Lecture 1: Cardiac Physiology - Depolarization to Contraction p1 wk2

These flashcards cover key concepts regarding the depolarization and contraction cycle of cardiac muscle, focusing on the mechanisms and physiological principles of action potentials and muscle contraction.

Pacemaker Cells

Cells in the SA node that spontaneously depolarize and generate action potentials.

SA Node

The primary pacemaker of the heart, initiating depolarization.

Action Potential

A rapid electrical impulse that triggers contraction in cardiac cells.

Funny Channels (IF channels)

Unique channels that are permeable to both potassium and sodium, responsible for the pacemaker potential.

T Type Calcium Channels

Calcium channels that open briefly at very negative voltages, facilitating depolarization during the action potential.

L Type Calcium Channels

Voltage-gated calcium channels that contribute to the depolarization phase of the action potential in heart muscle cells.

Repolarization

The process of returning the membrane potential back to its resting state following depolarization.

Vagal Stimulation

Activation of the vagus nerve which increases potassium permeability, leading to hyperpolarization and a decreased heart rate.

Conduction Velocity

The speed at which action potentials are transmitted through cardiac muscle.

Internodal Tracts

Specialized conducting pathways within the atria that assist in signal transmission to the AV node.

Absolute Refractory Period

The phase during which the cardiac cell cannot generate another action potential regardless of the stimulus strength.

Relative Refractory Period

The phase following the absolute refractory period where a new action potential can occur, but requires a stronger than normal stimulus.

Excitation-Contraction Coupling

The process linking the electrical signals of cardiac action potentials to the mechanical contraction of the muscle.

Calcium-Induced Calcium Release

The mechanism where influx of calcium triggers the release of additional calcium from the sarcoplasmic reticulum.

Sliding Filament Theory

A model explaining how muscle contraction occurs through the sliding of actin and myosin filaments.

ATP Production

The process of generating adenosine triphosphate primarily through aerobic respiration in cardiac cells.

Coronary Circulation

The flow of blood to and from the tissues of the heart muscle, supplying necessary oxygen.

Desmosomes

Cell structures that connect cardiac muscle cells and allow for mechanical stability.

Gap Junctions

Channels that allow electrical signaling between heart cells, enabling coordinated contractions.