Lymphatic System Flashcards
What does the lymphatic system consist of? (4)
Lymph
Lymphatic vessels
Lymphatic tissue
Red bone marrow
What are the functions of the lymphatic system? (3)
- Drainage of interstitial fluid
- Transporting dietary lipids and lipid soluble vitamins (A, D, E and K)
- Facilitation of the immune response
What is lymph fluid?
Lymph is a clear-to-white fluid made of: White blood cells, especially lymphocytes, the cells that attack bacteria in the blood.
What is hydrostatic pressure?
Hydrostatic pressure is the pushing force exerted by a fluid (~30-10 mmHg between the arterial end & venous end, respectively).
What is interstitial fluid pressure
Interstitial fluid pressure is proposed to be slightly negative -3 mmHg, which contributes to the outward pull of fluid from the capillaries.
What is colloidal osmotic pressure
Colloidal osmotic pressure is the pulling force created by blood proteins that are too large to pass through the pores of the membrane (~28 mmHg in the capillaries).
What is interstitial osmotic pressure
Interstitial osmotic pressure is ~8mmHg; created by small number of plasma proteins that have leaked into the extracellular tissue space.
How is lymph formed?
Lymph is formed from fluid that seeps through the thin walls of capillaries into the body’s tissues. This fluid contains oxygen, proteins, and other nutrients that nourish the tissues. Some of this fluid reenters the capillaries and some of it enters the lymphatic vessels (becoming lymph).
Describe the formation of lymph (interstitial fluid)
including pressure
- Blood hydrostatic pressure pushes blood plasma out of the blood capillaries to bathe the surrounding tissues
- The blood plasma is now known as 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
- However not all the interstitial fluid returns
- This fluid needs to be drained or else swelling will occur.
Where does drainage occur?
Drainage occurs via the lymphatic capillaries and lymph vessels
Describe the formation of lymph in lymphatic capillaries
- 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
How is lymph drained / how do lymph vessels work?
- Lymph capillaries join together to form lymph vessels
- Lymph vessels are similar to veins and have certain internal structures to ensure the one way flow of lymph…
- Lymph vessels drain into one of two ducts which return lymph to the blood
What does the right lymphatic duct do? (2)
- The right lymphatic duct drains the upper right side of the body and right arm
- The right lymphatic duct returns lymph to the right subclavian vein
What does the left thoracic duct do?
- The left thoracic duct drains the rest of the body
2. The left thoracic duct begins with the cisterna chyli and returns lymph to the left subclavian vein
What is the relationship between the lymphatic system and cardiovascular system?
- Plasma form interstitial fluid
- Interstitial fluid is returned to the plasma
- Fluid that is not returned to the plasma enters the lymph capillary to form lymph
- Lymph is returned to the cardiovascular system
What is oedema?
Palpable swelling produced by an increase in interstitial fluid volume
Evident once interstitial fluid volume increases to 2.5 – 3 L
What factors influence oedema?
- Increased capillary filtration pressure
- Decreased capillary colloidal osmotic pressure
- Increased capillary permeability
- Obstruction to lymph flow
which leads to Lymphoedema
List five lymph nodes
- tonsils
- Thymus
- Spleen
- Peyer’s patches (in intestine)
- Appendix
What do lymph nodes do and where are they found?
Lymph nodes filter lymph
Lymph nodes are found along the lymph vessels
Describe the afferent and efferent journey of lymph
Lymph nodes are bean shaped structures that receive lymph from afferent (going towards) vessels.
Lymph is then drained by efferent (going away from) vessels.
What surrounds lymph nodes?
A connective tissue capsule
What do Trabeculae in the lymph node?
- Trabeculae project inward from the capsule to form compartments
- Each compartment or lobule is made up of a framework cells of reticular cells
What do reticular cells do in the lymph node?
Reticular cells phagocytise unwanted substances
What are between the reticular cells?
lymphocytes
What do lymphocytes do in lymph nodes?
Lymphocytes produce antibodies
What are Peyer’s Patches?
Small masses of lymphatic tissue found throughout the ileum region of the small intestine.
Nodules are also found in the mucosa of other tubular structures in the respiratory, urinary and reproductive systems
What is Malt - Mucosa Associated Lymphoid Tissue
initiates immune responses to specific antigens encountered along all mucosal surfaces. MALT inductive sites are secondary immune tissues where antigen sampling occurs and immune responses are initiated.
Tonsils filter air what are the five kinds?
Five tonsils: 2 x Palatine (either side of the oral cavity) 2 x Lingual (at the base of the tongue) 1 x Pharyngeal or Adenoid (on the posterior wall of the nasopharynx)
Where is the thymus gland?
Found in the mediastinum above the heart
What surrounds the thymus gland?
connective tissue capsule with inward projecting trabeculae
What is the function of the thymus gland?
Function is to produce Thymic factor
Thymic factor is important in setting up the immune system and the formation of T Lymphocytes (T cells)
When is the immune system (thymus gland) at it’s most active?
- When it is being established
during childhood
As a result, the thymus is at it’s largest in childhood
After childhood the thymus decreases in size
This is known as ‘age involution’
Where is the spleen?
left side of abdominal cavity below the diaphragm
What is the spleen comprised of?
- Reticular cells
- Red pulp
- White pulp
What are reticular cells?
lymphatic tissue
What is the function of red pulp in spleen?
It removes worn out platelets and red blood cells, stores platelets and produces red blood cells in the foetus
What is the function of white pulp in the spleen?
carries out immune function and removes blood borne pathogens
What is the function of the spleen?
The spleen filters blood!