Lymphatic system Flashcards
What does the lymphatic system consist of?
- Lymph
- Lymphatic vessels
- Lymphatic tissue
- Red bone marrow
What are the functions of the lymphatic system?
- Drainage of interstitial fluid
- Transporting dietary lipids and lipid soluble vitamins (A, D, E and K)
Explain the formation of lymph
- Blood plasma leaks out of capillaries into the surrounding tissues due to hydrostatic pressure, forming interstitial fluid.
- The blood protein albumin is too large to leave the capillaries and creates an osmotic pressure inside the capillary
- The blood osmotic pressure pulls interstitial fluid back into the blood capillaries.
- Not all interstitial fluid returns, this fluid needs to be drained or else swelling will occur. Drainage occurs via the lymphatic capillaries and lymph vessels.
- Lymphatic capillaries are “blind ended”. Internally they have a lower pressure than the interstitial fluid
Fluid enters the lymph capillary via one way minivalves – once inside, it is known as Lymph.
Explain the drainage of lymph
- lymph capillaries join together to form lymph vessels. In the small intestine, lymph capillaries are known as lacteals.
- lacteals carry fat laden lymph known as chyle.
- the lacteals join together to form vessels.
- lymph vessels are similar to veins and have certain internal structures to ensure the one way flow of lymph
- lymph vessels then drain into one of two ducts called cisterns chyli, which return lymph to the blood
Explain the return of lymph to blood
- the right lymphatic duct drains the upper right side of the body and right arm
- the right lymphatic duct return lymph to the right subclavian drain
- the left thoracic duct drains the rest of the body
- the left thoracic duct begins with the cistern chill and returns lymph to the left subclavian vein
Lymph=
Lymph is colorless watery fluid flowing through your lymphatic system. It carries nutrients and proteins to your cells and tissues.
Oedema=
Swelling produced by an increase in interstitial fluid volume. Is closely linked with lymphatic system because the system plays a key role in maintaining fluid balance.
Oedema is evident once interstitial fluid volume increases to 2.5 - 3L.
Factors that influence oedema include:
1. Increased capillary filtration pressure
2. Decreased capillary permeability
3. Increased capillary permeability
4. Obstruction to lymph flow = lymphoedema
Lymphoedema
An imbalance in fluid dynamics across capillaries, leading to excessive fluid in tissues.
What are lymph nodes?
- found in lymph vessels
- surrounded by connective tissue capsule
- trabecular project inward from the capsule to form compartments, each made of a framework of reticular cells
- bean shaped structures that receive lymph from afferent (going towards) vessels
- the lymph is then drained by efferent (going away from) vessels. = lymph nodes filter lymph
Reticular cells=
- phagocytise unwanted substances
- between the cells are lymphocytes
- lymphocytes produce antibodies
The different reticular cells of lobule are: macrophages, lymphocytes, medullary sinus, reticular fibre
What are the different lymph nodes?
- tonsils (in pharyngeal region)
- thymus (in thorax)
- spleen (curves around left side of stomach)
- peyer’s patches (in intestine)
- appendix
Lymph nodules: Peyer’s patches=
are groupings of lymphoid follicles in the mucus membrane that lines your small intestine.
Collectively known as MALT:
- Mucosa
- Associated
- Lymphoid
- Tissue
Tonsils=
Surround the opening of respiratory digestive tracts. Tonsils filter air. There are 5 tonsils:
- 2x palatine (either side of oral cavity
- 2x lingual (at base of the tongue)
- 1x pharyngeal or adenoid (on posterior wall of the nasopharynx)
Thymus gland=
- Found in mediastinum of the heart
- Surrounded by a connective tissue capsule with inward projecting trabeculae
- Function to produce Thymic factor
- Thymic factor is important in setting up the immune system and the formation of T lymphocytes (T cells)
Spleen=
Located on the left side of abdominal cavity below the diaphragm. It filters blood.
Comprised of:
- Reticular cells (lymphatic tissue)
- Red pulp (removes worn out platelets and red blood cells, stores platelets and produces red blood cells in the foetus
- White pulp (carries out immune function and removes blood borne pathogens
