KA5- Arteries, veins and capillaries Flashcards
What is the function of arteries?
To carry blood away from the heart at a high pressure.
State the structure of an artery.
Connective tissue is the outer layer and contains elastic fibre.
Arteries have a ticker middle layer contains smooth muscle with more elastic fibres.
Endothelium lines the central lumen, where the blood flows through.
What is the function of elastic fibres in arteries?
The elastic walls of the arteries stretch and recoil to accommodate the surge of blood that enters them after each contraction of the heart.
What is vasoconstriction?
The smooth muscle can contract causing vasoconstriction and decrease in blood flow to capillaries.
What is the function of the veins?
To carry blood towards the heart at low pressure.
State the structure of the veins.
Connective tissue containing elastic fibres.
Thin muscular wall
Endothelium lines the lumen where the blood flows through.
Contain valves which prevent the back flow of blood.
What is the function of the capillaries?
Capillaries allow exchange of substances with tissues through their thin walls (one cell thick). Capillaries are the narrowest blood vessel that allows substances such glucose, amino acids to pass to cells and also waste substances such carbon dioxide can pass back into the blood for removal.
What is pressure filtration?
As blood is forced into the narrow capillaries it goes pressure filtration. Pressure filtration causes plasma to pass through capillary walls into the tissue fluid surrounding the cell.
How does exchange of materials occur between tissue fluid and cells?
Tissue fluid supplies cells with glucose, oxygen and other substances by diffusion out carbon dioxide and other waste products diffuse out of the cells and into the tissue cells to be excreted.
What happens to the tissue fluid?
Much of the tissue returns to the blood into capillaries by osmosis.
What is a lymph?
The tissue that does not return to the blood is referred to as lymph.
