue fluid
o Lymphoma= cancer of lymphatic vessels or system
Lymphatic Vessels
Lymphatic Capillaries
• Tiny, closed-ended vessels that take up excess
tissue fluid called lymph
• Lymphatic capillaries join lymphatic vessels
before entering one of two ducts:
1. Thoracic Duct
•
•
Returns lymph from body below the thorax, left arm, left
head, neck
To the left subclavian vein
2. Right Lymphatic Duct
•
•
Returns lymph from right arm, right side of head and neck
To the right subclavian vein
Lymphatic Organs
• Contain large numbers of lymphocytes (white
blood cells) = immunity
o B lymphocytes (B cells)
o T lymphocytes (T cells)
= both are produced and mature in the primary
lymphatic organs
A) Primary (1) Lymphatic Organs
1. Red Bone Marrow
2. Thymus Gland
1. Red Blood Marrow
(1 Lymphatic Organ)
• Site of stem cells that can produce blood cells
• In children, all bones contain RBM
• In adults: skull, sternum, ribs, clavicle, pelvic
bone (bone marrow transplant), and
vertebrae
• B cells are produced and mature
• T cells are produced-They mature in the
thymus
Red Bone Marrow
2. Thymus Gland
(1 Lymphatic Organ)
• Located between the trachea and the sternum
• Immature T cells migrate to the thymus and
mature
• The thymus gland is critical to immunity
because of its role in T cell maturity
B) Secondary (2) Lymphatic Organs
• In the 2 organs,
lymphocytes encounter
and bind with antigens
and become active cells
for immunity purposes.
• 2 organs:
1. Spleen
2. Lymph Nodes
1. Spleen
(2 Lymphatic Organ)
Red pulp
• Upper left of abdomen
• Filters blood:
– macrophages remove old and defective blood
cells
– Lymphocytes clean blood of foreign particles
– White pulp (inside the red pulp) contains small
lumps of lymphatic tissue
• You can live without your spleen, but it will be
harder to fight infections
Spleen
2. Lymph Nodes
(2 Lymphatic Organ)
• Small, ovoid structures that occur along
lymphatic vessels
• Cleans lymph by macrophages engulfing
pathogens (disease causing agents)
• Swollen lymph nodes (neck, armpit) are
evidence that the body is fighting infection
Lymph Nodes
13.2 Specific and Nonspecific
Defenses
• Immunity= the body’s capability to repel
foreign substances, pathogens and cancer
cells
o A) Nonspecific Immunity = indiscriminate barrier
o B) Specific Immunity= requires a certain antigen
to be present
o Antigen= any molecule that stimulates an
immune system
A) Nonspecific Defenses
4 Types:
1.
2.
3.
4.
Barriers to entry
Inflammatory Reaction
Natural Killer Cells
Protective Proteins
1. Barriers to Entry
(Nonspecific Defence)
• Mechanical barriers= skin and mucus
membranes
• Oil gland secretions= kill bacteria on the skin
• Ciliated cells= line the respiratory tract
• Stomach acid= low pH kills bacteria or inhibits
growth
• Beneficial helper bacteria= in large intestine
will kill invading bacteria
2. Inflammatory Reaction
(Nonspecific Defence)
• Inflammatory Reaction = series of events that occur
when tissue is damaged
I.
II.
III.
IV.
V.
Damaged tissues release  histamine and mast cells (white blood
cell)  causes capillaries to dilate bringing blood to the scene
(redness and heat)
Capillaries become more permeable accumulation of tissue fluid
swelling stimulates nerve endings = pain
Neutrophils and monocytes squeeze through capillary walls 
begin to phagocytize pathogens
Dendritic cells (in skin, lungs, intestine) and macrophages (in most
tissue)  phagocytize pathogens stimulate immune response
Blood clots wall of capillary  preventing blood loss
3. Natural Killer Cells
(Nonspecific Defence)
• Large, granular lymphocytes that kill virus
infected cells and tumor cells
• They bind to these cells and release a molecule
into the cell that causes apoptosis (=cell death)
• Cells in your body have “self” proteins
(recognition on the surface which bind to
receptors on NLK cells)
• Without these “self” proteins, the NK cells bind &
kill
Natural Killer Cells
4. Protective Proteins
(Nonspecific Defence)
• Blood plasma proteins = amplify the
inflammatory response by triggering a histamine
release & attracting phagocytes (neutrophils or
macrophages)
• Membrane attack complex= can be formed by
proteins that produce holes in the surface of
bacteria or viruses  then they burst
• Interferons= proteins produced by a virus infected
cell, warning other non infected cells in the area.
