Lymphatic system Flashcards
What is the purpose of the lymphatic system?
it is a system of vessels and lymphoid organs that drain tissue fluid from the extracellular compartment
- low pressure system as no driving force
Where is the lymphatic system absent?
immune-priviledged organs:
- CNS
- eyeball
- inner ear
- cartilage
- bone
What is the widest distributed tissue in the body?
Interstitial fluid
What are the key functional factors of the lymphatic system?
Helps capillaries return plasma proteins that leak into extracellular fluid back to circulation
Helps transport cellular debris that does not use the circulatory system
Essential for immunological functions of the body
Absorbs/ transports fats from the digestive system
Plays a major role in fluid balance of the body
Plays a major part in the determination of cell volume
What are the key clinical factors of the lymphatic system?
Major consituent of the immune system
It is a conduit for the spread of:
- infections
- malignancies
- can be a site of primary tumours
Blockage leads to lymphoedema
Primary site for infections
What is lymph?
Transudative fluid
Transparent and yellowish in appearance
Alkaline in nature
How is lymph formed?
formed when blood plasma leaves capillaries of the circulatory system passing into the extracellular compartment
- 9/10 of plasma returns in venous system
- 1/10 returns via lymphatic system
Bathes cells of the body
What is “chyle”?
lymph produced by the small intestine - absorbed fat
What is the composition of lymph?
Composed from water as a solvent and solutes H20 makes up 96% of its volume Solutes - proteins - lipids - glucose - electrolytes - cells - mainly lymphocytes
At rest, how much lymph is produced per day?
3-4 litres
- flows at a rate of 120ml/hour
- 100 ml flow through thoracic duct
- 20 ml flow through right lymphatic duct
What is the network of lymph channels?
Microscopic lymphatic capillaries to
lymphatic vessels to
collecting trunks to
ducts
It all drains back into the subclavian vein
What are the lymph organs?
Bone marrow Spleen Thymus gland Lymph nodes Tonsils
In a normal young adult how many lymph nodes are there?
400-450 lymph nodes
- on average 2/3s of lymph nodes are found in the abdomen
- head and neck: 60-70
- arms and superficial thorax: 40
- legs: 30
- thorax: 100
- abdomen and pelvis: 230
What is the structure of a lymph node?
Kidney or bean-shaped
Variable in size - range from tiny to 2.5cm in diameter
Lymph enters through afferent channels, percolates through sinuses and exits via efferent channels
They are inhabited by phagocytes and macrophages that clean up lymph
What are the 2 separate drainage systems?
Drainage of lymph in superficial structures (skin) - follow venous drainage and drain into deep lymph vessels
Drainage of lymph in deep structures (visceral organs) - tend to accompany arteries - likely use muscular pump to maintain flow
Drainage from these 2 systems drains differently
What are the 2 lymphatic ducts ?
right lymphatic duct
thoracic duct
- separated by the midline
What does the right lymphatic duct receive?
Drains lymph from the right upper quadrant of the body
- right side of head
- right side of neck
- right side of thorax
- right upper limb
enters venous system via the right venous angle (coming together of right internal jugular and right subclavian vein)
What does the thoracic duct receive?
Much larger
Drains lymph from the rest of the body that is not drained by the right lymphatic duct
Enters the venous system via the left venous angle (union of internal jugular vein and subclavian vein)
How do tumours lead to clinical presenting symptoms via lymphatic system?
Local invasion of tissues in which the primary growth arises
Infiltration of tissues adjacent to the site of the primary growth
Spread to tissues that are remote to the site of the primary growth
What are the general principles of infiltration of local tissues?
Cancerous growth might be contained locally to produce clinical signs arising from disruption of the local tissue alone
The growth may infiltrate tissues adjacent to the site of the primary growth through physical pressure of the growth
What are the general principles of spreading to remote sites?
Growth might breakdown the integrity of the structures and barriers to spread remotely
Clinical signs arising from complications of the growth may be due to:
- disruption of the site of the primary growth
- disruption of the primary site of the growth plus secondary sites not associated with the site of the primary growth
- disruption of secondary sites not associated with the site of the primary growth
What are the general principles of benign tumours?
Cell of a particular organ/tissue transform to replicate uncontrollably
Cancerous cells grow and divide to multiply
Such cancerous cells may:
- start to secrete factors that are detectable through diagnostics - chemical factors - can disrupt normal functioning
- new growth: - eventually reaches a size that is detectable and impairs normal functioning
cancerous cells may remain in the site of the primary growth
growths do not spread beyond the primary site
What are the general principles of metastatic tumours?
Cells of a particular organ/tissue transform to become cancerous
Cancerous cells grow and divide to multiply
Such cancerous cells may:
- start to secrete factors that are detectable through diagnostics - chemical factors - can disrupt normal functioning
- new growth: - eventually reaches a size that is detectable and impairs normal functioning
Such cancerous cells have the ability to secrete chemical signals that lead to spread of the growth to remote organs or trigger new cancerous growths in remote organs
Spread by metastasis
What are the routes of metastatic spread of cancers?
- invasion of tissues by general spread after breakdown of basement membranes of cells of primary growth
- invasion of tissues through fascial or neuro-vascular planes
- spread via arterial system
- spread via lymphatic system - direct invasion through lymph nodes
