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Structure & Function of Blood Vessels - Coggle Diagram
Structure & Function of Blood Vessels
Blood is transported in arteries, veins and capillaries
Blood is pumped away from the heart in the arteries and returned to the heart in the veins
Capillaries connect the blood vessels and molecules are exchanged between the blood and the cells across their walls
Arteries
Carries blood away from the heart
carries oxygenated blood except form the pulmonary artery
Carries blood under high pressure
Thick muscular and elastic walls to pump and accommodate blood
Lumen is narrow
Supported by connective tissue which provides strength
In order to control blood flow the muscles surrounding the arteries constrict causing vasconstriction and relax causing vasolidation
Veins
Carries blood to the heart
Carries deoxygenated blood, except in the pulmonary vein
Carries blood in low pressure
Have thin walls with less muscular tissue than arteries
Less connective tissue than arteries
Wide lumen
Veins contains valves which prevent the backflow of blood, ensuring blood travels in one direction only
Capillaries
Capillaries connect the smallest branches of arteries and veins
The walls are one-cell thick
Allow the exchange of molecules between the blood and cells - molecules can diffuse across their wall
Exchange of molecules:
Oxygen diffuses into cells and tissue fluid
CO2 diffuses out of cells through tissue fluid and into blood plasma
Glusose diffuses out of blood plasma through tissue fluid and into cells
Waste products diffuse from cells of the liver, to the tissue fluid, and across walls into blood plasma
As blood travels at a high pressure, pressure filtration occurs which results in plasma passing through walls into tissue fluid
Tissue fluid provides cells with useful substances (glucose and oxygen) and waste products are passed out of cells into tissue fluid to be removed
Most tissue fluid returns to the blood, any excess fluid is absorbed by the lymphatic system which is returned to the circulatory system as a lymph
Plasma proteins are found in plasma but not tissue fluid