Introduction to the Lymphatic System Flashcards
What is the lymphatic system?
If the cardiovascular system (heart and circulation) is the supply system of the body then the lymphatic system is the cleansing system
If the heart circulates blood containing oxygen, nutrients and fluid to all tissues of the body then the lymphatic system acts as a counter-current system draining from the tissues all waste materials and recycling surplus fluid, salts, proteins, fat and immune cells back to the body
How does the lymphatic system work?
Lymph drainage begins with absorption of fluid from the tissues
Lymph is transported through larger collecting lymphatic vessels to lymph nodes
Lymph nodes filter the lymph where there is also interaction with the immune system
After passing through a series of lymph nodes large lymphatic vessels eventually discharge lymph into great veins of the neck
What is lymph?
Lymph is interstitial (tissue) fluid containing salts, proteins and cells, originally formed from a plasma ultrafiltrate
What are lymph nodes (glands)?
Lymph glands are filter stations positioned at intervals along the lymph drainage route
They perform two basic functions:
1. To clean up the lymph before it re-enters the bloodstream, by sieving out, trapping and destroying (inorganic) foreign materials
2. Monitoring the lymph for telltale signs of (organic) predators e.g. infection, so play a vital role in our immune system responses
What is the first function of the lymphatic system?
The first function of the Lymphatic System is fluid balance (homeostasis)
Tissue fluid homeostasis is simple: the blood vessels supply fluid and the lymph drains it away
What is chronic oedema? How does it work?
Chronic oedema= lymphatic failure
Wither lymph drainage is insufficient or lymph load (vascular fluid filtration) exceeds lymph drainage capacity
Mechanisms for chronic oedema
Lymphatic failure with increased capillary filtration (high lymph load overwhelming lymph drainage capacity) = relative lymphatic failure e.g. heart failure, venous oedema
Lymphatic failure with no increase in capillary filtration (normal lymph load)= absolute lymphatic failure (lymphoedema)
Lymphatic failure resulting from sustained increased capillary filtration exhausting lymph drainage capacity= absolute lymphatic failure (lymphoedema) e.g. Post-thrombotic syndrome, longstanding venous hypertension
What is venous oedema?
High lymph load from venous hypertension overwhelming lymph drainage
What is lymphoedema?
Lymphoedema is one of the major consequences of lymphatic failure
Lymphoedema results in swelling such as a leg with build up of fluid, cells and fat, as well as a predisposition to infections
What happens to venous oedema if it persists?
If oedema persists after-treatment of the veins then the lymph drainage is permanently damaged and a state of lymphoedema now exists
How can lymphoedema occur from heart problems?
Lymphoedema following treated heart failure
Eventual and permanent failure of lymph drainage from high sustained lymph load ( equivalent to hypertensive heart failure)
What is the second function of the lymphatic system?
The second function of the Lymphatic System is tissue immunosurveillance
The Lymphatic System houses the immune system and is responsible for tissue immune cell trafficking
A common complication of impaired lymph drainage is function e.g. cellulitis
What is the third function of the lymphatic system?
The third function of the Lymphatic System is fat homeostasis
The Lymphatic System is responsible for gut fat absorption and peripheral fat resorption
How does the lymphatic system relate to cancer?
The lymphatic system is mainly responsible for the spread of cancer
A sentinel lymph node biopsy is designed to detect the lymphatic spread of cancer and guide treatment
What is primary lymphoedema?
Primary Lymphoedema (intrinsic failure of the lymphatic system) Chronic oedema caused by a developmental abnormality of the lymphatic system Phenotype vary in age of onset, site, inheritance patterns, associated features and genetic causes
How is lymphoedema managed?
Because there is not one drug or one operation known to improve lymph drainage, treatment has to be physically based, intended to stimulate lymph drainage and reduce blood vascular filtration (lymph load)
