Lymphatic System Flashcards
What is lymph?
Lympth is interstitial fluid that has entered the lymphatic vessels. Lymph is a clear, pale-yellow fluid
Lympathic system consists of
lymphatic vessels, lymph, lymph nodes, thymus, spleen, GALT & MALT, red bone marrow
Lymphatic tissue is made of
Lymphatic tissue is made of a specialized form of reticular connective tissue. Lymphatic tissue contains large numbers of lymphocytes
Functions of Lymphatic System
- Drains excess interstitial fluid
- Transports dietary lipids
- Carries out immune responses
Lymphatic Vessels & Lymph Circulation
1, Begins as lymphatic capillaries
(tiny and closed at one end and located in spaces between cells)
2. Lymphatic capillaries unite to form larger lymphatic vessels (resemble veins but have thinner walls and more valves)
3. Lymph flows through lymph nodes
In skin:
Lymphatic vessels located in subcutaneous tissue, following the same route as veins
In viscera:
Lymphatic vessels follow same route as arteries, forming plexuses (networks) around viscera
Tissues that lack lymphatic vessels:
Avascular tissues, eg. cornea, lens, cartilage, CNS - brain and spinal cord
Structure of lymphatic capillaries
Larger in diameter than blood vessels
Have a one way structure - only permits in flow of interstitial fluid
Flow of Lymph
Blood capillaries (blood) > Interstitial spaces (interstitial fluid) > Lymphatic capillaries (lymph) > Lymphatic vessels (lymph) > Lymphatic ducts (lymph) > Junction of the internal jugular and subclavian veins (blood)
Lymphatic Ducts
Lymph passes from trunks into two main channels
- Thoracic duct (aka left lymphatic duct)
- Right lymphatic duct
Thoracic duct
The thoracic duct is the main duct for the return of lymph to blood
- 38-45cm long
- Main duct for the return of lymph to blood
- Drains lymph from most of the trunks: L & R Lumbar, Intestinal, L Jugular, L Subclavian, L Bronchomediastinal
- Then drains lymph into venous blood stream at junction of L internal jugular & L subclavian vein
Spleen
white pulp, red pulp
Lymph nodes
Act as a filter, cleaning the lymph
Same two pumps involved in venous return of blood to heart maintain flow of lymph
- Skeletal muscle pump – “milking action” of skeletal muscles compresses lymphatic vessels
- Respiratory pump – Pressure changes occuring during inhalation and exhalation