The Cardiovascular System: Heart and Blood Vessels

Comprehensive vocabulary flashcards covering the anatomy and physiology of the heart and blood vessels, including the cardiac cycle, electrical conduction, and blood pressure regulation.

Pulmonary circulation

The circulatory route where oxygen-poor blood travels from the heart to the lungs via arteries to pick up oxygen and release carbon dioxide, then returns to the heart as oxygen-rich blood via veins.

Systemic circulation

The circulatory route where oxygen-rich blood moves from the heart to the rest of the body to provide oxygen and nutrients to cells, and then returns to the heart as oxygen-poor blood.

Double pump

A description of the heart because it consists of two side-by-side pumps: the right side for pulmonary circulation and the left side for systemic circulation.

Myocardium

The middle layer of the heart wall composed of short, branched cardiac muscle tissues housing one or two central nuclei.

Endocardium

The innermost layer of the heart wall, continuous with the endothelial lining of blood vessels, which lines the heart chambers and covers the cardiac skeleton of valves.

Coronary circulation

The flow of blood that supplies the heart muscle itself with oxygen and nutrients, involving coronary arteries and cardiac veins.

Coronary sinus

A vessel that collects oxygen-poor blood from the cardiac veins and empties it into the right atrium.

Ischemia

A condition characterized by reduced blood flow to the heart muscle, causing the heart to receive less oxygen than it needs.

Angina pectoris

Chest pain or pressure caused by temporary ischemia where the heart muscle does not get enough oxygen but the tissue has not died.

Myocardial infarction

Commonly known as a heart attack, it occurs when a coronary artery becomes blocked and stops blood flow, causing part of the heart muscle to die.

Sinoatrial (SA) node

The pacemaker of the heart that starts each heartbeat by generating electrical impulses automatically without any external signal.

Resting potential (Cardiac)

The electrical state of a heart muscle cell when it is not contracting, typically at about $-90\,mV$.

Depolarization (Cardiac)

The phase of the action potential where sodium ($Na^+$) enters the cell, making the inside of the cell more positive.

Plateau phase

A unique phase in cardiac action potentials where calcium ($Ca^{2+}$) enters the cell while potassium ($K^+$) leaves, keeping the membrane potential positive for a longer time.

Repolarization (Cardiac)

The phase where potassium ($K^+$) leaves the cell, returning the membrane potential to its resting level.

P wave

The part of an ECG representing atrial depolarization, during which the atria contract and push blood into the ventricles.

QRS complex

The part of an ECG representing ventricular depolarization and contraction; it also hides the occurrence of atrial repolarization.

T wave

The part of an ECG representing ventricular repolarization, during which the ventricles relax.

Atrial systole

The phase of the cardiac cycle where the atria contract, triggered by the SA node, to push the final top-off volume of blood into the ventricles.

Isovolumetric ventricular contraction

The phase where ventricles begin to contract and pressure rises quickly, causing the AV valves to close and produce the 'lub' sound while all valves remain closed.

Ventricular ejection

The phase where ventricular pressure exceeds arterial pressure, causing the semilunar valves to open and blood to be pushed into the aorta and pulmonary trunk.

Isovolumetric relaxation

The phase where ventricles relax and pressure falls, causing semilunar valves to close and produce the 'dub' sound while all valves are briefly closed.

PR interval

The time from the start of the P wave to the start of the QRS complex, representing atrial depolarization, AV node delay, and conduction through the AV bundle.

ST segment

The portion of the ECG representing the time when the ventricles are fully depolarized and contracting.

Lub

The first heart sound caused by the closure of the atrioventricular valves (mitral and tricuspid) at the start of ventricular systole.

Dup

The second heart sound caused by the closure of the semilunar valves (aortic and pulmonary) at the end of ventricular systole.

Arrhythmia

An abnormal heart rhythm caused by problems in the heart’s conduction system, such as tachycardia ($>100\,bpm$) or bradycardia ($<60\,bpm$).

Murmur

An abnormal heart sound caused by turbulent blood flow, usually due to valve problems like stenosis or regurgitation.

Cardiac output (CO)

The volume of blood the heart pumps per minute, calculated as $CO = HR \times SV$.

Frank-Starling Law of the Heart

The principle stating that the greater the ventricular filling (preload), the greater the stroke volume due to the stretching of muscle fibers.

Afterload

The pressure the ventricles must overcome to eject blood; higher levels decrease stroke volume.

Baroreceptors

Blood pressure receptors located in the carotid arteries and aortic arch that send signals to the medulla to regulate heart rate and contractility.

Bainbridge reflex

The increase in heart rate resulting from high blood volume stretching the atria, causing more blood to be pumped out.

Systolic pressure

The top number in a blood pressure reading representing the pressure when the ventricles contract.

Diastolic pressure

The bottom number in a blood pressure reading representing the pressure when the ventricles relax.

Total Peripheral Resistance (TPR)

The resistance blood encounters as it flows through vessels, affected by vessel length, blood viscosity, and vessel radius.

Vessel radius

The most important factor affecting resistance; vasoconstriction increases resistance while vasodilation decreases it.

Blood flow formula

The mathematical relationship where flow is determined by pressure divided by resistance: $\text{blood flow} = \frac{\text{pressure}}{\text{resistance}}$.