Blood vessels 2
Redundant supply and drainage to tissues and organs
Anastomoses between adjacent arteries or veins reduce impact of occlusion (blockage) of single blood vessel
venoconstriction
Body maintains blood volume in arterial system even in case of hemorrhage by reducing volume of blood in venous system Controlled by vasomotor center in medulla oblongata Sympathetic nerves stimulate smooth muscles in medium-sized veins -a decrease in peripheral vein diameter is called
Capillary beds
Contain several connections between arterioles and venules Initial part of connection passageway, metarteriole, has smooth muscle that can contract to change vessel diameter Flow within each capillary variable, adjusted by precapillary sphincters
Pulmonary veins
Deliver oxygen rich blood from the lungs to the left atrium; two right and two left
Valves
Flap of tissue in the heart and large veins that prevents blood from flowing backwards. Contraction of skeletal muscle squeezes blood toward heart Valves permit blood flow in one direction and prevent backflow of blood toward capillaries
Varicose veins
Impaired venous return results in increased capillary pressure causing edema, and superficial, darkened, raised, tortuous veins. The greater saphenous vein is most commonly effected.
Right and left symmetry
Peripheral distribution of arteries and veins on body's right and left sides generally identical Exception in largest vessels near the heart
One vessel but many names
Single vessel changes names as crosses anatomical boundaries, allowing for accurate anatomical descriptions Example: external iliac artery becomes femoral artery
hemorrhoids
Swollen, painful rectal veins; often a result of constipation
Alveolar capillaries
Terminal air sacs called alveoli that are surrounded by a network of capillaries for gas exchange; where gas exchange occurs
Pulmonary circuit
The pulmonary circuit, which is relatively short, carries deoxygenated blood from the right ventricle to the lungs and returns oxygenated blood to the left atrium
Venous system
The venous system has low pressures and contains almost two-thirds of the body's blood volume (64%)
Pulmonary trunk
large artery coming out of right ventricle that branches into: Right and left pulmonary arteries