HESI Cardiovascular system Part 2 Flashcards
Within the intercalated discs, adjacent cells are connected by ___ and ____ ___
desmosomes
gap junctions
action potentials in the heart come form specialized cardiac muscle cells called ______ cells
autorhythmic cells
The autorhythmic cells are concentrated in 2 areas, the ___ __ and the ___ ___
sinoatrial node
atrioventricular node
The sinoatrial node is located in the
right atrium
The atrioventricular node gets its action potential from the
sinoatrial node
The cardiac cycle is initiated by the
sinoatrial node
The atrioventricular node sends action potential to the
atrioventricular bundle (bundle of His)
The ventricles are stimulated by impulses from the ___ ___
atrioventricular bundle
the ___ ___ conduct the action potential from the inter ventricular septum down to the apex and back up through the ventricles
purkinje fibers
the first step in cardiac muscle contraction, depolarization occurs when channels open to allow ___ to enter
Na+
the second step in cardiac muscle contraction, ___ enters the cytosol from the sarcoplasmic reticulum and also form outside the cell
Ca2+
Within the cell, Ca2+ binds to
troponin
Once Ca2+ binds to troponin, this stimulates ___-___ binding which leads to the sliding of actin filaments past myosin filaments
cross-bridge
repolarization occurs as ___ channels opens and ___ diffuses out of the cell
K and K
Compared to skeletal muscle, the refractory period of cardiac muscle is
longer, ensuring each contraction is followed by enough time to allow the heart chamber to refill with blood before the next contraction
In an ECG, the ___ wave is small, representing the depolarization of the atria.
P
During this wave, muscles of the atria are contracting
P
ECG, a rapid down-up-down movement
QRS
Represents the depolarization of the ventricles
QRS
represents the repolarization of the ventricles
T
A contraction event (of either atria or ventricles) is called
systole
a relaxation event is referred to as
diastole
The ___ ventricular relaxation is the period during which the ventricles are released and the AV and semilunar valves are still closed. The volume of the ventricles remains unchanged
isovolumetric ventricular relaxation
Ventricular filling begins as the AV valves open and blood fills the ventricles. The ventricles remain in ___ during this time
diastole
Blood fills the ventricles in 3 phases. First it flows in quick since there’s plenty of space. Second it flows slower since there’s less room. Third, atrial systole forces the last of the blood in. The final amount of blood at this point is called the ___ ___
end-diastolic volume
Ventricular contraction (systole) starts as the action potential form the ___ node enters the ventricle.
AV node
___ contraction occurs when the AV valves are forced shut. During this brief period, while semilunar valves are still closed, the volume of the ventricles remains unchanged
isovolumetric contraction
The amount of blood remaining in the ventricles after relaxing is the ___ ___
end-systolic volume
___ ___ is the volume of blood ejected by each ventricle during a single contraction
stroke volume
___ ___ is the number of heartbeats per minute
heart rate
