Lymphatic System and Immunity

These flashcards cover key vocabulary and concepts from the lecture on the lymphatic system and immunity.

Lymphatic System

A network of vessels that regulates fluid volume, absorbs dietary fats, and filters pathogens.

Interstitial Fluid

Fluid that surrounds tissue cells, which is returned to the bloodstream by the lymphatic system.

Lymph

Fluid that has entered lymphatic vessels from interstitial fluid.

Describe Lymphatic Capillaries and compare them to blood capillaries

blind-ended, highly permeable vessels with overlapping valves, unlike blood capillaries which form continuous loops and are less permeable.

Lymphatic Trunks

Large vessels formed by the union of collecting vessels, transporting lymph toward larger ducts.

Thoracic Duct

drains the rest of the body, and Empties lymph into the left subclavian vein

Right Lymphatic Duct

Drains Right arm, right side of head/neck, right thorax and Empties lymph into the right subclavian vein

Lymph Nodes

Small, bean-shaped organs that filter lymph and house immune cells.

Macrophages

Cells that phagocytize foreign substances and activate T cells.

T Cells

Lymphocytes that manage immune responses and attack infected cells.

B Cells

Lymphocytes that produce plasma cells, which secrete antibodies.

Dendritic cells

Capture antigens and deliver them to lymph nodes, and activate T cells

Lymphoid Tissue

Tissue that houses lymphocytes and provides a site for their proliferation.

Composed of reticular connective tissue

Diffuse Lymphoid Tissue

It monitors tissues for pathogens and supports early immune responses, especially at mucosal surfaces.

Lymphoid Follicles

Solid, spherical bodies of tightly packed lymphoid cells and reticular fibers.

Thymus

Maturation and education of T cells for adaptive immunity.

Spleen

A lymphoid organ that performs immune surveillance, cleanses blood, and stores blood cells.

Red Pulp

Area of the spleen rich in RBCs and macrophages for disposal of worn-out cells.

White Pulp

Lymphocyte-rich region of the spleen involved in immune function.

Mucosa-associated Lymphoid Tissue (MALT)

Lymphoid tissues located in mucous membranes protecting against pathogens.

Peyer's Patches

Clusters of lymphoid follicles in the wall of the small intestine that destroy bacteria.

Tonsils

Lymphatic tissues that gather and remove pathogens in food or air.

Cortex (of lymph node)

Outer region containing lymphoid follicles and germinal centers with dividing B cells.

Medulla (of lymph node)

Inner region of a lymph node containing medullary cords with B cells, T cells, and plasma cells.

Afferent Lymphatic Vessels

carry lymph into a lymph node for filtration

Efferent Lymphatic Vessels

carry lymph away from a lymph node, after it has been filtered, toward the larger lymphatic trunks and back to circulation.

Lymph Sinuses

spaces/channels inside lymph nodes that allow lymph to flow slowly so immune cells can filter and remove pathogens or debris.

Lymphatic Collecting Vessels

thin-walled, have many valves, and carry lymph at low pressure—unlike blood vessels, which have thicker walls and higher pressure.

Anastomose

The joining of two vessels, which occurs frequently in collecting lymphatic vessels.

Cisterna Chyli

A dilated sac at the base of the thoracic duct that collects lymph from the lower body.

Valves in Lymphatics

Structures that prevent backflow of lymph within lymphatic vessels.

Reticular Cells

Fibroblastic cells that make reticular fibers to support lymphocytes.

Regulatory T Cells

A subtype of T cells involved in maintaining immune tolerance.

Proliferation Site

Area where lymphocytes multiply and develop, often in lymphoid tissues.

Illicit conditions

States or situations that may compromise the lymphatic system's function.

Blood-thymus Barrier

A protective barrier that isolates T cells from antigens during maturation.

Fibrous Capsule

The connective tissue covering that encapsulates a lymph node.

Trabeculae

Extensions of the capsule that divide and support lymph nodes.

Germinal Center

A region in a lymph node follicle where B cells proliferate and differentiate.

Lymphatic Vessels

Vessels that collect and transport lymph throughout the body.

