Heart Physiology

The heart is a vital organ responsible for pumping blood throughout the body.

The heart has four distinct chambers: the right atrium, left atrium, right ventricle, and left ventricle.

The right heart manages the pulmonary circulation, responsible for transporting blood to the lungs to pick up oxygen.

The left heart is responsible for systemic circulation, delivering oxygenated blood to the rest of the body.

The atria act as primer pumps, receiving blood from the circulatory system and slightly pushing it towards the ventricles.

The ventricles are the primary pumping chambers, forcefully sending blood to the lungs (right ventricle) or the body (left ventricle).

The heart has four valves that act as one-way gates, preventing backflow of blood.

The tricuspid and mitral valves are located between the atria and ventricles, ensuring blood flows from atria to ventricles.

The aortic and pulmonary valves are located between the ventricles and their respective arteries, preventing blood backflow from arteries to ventricles.

The AV valves close when pressure pushes blood backward, preventing it from entering the atria.

A forward pressure gradient forces blood through the AV valves, allowing it to enter the ventricles.

Semilunar valves need a brief backflow of blood to close and seal properly.

Papillary muscles are small muscles within the ventricles attached to the AV valves by chordae tendineae (tough tendons).

Contraction of papillary muscles pulls the valve vanes inward, preventing them from bulging back during ventricular contraction.

The pericardium is the outer layer of the heart, a sac-like covering that provides protection and lubrication.

The myocardium is the middle layer, composed of striated muscle cells responsible for the heart's pumping action.

The endocardium is the inner layer lining the chambers of the heart, composed of smooth endothelial cells.

The autonomic nervous system regulates heart rate and rhythm through sympathetic and parasympathetic nerves.

Sympathetic nerves increase heart rate and contractility, preparing the body for 'fight or flight' responses.

Parasympathetic nerves (vagus nerves) slow down heart rate and promote relaxation.

The intercalated disc is a specialized junction between adjacent heart muscle cells, allowing for efficient communication.

Gap junctions are a type of intercellular connection within intercalated discs, facilitating rapid diffusion of ions, oxygen, and nutrients.

An atrial syncytium refers to the connected network of muscle cells in the atrial walls.

A ventricular syncytium refers to the connected network of muscle cells in the ventricular walls.

The atria and ventricles are separated by fibrous tissue, preventing direct electrical conduction between them.

The heart's electrical activity is vital for coordinating contractions, enabling efficient blood pumping.

Electrocardiography (ECG/EKG) records the electrical activity of the heart using electrodes placed on the skin.

The mechanical function of the heart refers to its ability to pump blood from the atria to ventricles and then to the lungs and body.

Electromechanical function describes the integrated interplay between the heart's electrical and mechanical activities, leading to efficient blood flow.