35 Questions
What occurs at 0mV during repolarization?
Ca++ channels close
What prevents premature contractions in the heart?
Long refractory period
Which node would fire 80 - 100 times per minute without endocrine control?
SA node
What component of an ECG records electrical signals of the heart?
Electrodes on the body
Which part of the heart has the lowest firing rate recorded at 28 BPM?
Purkinje fibers
What is the approximate volume of fluid pumped by the heart per minute?
5.25 L
In the heart, where does the base location relative to the apex?
Superior and medial
Which blood vessels attach at the base of the heart?
Aorta and pulmonary trunk
What is the function of ventricles in the heart?
Pump blood to the lungs or body
Which layer of the heart produces lubricating fluid in the pericardial cavity?
Visceral layer
What is the middle thickest layer in the heart that consists of muscle cells, nerve fibers, and blood vessels?
Myocardium
What does the T wave represent in the cardiac cycle?
Repolarization of ventricles
Which phase of the cardiac cycle involves the pumping of blood into circulation?
Ventricular systole
What is the main function of an artificial pacemaker?
Ensuring effective heart contractions with electrical impulses
What is the role of myoglobin in heart muscle cells?
Storing oxygen in muscle cells
Which valve closes during ventricular diastole?
Atrioventricular valve
What is the normal amount of blood pushed out by the ventricles during each heartbeat?
$70-80$ mL
Which heart sound is associated with the closing of atrioventricular valves?
S1
What does S2, the second heart sound, represent?
Closing of semilunar valves
Which condition is referred to as S7?
Presence of S3 and S4 together
What is the formula for Cardiac Output (CO)?
CO = HR * SV
What is the normal range for Ejection Fraction?
50% - 70%
What is the difference between Cardiac Reserve and Max HR?
Cardiac Reserve is the difference between Max CO and Resting CO
'Target heart rate' refers to a range that aims to keep what high?
Cardiac Output
'What can decrease heart rate among the following factors?'
Acidosis (excess hydrogen ions)
Which layer of the heart covers the heart valves and is continuous with the lining of blood vessels?
Endocardium
What cells release endothelins and regulate growth patterns of cardiac muscle cells?
Endothelial cells
Which valve separates the left atrium from the left ventricle?
Mitral valve
In which chamber of the heart are pectinate muscles present?
Right atrium
Which part of the heart receives oxygenated blood from the pulmonary veins?
Left atrium
What structure in the heart closes due to papillary muscles?
Atrioventricular valves
What cells in the heart have a long refractory period to prevent tetany?
Cardiac muscle cells
Where is the Sinoatrial (SA) node located in the heart?
Right atrium
What structure receives an impulse from the AV node and branches into right and left bundle branches?
Bundle of His
What happens at +30mV in cardiac contractile cells during membrane potentials?
Na+ channels close and Ca++ channels open.
Test your knowledge on the key features of cardiac action potential, including the role of calcium and potassium channels, refractory period, and conduction pathways in the heart.
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