lymphatic system

Lymphatic System Overview

  • Chapter 31: Lymphatic System

  • Copyright 2019, Elsevier Inc. All Rights Reserved.

Learning Objectives

  • Lesson 31.1: Structures and Functions of the Lymphatic System

    1. General functions of the lymphatic system & primary lymphatic structures.

    2. Chemical structures of lymph vs. interstitial fluid.

    3. Lymphatic drainage: right lymphatic duct & thoracic duct.

    4. Comparison of lymphatic vessels & veins.

  • Lesson 31.2: More Structures and Functions

    5. Lymphatic system's role in fat absorption from the small intestine.

    6. Lymphatic pump and lymphokinetic actions.

    7. Structure and function of lymph nodes as biological filters.

    8. Location & functions of major lymph node groups. 9. Lymphatic drainage of the breast.

    10. Structure and function of the thymus and spleen.

    1. Disorders of the lymphatic system.

Overview of the Lymphatic System

  • Fluid Balance

    • Maintains internal fluid balance; absorbs interstitial fluid.

    • Edema can cause tissue destruction.

    • Lymph vessels collect excess fluid & return it to venous blood.

    • Acts as a component of the circulatory system; returns substances to circulation.

Role of the Lymphatic System in Fluid Balance

  • Interstitial fluid (IF) moves through blood capillaries.

  • Lymphatic capillaries collect excessive IF and return lymph fluid to veins.

Structures of the Lymphatic System

  • Comprises lymph, lymphatic vessels, and lymphoid tissue structures:

    • Lymph Nodes—filter lymph along collecting vessels.

    • Tonsils—act as first line of defense.

    • Thymus—maturation of T cells.

    • Spleen—filters blood and supports immune functions.

    • Bone Marrow—produces immune cells.

Lymph and Interstitial Fluid Comparison

  • Lymph: Clear, watery, isotonic fluid in lymphatic vessels.

  • Interstitial Fluid: Fills spaces between cells, lower protein concentration.

Lymphatic Vessels: Distribution

  • Lymphatic Capillaries: Microscopic, blind-end, composed of single-layer endothelial cells.

  • Lymphatic Ducts:

    • Lymph from the right upper quadrant drains into the right lymphatic duct then to the right subclavian vein.

    • Lymph from the rest of the body drains into the thoracic duct (originates in cisterna chyli).

Structure of Lymphatic Vessels

  • Thinner walls, more valves, and often contain lymph nodes.

  • Increased diameter leads to thicker walls.

  • Contain one-way valves, contributing to a beaded appearance.

  • Capacity for repair/regeneration post-damage.

Lymphatic Vessels: Functions

  • Removes large molecules and particulate matter from interstitial spaces.

  • Lacteals absorb fats from the small intestine.

Lymph Flow and the Lymphatic Pump

  • Continuous filtration of water and solutes from capillaries into interstitial fluid.

  • Majority of proteins leak out and are returned via lymphatics.

  • Lymphokinesis: Movement of lymph, aided by valves ensuring flow direction.

Defense Functions of Lymph Nodes

  • Mechanical Filtration: Stops particles from advancing further.

  • Biological Filtration: Phagocytosis to destroy/removal of particles.

  • Hematopoiesis: Final maturation of immune cells.

Disorders of the Lymphatic System

  • Lymphedema: Swelling in tissues due to lymphatic obstruction.

  • Elephantiasis: Severe lymphedema leading to enlarged limbs.

  • Tonsillitis: Signs include fever, sore throat, difficulty swallowing.

  • Lymphoma: Malignant tumors originating in lymphatic tissue.

Lymphatic Drainage of the Breast

  • Breast cancer common; lymphatic pathways facilitate spread of infection.

  • Drains via superficial vessels (over skin) and deep vessels (underlying breast tissue).

  • Sentinel Lymph Node: First node cancer may spread to.