Blood Vessels Arteries Veins Capillaries Three Types of

Blood Vessels Arteries, Veins, Capillaries

Three Types of Blood Vessels - An elastic tubular channel that circulates blood through tissues and organs. – Arteries – Capillaries – Veins http: //www. youtube. com/watch? v=Cj. NKb. L_-cw. A

Arteries n n n Carries blood away from the heart Thick layers of smooth muscle Elastic walls High pressure The blood in arteries is bright red in color because it contains oxygen.

Arteries Continued n n Usually transports oxygenated blood from the heart to the body (systemic circuit) Pulmonary circuit (pulmonary arteries) – transports deoxygenated blood from the heart to the lungs (*only arteries that carry oxygen-depleted blood) Arterioles – smallest arteries Aorta – largest artery (connects to the left ventricle of the heart)

Artery Structure An artery has three layers: 1) An outer layer of connective tissue (tunica externa) 2) A thick middle layer of smooth muscular and elastic fibers (tunica media) 3) An innermost layer of epithelial cells (endothelium or tunica intima – a smooth, thin sheet of tightly packed cells) n

Artery * Arteries have to be strong to withstand pressure from the beating heart. Elastic tissue and strong muscles allow them to expand constrict. The inner layer is very smooth so that the blood can flow easily with no obstacles in its path.

Capillaries § Connects arteries to veins § The smallest blood vessels, only one-celled thick (endothelial cells) §Capillaries remove nutrients (including oxygen) from the blood in the arteries, and distribute the nutrients to the organs throughout the body. §Capillaries remove cellular waste (including carbon dioxide) from the blood and distribute the waste into the blood in the veins, where it will be later removed. §Large surface area

Transported Materials

Veins n Carries blood to the heart n Thinner walls (smooth muscle) n Low pressure (less than 1/10 of the pressure in the aorta) n Usually transports deoxygenated blood n The pulmonary veins carry oxygenated blood from the lungs to the left atrium (*only veins which carry oxygen-rich blood)

Veins Continued n The blood in the veins is dark red in color because it contains very little oxygen n Many contain one-way valves, which prevent backflow of blood n The squeezing together of skeletal muscles and valves assist blood in returning to the heart n Venules - smallest vein

Vein Structure n Same three layers as arteries (tunica externa, tunica media, tunica intima). However, the muscles and elastic fibres are much thinner and contain less tissue than arteries. * The walls of veins are not as strong as the walls of the arteries because they farther away from the heart, meaning they are subject to less pressure from the heart.

Although veins are often depicted by blue colouring, the blood inside is a dark red. Arteries are depicted by red and the blood inside is a bright red colour due to the high oxygen levels. http: //www. youtube. com/watch? v=3 Fq 950 Q 9 Gs. Q

Artery vs. Vein

Artery vs. Vein • http: //www. youtube. com/watch? v=iq. RTd 1 NY-p. U&safe=active

Contrasting Arteries and Veins

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