Lymphatic System

What are Lymphocytes?

A type of white blood cell responsible for mediating the immune response. There are three types.

What are the three mechanisms which keep lymph flowing?

Smooth muscle layer of lymph trunks and one-way valves, contraction of skeletal muscle, negative pressure in the thoracic cavity created by respiratory pumps.

Lymph nodes

are located along the lymph trunk, where lymph circulates in an accumulation of lymphocytes and macro-phages, which filter out pathogens.

T Lymphocytes (T Cells) are

cells that recognize and attack microbes and foreign cells by attaching and secreting toxins that kill the invaders. "Cell-Mediated Immunity" - attacking the invader directly.

Lymphoid tissues are

connective tissues that have accumulations of lymphocytes.

Lymph capillaries differ from blood capillaries in that they

have no basement membrane, have large pores in their walls to allow non-selective movement of large molecules, and they dead end into the tissues.

The thymus

houses T Cells and reaches its greatest size during puberty and gradually atrophies during adulthood.

Natural Killer Cells (NK Cells)

recognize and kill abnormal cells in the body, such as cancer cells. They work similar to T Cells

The spleen

removes old red-blood cells and their store iron. It is also a site of B Cell and T cell proliferation and storage.

B Lymphocytes (B Cells) are

responsible for synthesizing and secreting proteins called antibodies that recognize and attack invading microbes and foreign cells called "Humoral Immunity"

The left (thoracic) lymph duct drains into

the left subclavian vein from the left side of the body and the right side that is inferior to the diaphragm.

The right lymph duct drains into

the right subclavian vein from the right side of the body that is superior to the diaphragm.

MALT Tissues include:

tonsils, peyer's patches, vermiform appendix.

What is the secondary function of the Lymphatic System?

To maintain the volume balance between the blood and the interstitial fluids.

Lymphoid organs include:

Lymph nodes, thymus and spleen, which are encapsulated by a layer of connective tissue.

MALT stands for

Mucous-Associated Lymphatic Tissues. They serve as a line of defense against pathogens.

What is the primary function of the Lymphatic System?

The production, maintenance and distribution of blood cells, called lymphocytes