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Lymphatic and Immune System
Natalie Sanchez, Elizabeth Garcia, Briana Pelayo
About the Lymphatic System
● The lymphatic system is a component of the immune system and the
cardiovascular system
● Structures of the lymphatic system extend throughout the whole body but
exceptions include the central nervous system
● Some major structures in the lymphatic system are the lymphatic capillaries,
lymphatic vessels, lymphatic trunks and ducts, lymph nodes, thymus, spleen, and
tonsils.
Lymphatic System
Functions of the Lymphatic System
● Main functions of the lymphatic system is
o Drainage of fluid, that surrounds tissues and organs and returns it to
blood
o The lymphatic system also helps with the development of immune
cells so it helps the body attack pathogens and protects from diseases
o Excessive amounts of fatty acids and fat molecules in the circulatory
system is absorbed by lymphatic system accumulated in the form of
chyle (happens in the small intestine)
Lymphatic Capillaries
Location
● Parallel to networks of blood capillaries
● Also found in the small intestine
Function
● Drainage of any lymph that has not been absorbed
into bloodstream
Special lymphatic capillaries
● in the small intestine
● absorbs fats and transports them to the venous circulation
Lymphatic Vessels
Location
●Located all over body exceptions are central nervous system, bone marrow, teeth, and
avascular tissue
3 Layers
1.endothelial lining
2.smooth muscle and elastic fiber
3.connective tissue
Function
●helps prevent the backflow of lymph
Lymphatic Trunks
Location
●
located all over the body
Function
●
Trunks drain into ducts which bring lymph back into
blood by emptying into the respected veins
About
●
●
Lymphatic trunks named after regions
where they get lymph from
Major Lymphatic Trunks
o lumbar
o bronchomediastinal
o subclavian
o jugular
o intestinal
Lymphatic Ducts
About
● Two ducts
o Right lymphatic duct
o Thoracic duct
● The intestinal and lumbar trunks merge to the thoracic duct
● Lymph empties into venous circulation at junctions of jugular vein and subclavian
vein
Lymph Nodes
Overall Function
●
●
functions differ by where they are located
filters harmful particles before lymph reaches the bloodstream
Location
●
along large lymphatic vessels, major lymph nodes are:
o
o
o
o
o
o
o
cervical region: which is located in the deep neck
axillary region: located in underarm receives lymph from upper limbs
supratrochlear region: located on the side of the elbow
inguinal region: located in the lower limbs
pelvic cavity: located within the pelvic cavity lymph from pelvic viscera
abdominal cavity: located within abdominal cavity lymph from abdominal viscera
thoracic cavity: located along the trachea and bronchi lymph from thoracic viscera
Thymus
Location
● upper part of the sternum
Function
● maturation of T lymphocytes
Spleen
Location
●left portion of abdominal cavity
3 Functions
1.stores products of RBC degradation
2.Erythrocyte production in fetus
3.Stores thrombocytes
About
●largest organ in the lymphatic system
●Structure includes:
o fibrous capsule
o trabeculae
o Red pulp
o white pulp
Tonsils
Location
● Found in the pharynx
Function
● Helps fight infections but if you have them
removed it will not cause infections.
Tissue Fluid Formation
● Interstitial fluid
● filtration from the plasma leads to the formation which increases the
hydrostatic pressure
● capillary blood pressure purifies water and other molecules from plasma
● plasma colloid osmotic pressure helps draw fluid back into the capillaries
● fluid returns to its venules
● the rest enter the lymph capillaries as lymph
● fluid contains nutrients, gases, & hormones
Lymph Formation & Function
● formed from the movement of
tissue fluid
● clear, colorless fluid
● contains white blood cells
● returns proteins from & excess
fluid to the bloodstream
● transports bacteria and fats
Lymph Flow
● only flows in one direction slowly toward the neck within the lymphatic
system
● flows into the venous bloodstream
● enters lymphatic system through the lymphatic capillaries
o flaplike valves created
o tissue fluid enters capillaries through the valves
● valves prevent it from flowing backwards
● through lymph vessels to lymph nodes
● through the subclavian veins where it empties
● flow because of:
o contracting skeletal muscles in limbs
o contraction of smooth muscles
o pressure changes in breathing
lymphatic capillary
lymphatic vessel
lymph node
lymphatic vessel
lymphatic trunk
lymph ducts
subclavian vein
Lymph Flow
Lymph Flow (cont.)
