(a) The carotid arteries supply the head. The neck and upper members
are supplied by the subclavian arteries.
(b) The aortic arch continues as a large single vessel known as the aorta
passing down through the trunk of the body in front of the vertebral column. It gives off
branches to the trunk wall and to the contents of the trunk.
(c) At the lower end of the trunk, the aorta divides into right and left iliac
arteries, supplying the pelvic region and lower members.
(3) Capillary beds of the body tissues. In the capillary beds of the tissues of
the body, materials (such as food, oxygen, and waste products) are exchanged
between the blood and the cells of the body.
(4) Venous tributaries. See figure 9-6 for an illustration of the main veins of
the human body.
(a) The blood from the capillaries among the tissues is collected by a
venous system parallel to the arteries. This system of deep veins returns the blood
back to the right atrium of the heart.
(b) In the subcutaneous layer, immediately beneath the skin, is a network
of superficial veins draining the skin areas. These superficial veins collect and then join
the deep veins in the axillae (armpits) and the inguinal region (groin).
(c) The superior vena cava collects the blood from the head, neck, and
upper members. The inferior vena cava collects the blood from the rest of the body. As
the final major veins, the venae cavae empty the returned blood into the right atrium of
(d) The veins are generally supplied with valves to assist in making the
blood flow toward the heart. It is of some interest to note that the veins from the head
do not contain valves.
(e) From that portion of the gut where materials are absorbed through
the walls into the capillaries, the blood receives a great variety of substances. While
most of these substances are useful, some may be harmful to the body. The blood
carrying these substances is carried directly to the liver by the hepatic portal venous
system. This blood is specially treated and conditioned in the liver before it is returned
to the general circulation by way of the hepatic veins.