Cardiac Muscle Cells and Heart Physiology

Flashcards covering key concepts related to cardiac muscle cells, their physiology, and the intrinsic mechanisms that regulate heart function.

Intercalated disc

Junctions between cardiac muscle cells that synchronize heart contractions and allow ion passage.

Cardiac Pacemaker Cells

Specialized cardiac cells that initiate and regulate the heartbeat.

Action Potential Plateau

A prolonged depolarization phase in cardiac muscles due to calcium influx.

CICR (Calcium-Induced Calcium Release)

The process by which calcium influx triggers the release of more calcium from the sarcoplasmic reticulum.

Intrinsic Cardiac Conduction System

The network of cardiac cells responsible for initiating and coordinating the heart's electrical impulses.

Muscle Fiber Types

Differentiation of muscle cells: Skeletal (voluntary), Cardiac (involuntary), Smooth (involuntary with intrinsic control).

Gap Junctions

Specialized intercellular connections that facilitate electrical coupling between adjacent cardiac cells.

T-tubules

Transverse tubules that help transmit action potentials to the interior of cardiac muscle cells.

Sinoatrial (SA) Node

The primary pacemaker of the heart, located in the right atrium.

Atrioventricular (AV) Node

The node that delays electrical impulses from the atria to allow for complete atrial contraction prior to ventricular contraction.

Cardiomyocytes

Heart muscle cells responsible for contraction and heart movement.

Refractory Period

A period during which cardiac muscle can't be stimulated again, preventing tetany.

Norepinephrine

A neurotransmitter that increases heart contraction force by activating beta-adrenergic receptors.

Acetylcholine

A neurotransmitter that decreases heart rate by acting on muscarinic receptors.

Troponin

A protein that regulates muscle contraction by binding calcium ions.

Myoglobin

Oxygen-binding protein in cardiac muscle cells that supports aerobic respiration.

Heart Rate Regulation

Controlled by the autonomic nervous system: sympathetic (increases rate) and parasympathetic (decreases rate).