Chapter 21: Circulatory System Flashcards
Types of blood vessels
arteries, arterioles, capillaries, venules, veins
Arteries
carry blood away from the heart
Arterioles
smallest branches of arteries
Capillaries
smallest blood vessels, responsible for material exchange between blood and interstitial fluid
Venules
collect blood from capillaries
Veins
return blood to heart
Where are the largest blood vessels attached?
to the heart
Aorta
the largest, elastic artery sends blood from LV to the systemic circulation
Pulmonary Trunk
major vein that sends blood from the RV to the pulmonary circulation
Differences between arteries and veins
-arteries and veins run side to side
-arteries have thicker walls and higher pressures
-relaxed artery has small, round lumen
-vein typically has a large, flat lumen
-vein endothelium contracts (not so for arteries)
-arteries are more elastic
-veins have valves but arteries do not
Smooth muscle tissue structure
long, slender, and spindle-shaped with central nucleus
-no T-tubules, myofibrils or sarcomeres
-scattered myosin fibers
-thin filaments attached to dense bodies, which transmit contractions from cell to cell
Smooth muscle control of contractions
-multiunit smooth muscle cells innervated by motor neurons
-visceral smooth muscle cells are not connected to motor neurons
-rhythmic cycles of activity controlled by pacesetter cells
Characteristics of capillary beds
aka capillary plexus
-connect one arteriole to one venule
-precapillary sphincters are found and guard entrances to each capillary; opens and closes, causing blood to flow in pulses
Thoroughfare channels (metarterioles)
direct connections between arterioles and venules controlled by smooth muscle segments
Collaterals
multiple arteries supplying one capillary bed
Arterial anastomoses
the fusion of 2 collateral arteries
Arteriovenous anastomoses
bypass capillary bed
Arteriovenous anastomoses
bypass capillary bed
Blood Colloid Osmotic Pressure (BCOP)
reabsorption at the capillary bed
-equal pressure required to prevent osmosis
-caused by blood proteins too large to cross capillary wall
Capillary Hydrostatic Pressure
out of capillary
Arteries carrying deoxygenated blood
-Pulmonary trunk; receives blood from RV
-Pulmonary arteries; deliver blood to the lungs
-Pulmonary arterioles; branch to capillary networks surrounding alveoli
Veins carrying oxygenate blood
-Venules join alveolar capillary networks
-Pulmonary veins arise from the joining of venules
Ascending Aorta
leaves the base of the heart and branches into aortic arch
Coronary arteries
branch from aortic sinuses to supply blood to the myocardium
