G.1

Atria

The receiving chambers of the heart.

Ventricles

Muscular chambers of the heart that pump blood out.

Septum

Muscular wall separating the ventricles of the heart.

Vena cavae

The major veins that transport deoxygenated blood to the right atrium.

Pulmonary veins

Veins that carry oxygenated blood from the lungs to the left atrium.

Atrioventricular valves (AV valves)

Valves located between the atria and ventricles.

Pulmonary circuit

The pathway that carries deoxygenated blood from the heart to the lungs.

Systemic circuit

The pathway that pumps oxygenated blood from the heart to the rest of the body.

Double circuit

Pattern of blood flow where blood is pumped twice for complete circulation.

Chordae tendineae

Tiny tendons that connect AV valves to the ventricles.

Semilunar valves

Valves located at the beginning of the arteries.

Aortic valve

The semilunar valve at the beginning of the aorta.

Pulmonary valve

The semilunar valve at the beginning of the pulmonary trunk.

Systolic pressure

Blood pressure during the contraction of the ventricles.

Diastolic pressure

Blood pressure when the ventricles are relaxed.

Hypertension

Condition of having higher blood pressure than normal.

Hypotension

Condition of having lower than normal blood pressure.

Medulla oblongata

Part of the brain that regulates blood pressure.

SA node

Sino-atrial node, the heart's natural pacemaker.

AV node

Atrioventricular node, a part of the electrical conduction system of the heart.

Purkinje fibres

Nerves that conduct impulses for ventricular contraction.

Cardiac cycle

The series of events that occurs during one heartbeat.

Electrocardiogram (ECG)

A representation of the electrical activity of a heartbeat.

P wave

ECG representation of atrial contraction.

QRS complex

ECG representation of ventricular contraction.

T wave

ECG representation of ventricular recovery.

Aortic bodies

Nerve receptors in the aorta sensitive to blood gas levels.

Blood pressure

The force of blood against the walls of blood vessels.

Capillary beds

Extensive networks of capillaries that connect the pulmonary and systemic circuits.

Tissue starvation

Condition that occurs when there is insufficient blood flow to a tissue.

Heart attack

Condition caused by insufficient blood delivery to the heart muscle.

Stroke

Condition caused by blocked or bleeding blood vessels in the brain.

Valves

Structures in the heart that prevent backflow of blood.

Blood flow

Movement of blood through the heart and blood vessels.

Chordae tendineae

Tendon-like structures that prevent inversion of AV valves.

Impulse

Signal sent by the SA node to stimulate heart contractions.

Relaxation

Phase of the cardiac cycle when the heart fills with blood.

Atrial contraction

Phase of the cardiac cycle where the atria contract to push blood into the ventricles.

Ventricular contraction

Phase of the cardiac cycle where the ventricles contract to send blood to the arteries.

Passive filling

Process of blood entering the heart due to low pressure.

Contraction

The tightening and shortening of the heart muscle.

Recovery

The phase in the cardiac cycle for muscle relaxing and filling.