Blood vessels Flashcards
Describe the function of an artery
Transports blood away from the heart
How is the artery wall adapted for its function?
Thick wall to withstand the high pressure of blood. Prevents the loss of blood from the vessel.
Contains elastic tissue to stretch as a pulse of blood travels through.
Contains muscle tissue which contracts to return wall to original (recoil).
Describe the function of a vein
Transports blood from the tissues to the heart
How is the vein wall adapted for its function?
Thin walls containing a little elastic and muscular tissue. Blood not travelling under high pressure so does not need a thick wall.
Contains valves to present the back flow of blood
What is the function of a capillary?
Formation of tissue fluid.
Deliver products of digestion and oxygen to the tissues.
Remove urea and carbon dioxide from the tissues
How is the capillary wall adapted for its function?
Walls are one cell thick - to provide a short diffusion distance
Walls are leaky to allow the formation of tissue fluid
What is tissue fluid?
Watery substance released by the capillaries.
Contains products of digestion (glucose, amino acids etc) and oxygen. It supplies the cells with the nutrients they need and removes waste materials (eg carbon dioxide)
How is tissue fluid formed?
Contraction of the left ventricle produces high hydrostatic pressure at arteriole end of capillary bed. Fluid is forced out of the thin wall of the capillary
How is tissue fluid removed from the tissues?
Blood plasma has a low water potential at the venuole end of the capillary bed due to the loss of water in making tissue .
Water moved by osmosis from the tissue fluid back into the blood through the capillary wall.
Lymphatic system also drains tissue fluid
