artery that carries blood out of the heart in the systemic circulatory system. All other systemic arteries arise from it.


smallest of all arteries, a resistance artery with a diameter range of 40–200 μm


any vessel that carries blood away from the heart

axillary artery

continuation of the subclavian artery extending through the axillary region and ending at the neck of the humerus

blood pressure

force that blood exerts against vessel walls


any of a vast network of tiny vessels that enable the exchange of nutrients and gases between tissues and blood

carotid artery

artery that carries blood to the neck and head regions

diastolic blood pressure

pressure that blood exerts on vessel walls during ventricular relaxation


accumulation of tissue fluid that occurs when the capillary filtration/reabsorption balance is disrupted, causing swelling

external iliac artery

artery that supplies blood to lower limbs

hydrostatic pressure

pressure exerted by a fluid due to gravity, including the force of blood against vessel walls

internal iliac artery

artery whose branches provide blood primarily to pelvic viscera (organs) and the pelvic wall

interstitial pressure

pressure exerted by interstitial fluids, those fluids in tissue spaces

oncotic pressure

difference between blood's high colloid osmotic pressure (COP), caused by proteins, and tissue COP. It opposes hydrostatic pressure, reabsorbing water into capillaries through osmosis.

peripheral resistance

resistance to blood flow that occurs in all vessels as blood moves from the heart. It is caused by friction of blood against vessel walls.

precapillary sphincter

smooth muscle sphincter at the opening of each capillary that controls whether the capillary is open or closed to arriving blood


device typically used to measure blood pressure, specifically systemic arterial blood pressure at the arm's brachial artery, which is at about the same height as the heart

subclavian arteries

arteries that provide blood to the head, neck, and upper limbs

systolic blood pressure

pressure that blood exerts against vessel walls during ventricular contraction

tunica externa

first or outermost layer of arterial and venous walls that serves as a vessel anchor

tunica intima

innermost layer of the walls of arteries and veins that contains the endothelium and comes into contact with blood in the lumen

tunica media

middle and typically thickest layer of arterial and venous walls. It consists in part of smooth muscle, which carries out vessels' vasodilation and vasoconstriction


decrease in vessel diameter produced by smooth muscle contraction. It decreases blood flow.


increase in vessel diameter resulting from smooth muscle relaxation


any vessel that collects blood and returns it back to the heart after it has been distributed by capillaries

venous return

flow of blood back from the body to the heart, accomplished by a combination of pressure, gravity, and contraction of skeletal muscles


smallest type of vein, 15–100 μm in diameter. It collects blood that has just passed through capillary beds.

vertebral artery

vessel originating from a subclavian artery, supplying blood to the brain stem, cerebellum, posterior of the brain, and upper spinal cord