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Lymphatic System
Cards on the Lymphatic System
37
Anatomy
Undergraduate 2
11/09/2010

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Cards

Term
Lymph Vessels
Definition

- Appearance- thin (not to be confused with arteries and veins)

- Function- to transport lymph fluid

Term
Lymph Fluid
Definition

- Appearance- Clear fluid, less protein than plasma

- Function- delivers the nutrients, oxygen, and hormones required by the cells

Term
Lymphoid Organs
Definition

- E.g.- tonsils, thymus, spleen

- Function- immune responses

Term
The Lymphatic System
Definition

- Complex network of capillaries, thin vessels, valves, ducts, nodes, and organs

- Function: to return lymph to the systemic venous system, to maintain blood volume and fluid levels

- Lymph=excess interstitial fluid

- Interstitial fluid delivers the nutrients, oxygen, and hormones required by cells

- Lymph must be filtered to check for foreign or pathological materials (e.g. cancers, bacteria)

- System contains lymphocytes- these cells are essential to the immune response

Term
Lymphatic Capillaries
Definition

- Blind ended capillaries present in most tissues- drain interstitial fluid from the surrounding extracellular matrix

- Capillaries run together to form larger vessels which deliver lymph into local ducts

- Walls act as one-way valves- when interstitial pressure rises, lymph is forced into vessels

- Pressure traps fluid in vessels and cannot escape

Term
Lymphatic Capillaries: Lacteals
Definition

- The small intestine contains special types of lymphatic capillaries called lacteals

- Lacteals pick up not only interstitial fluid, but also dietary lipids and lipid-soluble vitamins

- The lymph of htis area has a milky color due to the lipid content- also called chyle

Term
Lymph Nodes
Definition

- Some vessels connect directly to lymphatic organs, called lymph nodes

- Small, encapsulated lymphatic organs that contain T and B cells

Term
Afferent (toward node) Lymphatic Vessels
Definition
- Bring lymph to a lymph node where it is examined for foreign or pathogenic material
Term
Efferent (away from node) Lymphatic Vessels
Definition

- Once filtered, the lymph exits the lymph node through these

- Lymph nodes can occur singularly or in groups

Term
Cervical Nodes
Definition
Lymph from head and neck
Term
Axillary Nodes
Definition
Lymph from upper extremities and breast
Term
Inguinal Nodes
Definition
Lymph from lower extremities
Term
Lymphatic Ducts
Definition
Two major ducts exist in the body and both drain into the subclavian veins near the internal jugular vein
Term
Right Lymphatic Duct
Definition
Receives lymph from upper right quadrant of body
Term
Thoracic Duct
Definition

Receives lymph from upper left quadrant and from below diaphragm

Cisterna Chyli is the expanded inferior end of the thoracic duct located in the abdomen

Term
Lymphatic Capillaries, Vessels, Nodes and Ducts
Definition
Note the relationship to the blood circulatory system
Term
Lymphatic (Lymphoid) Cells
Definition

- Located in both the lymphatic and cardiovascular systems

- Cells work together to elicit an immune response

- Search and destroy antigens

Term
Antigens
Definition

Any substances that are perceived as abnormal in the body (virus, cancers, bacteria)

 

Term
Antibodies
Definition
Proteins produced by some lymphatic cells that bind and either immobilize or identify the foreign (bad) substance for destruction and removal
Term
Memory Cells
Definition

- Retain memory of past encounters with a particular antigen; elicit a heightened response during subsequent encounters

- Allergies worsen with the increased frequency of exposures

Term
Macrophages
Definition
Phagocytosis of foreign substances (migrate into lymph from blood stream)
Term
Epithelial Cells
Definition
Skin/tissue cells
Term
Dendritic Cells
Definition
Internalize antigens from lymph and present them to other cells (3 lymphocytes types)
Term
Lymphocytes
Definition
Move through the lymphatic system to search for antigens
Term
T-lymphocytes
Definition
also called T-cells; mature in the thymus
Term
B-lymphocytes
Definition
also called B-cells; mature in bone marrow
Term
NK Cells
Definition

