Lymphoedema is a swelling in the legs which may be caused by a blockage in the lymphatic system. Suggest how a blockage in the lymphatic system could cause lymphoedema.
Excess tissue fluid cannot be (re)absorbed / builds up
What creates hydrostatic pressure?
Pumping of the heart
How does tissue fluid return to the blood stream?
Via capillaries and lymphatic system
The hydrostatic pressure of the blood at the arteriole end of the capillary helps to form tissue fluid. Explain how.
Hydrostatic pressure higher than osmotic “effect”; Forces / squeezes / pushes out / water / small molecules / ions / examples;
What is the role of the heart in the formation of tissue fluid?
Ventricle contraction produces high hydrostatic pressure
What is filtration cause by pressure called?
Ultrafiltration
The hydrostatic pressure falls from the arteriole end of the capillary to the venule end of the capillary. Explain why.
Loss of water / loss of fluid / friction (against capillary lining).
What does tissue fluid contains
Glucose, amino acids, fatty acids, ions, oxygen
Explain how fluid leaves the capillary at the arterial end.
hydrostatic pressure / blood pressure / arterial pressure; greater than osmotic effect which forces molecules / fluid out;
How does lymph re-enter the blood stream?
Veins near the heart
How is lymph moved around the lymphatic system
Contraction of body muscles / Hydrostatic pressure of tissue fluid
Which substances are not found in tissue fluid
Blood cells, proteins
High absorption of salt from the diet can result in a higher than normal concentration of salt in the blood plasma entering capillaries. This can lead to a build-up of tissue fluid.
1. (Higher salt) results in lower water potential of tissue fluid; 2. (So) less water returns to capillary by osmosis (at venule end);
Which location as the highest water potential at the arterial end of the capillary?
Tissue fluid
What is the purpose of tissue fluid
Allows exchange between blood and cells
Why do substances move out of the tissue fluid at the venous end of the capillary?
Pressure outside the capillary greater than tissue fluid
Why do substances move into tissue fluid at the arterial end of the capillary?
Pressure inside capillary greater than tissue fluid
Which location has the highest water potential at the venous end of the capillary?
Tissue fluid
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