The Lymphatic System Flashcards
Whats the lymphatic system?
The lymphatic system is a secondary circulatory system and a major part of the immune system. It consists of:
- lymphatic capillaries and lymph vessels
- lymph nodes
- lymphatic tissue
What are vein like lymph vessels and what do they do?
a network of tiny, thin-walled vessels called lymphatic capillaries. Lymphatic capillaries are designed to pick up the fluid that leaks into your tissues from your bloodstream and return it to your circulatory system.
What are lymph nodes?
sac-like organs that trap pathogens and foreign substances, which contain large numbers of white blood cells
Whats lymphatic tissue ?
Found in the spleen, thymus and tonsils – these contain large amounts of white blood cells and are involved in their development
What is lymph?
A colourless fluid containing white blood cells, which bathes the tissues and drains through the lymphatic system into the bloodstream.
It is formed when the fluid that is in the gaps of all cells drains into lymph capillaries
Where are lymph nodes found?
Lymph nodes are located throughout the body but the largest groupings are found in the neck, armpits, and groin areas.
Give some examples of lymph organs:
Thymus
Spleen
Tonsils
What is tissue fluid?
Tissue fluid is the liquid that surrounds the cells, allowing for transport between blood and cells (e.g. Respiratory gases) - DIFFUSION
Capillary walls are partially permeable
Tissue fluid is the result of an interplay of:
1. Hydrostatic pressure 2. Osmosis
Whats hydrostatic pressure?
As the capillaries are narrower than the arterioles, a pressure builds up
due to heart contractions which forces tissue fluid out of the blood plasma
How is hydrostatic pressure resisted?
Pressure of the tissue fluid on the capillaries (from the outside)
The lower water potential of the blood (caused by plasma proteins – too large to leave the blood)
How is tissue fluid formed?
1)Hydrostatic pressure
Hydrostatic pressure forces fluid out of the capillaries
Fluid moves out through tiny gaps in the capillary walls.
Dissolved gases and nutrients move with it but
Larger plasma proteins and cells do not
2)Osmosis
A net loss of water from the capillaries due to hydrostatic forces gives them a more negative water potential allowing osmosis to take place
Water moves down the water potential gradient into the capillaries
There is a net loss of fluid from the capillaries at the arterial end and a net gain at the venous.
Where is hydrostatic pressure at its highest?
Hydrostatic pressure is much higher at the arterial end of the capillaries than the venous end
This means that the net movement is different at either end of the capillary network.
What substances are found in tissue fluid?
glucose, amino acids, fatty acids, salts and oxygen = all delivered to the cells.
carbon dioxide and other waste substances = removed from the cells.
What does lymph do?
Note that not all fluid passes back into the capillaries.
The excess output needs to be collected to avoid tissue swelling
This net excess is drained into the vessels of the lymphatic system – this fluid is known as lymph
Lymph passes through the lymphatic system and drains back into the circulatory system
Lymph contains lymphocytes (type of white blood cell) which are made in lymph nodes.
Lymphocytes are part of the immune system and help to filter out foreign material from the lymph
How does blood pressure change in the capillary?
Blood pressure falls along the capillary because of
friction
resistance of the walls
and reduced volume of blood.
