The Lymphatic System

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The Lymphatic System
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Roles of the Lymphatics system

• Functions of the lymphatic system
• Fat absorption
• Intestinal lipid absorption places chylomicrons
  (intestinal lipid carriers) into the lymphatic
  system rather than the hepatic portal system
• Systemic circulation has first-pass access to
  intestinal lipids and fat-soluble vitamins
  (unlike amino acids glucose)
• Returns interstitial fluid to circulation
• Retains lymphocytes (lymph-based cells) for
  immunity

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Lymphatic System

• Consists of
• - lymph
• - network of vessels
• - lymph nodes and nodules
• - primary organs
• - bone marrow
• - thymus
• Secondary organs
• Spleen
• Tonsils
• Other tissues
• Peyers patches
• Kuffers cells

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Lymph (lympha clear fluid)

• derived from tissue fluid
• contains more white blood cells than plasma
• must be returned to blood stream to maintain
  blood volume and pressure
• Lymph plasma - proteins

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Lymphatic circulation

• Lymphatic circulation returns excess tissue fluid
  back to the cardio-vascular system
• Blood plasma that seeps from the capillary beds
  is normally drawn back into the venous blood flow
  by diffusion/osmosis
• ? 15 does not return to venous flow and must be
  returned to circulation via lymphatic system

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Lymphatic capillaries
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Lymphatic capillaries

• Lymphatic capillaries are markedly similar to
  veins
• One-way valves requirement for skeletal muscle
  propulsion (skeletal muscle pump)
• Where lymphatics differ from venous system arises
  with lymph nodes
• Nodes or collections of reticular tissue along
  the lymphatic vessel tract

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Lymph vessels

• Capillaries merge to form larger vessels ? trunks
• no pump for lymph ? Lymph is kept moving by
• - constriction of vessels
• - skeletal muscle pump
• - respiratory pump

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Lymphatic nodes
Note how lymph enters the lymph nodes and
permeates through the reticular tissue where
immature lymphocytes are located. These immature
lymphocytes then sample the contents of the lymph
and develop tolerance or attack postures.
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Major Lymph Nodes

• cervical
• axillary
• inguinal
• mesenteric

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Lymphatic vessels and nodes
Lymph nodes usually located in characteristic
locations along the lymph network
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A disease of the lymphatic system bubonic plague
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Lymphatic circulation
Remember that lymph drainage is not proportional
right lymphatic duct only drains from upper
right torso into right subclavian vein.
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Lymphatic System

• Consists of
• - lymph
• - network of vessels
• - lymph nodes and nodules
• - primary organs
• - bone marrow
• - thymus
• Secondary organs
• Spleen
• Tonsils
• Other tissues
• Peyers patches
• Kuffers cells

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Primary organs Bone marrow
The bone marrow synthesizes all 3 blood cells and
elements. The B lymphocytes mature in the bone
marrow before their release
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Primary organs thymus

• Located in the chest, behind the sternum
• Large in children decrease in size during
  adulthood
• Promotes maturation of T-lymphocytes
• No function in adulthood?

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Secondary organs the spleen

• Left, upper abdomen, under the ribs
• Catastrophic injury when ruptured
• Receives blood from the splenic artery and export
  blood through the splenic vein
• Has white and red pulps
• white collection of T-lymphocytes
• Red red blood cells storage

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Tonsils

• Role Most likely samples pathogens passing by
  the mouth and upperairway can be removed
  without consequences
• 3 sets
• pharyngeal tonsils adenoids
• Palatine tonsils
• Lingual tonsils

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Other lymphatic tissues

• Peyers patches grouph of lymphatic cells
  present along the wall of the intestine. Catch
  pathogens which manages to cross.
• Appendix catches pathogen from the intestinal
  lumen. Frequently infected ? removed
• Kupffer cells phagocytic cells present in the
  liver.