What is the heart?
Hollow, muscular organ that pumps blood to tissues.
What is the weight of the heart?
Approximately 300 g.
Where does the heart occupy space?
Between the lungs (mediastinum).
What does the heart supply to tissues?
Oxygen and other nutrients.
What are the three layers of the heart?
Endocardium, Myocardium, Epicardium.
What does the endocardium do?
Lines the inside of the heart and valves.
What is the myocardium responsible for?
Contraction of the heart.
What is the epicardium?
Exterior layer of the heart.
What is the pericardium?
Thin layer of fibrous tissue that contains pericardial fluid.
What are the two layers of the pericardium?
Visceral pericardium and parietal pericardium.
What is systole?
Contraction of the heart's chambers.
What is diastole?
Relaxation of the lower chambers of the heart.
What are the upper chambers of the heart called?
Atria.
What are the lower chambers of the heart called?
Ventricles.
Where is the apical impulse located?
15th intercostal space, left mid-clavicular line.
What is cardiac output?
Volume of blood ejected by the heart each minute.
What is the normal cardiac output?
5 L/min.
What is the formula for cardiac output?
CO = HR x Stroke Volume.
What is the normal pulse rate?
60-100 beats/min.
What affects stroke volume?
Preload, contractility, afterload.
What is preload?
Degree of myocardial stretch at the end of diastole.
What is Starling's Law?
The more the heart is filled during diastole, the more forcefully it contracts.
What enhances contractility?
Catecholamines, sympathetic activity, medications like Digoxin, Dopamine, Dobutamine.
What is afterload?
Pressure that ventricles must overcome to eject blood.
What is the first heart sound (S1)?
Heard as the atrioventricular valves close.
What is the second heart sound (S2)?
Heard when the semilunar valves close.
What is the third heart sound (S3)?
May indicate decreased ventricular wall compliance.
What is the fourth heart sound (S4)?
Heard on atrial systole if resistance to filling is present.
What is automaticity in cardiac electrophysiology?
Ability to initiate an electrical impulse by itself.
What is excitability in cardiac electrophysiology?
Ability to respond to an electrical impulse.
What is conductivity in cardiac electrophysiology?
Ability to transmit an electrical impulse.
Where is the SINOATRIAL (SA) NODE located?
Junction of Superior vena cava & Right Atrium
What is the function of the SINOATRIAL (SA) NODE?
Pacemaker of heart
What is the heart rate initiated by the SINOATRIAL (SA) NODE?
60-100 bpm
Where is the ATRIOVENTRICULAR (AV) NODE located?
Interatrial septum
What does the ATRIOVENTRICULAR (AV) NODE do?
Delays electric impulse for ventricular filling
How long is the delay caused by the ATRIOVENTRICULAR (AV) NODE?
0.8 milliseconds
What is the heart rate of the ATRIOVENTRICULAR (AV) NODE?
40-60 beats/min
Where is the BUNDLE OF HIS located?
Interventricular septum
What does the BUNDLE OF HIS branch into?
Right main Bundle Branch and Left main Bundle Branch
Where are PURKINJE FIBERS located?
Walls of ventricles
What do PURKINJE FIBERS facilitate?
Ventricular contractions
What is the conduction rate of PURKINJE FIBERS?
20-40 beats/min
What can PURKINJE FIBERS function as if other pacemakers fail?
Backup pacemaker
What do parasympathetic impulses do to cardiac rate?
Slow it down
What do sympathetic impulses do to cardiac rate?
Increase it
Where are baroreceptors located?
Aortic arch and internal carotid arteries
What do baroreceptors sense?
Changes in blood pressure
What can hypotension lead to regarding baroreceptor stimulation?
Less stimulation
What is the P wave in an ECG?
Represents atrial muscle depolarization
What is the normal width of a P wave?
No wider than 0.12 seconds
What does the QRS complex represent?
Ventricular muscle depolarization
What is the normal width of the QRS complex?
0.04 to 0.10 seconds
What does the T wave represent?
Ventricular repolarization
What is the normal height of T waves?
Not more than 5 mm
What does the PR interval measure?
Time for impulse travel through atria, AV junction, and Purkinje system
What is the normal PR interval duration?
0.12 to 0.20 seconds
What does the QT interval represent?
Total time for ventricular depolarization and repolarization
What is the normal QT interval duration?
0.32 to 0.40 seconds
What risk is associated with a prolonged QT interval?
Lethal ventricular dysrhythmia called torsades de pointes
What does the PP interval measure?
Duration between the beginning of one P wave and the next
What does the RR interval measure?
Duration between the beginning of one QRS complex and the next
What does the U wave reflect in an ECG?
Purkinje fiber repolarization
When is the U wave usually seen?
When serum potassium level is low (Hypokalemia)
What is the most prevalent type of cardiovascular disease in adults?
Coronary artery disease (CAD)
What is the most common cause of cardiovascular disease?
Atherosclerosis
What can inadequate blood supply to cardiac cells lead to?
Ischemia
What are some modifiable risk factors for CAD?
Hyperlipidemia, smoking, hypertension, diabetes, metabolic syndrome, obesity, inactivity
What are some non-modifiable risk factors for CAD?
Family history, age, gender, race
What are possible clinical manifestations of CAD?
Chest pain, palpitations, dyspnea, syncope
What is a possible characteristic of heart disease in African Americans?
Higher incidence than in Caucasians
What are the clinical manifestations of heart disease?
Possibly normal asymptomatic periods
What symptom involves discomfort in the chest?
Chest pain
What symptom involves an awareness of heartbeats?
Palpitations
What is the term for difficulty in breathing?
Dyspnea
What is the medical term for fainting?
Syncope
What is Starling's Law?
The more the heart is filled during diastole, the more forcefully it contracts.
What enhances contractility?
Catecholamines, sympathetic activity, medications like Digoxin, Dopamine, Dobutamine.
What is automaticity in cardiac electrophysiology?
Ability to initiate an electrical impulse by itself.
What does the PR interval measure?
Time for impulse travel through atria, AV junction, and Purkinje system
What risk is associated with a prolonged QT interval?
Lethal ventricular dysrhythmia called torsades de pointes
What are some modifiable risk factors for CAD?
Hyperlipidemia, smoking, hypertension, diabetes, metabolic syndrome, obesity, inactivity
What is a possible characteristic of heart disease in African Americans?
Higher incidence than in Caucasians
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