Lymphatic System Flashcards
How many litres of lymph is collected every day?
3L. 20 litres leaves at the arteriole end and 17L returns at to the venous end.
What are the key components of the lymphatic system?
Lymph vessels Lymph fluid Tissues Organs Cells - lymphocytes (B + T cells, NK cells)
Where do lymph vessels tend to lie?
Adjacent to arteries and veins
In the limbs, deep lymphatics passes through muscles. What is the significance of this?
Skeletal muscle contraction aids lymph flow
What do larger lymphatics content in their vessel walls?
Smooth muscle, contraction of this is important to lymph flow
Where is there no lymphatics?
CNS
What 3 key things aid the flow of lymph?
- Pressure changes in the thorax
- Skeletal muscle contraction
- Pulsation of adjacent arteries
What could be the possible causes of lympoedema?
Patient may be born without enough lymphatics, or lymphatics not functioning properly.
Name examples of diffuse lymphatic tissues.
GALT - gastric associated
BALT - bronchus associated
MALT - mucosal associated
Name 3 lymph organs.
Thymus
Spleen
Lymph nodes
What is the function of lymph nodes?
Serves as a filter as lymph makes its way towards the vascular system.
Outline the structure of a lymph node?
Outer capsule
Afferent vessels entering the cortex and efferent vessels leaving at the hilum.
The cortex contains germinal centres.
What type of cell is abundant in germinal centres?
Follicular dendritic cells - present antigens to activate B cells
Professional APC’s - macrophages, B cells
What is the different between an inflammatory response and an immune response?
Inflammatory response occurs first - neutrophils and macrophages.
Immune response may then be stimulated by antigen presentation.
Through which vessel do lymphocytes enter the lymph nodes?
The feeding artery
What is lymphadenopathy?
Enlarged lymph nodes
What could be a cause of lymphadenophathy?
Infection - as lymph nodes fight infection, germinal centres swell with increasing number of lymphocytes.
Lymphoma often presents as this
What is the function of the spleen?
Filters blood in the same way that lymph nodes do.
Immune function - APC and antigen presentation
Additional haemoatopoetic function - removal and destruction of aged erythrocytes and platelets
Why can a ruptured spleen lead to death?
It has a very rich blood supply and is fragile, exsanguination.
What are the consequences of a splenectomy?
Increased risk of infection by incapsulated bacteria.
Increased risk of DVT - increased platelet?
Liver and bone marrow can take over role of erythrocyte removal.
What type of oedema is characterised by PITTING?
Oedema. (Not lympoedema)
During oedema, why is there increased swelling at the ankles?
Pressure is -10 at head and +90mm at feet. increased capillary hydrostatic pressure at feet.
What are causes of oedema?
Heart failure - increased back up of venous pressure
Liver failure - decreased albumin production
Kidney disease
What is the most common place to have oedema when lying down?
Sacrum of back
What are the major functions of complement?
- Opsonisation - c3b
- Inflammation - 5a
- Lysis - MAC complex destroys cells
What are the 2 main ways that phagocytes can destroy engulfed pathogens?
- Oxygen-dependent killing
2. Oxygen- independent killing
What is the pressure at the arteriole end of the capillaries and how does this impact fluid movement?
35mmHg.
Hydrostatic pressure > Oncotic pressure so fluid leaves the capillary at the arterial end.
What is the hydrostatic pressure at the venous end, what significance does this have?
15mmHg, Oncotic pressure> hydrostatic pressure so fluid returns to the venous end.
What is the capillary oncotic pressure?
25 mmHg
Give an example of a lymph node.
Tonsils - palatine, lingual, adenoid
