Blood flows through the body through, veins, arteries and capillaries.
Arteries take oxygenated blood away from the heart to the tissue. Arteries have thick muscular and elastic walls, the reason for this is because they have to flow blood through at a high pressure. When the heart forces blood into the artery it slightly expands as the muscles and fibres are stretched. These fibres then contract pushing the blood towards the capillaries . When you press an artery against something solid, there is a slight expansion and contraction. This happens once every heartbeat, this is what is known as a pulse. As the arteries get nearer to the tissue they get narrower, these narrow arteries are known as arterioles.
Capillaries are one cell thick so gaseous exchange can take place. Lots of capillaries are called capillary beds. with the being one cell thick this speeds up the diffusion of substances e.g glucose and oxygen.
Capillaries are found at the ends of arterioles and they take the blood a tissue. When the blood enters the capillaries, the pressure of this forces some of the plasma through the capillary walls.
Veins have a large lumen, have a smooth lining and are only one cell thick, they also have a tough fibrous outer layer.
Before leaving the tissue the blood from the capillaries flows into a slightly larger vessel called venules, the venules join up to form veins.
Veins take deoxygenated blood from the tissue back to the heart. The walls of the vein contain muscle and elastic fibres but they are much thinner than the walls of arteries, as they do not have the ability to cope with as much pressure. The pressure within the veins is sometimes so low it cannot keep the blood moving. To ensure movement in one direction, veins contain one way valves called pocket valves.
CGP NOTES/HANDOUTS
www.healthmassagers.co.uk
www.openlearn/open.ac.uk
Pic ref: http://www.quantumtheatre.co.uk/
Arteries take oxygenated blood away from the heart to the tissue. Arteries have thick muscular and elastic walls, the reason for this is because they have to flow blood through at a high pressure. When the heart forces blood into the artery it slightly expands as the muscles and fibres are stretched. These fibres then contract pushing the blood towards the capillaries . When you press an artery against something solid, there is a slight expansion and contraction. This happens once every heartbeat, this is what is known as a pulse. As the arteries get nearer to the tissue they get narrower, these narrow arteries are known as arterioles.
Capillaries are one cell thick so gaseous exchange can take place. Lots of capillaries are called capillary beds. with the being one cell thick this speeds up the diffusion of substances e.g glucose and oxygen.
Capillaries are found at the ends of arterioles and they take the blood a tissue. When the blood enters the capillaries, the pressure of this forces some of the plasma through the capillary walls.
Veins have a large lumen, have a smooth lining and are only one cell thick, they also have a tough fibrous outer layer.
Before leaving the tissue the blood from the capillaries flows into a slightly larger vessel called venules, the venules join up to form veins.
Veins take deoxygenated blood from the tissue back to the heart. The walls of the vein contain muscle and elastic fibres but they are much thinner than the walls of arteries, as they do not have the ability to cope with as much pressure. The pressure within the veins is sometimes so low it cannot keep the blood moving. To ensure movement in one direction, veins contain one way valves called pocket valves.
CGP NOTES/HANDOUTS
www.healthmassagers.co.uk
www.openlearn/open.ac.uk
Pic ref: http://www.quantumtheatre.co.uk/
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