Blood Vessels: The Vascular System. Transport blood to the tissues and back Carry blood away from the heart Arteries Arterioles Exchanges between tissues and blood Capillary beds Return blood toward the heart Venules Veins. Blood Vessels: The Vascular System. Figure 11.9a.
Capillary walls are essentially just the tunica intima (endothelium plus the basement membrane); thus, they are exceedingly thin.
Arteries are much closer to the pumping action of the heart and must be able to withstand the pressure fluctuations at such locations. Veins, on the distal side of the capillary beds of the tissues, are essentially low-pressure vessels that need less strength/support/ elasticity than do arteries.
The presence of valves, the milking action of skeletal muscles against the veins as the muscles contract, the respiratory pump (pressure changes in the thorax during breathing)
The thoracic pump draws blood from the extremities on inhalation and sends blood throughout the body on exhalationpulmonary capillary bed
Pulmonary arteries carry oxygen-poor blood and pulmonary veins carry oxygen-rich blood.
Left ventricle to ascending aorta aortic arch brachiocephalic artery subclavian artery axillary artery brachial artery radial (or ulnar) artery
Left ventricle ascending aorta aortic arch descending aorta right common iliac artery external iliac artery femoral artery poplitealartery anterior tibial artery dorsalispedis artery