35.1 THE LYMPHATIC SYSTEM Olivia KarrSarah HudimacTiffany KantartzisZach Thomas

Lymph – fluid inside lymphatic vessels A colorless liquid, but after a meal, it appears creamy

because of its lipid content. Collected lymph returns to a larger thoracic duct from

the body. Movement of lymph in lymphatic capillaries is largely

dependent on skeletal muscle contradiction.

Lymphatic Vessels – form a one-way system that begins with lymphatic capillaries.

Construction of the larger lymphatic vessels is similar to the cardiovascular veins.

Lymph gets pushed through these vessels.

Lymphatic vessels

Edema – localized swelling caused by the accumulation of tissue fluid that has not been collected by the lymphatic system.

This can happen if too much tissue fluid is made and/or if not enough of it is drained away.

Can lead to tissue damage and eventual death.

B Lymphocytes and T Lymphocytes – type of white blood cells that play a pivotal role in the immunity.

They are produced and mature in the primary lymphatic organs : red bone marrow and the thymus gland.

B cells mature in the bone arrow, but T cells mature in the thymus.

Edema

B lymphocytes & T lymphocytes

B

T

Red bone marrow – site of stem cells, which are ever capable of dividing and producing blood cells.

Common in children (most bones). In an adult it’s located in skull, sternum, ribs, vertebral

column, femurs and humorous. B cells mature.

Thymus gland – located in the thoracic cavity between the trachea and sternum ventral to the heart.

Largest in children and then shrinks as we get older. Not detectable in elderly. Connective tissues divide it into lobules, filled with T

cells.

Red bone marrow

Thymus gland

Lymph nodes – mass of lymphoid tissue located alone course of lymphatic vessel.

Ovoid structures occurring along lymphatic vessels. Cleans lymph. Connective tissue divides everything into nodules. Packed with B cells and contain a sinus. Spleen – located in the upper-left side of abdomen;

stores and purifies blood. Has red pulp that filters blood. Consists of blood vessels and sinuses where the

macrophages remove old and defective blood cells. Tonsils – patches of lymphatic tissue located in

pharynx. Perform same function of lymph nodes. Encounter pathogens and antigens first because of

location.

tonsils spleen

Lymph nodes