Lymphatic System Notes

Lymphatic System

A system that returns excess interstitial fluid to the bloodstream, transports dietary lipids and facilitates immune responses.

Interstitial fluid

Fluid found in the spaces between cells, similar to plasma but with lower protein content.

Lymph

A clear fluid derived from interstitial fluid, containing lymphocytes.

Lymphatic vessels

Vessels that carry lymph throughout the body, featuring thinner walls and more valves than blood vessels.

Lymph nodes

Bean-shaped organs that filter lymph, trap pathogens, and activate lymphocytes.

Spleen

An organ that filters blood, provides immune responses, recycles iron, and stores red blood cells.

Thymus

An organ located in the mediastinum, where T cells mature.

Tonsils

Clusters of lymphoid tissue that protect against pathogens entering through the oral and nasal cavities.

Red bone marrow

Primary organ for blood cell formation and B cell maturation.

Lacteals

Specialized lymphatic capillaries in the small intestine that absorb dietary fats.

Chyle

A milky fluid containing fat particles absorbed from the intestine.

Neoplasm

An abnormal growth of tissue, often referred to in the context of tumor formation.

Plasma

The fluid component of blood, containing water, electrolytes, and proteins.

Thickened walls

Refers to the structure of blood vessels as compared to lymphatic vessels.

Thoracic duct

The major lymphatic duct that drains lymph into the left subclavian vein.

Right lymphatic duct

Drains lymph from the right side of the head, neck, and right arm into the right subclavian vein.

Cisterna Chyli

A dilated sac that serves as a major collecting basin for lymph from the lower body.

Primary lymphatic organs

Organs such as red bone marrow and thymus involved in lymphocyte maturation.

Secondary lymphatic organs

Organs such as lymph nodes, spleen, and tonsils where immune responses occur.

MALT

Mucosa-associated lymphoid tissue found in mucous membranes.

Peyer’s patches

Aggregates of lymphoid tissue in the ileum that protect against pathogens in food.

Appendix

A structure at the junction of the small and large intestines involved in immune response.

Afferent lymphatics

Lymphatic vessels that carry lymph to the lymph nodes.

Efferent lymphatics

Lymphatic vessels that carry filtered lymph away from the lymph nodes.

Immune processing

The ability of lymph nodes to filter lymph and activate lymphocytes.

Modalities of lymph movement

Skeletal muscle contractions and respiratory movements that help move lymph through vessels.

Lymphatic capillaries

Blind-ended vessels that are more permeable than blood capillaries.

Comparative structure of blood and lymphatic vessels

Lymphatic vessels have thinner walls and more valves than blood vessels.

Lymphatic trunks

Collections of lymphatic vessels that drain large areas of the body.

Jugular trunks

Lymphatic trunks that drain lymph from the head and neck.

Subclavian trunks

Trunks that drain lymph from the upper limbs.

Bronchomediastinal trunks

Drains lymph from thoracic organs.

Intestinal trunk

Drains lymph from digestive organs.

Lumbar trunks

Drain lymph from the lower limbs and pelvic organs.

Lymphatic nodules

Clusters of lymphoid tissue distributed throughout the body.

Functions of the spleen

Filters blood, recycles iron, and provides immune responses.

Structure of the thymus

Composed of lobules with an outer cortex and inner medulla.

Capillary permeability

Lymphatic capillaries are more permeable than blood capillaries.

Slow lymph flow in nodes

Allows time for the immune system to process lymph.

Major functions of the lymphatic system

Return excess fluid, transport lipids, facilitate immune responses.

Lymphocyte

A type of white blood cell found in lymph.

Lymphatic system contribution to immunity

Houses and activates immune cells to respond to pathogens.

Comparison of blood and interstitial fluid

Interstitial fluid is similar to plasma but contains less protein.

Role of lymph nodes in immunity

Filter lymph and activate lymphocytes to combat pathogens.

Fluid entry into lymphatic capillaries

High permeability allows interstitial fluid to enter when pressure increases.

Function of lymphatic collecting vessels

Transport lymph from capillaries to trunks.

Anatomy of lymph nodes

Contain a capsule, cortex, germinal centers, and medulla.

Location of lymph nodes

Commonly found in the neck, armpits, and groin.

Function of tonsils

Trap pathogens entering through oral and nasal cavities.

Structure of lymphatic vessels

Thinner walls and more valves allow for lymph movement.

Function of red bone marrow

Site of hematopoiesis and B cell maturation.

Maximum size of thymus

Reaches peak size during childhood, involutes in adulthood.

Function of lacteals

Absorb dietary fats and fat-soluble vitamins.

Size comparison of lymph and blood vessels

Lymphatic vessels are larger in diameter than blood vessels.

Pathway of lymph circulation

Lymph flows from capillaries to vessels, trunks, ducts, and venous circulation.

Role of diaphragm in lymph flow

Respiratory movements aid in lymph circulation.

Lymphatic vessel structure

Endothelial cells overlap to create one-way valves.

Purpose of lymphatic system

Maintains fluid balance, absorbs fat, and contributes to immune defense.

Definition of Peyer’s patches

Lymphoid tissue aggregates in the ileum for pathogen protection.

Comparison of lymph to chyle

Chyle contains fat absorbed from the intestine, whereas normal lymph does not.

Location of MALT

Found in mucous membranes of digestive and respiratory tracts.

Red pulp of spleen

Part of the spleen responsible for filtering blood.