Quiz 6 Flashcards
what is the first heart sound
closing of the atrial ventricular valve
what is the closing of the atrial ventricular valve
start of ventricular systole
what is the second heart sound
closing of the semi lunar vales
what does the closing of the semi lunar valves signal
end of ventricular systole
what is an EKG (ECG)
electrocardiogram
when are the semilunar valves open
only open when pressure in ventricles is higher than pressure in atria
what is the ejection phase
when pressure is enough to push blood through valves
what is the formula for how much blood is ejected in a heart cycle
EDV-ESV=Stroke volume
what is EDV
end diastolic volume
what is ESV
end systolic volume
what is diastasis
a brief situation where blood leaves ventricles even though atrial pressure is slightly higher
what is isovolumetric relaxation
semilunar valves close as vestricles relax
what is ventricular filling due to
due to inertia
when is passive return used
as long as atrial pressure is higher than ventricular pressure the atriaventricular valve will be open
which circuit is high pressure and which is low pressure
systemic is high, pulmonary is low
how much blood remains in atria at all times
around 40-50ml
what is the blood remaining in the atria
end systolic volume
what is the p wave
synchronous contraction of the left and right atria
what are the three steps to ventricular systole
isovolumetric contraction, ejection phase, diastasis (inertia)
what is ventricular diastole
isovolumetric relaxation
when is the atrioventricular valve open
during atrial systole, during ventricular filling
when is the atrioventricular valve closed
isoventricular contraction, ventricular ejection, isovolumetric relaxation
when is the aortic valve open
ventricular ejection
during atrial systole the ventricles are already filled, why is blood still put into the ventricles
its a sort of topping off of the tank, its not a meaningful impact of the heart during rest
what is the p wave
atrial systole
what is the qrs wave
isovolumetric contraction
what is the t wave
ventricular ejection
what is end diastolic volume
maximum volume in ventricles when atria in systole
what is the approximate EDV
120ml
what is cardiac output
amount of blood pumped per unit time (L/min)
what is the approximate cardiac output for one circuit
5-6L/circuit of circulation
why does the amount of oxygen in the blood matter for aerobic organisms
to prevent hypoxia
how many liters of blood is pumped per minute for most adult humans
25-27 liters
what is stroke volume
amount of blood ejected per heart beat
how do you calculate cardiac output
HR x SV = CO
what is tachycardia
heart beating excessively fast, ventricles not able to fill before ejecting blood
whats the max amount of blood a human can pump in exercise
max is 35L for amazing athletes
what fold of increase can heart rate have at resting versus excercising
heart rate can have 3 fold increase
what fold of increase can stroke volume have at resting versus excercising
stroke volume can have 2 fold increase
what does HCN channels stand for
hyperpolarization activated cyclic nucleotides
what are HCN channels
different cyclic nucleotides when make k influx
what is the SA node RMP
-65mV
what is the myocardial cell RMP
-85mv
what are the excitable tissues of the heart
SA node, AV node, bundle of His, purkinje fibers
whats the reason to have myogenic specialized muscle tissue
to activate the heart and transfer action potential
where is the SA node
right atrium
what does SA stand for
sinoatrial
what kind of cells are in the SA node
cells that have autorythmisity (pacemaker potential)
what is a cellular pacemaker
cells spontaneously depolarizing
what does RMP stand for
resting membrane potential
what is RMP due to
K efflux
what is pacemaker potential driven by
sodium influx
what action potential do cells have in SA node
100 AP/min
where is the AV node
at the boundary between atria and ventricles
which node has a higher pacemaker potential
SA has higher
what is AV delay
0.05m/s
where do you get specialized conduction
bundle of His and purkinje fibers
what are the bundle of his and purkinje fibers
elongate cells specialized for rapid AP conduction
what is a rapid AP conduction value
5m/s
what are cells of node trying to act like
trying to act like axons
when are voltage gated calcium channels open
when SA node pacemaker potential has hit threshhold
what are between cardiac muscle cells
gap junctions
what do gap junctions allow for
ion transfer (electrical charge transfer)
what do inactive voltage gated sodium channels allow for
relaxation
what ensures relaxation
protractive repolarization
what does bundle of his and purkinje fibers cause
rapid depolarization of ventricles
what is the parasympathetic division
autonomic nervous system
what nerve is part of the parasympathetic division
vagus nerve
what number cranial nerve is the vagus nerve
10
what does the vagus nerve do
reduces the heart rate
what innervates the SA node and the myocardium
parasympathetic division
what reduces heart rate so diastole lasts longer
parasympathetic division
what causes HCN channels
cGMP
what does RMP reduction do
hyperpolarizes SA node
what does cGMP do
reduces cytoplasmic Ca
when does vagus activity decrease
when exercising
what nerve takes over when vagus is decreased
sympathetic
what does the sympathetic nerve give
norepinephrine mostly as a neurotransmitter (and a little bit of epinephrine)
when does calcium pool in the body
when heart beat increases
why does calcium pool with increased HR
not enough time in diastole to remove it
what does Na act as when calcium is pooling
acts as a cotransport agent
is the vagus nerve sympathetic is parasympathetic
parasympathetic
whats the major nerve in sympathetic
accelerator nerve
what does the sympathetic division do
releases norepinephrine, activates adrenal medulla to release epinephrine, increases HR
