Lymphatic System

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Lymphatic System

• Chapter 20
• Dr. Ackman

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Lymphatic System

• Lymphatic system
• 1- Network of lymphatic vessels (lymphatics)
• Transmit fluid back to the blood from the
  extracellular spaces
• Interstitial fluid
• 2- Lymphoid tissue (tonsils, spleen)
• Phagocytic cells and lymphocytes that act as a
  defense mechanism

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Lymphatics

• 3L of fluid remains in tissue spaces per day
• Lymphatics drain fluid and plasma proteins
• Returns fluid to maintain blood volume
• Lymph interstitial fluid in lymphatics

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Structure of lymphatics

• Lymphatics
• Widespread in tissue
• Absent in bone, teeth, and CNS
• One way system
• Blind ended ducts
• Anchored to surrounding tissue
• Collagen fibers

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Structure of Lymphatics

• Lymphatics
• Very permeable
• Minivalves
• Endothelium not tight
• Collagen valves anchored to tissue
• Increase pressure opens valves
• Interstitial fluid flows in to lymphatic

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Lymphatics

• Lymphatics
• Increased pressure in lymphatics causes valves to
  close
• Fluid accumulates in tissue
• Inflammation allows large particles to enter
  lymphatics
• Bacteria, virus, and cancer cells

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Lymphatics in digestive tract

• Lymphatics in digestive system
• Lacteals
• Absorb digestive fats
• Chyle

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Lymphatic vessels

• Lymphatic vessels
• Similar tunics
• Usually travel with veins superficially
• Usual travel with arteries deeper
• Collecting vessels thinner than veins
• Cisterna chyli
• Collects lymph from lower limbs

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Lymphatic Vessels

• Lymphatic references
• Thoracic duct brings lymph from lower body to
  left subclavian vein
• Right lymphatic duct empties into right
  subclavian
• Lymphangitis
• Inflammation of lymphatic vessels

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Transport of lymph

• Utilizes same mechanism as veins
• Valves prevent backflow of lymph
• Muscle pump
• Pulmonary pump
• Low pressure

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Lymph flow

• Lymphedema
• Accumulation of fluid due to blockage of
  lymphatic vessel
• Cancer
• Inflammation
• Infection

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Lymphoid cells and tissue

• Lymphocytes
• T cells
• B cells
• Plasma cells produce antibodies
• Macrophages
• Phagocytize foreign particles

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Lymphoid Tissue

• Lymphoid tissue
• Component of immune system
• Houses and provides site for lymphocytes to
  proliferate
• Surveillance for macrophages and lymphocytes will
  leave and go other parts of body
• Composed of reticular connective tissue

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Lymphoid Tissue
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Lymph nodes

• Clusters of lymphoid tissue along lymphoid
  vessels
• Lymph is filtered as it flows back to the blood
• Two functions
• Lymph filters
• Activate immune system

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Structure of Lymph Node

• Afferent lymphatic vessels
• Bring lymph to lymph node
• Subcapsular sinus
• Lymph circulates within node
• Efferent lymphatic vessels
• Take lymph away from lymph node

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Swollen Glands??

• Inflamed lymph nodes
• Lymphadenitis
• Local drain specific body region
• Generalized more than one regional node
  enlarged
• Buboes
• Black Death plague
• Sites of Cancer metastasis
• Lymph nodes filter out cancerous cells

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www.cdc.gov/ncidod/dvbid/ images/bubo.jpg
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Other Lymphoid Tissue

• Spleen
• Located left side of abdominal cavity
• Lymphocytic proliferation
• Immune surveillance and response
• Breaks down products of red blood cells
• Salvages hemoglobin
• Site of erythrocyte production in fetus
• Stores blood platelets
• Often injured
• Splenectomy
• Diminished immune surveillance

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Spleen
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Lymphoid Tissue

• Thymus
• Important early childhood
• T lymphocytes mature

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Other lymphoid tissue

• Tonsils
• Palatine tonsils
• Paired back of throat
• Lingual tonsils
• Base of tongue
• Pharyngeal tonsils
• Adenoids
• Tubal tonsils
• Surround auditory tube
• Tonsils act as first line of defense to invasive
  organisms

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Misc Lymphoid tissue

• Appendix
• Peyers patches
• MALT
• Mucosa associated lymphatic tissue