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The Human Body in Health and Illness, 4th edition
Barbara Herlihy
Chapter 20:Lymphatic System
1
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
reserved.2
The Lymphatic System: Functions
• Returns interstitial fluid to the blood
• Absorbs fats and fat-soluble vitamins
• Helps the body defend itself against infection
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.3
Lymphatic Vessels and Veins• Veins and lymphatic vessels drain interstitial fluid.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.4
Formation of Lymph
Blood interstitial fluid lymph
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.5
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
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.6
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.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.7
Lymphatic Drainage: Main Ducts
• Two drainage areas: Right lymphatic duct and thoracic duct
• Both ducts drain into subclavian veins.
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.8
Lymphoid Organs
• Lymph nodes• Tonsils • Thymus gland• Spleen• MALT (mucosal-associated lymphoid tissue)
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.9
Lymph Node: Two Compartments
• Lymph nodules– Lymphocytes and
macrophages– Immunity,
phagocytosis
• Lymph sinuses– Are lymph-filled
spaces– Bathe lymph nodules
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.10
Lymphatic System: Diffuse
• Lymphatic vessels drain most of the body.
• Nodes are grouped.– Cervical– Axillary– Inguinal
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.11
Lymphoid Organs: Tonsils
• Pharyngeal tonsils or adenoids
• Palatine tonsils often target of tonsillectomy
• Lingual tonsils
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.12
Lymphoid Organ: Thymus Gland
• Assists development of immune system before puberty
• Secretes thymosins • Produces T cells
(lymphocytes)
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.13
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
Copyright © 2011, 2007 by Saunders, an imprint of Elsevier Inc. All rights
reserved.14