Lympatic System Flashcards
What is the lymphatic system?
A large network of lymphatic vessels that carry a clear fluid called lymph directly towards the heart
How is excess fluid drained from the tissues?
lympatic capillaries
Name the components of the lymphatic system
- lymph and lymphatic vessels
- lymph nodes
- lymph organs
- diffuse lymphoid tissues
- red bone marrow
Give examples of lymph organs
Spleen
Thymus
Give examples of lymphoid tissue
Tonsils
Adenoids
What are the 3 functions of the lymphatic system?
tissue drainage
immunity
absorption
Explain the function of ‘tissue drainage’
Drainage of interstitial fluid. The fluid that cells are bathed in, originating in the plasma
Explain the function of ‘immunity’
Production, maturation and activation of lymphocytes (type of white blood cell)
Explain the function of ‘absorption’
absorption of fats from small intestines
Describe ‘lymph’
clear, watery fluid, similar in composition to the plasma but without plasma proteins
Where are lymphocytes found and what do they do?
Both the blood and lymph contain lymphocytes. The white blood cells responsible for adaptive immunity
Where is lymph derived from?
Interstitial fluid and they are identical in composition
Explain how lymph is derived from interstitial fluid
within the tissues, there is an exchange of water (fluid) and solutes between the plasma and the interstitial fluid compartment.
An excess tissue fluid is drained by lymphatic capillaries.
Fluid within the lymphatic vessels is termed lymph
What is ‘lymph’?
fluid within the lymphatic vessels
When lymph is derived from interstitial fluid, should plasma proteins enter the interstitial fluid, what happens?
the plasma proteins will enter the lymphatic capillaries and be returned to the blood circulation
How are plasma proteins found in interstitial fluid returned to the blood?
FILTRATION of water into the tissue fluid from the blood.
Tissue fluid formed from drainage out of the blood, carried to the lymphatic capillaries and a proportion drained back through to blood flow through osmosis
Define ‘osmosis’
Osmosis is the movement of water or other solvent through a plasma membrane from a region of low concentration to high concentration
What happens to the lymphatic tumour?
bacteria and cell debris will be drained into the lymphatic tumour located within the tissues
Explain how the lymphatic system and circulatory system are strongly connected
the two systems run alongside each other, often as a parallel set of vessels. Nearly all organs have a blood supply, so nearly all organs have a lymphatic drainage
How are veins and lymphatic vessels described to be similar?
Lymphatic vessels are used for the drainage of lymph, just as veins are for the drainage of blood
Lymph flows along lymphatic vessels and through…
..a series of lymph nodes
How does lymph move?
largely through the squeezing action of adjacent muscles
What keeps lymph flowing in the right direction?
valves
Describe lymph nodes
bean-shaped organs, lie often in groups along the lymph vessels,c containing a meshwork of fibres
Before returning to the venous circulation, how many lymph node does lymph usually pass through?
8-10 nodes
What doe lymph nodes contain?
Millions of immune cells, particularly lymphocytes, dendritic cells and macrophages
Lymph nodes can be described as filtering devices, why?
They filter matter such as, bacteria, cell debris, tumour cells
How do lymph nodes filter matter?
engulf and break them down using macrophages
What cells multiply in lymph nodes?
T and B cells
T = thymus cells
B = bone marrow derived
Both are types of lymphocytes
What is ‘the spleen’ and where is it located?
essentially a very large lymph node, situated at the back, behind the stomach
What does the spleen do?
breaks down the old red blood cells
can store blood
What’s the importance of the spleen in pregnancy?
It is the site of red blood cell production in the foetus (as apposed to bone marrow in the adult)
Where does maturation thymus lymphocytes occur?
The thymus gland
What do bone marrow cells (B Cells) do?
Produce antibodies which can circulate around the body
During maturation of thymus lymphocytes, what is removed?
Thymus cells (T cells) that recognise ‘self’ antigens
What are ‘self’ antigens?
are (usually) proteins from our own tissues against which we could potentially mount an immune response
What does MALT stand for?
Mucosa-associated lymphoid tissue
What is the MALT?
A diffuse system of small concentrations of lymphoid tissue found in various submucosal membrane sites of the body such as; GI tract, oral passage, thyroid, breast, eyes and skin
What is MALT populated by?
lymphocytes such as T and B cells, as well as plasma cells and macrophages, each of which is situated to encounter antigens passing through the mucosal epithelium
What is lymphoid tissue?
isolated patches all round the body where they may be a site of infection
What is mucous?
lining of the gut
Give an example of MALT
The tonsils - patches of lymphoid tissue containing T and B cells
The lymphatic system is a closed system. True or False?
False.
It is an open system. Continuous fluid and drainage action from the lymph
