Cardiovascular System Overview

The system that circulates blood throughout the body, consisting of the heart, blood, and blood vessels.

The primary organ of the cardiovascular system, responsible for pumping blood throughout the body.

The stable state of the heart, involving its function and balance.

The pointed tip of the heart, formed by the left ventricle, pointing slightly left.

The opposite end of the heart from the apex, formed by the atria, angled posteriorly.

The outermost layer of the pericardium, made of dense, inelastic connective tissue, protecting the heart from overstretching.

The inner layer of the pericardium, divided into parietal and visceral layers, creating a lubricating sac around the heart.

The inner layer of the serous pericardium, directly surrounding the heart, also known as the epicardium.

Cardiac muscle contraction requires the presence of potassium (K+), sodium (Na+), and calcium (Ca2+) ions. Excess K+ can block action potentials, excess Na+ can outcompete Ca2+ for cell entry, and excess Ca2+ can increase the rate and strength of heart contraction.

The maximum heart rate an individual can achieve is determined by age. The formula is: Maximal heart rate = 220 bpm - age (in years).

Preload refers to the stretching of the heart muscle as it fills with blood. It's like stretching an elastic band - the more you stretch it, the more forcefully it will contract. Preload is influenced by the duration of diastole and venous return.

Contractility describes the strength of the heart muscle's contraction, given a specific preload. Positive inotropic agents promote calcium influx during action potentials, increasing the force of contraction. Negative inotropic agents decrease calcium influx or increase potassium efflux, reducing contraction force.

Afterload represents the pressure the heart muscle must overcome to push blood out of the ventricles and into the arteries. High blood pressure (hypertension) increases afterload, requiring the heart to work harder to pump blood against higher resistance.

The outermost layer of the heart wall, also known as the visceral serous pericardium. A serous membrane consisting of mesothelium and connective tissue, rich in blood vessels and lymphatics, making the heart slippery.

The thickest layer of the heart wall, composed of cardiac muscle tissue. It's responsible for the forceful contractions that pump blood throughout the body.

The innermost layer of the heart wall, lining the chambers and valves. Made of endothelium, it reduces friction between blood and the heart.

The two superior chambers of the heart, responsible for receiving blood from veins.

The two inferior chambers of the heart, responsible for pumping blood into arteries.

The groove that runs the boundary between the right atrium and right ventricle, containing coronary arteries and possibly fat.

The groove that runs the boundary between the left and right ventricles, containing coronary arteries and possibly fat.

The valves located between the atria and ventricles. They are composed of flaps of tissue called cusps, preventing backflow of blood from ventricles into atria.

Valves located between the ventricles and the large arteries. They prevent backflow of blood from arteries into ventricles.

Four rings of dense connective tissue that encircle the heart valves, fusing at the interventricular septum. It provides support, prevents valve overstretching, anchors cardiac muscles, and insulates electrically between atria and ventricles.

Cardiac muscle cells primarily oxidize glucose (35%) and fatty acids (60%) for energy. They can also utilize lactic acid and directly generate ATP through creatine phosphate.

Creatine kinase is an enzyme abundant in cardiomyocytes that helps generate ATP through the phosphorylation of creatine. Elevated levels in the blood can indicate myocardial infarction.

Blood vessels that supply the heart with oxygenated blood. These include coronary arteries, which carry oxygenated blood to the heart muscle, and coronary veins, which carry deoxygenated blood away from the heart muscle.

Systole refers to the contraction phase of the heart chambers, either atria or ventricles, where blood is pumped out.

Specialized muscle tissue found only in the heart that is responsible for the heart's pumping action. Characterized by branching cells, rich in mitochondria, and the presence of intercalated discs.

Diastole is the relaxation phase of the heart chambers, where the chambers fill with blood.

The ability of the heart to generate its own electrical impulses, allowing it to beat without external stimulation.

An electrocardiogram (ECG) measures electrical currents generated by action potentials traveling through the heart muscle.

A specialized network of autorhythmic muscle cells within the heart that generates and conducts electrical impulses to coordinate heart contractions.

The P wave represents atrial depolarization, which triggers atrial systole. It signals the start of atrial contraction.

The QRS complex represents ventricular depolarization, triggering ventricular systole. It signifies the start of ventricular contraction.

The primary pacemaker of the heart, located in the right atrium, responsible for initiating the electrical impulses that trigger heart beats.

The T wave represents ventricular repolarization, leading to ventricular diastole. It signals the start of ventricular relaxation.

Specialized junctions between cardiac muscle cells that allow for rapid communication and coordinated contraction. They contain desmosomes for strong adhesion and gap junctions for electrical coupling.

A rapid change in the electrical potential across the membrane of a cardiac muscle cell, responsible for initiating contraction. It has three phases: depolarization, plateau, and repolarization.

Cardiac output (CO) is the volume of blood pumped by the ventricles per minute. It's a measure of the heart's efficiency in delivering blood.

A period of time after an action potential during which a cardiac muscle cell cannot be stimulated again. This ensures adequate time for the heart to relax and refill with blood.

Stroke volume (SV) is the amount of blood pumped out of the ventricles with each beat.

Sustained muscle contraction not possible in cardiac muscle due to long refractory periods. This allows for the heart to relax and refill between contractions.