Circulation

The circulatory system acts as a transportation network for our cells and tissues It supplies nutrients and removes wastes It is 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)