Card Set Information
Bio MCAT Cardiovascular System
no openings to leave the vessels
systematic circulation (path)
- aorta - arteries, arterioles, capillaries
capillaries - collected into venules - veins - superior and inferior vena cava -
right ventricle - pulmonary arteries - arteries - capillaries in lungs:
venues - veins - pulmonary veins - left atrium [heart]
Is the heart a muscle?
systole v. diastole
systole = ventricles contract
diastole = relaxation of heart and then contraction of aorta
how is the blood propelled?
how is hydrostatic pressure initiated?
contraction of the heart
how is the rate of contraction controlled?
does ANS initiate contraction?
How does it contract then?
How does it contract? (method)
sinoatrial node (SA) in right atrium contracts at regular intervals
How is the contraction spread?
via electrical synapses from
How is contraction slowed down?
Where is the Action Potential spread to next?
atrioventicular node (AV node)
what happens when AP reaches AV node, before ventricles can contract?
AV node contracts slower, allowing atria to contract and squeeze contents into ventricles
So, AV node does what to contraction of ventricle in heart?
delays contraction -
pauses for a fraction of a second
Where is Action Potential spread down?
bundle of His
What is the bundle of His?
wall separating ventricles
What are Purkinje fibers?
branches out AP through gap junctions throughout the cardiac muscles
advantages of purkinje fibers
allows for more unified, stronger contraction
Are arteries elastic?
What does that say about arteries?
they stretch when filled with blood
What allows them to stretch?
wrapped by smooth muscle
How is the smooth muscle that allows for elasticity controlled?
sympathetic nervous system
large arteries (muscle and sympathetic control)
have less smooth muscle
less affected by sympathetic innervation
Are they wrapped by smooth muscle?
What does constriction and dilation of arterioles control?
regulate blood pressure
capillaries (relative size)
intermediate for nutrient and gas exchange with tissue
methods for material to cross capillary walls:
2. diffusion or transport (membrane)
3. mvmt. through pores
4. mvmt. through space between cells
when blood flows into capillary what is greater hydrostatic or osmotic pressure?
So in what direction is the net fluid flow?
out of the capillary
What happens when fluid flows out?
hydrostatic pressure drops from arteriole to venule -
osmotic pressure is greater at the venule end
So in what direction is net fluid flow now?
fluid that is not reabsorbed is sent to the lymph
What percentage of fluid is lost in the process
venules and veins
similar to arterioles and arteries
in systematic circulation what is the main function of veins and venues?
hold about 64% of blood in body at rest
How much blood do arteries, arterioles, and capillaries hold
artery v. veins (direction of blood flow)
artery = caries blood
vein = carries blood
velocity of blood flow
inversely proportional to cross-sectional area
cross sectional area - greater in capillaries, arteries, or veins?
greatest in capillaries
so blood moves slowest through....
flow rate of blood in capillaries
blood pressure is greater where?
increases near the heart
decreases near the capillaries