Lymphatic System Overview Quiz

Lymphatic System Overview

• The lymphatic system is a vascular network of tubes and ducts, collecting, filtering, and returning lymph to blood circulation.
• It functions as a separate system despite consisting of organs working together for specific functions. A major role includes defense against diseases.
• Key functions include: transporting excess fluid from interstitial spaces back to the bloodstream, absorbing lipids from the digestive system and transporting them to venous circulation.
• The system defends against invading microorganisms/diseases in lymph nodes. Lymph nodes and other lymphatic organs filter lymph to remove microorganisms.

Lymphatic System Components

• The lymphatic system consists of lymphatic capillaries, vessels, trunks, ducts, and organs/tissues:
  • Lymphatic capillaries: begin as blind-ended tubes in tissue spaces; found throughout the body except in the epidermis, CNS, cornea of the eye, and bones; highly permeable.
  • Lymphatic vessels: form from merging lymphatic capillaries, found alongside arteries and veins, carry lymph away from tissue spaces back to venous system. These vessels have one-way valves to prevent backflow.
  • Lymphatic trunks: formed from merging lymphatic vessels; drain lymph; include jugular, subclavian, bronchomediastinal, lumbar, and intestinal trunks.
  • Lymphatic ducts: formed from merging lymphatic trunks; include the right lymphatic duct and thoracic duct, which drain lymph into the venous system. The right lymphatic duct drains the upper right side of the body—head, neck, right upper extremity, and right side of the thorax—while the thoracic duct drains lymph from the rest of the body.
• Lymphatic organs and tissues: include the thymus, lymph nodes, spleen, tonsils, and bone marrow

Lymph

• Lymph is a clear, colorless fluid similar to blood plasma.
• Transported plasma protein that seeps out of capillary beds back to the blood stream.
• Carries larger particles (bacteria, cell debris) from damaged tissue for filtering by lymph nodes.
• Contains lymphocytes for defense mechanisms.
• In small intestine lacteals fats absorbed into lymphatic—give lymph milky appearance.
• Lymph returning to bloodstream prevents edema & helps maintain normal blood volume, plasma protein concentration, and blood pressure.

Lymph Node Functions

• Oval structures located along lymphatic vessels.
• Contain lymphocytes (immune cells) and macrophages.
• About 600 lymph nodes are available throughout the body, concentrated near mammary glands, axilla (armpit), and groin.
• Lymph enters lymph nodes through afferent lymphatic vessels and exits through efferent lymphatic vessels.
• Functions include: filtering foreign substances, phagocytosis, and proliferation of lymphocytes (immune cells).

Lymph Node Clinical Applications

• Incomplete phagocytosis or bacterial invasion can lead to lymph node inflammation/enlargement (lymphadenopathy).
• Lymph node location and lymph flow direction are crucial for diagnosing and predicting cancer spread (metastasis).
• Axillary lymph nodes are often removed during breast surgery (mastectomy) to prevent cancer spread.
• Hodgkin's lymphoma is a type of cancer affecting the lymphatic system, spreading from one lymph node to another.

Spleen

• Largest lymphatic organ in the body, located in the left upper quadrant between the stomach and diaphragm.
• Consists of white pulp (lymphocytes—T and B cells) and red pulp (blood & macrophages).
• Functions:
  • Phagocytosis (removing worn-out RBCs, WBCs, and platelets).
  • Lymphocyte/s activities to react to pathogens in the blood.
  • Blood storage (up to 350 mL).
  • Immune response (activated by antigens).
  • Erythropoiesis (RBC production during pregnancy).
• Injury to the spleen often requires splenectomy (removal) to prevent excessive bleeding.

Mucosa-Associated Lymphoid Tissue (MALT)

• Lymphatic tissue NOT in a capsule, located in mucous membranes, contains B and T cells (migrated from bone marrow and thymus).
• Detecting invaders early and filtering lymph.
• Main groups include tonsils and lymphoid follicles, Peyer’s patches (small intestine).
• Tonsils (pharyngeal, palatine, lingual): protect the body from foreign substances, such as bacteria and viruses, in nasal and oral cavities.

Thymus

• Located between sternum and heart.
• Contains T cells, epithelial cells, and macrophages.
• Site of T cell maturation before they enter the bloodstream.
• Hormone thymosin promotes thymus and other lymphoid tissue maturation.
• Shrinks in adolescence, with T-lymphocytes response to antigens declining. Replaced with adipose tissue after puberty.

Bone Marrow

• Soft tissue within bones.
• Responsible for producing blood cells (RBCs, WBCs, platelets).
• Bone marrow stem cells are important for immunity by generating lymphocytes.
• Certain white blood cells mature in the bone marrow

Lymph Flow Maintenance

• Skeletal muscle contractions compress lymphatic vessels to move lymph.
• Breathing movements (respiratory pump) cause pressure differences within the body, aiding lymph flow.
• Smooth muscle contractions in lymphatic vessels aid lymph flow.
• Lymphatic vessel valves prevent lymph backflow.

Edema

• Edema is excess interstitial fluid in tissue spaces.
• Causes: lymphatic system obstruction, lack of skeletal muscle contractions, increased capillary blood pressure.
• Common complication of lymphatic vessel obstruction.

Lymphatic Filariasis

• Caused by filarial worms carried by mosquitoes.
• Adult worms reside in lymphatic nodes, blocking lymph flow.
• Known as elephantiasis, causing severe swelling.

Test your knowledge about the lymphatic system with this quiz. Topics include lymph nodes, lymphatic capillaries, spleen functions, and the role of adenoids. Perfect for students studying human biology or anatomy.