37 Questions
What happens at 0mV in the cardiac action potential?
Ca++ channels close and K+ channels open
What is the purpose of the long refractory period in the cardiac cycle?
To prevent premature contractions
Which part of the heart's conduction system would typically fire the slowest?
Purkinje fibers
What is the purpose of Ca++ binding to troponin in muscle contraction?
To allow myosin and actin cross bridge formation
What is the purpose of an ECG or EKG recording?
To record electrical signals of the heart
Where is the heart located in the body?
Between the lungs in the mediastinum
What is the function of the atria in the heart?
Collect blood and push it into lower chambers
Which chamber in the heart is responsible for pumping blood to the body or lungs?
Left ventricle
What is the main function of the pulmonary vein?
Carry oxygenated blood
What is the role of the epicardium in the heart?
Produces lubricating fluid
Which layer of the heart is considered the most superficial?
Epicardium
What is the main function of an artificial pacemaker?
To deliver electrical impulses for effective heart contractions
During which phase of the cardiac cycle does systole occur?
During atrial contraction
What is the main purpose of an AED (automated external defibrillator)?
To correct fibrillations
Which wave represents the repolarization of the ventricles in an electrocardiogram?
T wave
What phase of the cardiac cycle involves the closing of semilunar valves and opening of atrioventricular valves?
Ventricular systole
What is the purpose of myoglobin in heart cells?
To store oxygen in muscle cells
Which heart sound is associated with the closing of atrioventricular valves?
S1
What is the normal range for Cardiac Output (CO) in liters per minute?
4 - 8 L/min
What is the formula to calculate Cardiac Output (CO)?
CO = HR * SV
What does Ejection Fraction represent in cardiac physiology?
Percentage of blood pumped by the heart
Which factor can decrease Heart Rate (HR) according to the text?
Hypoxia (lack of oxygen)
Where does nervous control of Heart Rate come from?
Medulla oblongata
What is the main effect of sympathetic stimulation on the heart?
Shortens the repolarization period
Which response best describes Ejection Fraction?
The percentage of blood pumped out of the heart with each beat
What is the impact of increased thyroid hormone levels on Heart Rate?
Increases HR and contractility
What happens to Stroke Volume if there is less ventricular filling time?
It decreases
Which layer lines the chambers of the heart and covers the heart valves?
Endocardium
What are endothelins released by the endothelium known for?
Regulating growth patterns of cardiac muscle cells
Which structure in the heart divides it into chambers?
Septum
Which valve separates the left atrium from the left ventricle?
Mitral valve
Why do semilunar valves make an audible sound when they close?
They have no muscular attachments
What is the function of papillary muscles in the heart?
To close the tricuspid and mitral valves
What is the main function of coronary circulation?
To bring blood to the myocardium and other components
Which cell type initiates and propagates the action potential through the heart?
Myocardial conducting cells
What is the main role of the SA node in cardiac conduction?
Sets normal cardiac rhythm
What is the significance of gap junctions in cardiac muscle cells?
Allow ions to travel between cells for proper contractile rhythm
Test your knowledge on the conduction of electrical impulses in the cardiac muscle and the refractory period. Learn about the role of calcium ions, channels, and the actions of different nodes and bundles in the heart's electrical system.
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