Lymphatic system overview Flashcards
Components of the lymphatic system
Lymph vessels, ducts and capillaries Lymph nodes Spleen Thymus Tonsils Gut Associated Lymph Tissue (GALT) Lymph! (and chyle, the lymph from the GIT)
What does the lymphatic system do?
Return tissue fluid to the circulation
Filter potentially damaging material
Produce antibodies and lymphocytes for the defense of the body
Transport digested fat from the intestine to the liver/storage sites around the body
Major lymphatic ducts
Right lymphatic duct
Tracheal duct
Cisterna chyli
Thoracic duct
Major lymphatic nodes
Parotic Mandibular Lat retropharyngeal (inconsistent) Superficial cervical (near scapula, sometimes called suprascapular) Axillary Inguinal Popliteal Non palpable: femoral, mesenteric, bronchial
Inguinal nodes
Two nodes either side of the groin, between the thigh and abdominal wall
Submandibular nodes
2-5 nodes lying at the edge of the angle of the jaw
Prescapular nodes
Cranial to scapula
Axillary nodes
Within tissues of the axilla (armpit)
Popliteal nodes
Within the tissuesof the gastrocnemiusmuscle, caudal to the stifle joint
Anatomy of a lymphatic node
Bean-shaped – indented area named hilus
Capsule – fibrous connective outside layer
Cortex - location of resident lymphocytes
Medulla - contains tissue macrophages embedded in a coarse fibrous mesh
Spleen in regards to the lymphatic systom
Largest lymphoid organ in the body
Haemopoietic multi-lobal
Attached to the greater curvature of the stomach on left side of abdomen
Storage of blood removal of old RBC, activation of WBC
Removal of bacteria and foreign material by the action of phagocytic cells
Splenic artery (branch of celiac) – splenic vein (portal vein)
Though the spleen has important functions, it is not essential to life and may be surgically removed if necessary (splenectomy)
Thymus in regards to the lymphatic sustem
Thorax, cranial to the heart
Most prominent in young animals (shrinks with time)
Produces lymphocytes (thymocyctes and T-cells)
Tonsils
Lymphoid tissue in pharynx
Prevent spread of infection into the respiratory or digestive systems
Located at the beginning of the lymph drainage system, not along the lymph vessels like lymph nodes
Gut associated lymph tissue (GALT)
Lymphoid tissue found in the intestinal mucosa and submucosa
Largest lymphoid organ in the body (in terms of volume, but in one piece it is still the spleen!)
Peyer’s patches
Located in the wall of the intestine and assist with the battle against invading antigens
How is lymph formed?
The lymphatic system circulates the lymph which is like plasma but with more lymphocytes, more fat (lipids) and less proteins
Lymph only moves towards the heart (unidirectional) and enters via cava
No pump! - body movements propel lymph towards the heart
Arterial blood under pressure forces fluid out of the capillaries & into the tissues
Lack of blood pressure results in less fluid being absorbed back to veins & so fluid accumulates in tissues (interstitial fluid)
Excess of interstitial fluid is drained to lymphatic capillaries
Lymphatic capillaries merge to form larger vessels which have valves
Lymphatic vessels drain into ducts
Lymph is filtered in lymph nodes
Blood plasma
Position: In arteries, capillaries & veins
Protein content: High
Oxygen & nutrient content: High
Waste content: Low (removal via kidney)
Cell content:RBCs, WBCs…
Tissue fluid
Position:Between cells in tissues
Protein content: Very low
Oxygen & nutrient content:High (arterial end)
Low (venous end)
Waste content: Low (arterial end)
High (venous end
Cell content:WBCs (neutrophils) patrolling & protecting tissues
Lymph
Position:In lymph vessels, same structure as veins
Protein content: Very low
Oxygen & nutrient content:Low oxygen
Varied nutrient
Waste content:High
Cell content:WBCs as tissue fluid & lymphocytes matured in lymph nodes