Also produce substance that interfere with viral
replication
B) Specific Defences
• Takes 5-7 days to activate, but then last a long time
• Depend on the action of B cells & T cells
• Through antigen recognition because of specific
antigen receptors
• Each lymphocyte has 1 receptor type (lock & key)
o B cells= give rise to plasma cells, which produce antibodies
to combine with and neutralize an antigen
o T cells= do NOT produce antibodies  they release
chemicals to regulate the immune response or develop into
cytotoxic T cells= attack and kill virus infected cells and
tumor cells
• Once the threat has passes apoptosis (programmed
cell death)
Specific Defences Continued
Characteristics of B cells
Antibody mediated immunity against pathogens
Produced and mature in bone marrow
Reside in lymph nodes and spleen, circulate in blood
and lymph
Directly recognize antigen  undergo clonal
selection
Clonal expansion produces antibody secreting plasma
cells and memory B cells
Figure 13.5 in textbook
Structure of an Antibody
• Antibody = Immunoglobulins (IgGs)
Specific Defences Continued
Characteristics of T cells
 Cell mediated immunity against virus infected
cells and cancer cells
 Produced in bone marrow, matures in thymus
 Antigen must be present in groove of an MHC
molecule
 Cytotoxic T cells destroy non-self protein-bearing
cells
 Helper T cells secrete cytokines that control the
immune response
Look at Figure 13.7 in Textbook
Clonal Selection Theory
13.3 Induced Immunity
• Induced immunity= occurs naturally through
infection or is brought about artificially
• Two types:
1. Active Immunity
2. Passive Immunity
1. Active Immunity
• Develops naturally  after infection of a pathogen
• Induced through immunization  the use of a
vaccine (substances that contain an antigen to
which the immune system responds and prepares
antibodies for)
– After a vaccine is given, the immune response can be
followed by measuring the amount of the developed
antibodies in the plasma = antibody titre (the
blood/plasma sample & test)
– “Boosters” are secondary vaccines given to “boost” the
level of the titre, and to ensure proper antibody level
2. Passive Immunity
• Occurs when an individual is given prepared antibodies
• It is temporary as the antibodies are NOT produced by
the individual’s plasma cells
Infants:
1. Newborns- have passive immunity to some diseases
because antibodies have crosses the placenta from
the mother’s blood (last a few months)
2. Breast feeding- in the first few days, mother’s milk
contains colostrum (fluid high in antibodies) that
helps passive immunity
• Antibody injections- can help prevent illness in a
person unexpectedly exposed to an infectious disease
ex. Antivenom injections (snake bite)
13.4 Immunity Side Effects
Allergies:
• Hypersensitivities to substances called allergens
ex. Food, animal hair, pollen
• The allergic reaction can be immediate (common)
or delayed (not common):
– Allergens (antigens) attach to the antibodies on mast
cells in tissues and bloodstream
– Histamine is released (air born allergens) causes
mucous membranes of nose and eyes to release fluid
– Airway can restrict causing breathing difficulties
(especially if the person has asthma)
– Food allergies cause nausea, vomiting and diarrhea
Allergies continued
Anaphylatic Shock:
• Immediate and often life threatening response
to an allergen, because it has entered the
blood stream
• Blood pressure drops rapidly because of
increased permeability of the capillaries by
histamine
• Drug to help = Epinephrine (EpiPen) =
Adrenaline
Blood Type- ABO System
Blood
type
Antigen Antibody Can receive
on RBC in
blood from
plasma
Can donate
blood to
% of population
Caucasian
1st
nation
African
American
A
A
Anti-B
A,O
A, AB
41
8
27
B
B
Anti-A
B,O
B, AB
9
1
20
AB
A,B
none
A,B,AB,O
(universal
recipient)
AB
3
0
4
O
none
Anti-B &
Anti-A
O
A,B,AB,O
(universal
donor)
47
91
49
Agglutination= clumping of red blood cells can cause
blood to stop circulating  happens when certain blood
types combine
Blood Type – Rh Factor
• Important antigen on red blood cells in
matching blood types
 Rh positive (Rh+)= (85% of US population)
 Rh negative (Rh-)= (15% of US population)
• If mother and baby have different Rh factor 
can affect subsequent pregnancies because of
antibody production  give Rh
immunoglobulin injection
More Immunity Issues
• Tissue Rejection= rejection of transplanted tissue
because recipient’s immune system doesn’t
recognize as “self” immunosuppressive drugs
• Autoimmune disease= T cells or antibodies
mistakenly attack the body’s own cells if they
bear foreign antigens
–
–
–
–
–
Myasthenia gravis
Multiple sclerosis (MS)
Systemic lupus erythematosis (SLE)
Rheumatoid arthritis
Severe combined immunodeficiency disease (SCID)