blood from the heart gets around the body through blood vessels There are 3 types of blood vessels a. ARTERY b. VEIN c. CAPILLARY

Elastic layer Elastic layer Thin smooth muscle Thick smooth muscle

Arteries carry blood away from the heart. The ARTERY Arteries carry blood away from the heart. the elastic fibres allow the artery to stretch under pressure thick muscle and elastic fibres the thick muscle can contract to push the blood along.

Copyright Pearson Prentice Hall Blood Vessels In the circulatory system, there are three types of blood vessels—arteries, capillaries, and veins. The walls of these vessels contain connective tissue, smooth muscle, and endothelium. Copyright Pearson Prentice Hall

Aorta Transport oxygenated blood from left ventricle to rest of body Forms the characteristic aortic arch Largest artery of the body

Pulmonary arteries Brings deoxygenated blood from right ventricle to lungs to uptake oxygen The ONLY arteries that transport deoxygenated blood 2 pulmonary arteries – one to each lung

The CAPILLARY Capillaries link Arteries with Veins they exchange materials between the blood and other body cells. the wall of a capillary is only one cell thick The exchange of materials between the blood and the body can only occur through capillaries.

Copyright Pearson Prentice Hall Blood Vessels In the circulatory system, there are three types of blood vessels—arteries, capillaries, and veins. The walls of these vessels contain connective tissue, smooth muscle, and endothelium. Copyright Pearson Prentice Hall

The CAPILLARY A collection of capillaries is known as a capillary bed. artery vein capillaries body cell

Veins carry blood towards from the heart. The VEIN Veins carry blood towards from the heart. veins have valves which act to stop the blood from going in the wrong direction. thin muscle and elastic fibres body muscles surround the veins so that when they contract to move the body, they also squeeze the veins and push the blood along the vessel.

Copyright Pearson Prentice Hall Blood Vessels In the circulatory system, there are three types of blood vessels—arteries, capillaries, and veins. The walls of these vessels contain connective tissue, smooth muscle, and endothelium. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Blood Vessels Valve open Large veins contain valves that keep blood moving toward the heart. Many veins are located near and between skeletal muscles. Valve closed Valves closed Contraction of skeletal muscles helps move blood in veins toward the heart.  Copyright Pearson Prentice Hall

Superior Vena Cava Brings deoxygenated blood from head and arms to right atrium of heart

Inferior Vena Cava Brings blood from bottom part of body into right atrium of heart

Pulmonary Vein Transports oxygenated blood from the lungs back to the left atrium of heart The ONLY vein that carries oxygenated blood 2 pulmonary veins – one from each lung

Hydrostatic & Osmotic Pressures The high hydrostatic pressure on the arterial side squeezes water and nutrients out of the capillaries. Water leaving the capillaries builds up the osmotic pressure because the blood components have become more concentrated. Towards the venal end, water and waste materials are sucked into capillaries by the osmotic pressure.

Arteries and Arterioles Veins and Venules Capillaries Arteries and Arterioles                                                                                                                                                                                   Function is to carry blood from tissues to the heart Function is to allow exchange of materials between the blood and the tissues Function is to carry blood from the heart to the tissues Thin walls, mainly collagen, since blood at low pressure Very thin, permeable walls, only one cell thick to allow exchange of materials Thick walls with smooth elastic layers to resist high pressure and muscle layer to aid pumping Function : Carry blood towards from heart Function : Carry blood away from heart

Arteries and Arterioles Veins and Venules Capillaries Arteries and Arterioles Large lumen to reduce resistance to flow. Very small lumen. Blood cells must distort to pass through. Small lumen Many valves to prevent back-flow No valves No valves (except in heart) Blood at low pressure Blood pressure falls in capillaries. Blood at high pressure Blood usually deoxygenated (except in pulmonary vein) Blood changes from oxygenated to deoxygenated (except in lungs) Blood usually oxygenated (except in pulmonary artery)

Valves Textbook pg 130 Found in the heart and veins Folds of the inner walls of heart and veins Shaped like half moons, so called semilunar valves Function: Prevent backflow of blood. Textbook pg 130 NEXT

Unidirectional flow of blood BACK

Vericose Veins When the valves in the veins near the surface of the skin fail to close properly Allow blood to accumulate in the veins Causes vein to bulge (swollen appearance) NEXT

Valves fail to close properly BACK