Key Terms
abdominal aorta
portion of the aorta inferior to the aortic hiatus and superior to the common iliac arteries
adrenal artery
branch of the abdominal aorta; supplies blood to the adrenal (suprarenal) glands
adrenal vein
drains the adrenal or suprarenal glands that are immediately superior to the kidneys; the right adrenal vein enters the inferior vena cava directly and the left adrenal vein enters the left renal vein
anaphylactic shock
type of shock that follows a severe allergic reaction and results from massive vasodilation
angioblasts
stem cells that give rise to blood vessels
angiogenesis
development of new blood vessels from existing vessels
anterior cerebral artery
arises from the internal carotid artery; supplies the frontal lobe of the cerebrum
anterior communicating artery
anastomosis of the right and left internal carotid arteries; supplies blood to the brain
anterior tibial artery
branches from the popliteal artery; supplies blood to the anterior tibial region; becomes the dorsalis pedis artery
anterior tibial vein
forms from the dorsal venous arch; drains the area near the tibialis anterior muscle and leads to the popliteal vein
aorta
largest artery in the body, originating from the left ventricle and descending to the abdominal region where it bifurcates into the common iliac arteries at the level of the fourth lumbar vertebra; arteries originating from the aorta distribute blood to virtually all tissues of the body
aortic arch
arc that connects the ascending aorta to the descending aorta; ends at the intervertebral disk between the fourth and fifth thoracic vertebrae
aortic hiatus
opening in the diaphragm that allows passage of the thoracic aorta into the abdominal region where it becomes the abdominal aorta
aortic sinuses
small pockets in the ascending aorta near the aortic valve that are the locations of the baroreceptors (stretch receptors) and chemoreceptors that trigger a reflex that aids in the regulation of vascular homeostasis
arterial circle
(also, circle of Willis) anastomosis located at the base of the brain that ensures continual blood supply; formed from branches of the internal carotid and vertebral arteries; supplies blood to the brain
arteriole
(also, resistance vessel) very small artery that leads to a capillary
arteriovenous anastomosis
short vessel connecting an arteriole directly to a venule and bypassing the capillary beds
artery
blood vessel that conducts blood away from the heart; may be a conducting or distributing vessel
ascending aorta
initial portion of the aorta, rising from the left ventricle for a distance of approximately 5 cm
atrial reflex
mechanism for maintaining vascular homeostasis involving atrial baroreceptors: if blood is returning to the right atrium more rapidly than it is being ejected from the left ventricle, the atrial receptors will stimulate the cardiovascular centers to increase sympathetic firing and increase cardiac output until the situation is reversed; the opposite is also