1. The clear, watery fluid carried in lymphatic channels

2. Similar composition to blood plasma but usually lower in protein

1. Capillaries where lymph starts out

2. Incomplete basal lamina and no smooth muscle

3. Lie close to blood capillaries (except in CNS)

4. More permeable than blood capillaries (easier for large molecules and cells to pass through)

5. Have valves for one-way flow

1. Larger lymphatic capillaries that travel with superficial and deep veins

2. Have smooth muscle (unlike lymph capillaries) that contract to propel lymph

1. Little bean-shaped organs, through which lymph passes, that remove debris and monitor the lymph for pathogens

2. Found in axilla, groin, neck, thorax, and mesentaries

3. Play central role in recognizing antigens and initating immune responses to destroy them

The union of the subclavian vein and internal jugular vein into which the right lymphatic duct and thoracic duct empty lymph into the blood on each side

1. Carries fluid collected only from the upper right quadrant of the body

2. Empties into right venous angle

1. Conveys fluid from all parts of the body inferior to the diaphragm and from the left side of the body superior to the diaphragm

2. Empties at left venous angle

Lymphatics pick up excess extracellular fluid and protein from most tissues and return it (as lymph) to the bloodstream

Lymphatics carry lymph to the lymph nodes, where cells of the immune system identify foreign substances and mount an immune response

Lymphatics carry chylomicrons (little packages of fat) from lacteals (blind capillaries in the small intestine) to the bloodstream

Lymph from lacteals

1. Inflammation of the lymphatic vessels that drain an infected area

2. Infectious agents enter lymphatic vessels directly through an abrasion or wound, or as a complication of infection

3. Inflammation of the vessels and subsequent infection produces painful red streaks on the skin that gradually extend proximally toward regional lymph nodes

1. Inflammation of a lymph node

2. Clinically manifested as painful nodal enlargement

Substance that triggers an immune response and can bind to an antibody or a T-cell antigen receptor

Y-shaped plasma proteins that bind specifically to antigens, inactivating them or marking them for destruction by immune system cells

Produce immunoglobulins (antibodies)

Mature B-cells that have highest rate of immunoglobulin secretion

1. Surface proteins that present antigen peptides to T-cells and help a person's immune system distinguish between "self" and "non-self"

2. MHC proteins are the main antigens recognized in organ transplant rejection

(MHC I, MHC II)

Present on the surface of all nucleated cells

Present predominantly on antigen-presenting cells

Surface protein on T-cells that recognizes complexes of MHC molecules adn antigen peptides on APCs

1. Cells that can partially digest a foreign particle, attach a small piece of that protein to an MHC II molecule, and present the antigen-MHC II complex on the surface for inspection by T-cells (antigen processing)

2. Include macrophages, dendritic cells (Langerhans cells), and B-cells

3. Are mobile

1. T-cells

2. B-cells

3. Natural killer cells (NK cells)

1. Born in the bone marrow, become immunocompetent in the thymus, and found in lymphatic tissues and organs throughout the body

2. Characterized by TCR

3. Only recognize peptide antigens that are bound to MHC I or MHC II

1. Originate and mature in bone marrow

2. Found in lymphatic tissues and organs throughout the body

3. B-cell antigen receptors are surface-bound immunoglobulin (Ig) molecules

4. Can react directly with many different kinds of antigens

5. When activated by antigen, they form plasma cells (antibody secreting cells)

Lack molecular markers characteristic of T-cells and B-cells adn are predominantly involved in innate immunity

1. Macrophages in lymph nodes phagocytose any impurities

2. Lymph enters node via afferent lymphatic vessels

3. Percolates through sinuses

4. Exits node through hilum via efferent lymphatic vessels

A dilated vessel in the abdomen that becomes the thoracic duct, into which vessels from the abdominal viscera drain

Darkly (highly cellular) staining outer part of lymph node that contains lymph follicles composed of B-cells

Lighter staining region of follicles that represents proliferation of B-cells in response to antigenic stimulation

A follicle without a germinal layer

A follicle with a germinal center that results from antigenic stimulation of a primary follicle

1. Layer just deep to cortex

2. Highly cellular (darkly staining)

3. Lacks follicles

4. Contains mostly T-cells that have arrived from blood or lymph to inspect antigens on APCs

1. Inner part of lymph node abutting the hilum

2. Stains more lightly (prominence of sinuses with fewer cells)

3. Composed of cords and sinuses

The major site of plasma cell differentiation and antibody production in the medulla

Separate the cords and contain numerous macrophages and reticular fibers that form a network that slows the flow of lymph and enhances filtration

1. Enlargement of lymph nodes, usually due to the proliferation of lymphocytes in response to common bacterial and viral infections

2. "Swollen glands" are enlarged lymph nodes

3. Common in young children

1. Lateral axillary nodes

2. Anterior axillary nodes

3. Posterior axillary nodes

4. Central axillary nodes

5. Apical axillary nodes

1. Located in lateral axilla

2. Receive most of the lymph from the upper limb

1. Located near anterior axillary fold

2. Receive lymph from anterior thoracic wall, including most of the breast

1. Located deep in the posterior axillary fold

2. Receive lymph from upper back

1. Located high and deep within the axilla on the chest wall

2. Receive lymph from the anterior, lateral, and posterior axillary nodes and pass it on the the apical axillary nodes

Located at the apex of the axilla near the proximal part of the axillary vessels

1. Located inferior to clavicle in the shallow groove between the deltoid and pectoralis major

2. Receives lymph from lateral axillary nodes and drains into apical axillary nodes

One or two relatively small nodes just anterior and superior to the medial epicondyle of the elbow that may become enlarged when parts of the hand or forearm are infected (e.g. cat scratch disease)

1. Procedure to treat breast cancer

2. A variable number of axillary nodes are removed to assess the spread of malignant cells and prevent further metastasis

3. May lead to lymphedema of the upper limb ("arm swelling")

1. Relatively large nodes located in the superficial fascia of the groin and form a T-shape

2. Horizontal group parallels inguinal ligament

3. Vertical group is parallel to greater saphenous vein

4. Receive lymph from the majority of the lower limb and parts of abdominal wall (except testes)

5. Swelling in this region is commonly associated with sexually transmitted diseases of the genitalia

1. Located in femoral canal medial to femoral vein

2. Receives lymph from popliteal lymph nodes and deep regions of the lower limb (except gluteal region)

The lower extremity is drained primarily by superficial lymphatics that travel with the great saphenous vein or lesser saphenous vein

Receives lymph from superficial inguinal nodes and deep inguinal nodes

Receives lymph from deeper regions of the gluteal region

1. Formed by the fusion of external and internal iliac nodes

2. Continue along the sides of the aorta as para-aortic nodes