Heart Main points

These flashcards cover the key terms and concepts related to cardiac physiology, including the heart's conduction system, cycle, and regulation.

Pacemaker Potential

An unstable resting potential that gradually depolarizes in certain cardiac muscle cells, leading to action potentials.

Intrinsic Conduction System

The group of cardiac muscle cells that coordinate the heart's rhythm and include the SA node, AV node, and more.

SA Node

The pacemaker of the heart that initiates depolarization and sets the sinus rhythm.

Arrhythmias

Abnormal heart rhythms that can occur due to defects in the intrinsic conduction system.

Cardioacceleratory Center

The region in the medulla that increases heart rate through sympathetic innervation.

Postganglionic Neurons

Neurons that innervate the SA and AV nodes and cardiac muscle, influencing heart activity.

Sodium Channels

Channels that open during depolarization of cardiac myocytes, allowing sodium to enter.

Action Potential

A change in membrane potential that leads to the contraction of cardiac muscle cells.

Electrocardiogram (ECG)

A graphic representation of the heart's electrical activity during the cardiac cycle.

P Wave

The component of an ECG representing atrial depolarization.

Cardiac Cycle

The sequence of events during one heartbeat, including diastole and systole.

Stroke Volume

The amount of blood pumped by a ventricle with each contraction.

Cardiac Output

The amount of blood pumped by each ventricle in one minute, typically about 5 L/min.

End Diastolic Volume (EDV)

The total volume of blood in a ventricle at the end of diastole before contraction.

Vagal Tone

The influence of the parasympathetic nervous system on maintaining a resting heart rate.

Congestive Heart Failure

A condition where the heart cannot pump enough blood to meet the body's needs.

Murmurs

Abnormal heart sounds usually caused by turbulent blood flow due to valve problems.