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Circulation
The circulatory system acts as a transportation network for our cells and tissues
It supplies nutrients and removes wastes It is 96000 km long
Circulatory system
Blood vessels: arteries
Carry blood away form the heart to the tissues Thick artery walls withstand and maintain the
pressure generated by the heart Arteries branch into smaller arteries and eventually
become arterioles Arteriole walls are much thinner. Smooth muscle
allows them to increase/decrease in diameter depending on where blood is needed
When vessels are dilated, blood pressure is lowered
Blood vessels: capillaries
Connect arteries with veins in tissues Arterioles branch into smaller vessels called
capillaries Capillary walls are only one layer of endothelial
cells thick They are the site of diffusion into and out of the
blood Nutrients diffuse from blood to tissues Wastes diffuse from tissues to blood
Blood vessels: veins Carry blood from capillaries to the heart Once blood has traveled through capillaries it enters
venules As venules join together and get larger, they become
veins Veins are composed of three layers of tissue (like
arteries) but the middle layer is much thinner Veins can stretch easily to increase blood volume Many veins contain valves (such as in your legs and
arms) which prevent back flow Skeletal muscle contractions help move blood back
to the heart
Vascular pathways: pulmonary circuit
Carries blood to and from the lungs Composed of pulmonary arteries and pulmonary
veins
Vascular pathway: systemic circuit Carries blood to all the
bodies tissues Aorta Subclavian artery/veins
(arms) Carotid arteries (neck) Iliac artery/vein (hips) Femoral artery (leg) Coronary artery (heart)
• Jugular vein (neck)
• Mesenteric arteries and veins (intestine)
• Renal artery/vein (kidneys)
• Hepatic portal vein (small intestine to liver)
• Hepatic vein (liver to inferior vena cava)
Measuring pulse
• Radial (wrist)
• Cartodid (neck)
• Brachial (arm)
• Femoral (leg)