Cardiac Physiology and Anatomy Overview

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Questions and Answers

What is the normal heart rate of a healthy adult in beats per minute?

90 beats/min

60 beats/min

100 beats/min

75 beats/min (correct)

Which components are part of the conduction system of the heart?

Coronary arteries and Capillaries

Aorta and Pulmonary vein

Mitral valve and Tricuspid valve

Bundle of His and Purkinje fibers (correct)

How long does one complete cardiac cycle take?

0.8 seconds (correct)

0.5 seconds

1.5 seconds

1 second

What are the two bundle branches in the conduction system of the heart?

Right and Left (D) Signup and view all the answers

Which term describes the sequence of events in a single heartbeat?

Cardiac cycle (C) Signup and view all the answers

What is the primary purpose of chest leads in electrocardiography?

To record electrical activity from six electrodes (D) Signup and view all the answers

Which of the following is NOT a chest lead?

L1 (D) Signup and view all the answers

How many electrodes are used to record bipolar leads?

Three (D) Signup and view all the answers

What is the maximum number of chest leads used in an electrocardiogram?

6 (B) Signup and view all the answers

What distinguishes bipolar leads from chest leads?

Bipolar leads are recorded by electrodes placed on the limbs (C) Signup and view all the answers

What occurs during the first heart sound, known as 'lubb'?

Ventricular contraction and closure of A-V valves (D) Signup and view all the answers

What is the second heart sound, known as 'dupp', associated with?

Ventricular contraction and closure of semilunar valves (A) Signup and view all the answers

What does a murmur indicate in the context of heart sounds?

An abnormal heart sound (A) Signup and view all the answers

What does an electrocardiogram (ECG) measure?

The electrical activity of the heart from the body surface (D) Signup and view all the answers

Which valves are involved in the 'lubb' heart sound?

Both A-V and semilunar valves (D) Signup and view all the answers

What event results in the second heart sound (S2)?

Closure of the semilunar valves (D) Signup and view all the answers

What happens when the pressure inside the ventricles becomes very low?

The atrioventricular valves open (C) Signup and view all the answers

What role do the atria play in the cardiac cycle after the passive filling of the ventricles?

They contract to complete the filling of the ventricles (B) Signup and view all the answers

What initiates the new cycle in the cardiac cycle?

Contraction of the atria (B) Signup and view all the answers

What does passive filling of the ventricles rely on?

Low pressure in the ventricles (C) Signup and view all the answers

What does the P wave in an electrocardiogram represent?

Atrial depolarization (B) Signup and view all the answers

Which wave in an electrocardiogram corresponds to ventricular depolarization?

QRS complex (A) Signup and view all the answers

What does the T wave indicate in an electrocardiogram?

Ventricular repolarization (D) Signup and view all the answers

Which statement is true about atrial repolarization in the electrocardiogram?

It is obscured by the QRS complex. (C) Signup and view all the answers

What is primarily observed in the QRS complex?

Ventricular depolarization (A) Signup and view all the answers

What is the QT interval duration?

0.43s (D) Signup and view all the answers

The QT interval is primarily associated with which phase of the cardiac cycle?

Ventricular depolarization and repolarization (B) Signup and view all the answers

What does a prolonged QT interval indicate?

Risk of arrhythmias (B) Signup and view all the answers

Which electrical events are involved in the QT interval?

Ventricular depolarization and repolarization (C) Signup and view all the answers

How is the QT interval measured on an electrocardiogram?

From the beginning of the Q wave to the end of the T wave (A) Signup and view all the answers

Study Notes

Cardiac Physiology Overview

The heart has 4 chambers: 2 atria and 2 ventricles
It has 4 valves: mitral, tricuspid, aortic, and pulmonary
The heart's function is based on a coordinated system called a functional syncytium
Cardiac muscle cells are stimulated as a unit.
The main energy source for cardiac muscle is fat, not glucose
Blood flow is mainly during diastole, rather than systole

Anatomy of the Heart

The diagram identifies key heart structures: superior vena cava, inferior vena cava, right atrium, right ventricle, left atrium, left ventricle, right pulmonary arteries, pulmonary trunk, left pulmonary arteries, pulmonary veins, aorta, brachiocephalic artery, left common carotid artery, left subclavian artery, atrioventricular (tricuspid) valve, mitral valve (bicuspid), chordae tendineae, papillary muscles, pulmonary trunk, pulmonary arteries, atrioventricular valves, semilunar valves

Cardiac Cycle

The normal heart rate is approximately 75 beats per minute
Each beat is one cardiac cycle. A full cycle takes about 0.8 seconds
Cardiac phases breakdown:
- Atrial systole (0.1 seconds)
- Ventricular systole (0.3 seconds)
- Atrial diastole (0.7 seconds) & ventricular diastole (0.3 seconds)
Systole is the contraction phase, ejecting blood from the ventricles- Normal systolic pressure is 120 mmHg.
Diastole is the relaxation phase, refilling the chambers- Diastolic pressure is 80 mmHg.
The atria contract to fill the ventricles, providing 30% of ventricular filling
70% of ventricular filling occurs passively

Ventricular Systole

When ventricles contract, mitral & tricuspid valves close
This creates the first heart sound (S1)
Ventricular contraction continues opening aortic and pulmonary valves to eject blood
About 70 ml of blood are ejected per ventricle (stroke volume)

Atrial and Ventricular Diastole

Atrial diastole: blood enters the atria (venous return)
Ventricular diastole: ventricles relax, aortic & pulmonary valves close causing the second heart sound (S2)

Heart Sounds

Lubb: first heart sound; occurs during ventricular contraction; caused by the closing of the mitral and tricuspid valves
Dub: second heart sound; occurs during ventricular contraction; caused by the closing of the aortic and pulmonary valves
A murmur is an abnormal heart sound

Heart Sound Locations

Aortic area
Tricuspid area
Pulmonary area
Mitral area

Electrocardiogram (ECG)

Records electrical activity of the heart
Electrodes are used for recording
Leads connect two electrodes, often used to give an electrical picture of the heart
ECG recording: uni-polar (one active electrode), bi-polar (two active electrodes), inactive electrode commonly placed on the right leg

ECG Leads

Unipolar:
- Limb leads: aVR, aVL, aVF (recorded by 3 electrodes on the limbs)
Bipolar:
- Limb leads: I, II, III(recorded by 3 leads on the limbs).
Chest Leads (V1-V6): six electrodes placed on the chest (positions have location specifics)

ECG Components

P wave: atrial depolarization
QRS complex: ventricular depolarization
T wave: ventricular repolarization
Intervals:
- PR interval (0.12-0.2 seconds): time from SA node activation to ventricular depolarization
- QRS interval (< 0.1 seconds): time for ventricular depolarization
- QT interval (0.43 seconds): duration of ventricular depolarization and repolarization

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Description

Explore the basics of cardiac physiology, including the structure and function of the heart's chambers and valves. Understand the cardiac cycle, blood flow dynamics, and the unique characteristics of cardiac muscle. This quiz provides a comprehensive overview for students of cardiac anatomy and physiology.