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25 Cards in this Set

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ventricular systole
Ventricular systole is the contraction of the myocardium of the left and right ventricles.
At the beginning of ventricular systole, the pressure in the left ventricle increases. This soon eclipses the pressure in the left atrium, closing the mitral valve. The pressure in the left ventricle continues to rise, until the pressure in the ventricle is greater than the pressure in the aorta. This causes the aortic valve to open, allowing the blood to eject into the aorta, to perfuse the end organs of the body.
ventricular diastole
Cardiac Diastole is the period of time when the heart relaxes after contraction in preparation for refilling with circulating blood. Ventricular diastole is when the ventricles are relaxing,
atrial systole
As the atria contract, the blood pressure in each atrium increases, forcing additional blood into the ventricles. The additional flow of blood is called atrial kick.
atrial diastole
Atrial diastole is when the atria are relaxing
cardiac cycle
Cardiac cycle is the term referring to all or any of the events related to the flow or pressure of blood that occurs from the beginning of one heartbeat to the beginning of the next.
The frequency of the cardiac cycle is the heart rate. Every single 'beat' of the heart involves five major stages: First, "Late diastole" Second, "Atrial systole" Third,
"Isovolumic ventricular contraction"
Fourth, "ventricular ejection"& Fifth, "Isovolumic ventricular relaxation",
isovolumic ventricular contraction
It is when the ventricles begin to contract, AV valves close, as well as the semilunar valves and there is no change in volume.
isovolumic ventricular relaxation
The final stage of the Cardiac Cycle: "Isovolumic ventricular relaxation", Pressure decreases, no blood is entering the ventricles, ventricles stop contracting and begin to relax, semilunars are shut because blood in the aorta is pushing them shut.
ESV
End-systolic volume (ESV) is the volume of blood in the left ventricle at the end of contraction, or systole, and the beginning of filling, or diastole.
ESV is the lowest volume of blood in the ventricle at any point in the cardiac cycle.
EDV
End-diastolic volume (EDV) is the volume of blood in a ventricle at the end of filling (diastole). Because greater EDVs cause greater distention of the ventricle, EDV is often used synonymously with preload, which refers to the length of the sarcomeres in cardiac muscle prior to contraction (systole). An increase in EDV increases the preload on the heart and, through the Frank-Starling mechanism of the heart, increases the amount of blood ejected from the ventricle during systole (stroke volume).
ventricular ejection
??
cardiac contractile cells
cardiac contractile cells, of course, contract when stimulated CONTRACTILE CARDIAC MUSCLE
CELLS ARE SHORT, HAVE LARGE
DIAMETERS, ARE BRANCHED, AND
HAVE INTERCONNECTIONS CALLED

look at graph
cardiac autorhythmic cells
Autorhythmic cells, on the other hand, are self-stimulating & contract without any external stimulation.Autorhythmic cells exhibit PACEMAKER POTENTIALS. look at graph
intercalated disks
An intercalated disc is an undulating double membrane separating adjacent cells in cardiac muscle fibers.
Intercalated discs support synchronized contraction of cardiac tissue.
Three types of membrane junctions exist within an intercalated disc—fascia adherens, macula adherens and gap junctions.
Fascia adherens are anchoring sites for actin, and connects to the closest sarcomere.
Macula adherens stop separation during contraction by binding intermediate filaments joining the cells together also called a desmosome.
Gap junctions allow action potentials to spread between cardiac cells by permitting the passage of ions between cells, producing depolarization of the heart muscle
pacemaker potential
n the pacemaking cells of the heart ( SA node), the pacemaker potential is the slow, positive increase in voltage across the cell's membrane (the membrane potential) that occurs between the end of one action potential and the beginning of the next action potential.
This increase in membrane potential is what causes the cell membrane, which typically maintains a resting membrane potential of -70 mV[1], to reach the threshold potential and consequently fire the next action potential; thus, the pacemaker potential is what drives the self-generated rhythmic firing of pacemaker cells,
sympathetic effect on autorhythmic cardiac cells
increases heart rate and force of contractions
parasympathetic effect on autorhythmic cardiac cells
decrease heart rate and force of contractions
sinoatrial node
SA node is the impulse generating (pacemaker) tissue located in the right atrium of the heart, and thus the generator of sinus rhythm.
It is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava. These cells are modified cardiac myocytes. Though they possess some contractile filaments, they do not contract.
atrioventricular node
The atrioventricular node is a part of electrical control system of the heart that co-ordinates heart rate.
It electrically connects atrial and ventricular chambers.
The AV node is an area of specialized tissue between the atria and the ventricles of the heart, which conducts the normal electrical impulse from the atria to the ventricles. The AV node is quite compact (~1 x 3 x 5 mm).[2] It is located at the center of Koch's Triangle
bundle of His
The bundle of His is a collection of heart muscle cells specialized for electrical conduction that transmits the electrical impulses from the AV node to the point of the apex of the fascicular branches. The fascicular branches then lead to the Purkinje fibers which innervate the ventricles, causing the cardiac muscle of the ventricles to contract at a paced interval.
purkinje fibers
purkinje fibers are located in the inner ventricular walls of the heart, These fibers are specialized myocardial fibers that conduct an electrical stimulus or impulse that enables the heart to contract in a coordinated fashion.
P Wave
The P wave represents the wave of depolarization that spreads from the SA node throughout the atria, and is usually 0.08 to 0.1 seconds (80-100 ms) in duration. The brief isoelectric (zero voltage) period after the P wave represents the time in which the impulse is traveling within the AV node and the bundle of His
QRS Wave
The QRS complex represents ventricular depolarization.
The duration of the QRS complex is normally 0.06 to 0.1 seconds.
This relatively short duration indicates that ventricular depolarization normally occurs very rapidly.
If the QRS complex is prolonged (> 0.1 sec), conduction is impaired within the ventricles.
T Wave
The T wave represents ventricular repolarization and is longer in duration than depolarization
heart murmur
A heart murmur is an extra or unusual sound heard during a heartbeat. Murmurs range from very faint to very loud. They sometimes sound like a whooshing or swishing noise.

Normal heartbeats make a "lub-DUPP" or "lub-DUB" sound. This is the sound of the heart valves closing as blood moves through the heart.
heart valve
the heart valves maintain the unidirectional flow of blood in the heart by opening and closing depending on the difference in pressure on each side.