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