Chapter 42: Circulation and Gas Exchange (897-922) Flashcards
What surfaces does fluid cover in gastrovascular cavities?
both inner and outer tissue layers: facilitates exchange of gases and cellular wastes
What kinds of organisms can survive without a circulatory system?
planarians, mother other flatworms
open circulatory system
circulatory fluid bathes the organs directly: arthropods and most molluscs
What is the circulatory fluid of open circulatory systems?
hemolymph: also interstitial fluid that bathes the body cells
closed circulatory system
blood si confined to vessels that branch into smaller ones that infiltrate the organs: chemical exchange occurs between blood and interstitial fluid and body cells
What organisms have closed circulatory systems?
annelids, cephalopods, all vertebrates
benefits of closed circulatory systems
relatively high blood pressures (effective delviery), larger and more active animals, well suited to regulation of food distribution to different organs
benefits of open circulatory systems
lower hydrostatic pressures, less energy-costly, additional functions such as movement
cardiovascular system
closed circulatory system of humans and other vertebrates: blood circulates to and from heart through vessel network
arteries
carry blood away from heart to organs
arterioles
small vessels that convey blood to capillaries
capillaries
microscopic vessels with thin, porous walls: make up capillary beds in every tissue; good for diffusion
venules
capillaries converge into venules
veins
venules converge into veins, which bring blood back to the heart
atria
chambers that receive blood
ventricles
chemabers responsible for pumping blood back out of the heart
single circulation
blood passes through the heart once per circuit: bony fishes, rays, sharks: two-chambered hearts
how does single circulation work?
blood enters atrium, transferred to ventricle, pumped to gills to receive oxygen, back to capillaries, back to heart
double circulation
two circuits: amphibians, reptiles, mammals
pulmonary circuit
right side of heart: oxygen-poor blood delivered to capillary beds of gas exchange tissues for oxygen
systemic circuit
left side: oxygen rich blood propelled to rest of body, then returns to heart for recirculation through the systemic circuit
blood flow in mammalian circulation
RV - pulmonary arteries - capillary beds of lungs - oxygenated - pulmonary veins - LA - bicuspid - LV - aorta - arteries and coronary artery - capillary beds of body - deoxygenated - veins - superior and inferior vena cava - RA - triscuspid - RV - repeat
which heart chambers have thicker walls and contract more forcefully?
ventricles
systole
contraction phase of the cardiac cycle
diastole
relaxation phase of the cardiac cycle
what two factors control cardiac output?
heart rate and stroke volume
atrioventricular valve
lies between the atrium and ventrium on each side: anchored by strong fibers that prevent them from turning inside out
semilunar valves
two exits of the heart: where aorta leaves LV, where pulmonary artery leaves RV
