Chapter 19.6: The Circulatory System — Heart

What is systole?

Contraction of the heart

What is diastole?

Relaxation of the heart

What is cardiac output (CO; Cardiac Output)?

Volume of blood ejected by each ventricle per minute

What is heart rate (HR; Heart Rate)?

Number of heartbeats per minute

What is stroke volume (SV; Stroke Volume)?

Amount of blood pumped per beat

What is the sinoatrial node (SA node; Sinoatrial Node)?

Pacemaker of the heart; initiates heartbeat and sets heart rate

What is the atrioventricular node (AV node; Atrioventricular Node)?

Electrical gateway to ventricles; delays signal for proper contraction sequence

What is the atrioventricular bundle (AV bundle; Atrioventricular Bundle, also called Bundle of His)?

Conducts electrical signals from AV node to bundle branches

What are Purkinje fibers (Purkinje Fibers, also called Subendocardial Branches)?

Fibers spreading signals through ventricular myocardium

What does bpm stand for?

Beats per minute

What does mL stand for?

Milliliters

What does ACh stand for?

Acetylcholine

What does NE stand for?

Norepinephrine

What does Epi stand for?

Epinephrine

What does cAMP stand for?

Cyclic adenosine monophosphate

What does K⁺ stand for?

Potassium ion

What does Ca²⁺ stand for?

Calcium ion

What is vagal tone?

Resting influence of the parasympathetic system (via vagus nerve) on heart rate

What is hyperkalemia?

Excess potassium ions (K⁺)

What is hypokalemia?

Low potassium ions (K⁺)

What is hypercalcemia?

Excess calcium ions (Ca²⁺)

What is hypocalcemia?

Low calcium ions (Ca²⁺)

What is preload?

Ventricular stretch before contraction

What is contractility?

Strength of ventricular contraction independent of preload

What is afterload?

Resistance ventricles must overcome to eject blood

What is the Frank

Starling law?

What is cardiac reserve?

Difference between resting and maximum cardiac output (CO)

What are positive chronotropic agents?

Factors that increase heart rate (HR) (e.g., sympathetic system, epinephrine, norepinephrine, thyroid hormone, glucagon, nicotine, caffeine, hypocalcemia)

What are negative chronotropic agents?

Factors that decrease heart rate (HR) (e.g., parasympathetic system, acetylcholine [ACh], hypercalcemia, hypokalemia, beta blockers)

What are positive inotropic agents?

Factors that increase contractility (e.g., calcium ions [Ca²⁺], epinephrine, norepinephrine, glucagon, digitalis)

What are negative inotropic agents?

Factors that decrease contractility (e.g., hyperkalemia, hypocalcemia)

What does an electrocardiogram (ECG; Electrocardiogram) measure?

Electrical activity of the heart

What is coronary artery disease (CAD; Coronary Artery Disease)?

Atherosclerotic buildup narrowing coronary arteries, risking myocardial infarction (heart attack)

What is acute pericarditis?

Inflammation of pericardium, causing pain and friction rub

What is cardiomyopathy?

Disease of heart muscle, leading to dilation or failure

What is infective endocarditis?

Bacterial infection of the endocardium

What is myocardial ischemia?

Reduced blood supply to heart muscle, risking infarction

What is pericardial effusion?

Fluid buildup in pericardial cavity, risking tamponade

What are septal defects?

Abnormal openings in heart septa, causing pulmonary hypertension and potentially fatal in childhood

What is ventricular hypertrophy?

Thickening of ventricular walls, often from long