Gross Anatomy L3 Circulatory System

pulmonary system

system where poorly oxygenated blood pumped from R ventricle to lungs via pulmonary aa for gas exchange and returning oxygenated blood to L atrium via pulmonary vv

systemic circulation

well oxygenated blood pumped from ventricle to the rest of the body

lymphatic system

system where transportation of extracellular fluid, plasma proteins, cellular debris, and infectious agents occur

veins

vessel that transports blood to the heart

arteries

vessel that carries blood away from the heart

capillaries

vessel that is the site of gas exchange

tunica intima

thin endothelial lining the lumen of vessels

tunica media

middle layer of smooth muscle in vessels

tunica adventitia

outer connective coat of vessels

endocardium

inner/deep layer of endothelium and subendothelial tissue of the heart

myocardium

middle layer, cardiac muscle of the heart

epicardium

outer/most superficial layer, includes visceral serous pericardium

large elastic arteries

receive blood from the heart and include aorta, pulmo trunk, and various branches (brachiocephalic trunk, common carotid arteries, subclavian arteries, common iliac artery), large amounts of elastic tissue in tunica media allow vessels to expand/contract with cardiac output and maintain blood pressure

medium muscular (distributing) arteries

generally smaller than elastic arteries with well developed walls containing smooth muscle, muscle facilitates vasoconstriction (brachial arteries, radial arteries, ulnar)

vasoconstriction

autonomic system increases blood pressure by squeezing smooth muscle walls (medium muscular arteries)

vasodilation

autonomic system decreases blood pressure by relaxing smooth muscle walls (medium muscular arteries)

small arteries

vessels that have relatively small lumen and thick muscular walls, typically not named

arterioles

vessels with smallest lumen and thick walls and distribute blood to capillaries

anastomosis

communications btwn blood vessels that provides alternate routes for blood to flow (collateral circulation). commonly found around joints, in the abdominal cavity, other areas where movement can/often restricts vasculature

terminal, end arteries

lack anastomoses thus the only supply to target issue (retinal artery)

veins

vessel that transports blood at BP, thinner walls thicker lumen, typically have valves to prevent retrograde flow

musculovenous pump

as blood in the venous system is under low pressure and often going against gravity, it requires external forces such as muscle contractions to push it to the heart

venules

small unnamed vessels that drain capillaries, often form plexus (connecting networks)

medium veins

vessels that drain venous plexuses and typically have same name as aa they accompany. types include superficial and deep/accompanying

superficial veins

medium veins located in subcutaneous tissue, generally highly variable, communicate with deep vv via valved perforating branches

deep accompanying veins

depicted as one in texts when it may have multiple branches of same vein, consist of multiple anastomosing channels that surround the similarly named artery which are both wrapped in a vascular sheath. expansion of the artery combined with the sheath helps propel venous return to the heart

large veins

drain medium veins and typically consist of a single large vessel accompanying an artery with the same name

varicose veins

occur when walls lose elasticity or investing fascia becomes incompetent thus inhibiting musculovenous pump. blood pools due to gravity - dilating vessels result in valve incompetency and/or destruction

capillaries

vessels that are site of gas and nutrient exchange, arranged in networks connecting arterioles to venules, only tunica intima

arteriovenous anastamoses

connections btwn arterioles and venules proximal to capillary bed providing shunt for ateriole flow direct to venous system. numerous in skin leads to thermoregulation

portal venous system

system where blood flows through two sets of capillaries before returning (ie hepatic)