Lymphatic System: Anatomy and Physioloogy

What is the lymphatic system?

Component of circulatory system

Capillaries, afferent vessels, nodes, efferent vessels and organs

What is the function of the lymphatic system?

Immune function

Regulation of extra cellular fluid drainage

What are the two main structures forming 80% of total lymph?

Liver

Intestines

What are the three purposes of the lymphatic system?

Maintains tissue fluid homeostasis by collecting excess fluid and returns it to venous circulation

Absorption and transportation of dietary fats

Main channel of androgen and androgen presenting cells into lymph nodes

What is interstitial fluid?

Fluid from substances leaking out from capillaries found in spaces around cells

What are the two functions of interstitial fluid?

Carries oxygen and nutrients to cells

Removes cell waste products

What is hydrostatic pressure?

Pressure of any fluid enclosed in a space

What is a capillary hydrostatic pressure?

Pressure exerted by blood on wall of capillary causing fluid leak into tissues

What is interstitial fluid hydrostatic pressure?

Pressure exerted by fluid in spaces around cells

How does osmotic pressure in tissue fluid allow for reabsorption?

Higher water concentration in interstitial fluid means water is drawn back to blood capillaries

What is net filtration pressure?

Interaction of hydrostatic and osmotic pressure driving fluid out of the capillary

When is net filtration pressure the highest?

When blood enters a capillary bed

Where is net filtration pressure the lowest?

Venous end of the capillary

What is lymphatic fluid?

Interstitial fluid with varying amounts of cell debris

What are four features of the structure of lymphatic capillaries?

3 times wider than blood capillaries to allow absorption

Single endothelial cell layer lining

Discontinuous basement membrane

Anchoring filaments into surrounding tissue allowing capillaries to open

What are lymphatic vessels?

Convergences of lymphatic capillaries

What are afferent lymphatic vessels?

Carry unfiltered lymph fluid from the tissues to the lymph nodes

What are efferent vessels?

Carry filtered fluid from lymph node to lymph node until they return to the venom system

What is the function of endothelial valves?

Ensure travel in one direction until fluid reaches lymphatic vessels

What are the major lymphatic channels?

Right lymphatic duct

Thoracic duct

What is the function of the right lymphatic duct?

Receives fluid from the right side of the head, neck, thorax and upper limb

Drains into the venous system at the level of the right internal jugular vein and right subclavian vein

What is the function of the thoracic duct?

Receives fluid from 75% of the body and extends from T12 to the root of the neck

Drains into the subclavian vein

What is the cisterna chyli?

Anatomical variant

Expanded lymphatic sac converging the intestinal and lumbar lymphatic trunks

Joins bottom of thoracic duct at T12

What is the function of the cisterna chyli?

Temporarily stores lymph

What are lymph nodes?

Small structures surrounded by connective tissue capsule and divided into nodules

What are lymph nodules?

Masses of lymphocytes and macrophages separated by lymph sinuses

Where are superficial lymph nodes located?

Neck

Axilla

Thorax

Abdomen

Groin

What are the primary lymphoid organs?

Bone marrow and thymus

What are the three secondary lymphoid organs?

Lymph nodes, spleen, tonsils