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Lymphatic System

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  • Two most important functions of the lymphatic system

    1. Returns excess interstitial fluid to the bloodstream.
    2. Provides immune defense by filtering lymph and housing lymphocytes.

  • What is the lymphatic system?

    A network of vessels, nodes, and organs that transports lymph and supports immune function.

  • What is lymph?

    Clear fluid derived from interstitial fluid that circulates in lymphatic vessels.

  • What is interstitial fluid?

    Fluid that surrounds tissue cells, providing nutrients and removing waste.

  • What is plasma?

    The liquid component of blood that carries cells and proteins throughout the body.

  • Describe lymphatic vessels

    Thin-walled vessels that carry lymph from tissues toward the heart, equipped with valves to prevent backflow.

  • What are lymphatic capillaries?

    Small, blind-ended vessels that absorb interstitial fluid to form lymph.

  • What are lacteals?

    Specialized lymphatic capillaries in the small intestine that absorb dietary fats.

  • What is the right lymphatic duct?

    A duct that drains lymph from the right upper limb, right side of the head, and thorax into the right subclavian vein.

  • What is the thoracic duct?

    The largest lymphatic vessel that drains lymph from most of the body into the left subclavian vein.

  • What is the cisterna chyli?

    A sac-like reservoir at the start of the thoracic duct that collects lymph from the lower body.

  • Structure of lymphatic vessels

    Composed of three layers: endothelium, smooth muscle, and connective tissue with valves to ensure one-way flow.

  • Functions of lymphatic vessels

    Transport lymph, maintain fluid balance, and facilitate immune cell movement.

  • What is the lymphatic pump?

    Mechanism using skeletal muscle contractions and vessel valves to propel lymph through vessels.

  • Structure of lymph nodes

    Small, bean-shaped organs with a fibrous capsule, cortex with lymphoid follicles, and medulla containing macrophages.

  • Functions of lymph nodes

    Filter lymph, trap pathogens, and activate immune responses.

  • Lymphatic drainage of the breast

    Primarily drains into the axillary lymph nodes, important in breast cancer spread.

  • Location of lymph nodes of greatest clinical importance

    Axillary, cervical, and inguinal regions due to their role in filtering lymph from major body areas.

  • What are tonsils?

    Lymphoid tissues in the pharynx that trap pathogens entering through the mouth and nose.

  • Location of the thymus

    Located in the anterior mediastinum, behind the sternum and above the heart.

  • Functions of the thymus

    Site of T lymphocyte maturation and development of immune tolerance.

  • Location of the spleen

    Located in the upper left abdomen, lateral to the stomach.

  • Functions of the spleen

    Filters blood, removes old red blood cells, and helps mount immune responses.