overview of the CVS Flashcards
what is the function of the CVS
bulk flow system
what does the CVS transport
oxygen and carbon dioxide nutrients metabolites hormones heat
how is the CVS flexible?
pump can vary output
vessels can redirect blood
vessels can store blood
describe the structure of the CVS
heart –> lungs –> heart –> body –> heart
the pumps are in series
what is important about the pumps being in series
output must be equal
most vascular beds are in …
parallel - blood goes to all of them at the same time
what is important about vascular beds being in parallel
all tissues get oxygenated blood
allows regional redirection of blood
there are some exceptions
what are the 2 exceptions to parallel vascular beds
hypothalamus and anterior pituitary
liver
these are known as portal systems
describe the hypothalamus and pituitary vascular bed
blood goes to the hypothalamus first then the anterior pituitary
describe the vascular bed in the liver
blood from the gut goes directly to the liver
the liver also has its own direct blood supply
CO vs oxygen consumption of the brain
13 vs 18
CO vs oxygen consumption of the heart
4 vs 10
CO vs oxygen consumption of the skeletal muscle
20 vs 20
CO vs oxygen consumption of the skin
9 vs 2
thermoregulatory functions
CO vs oxygen consumption of the kidneys
20 vs 6
recieves a lot more blood than it needs, necessary for pressure filtration
CO vs oxygen consumption of the abdominal organs
24 vs 30
how is blood redirected during exercise
pressure difference = mean arterial pressure - central venous pressure
this affects all tissue
what is the equation relating flow, pressure difference and resistance
flow = pressure difference / resistance
what is the equation for pressure difference
pressure difference = mean arterial pressure - central venous pressure
resistance is controlled by …
radius ^4
this selectively redirects flow
why are arterioles called resistance vessels
they act as the taps controlling resistance and therefore flow to each vascular bed
elastic arteries
aorta
wide lumen
elastic wall with lots of elastic fibres
dampen pressure variations
muscular arteries
wide lumen
strong, non-elastic wall
low resistance conduit
resistance vessels
arterioles narrow lumen thick, contractile, muscular wall control resistance and therefore flow allow regional redirection of blood
exchange vessels
capillaries
narrow lumen
thin wall - one cell thick, small barrier to diffusion
capacitance vessels
venules and veins wide lumen distensible wall low resistance conduit and reservoir allows fractional redistribution of blood between the veins and the rest of the circulation
define fractional distribution
how much of the total blood volume is sitting in the capacitance vessels
what is the role of the septum in the heart
divides the left and right side to separate oxygenated and deoxygenated blood
how is the myocardium different on the L and R side of the heart
heart muscle
thicker on the L
atrium
recieveing chamber
ventricle
pumping chamber
aorta
blood leaving LV to the body
vena cava
blood entering RA from the body
divided into inferior and superior
pulmonary trunk
artery taking blood away from RV to the lungs
pulmonary veins
vein taking blood into the LA from the lungs
aortic valve
semi-lunar valve
stops blood re-entering LV
pulmonary valve
semi-lunar
stops blood re-entering RV
mitral valve
L AV valve
bicuspid
tricuspid valve
R AV valve
chordae tendinae
tendinous chords attached to the valves to hold them in place
papillary muscles
muscles attached to the chords
allows the chords to shorten at the right time and prevents the valves inverting when the pressure is high
what causes valves to open/close
pressure in the heart
all the valves are passive
