Cell signalling

Sympathetic Nervous System

Increases heart rate and force of contraction via beta-1 adrenergic receptors.

Parasympathetic Nervous System

Decreases heart rate, particularly through the vagus nerve.

Beta-1 Adrenergic Receptors

Primarily responsible for increasing heart rate and the force of contraction.

Muscarinic M2 Receptors

Modulate heart rate primarily by decreasing heart rate through the autonomic nervous system.

Action Potential Firing

Increased sympathetic activity leads to a steeper slope in diastolic potential, resulting in quicker action potential firing in pacemaker cells.

Cyclic AMP (cAMP)

Second messenger that activates Protein Kinase A (PKA) in response to beta-adrenergic signaling.

Protein Kinase A (PKA)

Enzyme activated by cyclic AMP that phosphorylates target proteins to regulate cardiac function.

Excitation-Contraction Coupling

Biochemical process linking the electrical signals from cardiac muscle action potentials to muscle contraction.

Calcium Transients

Increases in intracellular calcium levels that precede cardiac muscle contraction.

Ryanodine Receptors (RyR2)

Calcium release channels in the sarcoplasmic reticulum activated by calcium influx.

Phosphodiesterases (PDEs)

Enzymes that degrade cyclic AMP, thereby modulating signaling cascades.

Adenylyl Cyclase

Enzyme that converts ATP to cyclic AMP, crucial for beta-adrenergic signaling.

Regulator of G Protein Signaling (RGS)

Proteins that enhance the intrinsic GTPase activity of G proteins, aiding in the termination of signaling.

G Protein-Coupled Receptors (GPCRs)

A large family of receptors, including adrenergic receptors, that transmit signals in response to various stimuli.

Beta-2 Adrenergic Receptors

Receptors that mediate vasodilation and can also affect cardiac function, often showing differential sensitivity.

Negative Feedback Mechanism

Regulatory process where increased activation leads to mechanisms that reduce overall signaling.

Receptor Desensitization

The process where prolonged exposure to agonists leads to reduced receptor responsiveness.

Clathrin-Mediated Endocytosis

Mechanism by which receptors are internalized after binding to ligands.

Calcium Sensing by Mitochondria

Mitochondria's ability to detect calcium levels and modulate energy production accordingly.

Differential Receptor Activation

Unique responses elicited by different adrenergic receptor subtypes under various physiological conditions.

Homologous Desensitization

Desensitization of a receptor which has been activated by its specific agonist.

Beta-3 Adrenergic Receptors

Receptors that can negatively impact cardiac contractility, particularly in heart disease.

Guanine Nucleotide Exchange Factors (GEFs)

Proteins that facilitate the exchange of GDP for GTP on G proteins, activating them.

Calcium-Induced Calcium Release

Mechanism where calcium influx triggers further calcium release from the sarcoplasmic reticulum.