Vascular Anatomy: Lymphatics Overview

Flashcards covering key terms and concepts related to the lymphatic system, its functions, structures, and components.

Lymphatic System

A network that includes lymph vessels, lymph fluid, specialized immune cells, and lymphatic organs, serving circulatory and immune functions.

Afferent Vessels - bring lymph fluid to lymph node

Efferent Vessels - take lymph fluid away from lymph node

Lymph Nodes

Small, bean-shaped structures distributed throughout the body that filter lymph fluid and house lymphocytes.

Protective fibrous outer capsule

Cortex - B-Lymphocytes

Medulla - lymphocytes, macrophages

Thymus

An organ divided into lobes located in the mediastinal cavity where T-cells mature.

Supplied by internal thoracic arteries

B-Cells

A type of lymphocyte that produces antibodies and matures in the bone marrow before entering circulation.

Macrophages

Immune cells that ingest and digest pathogens and cellular debris.

Lymph Fluid

Clear/yellow fluid that circulates through the lymphatic system, composed mainly of water, dissolved proteins, electrolytes, cellular waste, and white blood cells. Transports fats/fat-soluble vitamins from gut.

Originates from interstitial fluid that surrounds body tissues from plasma leaking from capillaries that is collected into lymphatic capillaries

Dumps into venous blood prior to entering heart

lymph nodes cleanse the fluid

Chylomicrons

Particles formed from dietary fats and fat-soluble nutrients that enter lymphatic capillaries in the small intestine via entry points called lacteals.

Cisterna Chyli

A sac-like reservoir in the lymphatic system that collects lymph fluid from the lower half of the body. Located in posterior abdominal cavity around L1-2 (post. to aorta)

Origin of Thoracic Duct

Fluid here often cloudy/milky from high fat concentrations via Intestinal Trunk

Thoracic Duct

The largest lymphatic vessel (15-18”) that collects lymph from the lower body and left side, delivering it to the venous circulation.

Begins at Cisterna Chyli, ascends thru diaphragm, into posterior mediastinum, to left of midline towards neck, behind left carotid. Dumps into left subclavian and left jugular veins.

Receives lymph from:

• Left Jugular Trunk

• Left Subclavian Trunk

• Left Bronchomediastinal Trunk

• Intestinal Trunk

• Lumbar Trunk

Lymphatic Trunks

Large lymphatic vessels that transport lymph from collecting vessels to ducts that dump into blood stream.

5 main Trunks (4 paired, 1 unpaired):

• Jugular: drain head/neck

• Subclavian: drain upper limbs, thoracic wall including breast

• Bronchialmedistinal: drains thoracic cavity (heart/lungs/trachea/mediastinum)

• Lumbar: drains lower limbs, pelvis, kidneys, abd wall; converge into Cisterna Chyli

• Intestinal (unpaired): drains stomach/intestines/pancreas/spleen/liver; joins into Cisterna Chyli

Bone Marrow

Primary site of lymphocyte production and maturation.

Reservoir for mature immune cells (memory B cells)

Memory B-Cells

Produce antibodies during immune response

T-Cells

Type of white blood cell that distinguish between foreign invaders and the body's own cells.

Key types include helper T-cells, cytotoxic (killer) T-cells, and regulatory T-cells, which have distinct functions in fighting infection, cancer, and controlling inflammation.

Lacteals

Lymphatic entry point for lipids within the small intestine

*Dietary fats and fat-soluble nutrients enter lymphatic system from GI tract, bypassing liver to enter blood stream directly

Spleen

Largest lymphatic system organ located in LUQ that filters blood, supports immune system, and manages body’s blood cell supply

Consists of fibrous outer layer (capsule) with trabeculae inner extensions dividing organ into compartments

White Pulp: tissues rich in lymphocytes B & T-cells) surrounded by arteries

Red Pulp: majority of spleen tissue, removes old/damaged/misshapen RBCs

Mucosa Lymphoid Tissues

Network of diffuse, unencapsulated lymphoid tissues located on mucous membranes throughout the body; Digestive, Respiratory, and Urinary Tract. Contain a mix of B & T-cells, macrophages, and dendritic cells.

Ex: Peyer’s patches, tonsils/adenoids, bronchial and nasal lymph tissues

Peyer’s Patches

Clusters of lymphoid tissue in the small intestine's lining. Act as immune sensors that monitor the gut's contents and are central to initiating immune responses to pathogens while also promoting tolerance to food antigens. Specialized cells in the patches capture antigens, triggering an immune response involving B and T lymphocytes, which can lead to the production of protective antibodies and alert other immune cells.  Most numerous in distal ileum.

Lymphatic Capillaries

Entry point of lymphatic system located throughout almost all body tissues.

are larger in diameter with thinner walls than blood capillaries

Composed of single layer of epithelial cells with flap-like openings acting as mini valves allow fluids/proteins/waste/pathogens/immune cells to enter

Right Lymphatic Duct

1 of 2 of the largest ducts of the lymphatic system located in right upper thoracic cavity (rt venous angle). Drains right upper quadrant of body.

Convergence of 3 trunks:

• Right Jugular Trunk: drains rt side of head/neck

• Right Subclavian Trunk: drains right upper extremity

• Right Bronchomediastinal Trunk: drains right thoracic cavity/lung/heart

Overview of Flow