Lymphatic System – Core Lecture Points

This flashcard set covers anatomy, physiology, and pathology of the lymphatic system: general functions, pathways, vessel structure, lymph formation, movement, lymph node structure and function, key organs (thymus, spleen), and lymphocyte origins.

What are the three main functions of the lymphatic system?

Return excess interstitial fluid to the bloodstream, absorb and transport dietary fats, and provide immune defense against pathogens.

Which cardiovascular system vessels does the lymphatic system closely assist?

The venous side (returns fluid to subclavian veins).

List the correct order of the major lymphatic pathway from tissue spaces to the bloodstream.

Lymphatic capillaries → lymphatic vessels → lymph nodes → lymphatic trunks → collecting ducts (thoracic or right lymphatic) → subclavian veins.

How do the walls of lymphatic vessels compare with veins?

They have the same three layers—endothelium, smooth muscle, connective tissue—but are thinner than veins.

Name the three layers of a lymphatic vessel wall from inner to outer.

Endothelial lining, smooth muscle layer, connective-tissue layer.

Which lymphatic vessels directly join lymph nodes?

Large lymphatic vessels (afferent vessels).

What are lymphatic trunks and how are they named?

Large vessels that drain lymph from regions; named for the regions they serve (lumbar, intestinal, intercostal, bronchomediastinal, subclavian, jugular).

Which body regions are drained by the right lymphatic duct?

Right side of head and neck, right upper limb, and right thorax.

Into which vein does the right lymphatic duct empty?

Right subclavian vein (at junction with right internal jugular).

Which collecting duct drains most of the body and where does it empty?

Thoracic duct; empties into the left subclavian vein (near the left internal jugular vein).

What is cisterna chyli?

An enlarged sac‐like beginning of the thoracic duct in the abdomen that receives intestinal and lumbar trunks.

Define tissue fluid.

Plasma-like fluid filtered from blood capillaries, containing water, dissolved substances, and small proteins.

What primary force forms tissue fluid from blood plasma?

Capillary blood (hydrostatic) pressure.

How is lymph formed from tissue fluid?

Elevated interstitial hydrostatic pressure forces tissue fluid into lymphatic capillaries where it becomes lymph.

Why does lymphatic drainage prevent oedema?

It removes excess interstitial fluid that filtration exceeds reabsorption, preventing fluid accumulation.

List four ways lymph is moved through lymphatic vessels.

Skeletal muscle contraction, respiratory movements, smooth muscle in vessel walls, and one-way valves preventing backflow.

What are the two primary functions of lymph nodes?

Filter potentially harmful particles from lymph and provide immune surveillance via lymphocytes and macrophages.

What is found in a lymph node’s germinal center?

Proliferating B lymphocytes.

Differentiate afferent and efferent lymphatic vessels.

Afferent vessels carry lymph into a node; a single efferent vessel exits at the node’s hilum.

Give five major locations of lymph node groups.

Cervical, axillary, inguinal, abdominal, and pelvic regions.

Which cells are produced and housed in lymph nodes besides those in red bone marrow?

Lymphocytes (B and T cells).

Why are macrophages abundant in lymph nodes?

To phagocytose foreign particles filtered from lymph.

What happens when lymphatic vessels are obstructed?

Fluid accumulates in interstitial spaces, causing localized edema (swelling).

Where is the thymus located and how does it change with age?

In the mediastinum behind the sternum; large in infancy and puberty, shrinks and is replaced by fat in adulthood.

What hormone is secreted by the thymus and what is its role?

Thymosins; they promote T lymphocyte maturation.

What key immune cells mature in the thymus?

T lymphocytes (T cells).

Where is the spleen located?

Upper left abdominal quadrant, inferior to the diaphragm, posterior and lateral to the stomach.

Name the two tissue types in the spleen and their primary contents.

White pulp—lymphocytes; Red pulp—red blood cells, macrophages, and lymphocytes.

List two major functions of the spleen.

Filters blood, removing old RBCs and pathogens; serves as a blood reservoir and immune response site.

Which precursor cells give rise to both B and T lymphocytes?

Stem cells in red bone marrow.

Where do B cells mature, and where do both B and T cells ultimately reside for immune responses?

B cells mature in bone marrow; both types populate lymphatic organs like lymph nodes and spleen.

What key role does the lymphatic system play in dietary fat handling?

Absorbs fats in intestinal lacteals and transports them (as chyle) to the bloodstream.

Explain the term "hydrostatic pressure of tissue fluid" in lymph formation.

Pressure exerted by accumulating fluid in interstitial spaces that forces fluid into lymphatic capillaries.

What structures ensure one-way flow of lymph within vessels?

Semilunar valves in lymphatic vessels.