Chapter 9 & 10 - Cardiac Physiology Flashcards
Dark areas crossing the cardiac muscles. They are actually cell membranes that separate individual cardiac muscles cells from one another.
Intercalated discs
3 major types of cardiac muscles in the heart
- Atrial muscle
- Ventricular muscle
- Specialized excitatory & conductive muscle fibers
The heart is composed of 2 syncitiums. What are those?
- Atrial syncitium
2. Ventricular syncitium
2 types of channels that cause an action potential in cardiac muscles
- The same fast sodium channels as those in skeletal muscles
- Slow calcium channels aka calcium sodium channels
It is the interval of time during which a normal cardiac impulse cannot reexcite an already excited area of cardiac muscle
Refractory period of the heart
The mechanism by which the action potential causes the myofibrils of the muscles to contract
Excitation-contraction coupling
The cardiac events that occur from the beginning of one heartbeat to the beginning of the next
Cardiac cycle
A period of relaxation in the cardiac cycle during which the heart fills with blood
Diastole
A period of contraction in the cardiac cycle
Systole
Atrioventricular valves
Tricuspid valve
Mitral valve
Semilunar valves
Aortic valve
Pulmonary artery valve
They do not help the valves close but instead they pull the vanes of of the valves inward toward the ventricles to prevent their bulging too far back toward the atria during ventricular contraction
Papillary muscles
The ____ valves are supported by the chordae tendinae
AV valves
Amount of energy that the heart converts to work during each heartbeat while pumping blood into the arteries
Stroke work output
The total amount of energy converted to work in 1 minute, hpthis is equal to the stroke workoutput times heart rate per minute
Minute work output
Load against which the muscle exerts its contractile force
Afterload
Degree of tension on the muscle when it begins to contract
Preload
End diastolic pressure when the ventricle has become filled
Preload
Pressure in the aorta leading from the ventricle
Afterload
Basic means by which the volume pumped by the heart is regulated
- Intrinsic cardiac regulation of pumping in response to changes in volume of blood flowing into the heart
- Control of heart rate & strength if pumping by ANS
The intrinsic ability of the heart to adapt to increasing volumes of inflowing blood
Frank-starling mechanism of the heart
Otto Frank & Ernest Starling
The greater the heart muscle is stretched durimg filling, the greater is the force of contraction and the greater the quantity of pumped blood into the aorta
Frank-Starling mechanism
Within physiologic limits, the heart pumps all the blood that returns to it by the way of the veins
Frank-Starling mechanism
Amount of blood pumped each minute
Cardiac output
A process that can cause automatic rhythmical discharge & contraction
Self-excitation
Pacemaker of the heart
SA node / sinoatrial node
A pacemaker elsewhere than sinus node. It causes an abnormal sequence of contraction of different parts of the heart and can cause significant debility of heart pumping
Ectopic pacemaker
