Cardiac Conduction System Quiz: Test Your Knowledge

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Questions and Answers

What causes typical repolarization of the cardiac cell?

Opening of K+ channels (correct)

Opening of Ca++ channels

Closing of K+ channels

Closing of Ca++ channels

Why does the long refractory period occur in the cardiac cycle?

To enhance contraction force

To prevent premature contractions (correct)

To speed up conduction

To increase heart rate

Which component of the heart's electrical system fires the fastest without endocrine control?

SA node (correct)

AV node

Atrioventricular bundle

Purkinje fibers

What is the main function of the troponin in the cardiac muscle contraction process?

Allowing myosin and actin cross bridge formation Signup and view all the answers

Which element is commonly used to record electrical signals of the heart in an abbreviated form?

Electrodes on the body Signup and view all the answers

Where is the heart located in the body?

In the thoracic cavity Signup and view all the answers

Which structure separates the heart from other structures?

Pericardium Signup and view all the answers

What is the main function of the ventricles in the heart?

Pump blood out to the body or lungs Signup and view all the answers

Which layer of the heart contains muscle cells, nerve fibers, and blood vessels?

Myocardium Signup and view all the answers

What is the main function of the auricles in the heart?

Collect blood and push it into atria Signup and view all the answers

Which blood vessel is unique in carrying deoxygenated blood?

Pulmonary artery Signup and view all the answers

Which layer lines the chambers filled with blood and covers heart valves?

Endocardium Signup and view all the answers

What is the main function of endothelins released by the endothelium?

Regulate growth patterns of cardiac muscle cells Signup and view all the answers

Which structure divides the heart into chambers?

Septum Signup and view all the answers

What is the function of the atrioventricular valves?

Separate atria from ventricles Signup and view all the answers

Which valve closes due to papillary muscles?

Mitral valve Signup and view all the answers

What ensures unidirectional blood flow in the heart?

Valves Signup and view all the answers

Where do coronary arteries branch off from?

Aorta Signup and view all the answers

What is the main function of the SA node in the heart?

Set the normal cardiac rhythm Signup and view all the answers

What role do Purkinje fibers play in cardiac conduction?

Spread impulses around the ventricles Signup and view all the answers

What happens during the plateau phase of cardiac contractile cells?

Ca++ channels close and Na+ channels are open Signup and view all the answers

During which phase of the cardiac cycle does the P wave represent the depolarization of the atria?

Atrial systole Signup and view all the answers

What is the main function of an artificial pacemaker?

Ensuring effective heart contractions Signup and view all the answers

Which phase of the cardiac cycle is characterized by the pumping of blood into circulation?

Ventricular systole Signup and view all the answers

What is the main function of an AED (Automated External Defibrillator)?

Correcting fibrillations Signup and view all the answers

Which phase of the cardiac cycle signifies the relaxation of the ventricles and closing of semilunar valves?

Ventricular diastole Signup and view all the answers

What does stroke volume represent in the cardiac cycle?

Amount of blood pushed out by ventricles Signup and view all the answers

What is the normal range of Cardiac Output (CO) in liters per minute?

4 - 8 L/min Signup and view all the answers

Which heart sound is associated with the closing of the atrioventricular valves?

S1 Signup and view all the answers

What causes heart murmurs according to the text?

Turbulent blood flow Signup and view all the answers

What is the formula for Stroke Volume (SV) according to the text?

SV = EDV - ESV Signup and view all the answers

Which nerve dominates the autonomic tone of the heart according to the text?

Vagus nerve Signup and view all the answers

What does an increased level of thyroid hormone do to heart rate and contractility?

Increases heart rate and contractility Signup and view all the answers

What can decrease heart rate according to the text?

Hypoxia (lack of O2) Signup and view all the answers

At what point during cardiac development are the atrioventricular valves formed?

Between weeks 5 - 9 Signup and view all the answers

How does exercise impact Cardiac Output (CO) according to the text?

Increases CO by 4-8 times Signup and view all the answers

What effect does sympathetic stimulation have on heart repolarization according to the text?

Shortens the repolarization period Signup and view all the answers

Study Notes

Heart Anatomy

The heart is a muscle that pumps 5.25 L of fluid per minute.
It is located between the lungs in the mediastinum, separated from other structures by the pericardium.
The heart sits in the pericardial cavity, with the base being superior and medial to the apex.
The great veins (superior and inferior vena cava) and arteries (aorta and pulmonary trunk) attach at the base.
The heart has a cardiac notch, a depression of the inferior lobe of the left lung.

Heart Structure

The heart has 4 chambers: 2 atria and 2 ventricles.
Atria are superior and collect blood, while ventricles are inferior and pump blood out to the body or lungs.
The heart has 2 circuits: pulmonary and systemic.
The right ventricle connects to the pulmonary trunk, and the left ventricle connects to the aorta.
CO2 leaves and O2 enters in the pulmonary capillaries.

Heart Membranes and Layers

The heart has 2 layers: fibrous and serous pericardium.
The serous layer has 2 sublayers: parietal and visceral layers separated by the pericardial cavity.
The cavity is filled with lubricating fluid.
The visceral layer is called the epicardium and produces fluid.

Heart Features

Auricles are thin-walled structures that can hold blood and empty into atria.
Sulci are fat-filled grooves that contain coronary blood vessels.

Layers

The epicardium is the most superficial layer.
The myocardium is the middle, thickest layer, consisting of muscle cells, nerve fibers, and blood vessels.
The endocardium is the innermost layer, lining the chambers filled with blood, covering heart valves, and continuous with the lining of blood vessels.
The endothelium releases endothelins, which are strong vasoconstrictors and may regulate growth patterns of cardiac muscle cells.

Internal Structures

Septum divides the heart into chambers and is a physical extension of the myocardium.
Fossa ovalis is a depression in the interatrial septum, which was a foramen ovale (opening) while a fetus.
Atrioventricular valves separate atria from ventricles, with tricuspid on the right and mitral or bicuspid on the left.
Semilunar valves separate ventricles from blood vessels, with pulmonary and aortic valves.

Chambers

Right atrium receives deoxygenated blood from the systemic circulation, contains pectinate muscles, and has a small contractile phase.
Right ventricle receives deoxygenated blood from the right atrium and has chordae tendineae connected to 3 papillary muscles that close the tricuspid valve.
Left atrium receives oxygenated blood from the pulmonary veins and has a small contractile phase (20%).
Left ventricle receives oxygenated blood from the left atrium and has a thicker muscle, with no moderator band.

Valves

Valves ensure unidirectional blood flow.
Semilunar valves have no muscular attachments and make an audible sound as they close.
Tricuspid and mitral valves close due to papillary muscles.
Valve disorders are usually caused by inflammation.

Coronary Circulation

Coronary circulation is cyclical and not continuous.
Arteries branch off the aorta just superior to the semilunar valve.
Coronary arteries bring blood to the myocardium and other components.
Anastomosis is the interconnection of blood vessels to allow blood to flow even if there is a partial blockage in another branch.
Coronary veins bring deoxygenated blood back to the right atrium.

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Description

Test your knowledge on cardiac physiology and the conduction system of the heart. Questions cover topics such as repolarization, refractory period, calcium ions, and the firing rates of different nodes in the heart.

Cardiac Physiology and Conduction System Quiz

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