-"Natural Killer Cells"; mature in bone marrow

- Comprise the small fraction (~2%) of the lymphcytes circulating in the blood that are neither T-cells or B-cells

- Called natural killer (NK) cells because they are already specialized to kill certain types of target cells, especially host cells that have become infected with a virus or have become cancerous

Term
Lymphopoeisis
Definition
Production and maturation of lymph cells, called lymphocytes
Term
Lymphocytes
Definition

- Cells migrate through the lymphatic tissues and monitor them for the presence of antigens (proteins on cell surfaces)

- Foreign antigens stimulate the production of antibodies

- Some cells produce antibodies bind to and immobilize the foreign or abnormal agent- by binding/immobilizing, identifies it to other elements of the immune system

- Some cells attact and destroy the antigen directly

- Other cells become 'memory cells' that remember past antigen encounters- can initiate an even faster and more powerful response should the same antigen appear again

Term
T-Lymphocytes
Definition

- 70-85% of body lymphocytes

- Plasma membrane contains a co-receptor that can recognize a particular antigen

- Several types of T-lymphocytes, each with a particular kind of co-receptor: 

- Helper T-lymphocytes

- Cytotoxic T-lymphocytes

Term
B-Lymphocytes
Definition

- 15-30% of body lymphocytes

- Contain antigen receptors that respond to one particular antigen and cause the production of immunoglobulins (Ig), or antibodies, that respond to that particular antigen

- Five man classes of immunoglobulins are called IgG, IgA, IgD, IgM, and IgE

- These immunoglobulins are released by the specific B-lymphocytes to immobilize or neutralize specific antigens

- Also yield memory B-lymphocytes

Term
Vaccines, B-Lymphocytes and Allergies
Definition

- Some vaccines introduce mild or dead forms of an antigen

- Allows the body to fight and eliminate the illness before any symptoms ever develop; allow for the development of memory B-lymphocytes

- Depending upon the life span of the particular memory B-lymphocytes, the vaccine may provide temporary or lifelong immunity

Term
Lymphatic Tissues and Organs: Tonsils
Definition

- Large clusters of lymphatic cells and extracellular matrix that are not completely surrounded by a connective tissue capsule

- Multiple germinal centers with invaginated outer edges called crypts- crypts help trap material and facilitate its identificaiton by lymphocytes

Term
Tonsils
Definition

- Pharyngeal tonsils (or adenoids) are in the posterior wall of the nasopharynx

- Palatine tonsils are in the posterolateral region of the oral cavity

- Lingual tonsils are along the posterior one-third of the tongue

Term
Lymphatic Tissues and Organs: Thymus
Definition

- A bilobed organ located in the anterior mediastinum

- Maturation site for T-lymphocytes (T-cells)

- In infants and young children, it is quite large and extens into the superior mediastinum as well

- Continues to grow until puberty, when it reaches a maximum weight of 30-50 grams

- Cells of the thymus regress after puberty, and it is eventually replaced by adipose connective tissue

- In adults, it atrophies and becomes almost nonfuncitonal

- immune cell producer

Term
Lymphatic Tissues and Organs: Spleen
Definition

- Largest lymphatic organ located in upper left quadrent of abdomen

- White pulp: initiates immune response when antigens detected in blood (antigen reseroir); phagocytizes bacteria and foreign materials

- Red pulp: reservoir for erythrocytes and platelets, phagocytizes old, defective erythrocytes and platelets

Term
Age changes to the Lymphatic System
Definition

- Thymus loses ability to mature and differentiate T-lymphocytes

- New T-lymphocytes can be produced only by replication (mitosis)

- Helper T-lymphocytes do not respond to antigens as well, and do not always reproduce rapidly

- Fewer B-lymphocytes and other kinds of T-lymphocytes

- Overall result: ability to provide immunity and fight disease decreases; elderly are more suseptible to illness, sickness, and cancers

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