I. Lymphatic Network
1. Fluid Balance - Transport lost fluid (lymph) back to
the circulatory system.
2. Defend the body against pathogens.
3. Fat absorption.
B. Lymphatic Capillaries
1. Microscopic dead end tubes found between cells.
(Not found in the brain, spinal cord, bone,
2. Similar to blood capillaries.
3. Loosely Joined endothelial cells
C. Lymphatic Vessels
1. Same three layers
D. Lymph Nodes
E. Lymphatic Trunks & Collecting
1. Trunks – merging vessels.
2. Collecting Ducts – One duct
before returning back to the
a. Thoracic Duct – left side
of the head, neck, thorax,
left arm, entire lower
1. Empties into left
2. Originates from
b. Right Lymphatic
Duct – Right side of
the head, neck, right arm
1. Empties into
F. Lymph Movement
1. Formation – Interstitial fluid formed by movement of
blood plasma out of the capillary bed.
a. Increased interstitial fluid, increase pressure forces
lymph pores open – fluid flows in.
a. Force of interstitial fluid entering vessel
b. Similar to veins:
2. Skeletal movement.
II. Lymphatic Organs
A. True organs
1. Lymhpoid tissue containing lymphocytes (white blood
B. Lymph Node
1. Cervical – neck
2. Axillary – armpit
3. Inguinal – groin
4. Deep with in
1. Afferent Lymphatic Vessels – Towards.
2. Hilus- Concave margin
3. Efferent Lymphatic Vessels – Away.
4. Fibrous Capsule
5. Cortex - Outer
6. Medulla – Inner
7. Trabeculae -Extensions
8. Lymph Nodules – Main structure of lymph nodes, gathering of
D. Node Function
1.Largest lymphatic organ
2. Fibrous Capsule – outer,
3. Red Pulp – Large number of red
4. White Pulp – Large number of
white blood cells.
1. Only active during immune
2. T cell production
1. Two Palatine – Back of palate
2. Two Pharyngeal –Upper throat
3. Two Lingual – Base of tongue
H. Peyer’s Patches
1. Clusters located along the small
III. Defense Mechanisms
A. Immune system has ability to recognize foreign
particles (pathogens &/or toxins).
B. Major Histocompatibility Complex (MHC) –
markers that can distinguish between self & non
C. Two types of defense.
1. Non Specific (innate)
2. Specific (adaptive)
D. Type of responses
E. Innate or Non Specific Mechanisms – Defends against all
types of pathogens & has the same response.
1. Mechanical barriers
b. Mucus membranes
2. Phagocytosis – Cellular Eating
d. Natural Killer Cells
3. Chemical Mediators
1. 20 proteins
2. Helps enhance phagocytes
1. Secreted by infected cells to
stimulate neighboring cells to
- chemical attraction
b. Local inflammation
c. Systematic inflammation
F. Specific Mechanisms – Adaptive Response
1. Ability to recognize a specific antigen or toxin.
a. Antigen recognition
2. Components of Immunity
a. Antigen – any substance that causes an immune
b. Antibody (Ab) (gamma globulins or
immunoglobulins)– protein molecule that is produced
in response to a specific antigen.
- 2 heavy chains
- 2 light chains
c. AB + Antigen = Antigen-Ab complex
d. Five Classes of Ab
1. IgG – Most common - small
2. IgA – protection on body surfaces
3. IgM – First to be produced – large
4. IgD – Antigen-antibody receptors
5. IgE – Allergies (bind to mast cells)
e. Variable region – made for specific antigens
f. constant region – same between all antibodies
e. Lymphocytes – come bone marrow
1. B-cells – develop in bone marrow
b. Plasma – AB
2. T-cell – develop in thymus
a. Killer T cells – destroy’s infected cell
b. Helper T cells – stimulates immune system
c. Suppressor T cells – stops the body’s response
d. Memory T cells – remembers for future infections
3. Cell Mediated – T cell
a. Kills invaded & infected
b. Macrophage identified an
antigen, phagocytized it, &
c. Process antigen is placed
on macrophage surface & is
presented to the T-cells.
d. Activates the T-cells.
Cell Mediated Response
4. Humoral Immunity – Ab Response
a. Macrophage identified an antigen,
phagotized it, & processed it.
b. Process antigen is placed on
macrophage surface & is presented
to the B-cells.
c. Activates the B-cells with the help
of Helper T-cells.
d. Grows & multiple into memory B
cells (immunization) & Plasma cells
e. AB production takes 3-5 days,
peaks in 3 weeks.
f. AB binds to antigen surface
forming the antigen-Ab complex
g. Labeled for destruction for natural
Specific response review
G. Allergic Response – Type of humoral resposne.
1. IgE Ab is released into blood in response to the allergen.
2. Comes into contact with the mast cell (concentrated in
skin & mucus layer).
3.Mast cell stores histamines.
4. IgE + Mast cell = release of histamine (causes
Ex. Hives & asthma
5. Immediate hypersensitivities – hay fever, asthma
6. Delayed hypersensitivities – poison ivy, soaps, cosmetics
H. Acquired Immunity
1. Persons ability to mount a defense.
2. Two Types
1. Naturally acquired
a. Active – develop after exposure.
ex- chicken pox, flu, measles.
b. passive – passed from 1 person to another.
ex- Polio, rubella – mother to baby by
placenta or breast milk.
2. Artifically Acquired - Vaccine
Killed or weaken virus that causes an
immune response with out the symptoms.
a. Active – Lifelong
ex. polio, measles
b. Passive – Short term
ex- rabies, hepatitis, tetanus, snake
1. Recycling valuable fluids.
2. Defense against diseases.
1. WBC are reduced which reduces the body’s ability to defend
a. Attacked by pathogens.
b. Low level production.
1. SCID – Severe Combined Immundeficiency
a. Born without the ability to produce active
B & T cells.
b. Treatment – bone marrow transplant.
a. Caused by HIV virus
b. Destroy’s the helper T cells – body never
knows it is getting invaded by other
c. ID in US – 1981
3. Hodgkins – Cancer
a. large multinucleated cell in affected
b. 15-38 & over 50 yrs old.