cardiovascular system Flashcards
functions of cv system
distribution of oxygen and thermoregulation
3 tunics (coats) or circulatory vessels
tunica intima, tunica media, tunica adventitia
tunica intima
thin endothelial lining
tunica media
middle smooth muscle layer
tunica adventitia
outer connective tissue coat
arteries
carry blood away from heart and distribute it to body
3 types of arteries
large elastic, medium muscular, small arteries & arterioles
large elastic
many elastic layers allow expansion when heart contracts
medium muscular
ability to vasoconstrict regulates body flow to different parts of the body as required
small arteries & arterioles
narrow lumina and thick muscular walls
veins
return poorly oxygenated blood to heart from capillary beds, thinner walls than arteries
small veins & venules
form plexuses
medium veins in limbs
valves permit blood flow toward the heart (musculovenous pump)
large veins
wide bundles of longitudinal smooth muscle and a well-developed tunica adventitia
2 mechanisms of veins
- skeletal muscle pump 2. venous valves (both of these assist veins in preventing back flow of blood, but do not eliminate it)
capillary
any of the fine branching blood vessels that form a network between the arterioles and venules, allow exchange of oxygen, nutrients, and other cellular materials surrounding tissues
simple endothelial tubes (capillary)
connection between arterial & venous sides of circulation
capillaries arranged in networks
capillary beds between arterioles and venules
arteriovenous anastomoses (AV)
shunts permit blood to bypass the capillaries, numerous in the skin (conserve body heat)
2 types of capillaries
continuous, sinusoidal
continuous capillary
(most common type) formed of tight junctions, small molecules are forced to pass between capillaries at intercellular clefts between membranes
sinusoidal capillary
(rarer) wider, leaky capillaries that allow the transfer of molecules that are larger
sinusoidal capillary
(rarer) wider, leaky capillaries that allow the transfer of molecules that are larger
pulmonary circulation
carries deoxygenated blood from heart to the respiratory surfaces of lungs for oxygenation and back into heart for distribution to the body
systemic circulation
all systemic arteries arise from aorta. aorta is divided into 4 main parts- ascending aorta, aortic arch, descending thoracic aorta, abdominal aorta
ascending aorta
right and left coronary arteries (supply the heart)
aortic arch
arteries to head, neck, upper limbs
descending thoracic & abdominal aorta
arteries to thorax, abdomen, pelvis, lower limbs
deoxygenated blood is carried toward heart by 3 major veins
superior vena cava (SVC), inferior vena cava (IVC), coronary sinus
superior vena cava (SVC)
drains head and upper limbs
inferior vena cava (IVC)
drains thorax, abdomen, and lower limbs
coronary sinus
drains wall of heart
azygos venous system function & unpaired vessels
drains blood from thoracic wall and some thoracic viscera into the superior vena cava (SVC) ; 1. azygous vein 2. hemiazygous vein 3. accessory hemiazygous vein
hepatic portal venous system
relays digestive products from the stomach & intestines to the liver for processing, detoxification, and storage
veins that form hepatic portal venous system
superior mesenteric vein, splenic vein, inferior mesenteric vein
anastomoses
coming together of neighboring vessels
importance of anastomoses
help oxygenated blood to continue to flow to tissues if joint is flexed / extended, circumnavigate blockage in arteries
varicose veins
abnormally weak and dilated veins as a result of loss of wall elasticity
