Chapter 020

The Human Body in Health and Illness, 4th edition

Barbara Herlihy

Chapter 20:Lymphatic System

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Lesson 20-1 Objectives

• List three functions of the lymphatic system.• Describe the composition and flow of lymph.• State the location of the following lymph

nodes: cervical nodes, axillary nodes, and inguinal nodes.

• Describe the four lymphoid organs: lymph nodes, tonsils, thymus gland, and spleen.

Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights

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The Lymphatic System: Functions

• Returns interstitial fluid to the blood

• Absorbs fats and fat-soluble vitamins

• Helps the body defend itself against infection


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Lymphatic Vessels and Veins• Veins and lymphatic vessels drain interstitial fluid.


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Formation of Lymph

Blood interstitial fluid lymph


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Lymph Nodes and Lymph Vessels

• Lymphatic vessels travel with veins, help with drainage

• Lymph travels through vessels to nodes

• Nodes: Sites of phagocytosis and immune response


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What Makes Lymph Move?

• Milking action of skeletal muscles– Exercise is good.

• Movement of chest during respiration– Creates variations in pressure.

• Rhythmic contractions of lymphatic smooth muscle– Vessel walls contract to push lymph along.


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Lymphatic Drainage: Main Ducts

• Two drainage areas: Right lymphatic duct and thoracic duct

• Both ducts drain into subclavian veins.


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Lymphoid Organs

• Lymph nodes• Tonsils • Thymus gland• Spleen• MALT (mucosal-associated lymphoid tissue)


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Lymph Node: Two Compartments

• Lymph nodules– Lymphocytes and

macrophages– Immunity,

phagocytosis

• Lymph sinuses– Are lymph-filled

spaces– Bathe lymph nodules


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Lymphatic System: Diffuse

• Lymphatic vessels drain most of the body.

• Nodes are grouped.– Cervical– Axillary– Inguinal


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Lymphoid Organs: Tonsils

• Pharyngeal tonsils or adenoids

• Palatine tonsils often target of tonsillectomy

• Lingual tonsils


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Lymphoid Organ: Thymus Gland

• Assists development of immune system before puberty

• Secretes thymosins • Produces T cells

(lymphocytes)


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Lymphoid Organ: Spleen• Red pulp: Venous

sinuses filled with blood and phagocytes

• White pulp: Contains lymphocytes

• Stores RBCs and platelets

• Removes old RBCs and platelets


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Entertainment & Humor

Chapter 020