Human Circulatory System and Cardiac Dynamics

Vocabulary flashcards based on the circulatory system, heart anatomy, cardiac cycle, electrical conduction system, and cardiac regulation notes.

Closed Circulatory System

A circulatory system where blood is always contained inside blood vessels and kept separate from the fluid surrounding all cells (extracellular fluid).

Pulmonary Circuit

The circulatory pathway that oxygenates blood by transporting it from the heart to the lungs and back to the heart.

Systemic Circuit

The circulatory pathway that delivers oxygenated blood from the heart to the rest of the body's cells and returns deoxygenated blood back to the heart.

Pericardium

A fluid-filled sac that contains and protects the heart, reducing friction as the heart beats.

Coronary Vessels

Specialized blood vessels that provide the heart muscle with its own blood supply to deliver oxygen and nutrients and remove wastes.

Atrium

A heart chamber that receives blood into the heart from the body or lungs.

Ventricle

A heart chamber that pumps blood out of the heart to the lungs or the body.

Inferior / Superior Vena Cava

Large blood vessels that return deoxygenated blood to the right atrium from the body.

Right Atrium

A thin-walled chamber of the heart that receives deoxygenated blood from the body.

Right Ventricle

A thick-walled chamber of the heart that pumps deoxygenated blood away from the heart to the lungs.

Atrioventricular (AV) Valves

Valves (tricuspid on the right, bicuspid on the left) that prevent the backflow of blood from the ventricles into the atria during ventricular systole.

Semilunar (SL) Valves

Valves (pulmonary on the right, aortic on the left) that control the flow of blood out of the heart and prevent backflow from arteries into the ventricles during diastole.

Pulmonary Arteries

Blood vessels that carry deoxygenated blood away from the heart to the lungs.

Pulmonary Veins

Blood vessels that carry oxygenated blood from the lungs to the heart.

Left Atrium

A thin-walled chamber of the heart that receives oxygenated blood from the lungs.

Left Ventricle

A thick-walled chamber of the heart that pumps oxygenated blood away from the heart to all parts of the body.

Aorta

The primary artery that carries oxygenated blood from the left ventricle to the tissues of the body.

Septum

A muscular wall that separates the left side and right side of the heart, preventing the mixing of oxygenated and deoxygenated blood.

Chordae Tendonae

Bands of connective tissue that support the atrioventricular (AV) valves.

Papillary Muscles

Muscles in the heart ventricles that control the chordae tendonae.

Autorhythmic

The characteristic of cardiac muscle that allows it to contract without requiring nervous system stimulation.

Systole

The stage of the heartbeat where the heart muscle contracts and actively pushes blood out of the chamber.

Diastole

The stage of the heartbeat where the heart muscle relaxes and the chambers fill with blood.

Lub Sound

The first sound of a heartbeat, produced when blood hits the closing atrioventricular (AV) valves during ventricular systole.

Dub Sound

The second sound of a heartbeat, produced when blood hits the closing semilunar (SL) valves during ventricular diastole.

SA Node

A specialized group of cells known as the pacemaker of the heart that initiates the contraction signal by generating an electrical impulse.

AV Node

A specialized cluster of cardiac cells that serves as the relay point for the electrical impulse between the atria and the ventricles.

Bundle of His and Bundle Branches

Specialized fibers that carry the electrical contraction signal from the AV node down to the apex (bottom) of the heart.

Purkinje Fibers

Specialized conduction fibers that spread the electrical signal to muscle cells in the ventricle walls, causing them to contract from the bottom up.

Vagus Nerves

Parasympathetic nerves that send impulses from the brain to slow down the heart rate during rest and digest states.

Cardioaccelerator Nerves

Sympathetic nerves that send impulses from the brain to speed up the heart rate during fight or flight states.

Medulla Oblongata

The part of the brain that determines what heart rate is needed at any given point in time.

Stroke Volume

The amount of blood pumped by the left ventricle in one contraction, averaging $70\,mL$ per beat at rest.

Cardiac Output

The volume of blood each ventricle pumps per minute, calculated using the formula $\text{Cardiac Output} = \text{heart rate} \times \text{stroke volume}$.