The Heart - Anatomy and Physiology

Comprehensive vocabulary flashcards covering heart anatomy, wall layers, chambers, valves, conduction system, and cardiac output physiology based on the lecture transcript.

Mediastinum

The space within the thoracic cavity, located medially between the lungs, where the human heart sits.

Pericardium

Also known as the pericardial sac, it is a tough membrane that separates the heart from other mediastinal structures.

Base of the heart

The superior surface of the heart where the great veins and great arteries are attached, located at the level of the (3rd) third costal cartilage.

Apex

The inferior tip of the heart that lies just to the left of the sternum between the junction of the fourth (4th) and fifth (5th) ribs.

Cardiac notch

A depression in the medial surface of the inferior lobe of the left lung reflected by the slight deviation of the apex to the left.

Myocardium

The middle layer of the heart wall that forms most of the wall and contains striated muscle fibers that cause contraction.

Endocardium

The heart's inner layer consisting of endothelial tissue with small blood vessels and bundles of smooth muscle.

Tricuspid valve

The right atrioventricular valve located between the right atrium and the right ventricle, typically consisting of three flaps or leaflets.

Chordae tendineae

Strong fibers that connect valve flaps to the papillary muscles to control the opening and closing of the atrioventricular valves.

Pulmonary valve

The right semilunar valve that emerges from the right ventricle at the base of the pulmonary trunk.

Mitral valve

Also called the bicuspid valve or the left atrioventricular valve, it is located at the opening between the left atrium and left ventricle and consists of two cusps.

Aortic valve

The aortic semilunar valve located at the base of the aorta that prevents backflow from the aorta into the left ventricle.

Intercalated discs

Structures found at the junction of different cardiac muscle cells that consist of desmosomes and gap junctions.

Sinoatrial (SA) node

The heart's primary pacemaker with a firing rate of $60$ to $100$ beats/minutes.

Atrioventricular (AV) node

A component of the conduction system with a firing rate of $40$ to $60$ beats/minutes; it introduces a delay of approximately $100\,ms$ for atrial blood pumping.

Purkinje fibers

Conductive components of the heart that distribute excitation through the ventricular myocardium with a firing rate of $20$ to $40$ beats/minutes.

Automaticity

The ability of cardiac pacemaker cells to spontaneously initiate an electrical impulse.

Excitability

A cell's response to an electrical stimulus, resulting from ion shifts across the cell membrane.

Conductivity

The ability of a cardiac cell to transmit an electrical impulse to another cardiac cell.

Contractility

The ability of a heart cell to contract after receiving a stimulus.

Prepotential

A slow influx of sodium ions in conductive cells until the threshold is reached, initiating spontaneous depolarization.

Plateau phase

A phase in the action potential of cardiac contractile cells caused by the influx of calcium ions, allowing the cell to fully contract before another electrical event.

Cardiac output (CO)

A measurement of the amount of blood pumped by each ventricle in one minute, calculated as $CO = HR \times SV$.

Stroke volume (SV)

The amount of blood pumped by each ventricle per contraction.

Preload

The stretch on the ventricles prior to contraction, influencing stroke volume.

Afterload

The force the ventricles must generate to pump blood against the resistance in the vessels.

Vagus nerve (Cranial nerve X)

The parasympathetic nerve that provides cardioinhibitory signals to slow cardiac activity.