cardio Chp 14 Flashcards
what divides the left and right halves of the heart?
the septum
what does the heart look like at day 25 of an embryo?
it is a single tube
how has the heart developed at four weeks of development?
the atria and ventricles can be distinguished and the heart begins to twist do that the atria move on top of the ventricles
which structures contain well oxygenated blood?
left atrium
left ventricle
pulmonary vein
aorta
which structures contain blood with lower oxygen content?
right atrium
right ventricle
venae cavae
pulmonary trunk (artery)
where does the right atrium receive blood from?
venae cavae
where does the right atrium send blood to?
right ventricle
where does the right ventricle get blood from?
right atrium
where does the right ventricle send blood to?
the lungs
where does the left atrium receive blood from?
pulmonary veins
where does the left atrium send blood to?
left ventricle
where does the left ventricle receive blood from?
the left atrium
where does the left ventricle send blood to?
the body except for the lungs
where does the venae cavae receive blood from?
systemic veins
where does the venae cavae send blood to?
the right atrium
where does the pulmonary trunk (artery) get its blood from?
right ventricle
where does the pulmonary trunk send blood?
the lungs
where does the pulmonary vein get it’s blood from?
veins of the lungs
where does the pulmonary vein send its blood?
left atrium
where does the aorta get its blood from?
the left ventricle
where does the aorta send its blood to?
systemic
which set of heart vales ensure one way flow?
atrioventricular valves
semilunar valves
where are the atrioventricular valves?
between the atria and the ventricles
which are artioventricular vales?
tricuspid valve on the right side bicuspid valve (mitral valve) on the left side
where are the semilunar valves?
between ventricles and arteries
which are semilunar valves?
aortic valve
pulmonary valve
why do the AV valves stay closed during ventricular contraction?
to prevent blood flow backward into the atria
what do the semilunar valves prevent?
blood that has entered back into the arteries from flowing back into the ventricles during ventricular contraction
what causes the semilunar valves to close?
pressure
pericardium
the fluid filled sac that encases the heart. It keeps out potential invaders and reduces friction due to movement of the heart
what are the layers of the heart?
endocardium
myocardium
epicardium
___ is the inner layer of epithelium
endocardium
___is the middle layer of cardiac muscle
myocardium
____ is the external membrane
epicardium
contractile cells
striated fibers that are organized into sarcomeres
autorhythmic cells are also called
pacemakers which work through gap junctions
what do autorhythmic cells do?
signal for contraction
autorhythmic cells are ____ compared to contractile cells
smaller and fewer
autorhythmic cells do not have
organized sarcomeres
what is the difference between cardiac muscle and skeletal muscle?
cardiac muscle is smaller and have a single nucleus per fiber
branch and join other cells through intercalated disks
the t-tubules are larger and branch
sarcoplasmic reticulum is smaller
mitochondria occupy 1/3 of cell volume
what allows force to be transferred in intercalated disks?
desmosomes
what provides the electrical connection between intercalated disks
gap junctions
why is muscle relaxation so important?
that is when ventricular filling takes place.
the long refractory period also prevents tetanus
in cardiac contraction, the force generated is proportional to:
the number of active crossbridges sarcomere length also affects the force of the contraction
how do we control strength in cardiac contraction?
with calcium
how do you produce a stronger contraction?
by increasing the number of crossbridges that form and power strokes that take place.
what happens when you have too much extracellular K+?
you keep depolarizing cells which can lead to ectopic foci and arrhythmias as well as stop the heart
what happens when you have extracellular Ca2+?
it prolongs the plateau phase and thus increases the time of contraction
increases calcium which increases the strength of contraction force
what does verapamil do?
it blocks ca influc to reduce contraction force
what does digitalis do?
it increases intracellular ca thus increasing contraction strength
which node sets the pace of the heartbeat at 70bpm?
sinoatrial node (SA)
what does the atrioventricular node do?
it routes the direction of the electrical signals so that the heart contracts from apex to base
what causes the first heart sound?
vibrations following closure for the AV valves
“lub”
what causes the second heart sound?
vibrations created by closure of semilunar valve
cardiac output:
the amount of blood pumped by each ventricle per minute
how do you calculate cardiac output?
heart rate (beats per min) X stroke vol (vol ejected per beat)
