Cardiac Structure Flashcards
Volume of blood is dependent on
amount of blood returning to the heart via venous channels as well as the time between heart contractions.
functions of heart rely on
orderly conduction of electrical signals and a series of valves that keep the blood flowing through the heart in the correct direction
cardiac output
defined as the amount of blood pumped out of the heart times the rate at which the heart is beating
stroke volume
the amount of blood pushed into the arteries is considered the stroke volume
the number of heart contractions in a minute is what?
heart rate
cardiac output per minute
stroke volume x heart rate
The cardiac contraction starts with
depolarization of the SA node.
SA node composed of
excitable cardiac tissue called P cells
P cells internal property
current drift will depolarize far enough to generate an active spike of a fast sodium transient about 80 times per minute
P wave
the spreading depolarization is seen as slight positive deflection in the anterior leads of the EKG and is referred to as the P wave
After the atria, where does the electrical signal go?
it eventually arrives at the AV node.
AV node
located just above the right AV valve anterior to the opening g of the coronary sinus
a short delay allows for
full contraction of the atria and completion of the atria filling the ventricles
AV node goes to
interventricular septum via AV bundle
QRS wave of the EKG
AV conduction and the resulting depolarization of ventricular myocytes
QRS corresponds to period of time in the cardiac cycle known as
ventricular systole
first heart sound
initiation of systole is heralded by closure of AV valve
P-R interval
time between initiation of P Wave and the initial deflection of the QRS
Abnormalities of PR interval indicates
varying degrees and severity of heart block
Irregular rhythm
determined by the distance between one P wave and the other P wave. is different
T wave
corresponds to the time when the ventricles begin to relaxand before the blood returns in volume to fill the heart chamber
T wave occurs
during systole, before the beginning of diastole
second heart sound
closure of semilunar valves, aortic, and pulmonic valves
S-T segment or intervale
time between ventricular myocyte contraction and relaxation
If the S-T segment is depressed
excessive strain or cardiac ischemia
Elevated S-T segment,
infarction or strain
Valves are attached to
fibrous rings that help limit current flow between atria and ventricles