Lymphatic System Functions

Regulates fluid volume, absorbs fats, and provides immune defense.

Low-pressure Circuit

Lymph moves through vessels at low pressure using muscles and valves—not a pump.

Nutrients for Lymphatics

absorbs lipids and fat-soluble vitamins from the small intestine and transports them to the bloodstream.

Memory Lymphocytes

Lymphocytes that provide long-term immunity by remembering previous antigens.

Antigens

Substances that evoke an immune response.

Antibody

A protein produced by B cells that binds to specific antigens.

Lymphatic Flow Stagnation

Slowed lymph movement due to fewer efferent vessels in lymph nodes.

Erythrocyte Recycling

The process of breaking down old red blood cells for reuse in the body.

Lymphatic Drainage

Movement of excess fluid from tissues back into the blood.

Leukocytes

White blood cells that are key components of the immune system.

Autologous Tolerance

The immune system's ability to tolerate its own tissues.

Genetic Immunity

Immunity that is inherently present in an individual at birth.

Epithelial Stroma

Supporting tissue in the thymus that assists T cell maturation.

Reticular Connective Tissue

Type of connective tissue that supports the cellular components of lymphoid organs.

Appendix Function

functions as a reservoir for beneficial gut bacteria and plays a role in immune defense by exposing immune cells to antigens.

Immune Memory

The ability of the immune system to remember previous infections.

Cisternae

Fluid-filled cavities involved in the transport of lymph.

Hematopoiesis

Formation of blood cellular components, occurring in the bone marrow.

Antigen-presenting Cells

Cells that process and present antigens to T cells.

Hemolysis

The breakdown of red blood cells, often performed by macrophages.

Lymphatic Drainage Pathway

Interstitial fluid → Lymphatic capillaries → Lymphatic vessels → Lymph nodes → Lymphatic trunks → Lymphatic ducts

Macrophage Function

Engulf and digest cellular debris and pathogens.

Phagocytosis

The process by which certain cells engulf and digest pathogens.

Immunocompetent

The ability of the immune cells to respond to pathogens.

What are the 5 lymphatic trunks and areas drained by each?

Paired lumber= lower limbs and pelvic area

Paired bronchomediastinal= thoracic cavity

Paired subclavian= upper limbs

Paired jugular trunks= head and neck

Single intestinal trunk= fat filled from intestine

What are the 2 lymphatic ducts ?

Thoracic duct and right lymphatic duct

What is the structure of a lymph node? (4)

External fibrous capsul

Trabeculae extend inward and divide node into compartments

Cortex- follicles with germinal centers and dendritic cells encapsulate follicles

Medulla-contain B cells, T cells, and plasma cells

What is bubo?

Swollen, tender, inflamed lymph node caused by infection. Commonly linked to bubonic plague

What is bubonic plague?

Severe infectious disease caused by Yersina pestis. Transmitted by fleas that feed on dead rodents. Once inside the body it travels to the lymphatic system, causing painful swollen lymph nodes.

Why is it called bubonic plague?

Term comes from Greek word bubo meaning swelling of the groin/lymph nodes. Since this form on plague causes buboes that is why it’s called bubonic plague

Why is it called black plague?

Dark discoloration caused by subcutaneous hemorrhages and its association with the widespread death during the 14th century pandemic.

What are the 5 cell types found in lymphoid tissue?

Macrophages

T cells

B cells

Dendritic cells

Reticular cells

What are the primary lymph organs? (2)

Red bone marrow and thymus

What are the secondary lymphoid organs? (4)

Nodes

Spleen

MALT

Diffuse lymphoid tissue

Red bone marrow (4)

Hematopoiesis

Producing lymphocyte stem cells

Maturing B cells

T-cell precursors from here but mature in thymus

How does the thymus differ from all other lymphoid organs ? (3)

Has no follicles because it lacks B cells

Does not directly fight antigens

Provide environment in which T lymphocytes become immunocompetent

How is lymph transported in the body (4)

Through lymphatic vessels using valves, skeletal muscle, respiratory movements, and smooth muscle contractions, returning to the bloodstream.