NSG 3160 EXAM 3 – COMPREHENSIVE CARDIAC
SYSTEM STUDY GUIDE (HEART SOUNDS, VALVES, ECG
& HEART FUNCTION REVIEW)
Heart Structure and Function
Circulatory Pathways
Right Side of the Heart: Pumps deoxygenated blood to the lungs.
Left Side of the Heart: Pumps oxygenated blood throughout the body
simultaneously.
Septum
The septum is the wall that separates the right and left sides of the heart,
preventing the mixing of oxygenated and deoxygenated blood.
Heart Valves
Atrioventricular (AV) Valves
Separate the atria from the ventricles.
Right AV Valve: Tricuspid valve — located at the 5th intercostal space, left sternal
border.
Left AV Valve: Mitral valve — located at the 5th intercostal space, left
midclavicular line.
Apical Pulse (Mitral Area / PMI / Apex):
Heard best at the apex of the heart, located at the 5th intercostal space along the
midclavicular line.
Semilunar (SL) Valves
Located between the ventricles and arteries.
Contain three cusps shaped like half-moons.
,Best heard at the base of the heart (top region).
Pulmonic Valve: Right side, 2nd left intercostal space.
Aortic Valve: Left side, 2nd right intercostal space.
Cardiac Cycle
Diastole Phase
The ventricles relax and fill with blood (2/3 of the cycle).
AV valves (tricuspid and mitral) remain open.
Atrial pressure is higher than ventricular pressure.
Early/Protodiastolic Filling: Initial filling phase.
Presystole/Atrial Systole: Second filling phase before contraction.
Systole Phase
Blood is ejected from the ventricles into the pulmonary and systemic arteries (1/3
of the cycle).
Ventricular pressure rises above atrial pressure, causing AV valves to close.
As pressure falls after ejection, semilunar valves close, preventing backflow.
Heart Sounds
S1 (“Lub”): Closure of AV valves — marks the beginning of systole.
S2 (“Dub”): Closure of semilunar valves — marks the end of systole.
Extra Heart Sounds
S3:
Occurs just after S2 (“Lub-Dub-Dub”).
,Indicates increased ventricular filling pressure (e.g., heart failure, mitral
regurgitation).
Low-pitched vibration heard best over the chest.
May be an early sign of heart failure.
S4:
Occurs at the end of diastole (presystole), just before S1 (“Dub-Lub-Dub”).
Caused by resistance to ventricular filling.
Heard best at the apex with the patient in a left lateral position.
Low-pitched and soft vibration.
Murmur:
An abnormal swishing sound due to turbulent blood flow or valve malfunction.
Electrical Conduction System
Automaticity: The heart’s ability to contract independently of neural or hormonal
control.
SA Node: Known as the “pacemaker” of the heart.
P Wave: Atrial depolarization.
PR Interval: From the beginning of the P wave to the start of the QRS complex.
QRS Complex: Ventricular depolarization.
T Wave: Ventricular repolarization.
, Cardiac Output (CO)
The amount of blood pumped by the heart in one minute (normally 4–6 liters).
Formula: CO = Stroke Volume (SV) × Heart Rate (HR)
Peripheral Vascular System
Carotid Artery: Located in the groove between the trachea and sternomastoid
muscle.
Palpate one side at a time to avoid compromising cerebral blood flow.
Jugular Vein: Drains blood from the head into the superior vena cava and then the
right atrium.
Assessment Findings
Jugular Venous Pulse Inspection
Position the patient supine at a 45° angle.
Remove the pillow and turn the head away.
SYSTEM STUDY GUIDE (HEART SOUNDS, VALVES, ECG
& HEART FUNCTION REVIEW)
Heart Structure and Function
Circulatory Pathways
Right Side of the Heart: Pumps deoxygenated blood to the lungs.
Left Side of the Heart: Pumps oxygenated blood throughout the body
simultaneously.
Septum
The septum is the wall that separates the right and left sides of the heart,
preventing the mixing of oxygenated and deoxygenated blood.
Heart Valves
Atrioventricular (AV) Valves
Separate the atria from the ventricles.
Right AV Valve: Tricuspid valve — located at the 5th intercostal space, left sternal
border.
Left AV Valve: Mitral valve — located at the 5th intercostal space, left
midclavicular line.
Apical Pulse (Mitral Area / PMI / Apex):
Heard best at the apex of the heart, located at the 5th intercostal space along the
midclavicular line.
Semilunar (SL) Valves
Located between the ventricles and arteries.
Contain three cusps shaped like half-moons.
,Best heard at the base of the heart (top region).
Pulmonic Valve: Right side, 2nd left intercostal space.
Aortic Valve: Left side, 2nd right intercostal space.
Cardiac Cycle
Diastole Phase
The ventricles relax and fill with blood (2/3 of the cycle).
AV valves (tricuspid and mitral) remain open.
Atrial pressure is higher than ventricular pressure.
Early/Protodiastolic Filling: Initial filling phase.
Presystole/Atrial Systole: Second filling phase before contraction.
Systole Phase
Blood is ejected from the ventricles into the pulmonary and systemic arteries (1/3
of the cycle).
Ventricular pressure rises above atrial pressure, causing AV valves to close.
As pressure falls after ejection, semilunar valves close, preventing backflow.
Heart Sounds
S1 (“Lub”): Closure of AV valves — marks the beginning of systole.
S2 (“Dub”): Closure of semilunar valves — marks the end of systole.
Extra Heart Sounds
S3:
Occurs just after S2 (“Lub-Dub-Dub”).
,Indicates increased ventricular filling pressure (e.g., heart failure, mitral
regurgitation).
Low-pitched vibration heard best over the chest.
May be an early sign of heart failure.
S4:
Occurs at the end of diastole (presystole), just before S1 (“Dub-Lub-Dub”).
Caused by resistance to ventricular filling.
Heard best at the apex with the patient in a left lateral position.
Low-pitched and soft vibration.
Murmur:
An abnormal swishing sound due to turbulent blood flow or valve malfunction.
Electrical Conduction System
Automaticity: The heart’s ability to contract independently of neural or hormonal
control.
SA Node: Known as the “pacemaker” of the heart.
P Wave: Atrial depolarization.
PR Interval: From the beginning of the P wave to the start of the QRS complex.
QRS Complex: Ventricular depolarization.
T Wave: Ventricular repolarization.
, Cardiac Output (CO)
The amount of blood pumped by the heart in one minute (normally 4–6 liters).
Formula: CO = Stroke Volume (SV) × Heart Rate (HR)
Peripheral Vascular System
Carotid Artery: Located in the groove between the trachea and sternomastoid
muscle.
Palpate one side at a time to avoid compromising cerebral blood flow.
Jugular Vein: Drains blood from the head into the superior vena cava and then the
right atrium.
Assessment Findings
Jugular Venous Pulse Inspection
Position the patient supine at a 45° angle.
Remove the pillow and turn the head away.