Non-Specific Cells
Mechanical Barriers
●
●
-
-
Skin (first line of defense)
epidermis is compacted with cells containing keratin
protects against infection and water
not penetrated by pathogens
Mucous membranes
tears(lacrimal apparatus) wash out eye to dilute
microbial growth
saliva dilutes microbes in the oral cavity
mucous prevents drying, trapping foreign items
nasal hairs trap particles in the respiratory tract, fluids
exert out
respiratory cilia sweeps mucous out
Non-Specific Cells
Chemical Protection - reduce bacterial
growth
● Skin
- perspiration has fatty acids, salts (NaCl), and
acid pH
- sebum forms oily layer
● Lysozyme
- enzyme breaks down bacterial cell walls
● Hyaluronic Acid
- gel like matrix in most connective tissues
- slows down speed of infectious diseases
● Gastric Juice
- hydrochloric acid of stomach is a barrier to the
intestine
Non-Specific Cells
● Vaginal Secretions
- lactic acid provides defense
- mildly acidic pH value
Phagocytes (second line of defense)
● Macrophages
- wander through tissues of microbes and cellular debris
● Neutrophils
- become phagocytic when encountering infectious disease
● Eosinophils
- deploy destructive granules against parasitic worms
Non-Specific Cells
Natural Killer Cells
● small population of lymphocytes
● defend against various viruses and cancer
cells
● secretes “cell-cutting” substances called
perforins
● perforins lyse cell membrane, destroying
infected cell
● secrete chemicals that enhance inflammation
Inflammation
● body’s defense against foreign
items
● can be caused by antibodies
attacking normal tissues that are
mistaken for antigens
● immune substances build up in
the tissues
● result is inflammation of the
skin, injury to the tissues and
pain
Allergies
● result from
hypersensitivity to weak
antigens
● allergens include dust,
pollen, mold, etc
● mast cells can release
histamine causing the
inflammation process
● histamine release can
cause anaphylaxis
Specific Cells
1. Antigens
- may be proteins, polysaccharides, glycoproteins, or glycolipids
1. Lymphocytes
- creates antibodies to fight against bacteria
a. T Cells
- T refers to thymus- derived lymphocytes
- some are abundant in the lymph nodes, thoracic duct
- secrete cytokines
- constitute 70-80% of circulating lymphocytes in blood
Specific Cells (cont.)
1. Helper T Cells
● stimulates B cell to create
antibodies
● CD4- type of helper t cell that is
the prime target of HIV
● releases cytotoxic t cells
2. Cytotoxic T Cells
● kills cancer cells and infected
cells
● becomes activated when it
combines with an antigen that
fits its receptors
Specific Cells (cont.)
3. Memory T Cells
●kills pathogen before it causes the body to show signs and symptoms
●can reproduce a faster and stronger immune response
●B Cells
1.constitute 20-30% of circulating lymphocytes
2.B cell receptor allows it to bind to a specific antigen
●Monocytes
1.helps break down bacteria
2.largest leukocytes
3.change into macrophages
Cardiovascular vs. Lymphatic System
- collecting and distributing oxygen, nutrients, and
hormones to tissues
- blood flows through a continuous circuit
- blood is pumped through the arteries and carried
to rest of the body
- blood is visible, damage to vessels is obvious
due to bruising and bleeding
❖ collects and removes waste left behindin
tissues
❖ flows through an open circuit from
tissues into lymphatic vessels
❖ does not pump. flows passively to lymph
capillaries
❖ invisible, damage is hard to detect until
swelling
Similarities
●
●
●
●
both circulate fluids
work to keep the body systems healthy and
supplied with nutrients
provide immune function
lymphatic system is a well known part of the
cardiovascular system
Works Cited
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2004. Print.
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