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The Lymphatic System The Lymphatic Systems Overview General - - PDF document
The Lymphatic System The Lymphatic Systems Overview General - - PDF document
The Lymphatic System The Lymphatic Systems Overview General Functions Organization Components Lymphatic System General Functions Transportation Excess fluid from capillary exchange Fats & fat soluble vitamins from lacteals in the
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Lymphatic System
General Functions
Transportation
Excess fluid from capillary exchange Fats & fat soluble vitamins from lacteals in the small intestines (chyle)
Defense
B and T cells macrophages
Production
Lymphocytes within primary lymphatic organs
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Lymphatic capillaries Lymphatic collecting vessels Lymph nodes Lymphatic trunks Lymphatic ducts
blood capillary
blood flow F R
Lymph
Lymphatic collecting vessels Venous Return
subclavian vein
Lymph Flow Through System
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Lymph Capillaries
Located near blood capillaries Differ from capillaries of the cardiovascular system Receive fluid from connective tissue
Increased volume of tissue fluid causes one way minivalve flaps open and allow fluid to enter Anchoring filaments stabilize the endothelial flaps
High permeability
Pros
uptake of tissue fluid
Cons
entrance of bacteria, viruses, and cancer cells
Lacteals – specialized lymphatic capillaries
Located in the villi of the small intestines Receive digested fats and fat soluble vitamins Fatty lymph – chyle
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Location and Structure of Lymph Capillaries
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Lymphatic Collecting Vessels
Accompany blood vessels Composed of the same three tunics as blood vessels Contain valves Lymph propelled by:
Skeletal muscle pump Arterial pulsing Tunica media
Lymph node location
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Lymph Nodes
Cleanse the lymph of pathogens Human body contains approximately 500 lymph nodes Lymph nodes are organized in clusters
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Lymph Nodes
Function
Lymph percolates through lymph sinuses Most antigenic challenges occur in lymph nodes Antigens destroyed – and activate B and T lymphocytes
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Lymph Node Structure
Major Structures:
- 1. The lymph node capsule
- 2. The subcapsular sinus
- 3. The lymph node cortex
beneath the subcortical sinus-the location of primary and secondary lymphoid follicles
- 4. The paracortex
the region surrounding and beneath the germinal centers
- 5. The medulla
deep to the cortex/paracortex, and composed of medullary cords and medullary sinuses
- 6. Medullary vessels
- 7. Afferent and efferent lymphatic
vessels
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Lymph Trunks
Formed from the convergence of lymphatic vessels Five major lymph trunks
Lumbar trunks
receives lymph from lower limbs
Intestinal trunk
receives chyle from digestive organs
Bronchomediastinal trunks
collects lymph from thoracic viscera
Subclavian trunks
receive lymph from upper limbs and thoracic wall
Jugular trunks
drain lymph from the head and neck
Left lumbar trunk Right lumbar trunk Intestinal trunk Right broncho- mediastinal trunk Left broncho- mediastinal trunk Left jugular trunk Right jugular trunk Right subclavian trunk Left subclavian trunk
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Lymph Ducts - detail
Thoracic duct
ascends along vertebral bodies from the cisterna chyli Empties into venous circulation at the junction of the left internal jugular and the left subclavian veins
Right lymphatic duct
Empties into right internal jugular and subclavian veins
Left lumbar trunk Right lumbar trunk Intestinal trunk Right broncho- mediastinal trunk Left broncho- mediastinal trunk Left jugular trunk Right jugular trunk Right subclavian trunk Left subclavian trunk Thoracic duct Right lymphatic duct
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Defensive Overview of the Lymphatic System
Defenses may be non-specific
- r specific (immunity)
Key cells – lymphocytes & macrophages
Recognizes specific foreign molecules Destroys pathogens effectively
Also includes lymphoid tissue and lymphoid organs
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Specific Defenses (immunity)
Types of immunity
Cell mediated immunity Antibody mediated (Humoral) immunity
Lymphocyte involvement
Depends on if B or T cell
B lymphocytes – become plasma cells
Secrete antibodies
Cytotoxic T lymphocytes
Destroy antigen-bearing cells
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Lymphocyte Development
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Lymphoid Tissue
Most important tissue of the immune system
Primary organs
site of development & maturation (bone marrow & thymus)
Secondary organs
site of activated lymphocyte populations (lymph nodes, lymphatic nodules, spleen)
Two general locations
Mucous membranes of:
Digestive, urinary, respiratory, and reproductive tracts Mucosa-associated lymphoid tissue (MALT or GALT) Lymphoid organs (marrow, thymus, nodes, nodules, spleen)
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Thymus
Immature lymphocytes develop into T lymphocytes Secretes thymic hormones Most active in childhood
Functional tissue atrophies with age
Composed of cortex and medulla
Medulla contains Hassall’s corpuscles
Hassall’s Corpuscle
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Spleen
Largest lymphoid organ
White pulp – thick sleeves of lymphoid tissue Red pulp – surrounds white pulp
Composed of:
Venous sinuses Splenic cords
Two main blood-cleansing functions
Removal of blood-borne antigens Removal and destruction of old/defective blood cells
Site of hematopoiesis in the fetus (prior to bone marrow development)
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Spleen
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Tonsils
Simplest lymphoid organs Four groups of tonsils
Palatine, lingual, pharyngeal, and tubal tonsils
Arranged in a ring to gather and remove pathogens Underlying lamina propria consists of MALT
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Aggregated Lymphoid Nodules and the Appendix
MALT – abundant in walls of intestines Fight invading bacteria Generate a wide variety of memory lymphocytes
Aggregated lymphoid nodules (Peyer’s patches)
Located in the distal part of the small intestine
Appendix - tubular offshoot of the cecum
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Disorders of the Lymphatic and Immune Systems
Chylothorax – leakage of fatty lymph into the thorax Lymphangitis – inflammation of a lymph vessel Mononucleosis – viral disease caused by Epstein-Barr virus
Attacks B lymphocytes
Elephantiasis
Blockage of lymphatic vessels by filarial worms
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