Lymphatic system

lymphatic system functions

1. Produces, maintain, & distributes lymphocytes

2. Return fluids from the peripheral tissue to blood

3. Distribute hormones, nutrients, waste products from tissue origin to blood circulation

lymph node

Monitors/cleans the composition of lymph

Spleen

Monitors/clean circulating blood

Thymus

Controls development and maintenance of T-lymphocytes

Lymphatic vessel

Thin, walled tubes distributed throughout the body

• Function: to carry lymph from the peripheral tissue to the cardiovascular system

Lymphatic capillaries (microscopic tubes)

made up of endothelium

• like blood capillaries but more permeable

Lymph

once the interstitial fluid drains into lymphatic capillaries

Flow of lymph

1. Lymphatic capillaries

2. Larger lymphatic vessels

3. Thoracic duct OR right lymphatic duct

4. Left or right subclavian vein

Thoracic duct

Arises in abdominal cavity, goes up towards the neck and empties into left subclavian vein

• Drain entire body below diaphragm & the left half of body above diaphragm

right lymphatic duct

Empties into right subclavian vein

• Drain right half of body above diaphragm

Capsule

Fibrous outer cover of the entire lymph node; helps protects the lymph node

trabeculum/trabecula

Tissue that divides up the lymph node into compartments

Afferent lymphatic vessels

Vessels that bring in lymph; always located in the larger curved outer area of the node

Efferent lymphatic vessel

Vessel that removes lymph out of the lymph node; always located near hilum/hilus

Hilum/hilus

The indentation on the outer part of the lymph node

Sinuses

Spaces or channel that carry lymph throughout the lymph node (also have fibers throughout); named after the location inside the node—subcapsular sinus, cortical sinus, medullary sinus

Subcapsular space

Located right below the capsule

Cortex

Located between subcapsular space and the medulla; contain the germinal centers (shaped like a triangle) & the cortical sinuses and is divided by the trabeculae

Medulla

Location where all of the cortex regions merge together; last area prior to lymph leaving the lymph node

Lymph sinuses

“Empty” spaces that hold lymph capillaries (where lymph flows) & that contain fibers

Macrophages

Phagocytize (ingest) foreign matter in lymph

• Majority live in the fibers of medullary sinus & a few live in the subcapsular sinus

T cells

Manage the immune response (some directly attack & destroy foreign cells)

• Located in the medulla only

B cell

Protected the body by producing plasma cells (daughter cells that secrete antibodies into the blood)

• Antibodies immobilize pathogen until it is destroyed by a macrophage

located in cortex & medulla

Spleen

Filters blood (macrophages in spleen remove bacteria & other pathogen) **does not filter lymph

• Destroys old red blood cells & recycled their parts

• Provided a reservoir of blood (storage)

• Active in immune response (has B & T cells)

• Produces blood cells (during fetal development

Thymus

Promotes the maturation of T lymphocytes

→ immature T cells go from red bone marrow (through blood) to thymus

• Concentration in the thymus & mature

• Leave into blood or lymph vessels & migrate to other lymphatic tissues/organs and become active in immune response

• No filtering function; no afferent vessels, only efferent vessels

• Does not plug a direct role in immune response

• Pathogen free environment

tonsils & pever’s patches (appendix included)

• Form a ring of lymphatic tissue around the entrance of pharynx (throat)

• Gather & remove pathogens entering the pharynx (through air & food)

• “Invite pathogens” so they can be remembered