CVS 6

Flashcards covering the extrinsic nervous and endocrine control of the heart.

Autonomic Nervous System

The nervous system that includes both the parasympathetic and sympathetic systems, influencing heart function.

Parasympathetic System

Part of the autonomic nervous system; releases acetylcholine (ACh) to slow heart rate.

Sympathetic System

Part of the autonomic nervous system; releases noradrenaline (NA) to increase heart rate and contraction strength.

Acetylcholine (ACh)

Neurotransmitter released by the parasympathetic system that acts on cholinergic receptors.

Cholinergic Receptors

Receptors that bind acetylcholine (ACh), including nicotinic and muscarinic receptors.

Nicotinic Receptors

Type of cholinergic receptor; at these receptors, ACh causes the opening of Na+ channels. Also found on skeletal muscle cells.

Muscarinic Receptors

Type of cholinergic receptor; at these receptors, ACh causes the opening of K+ channels.

SA Node Action Potentials

Electrical signals generated in the sinoatrial (SA) node that initiate heartbeats.

Hyperpolarization

Making the membrane potential more negative; a parasympathetic effect on the SA node.

Depolarization

Making the membrane potential less negative; a sympathetic effect on the SA node.

Adrenergic Receptors

Receptors that bind noradrenaline (NA) and adrenaline; Beta-1 (β1) receptors are mainly found on cardiac muscle cells.

Noradrenaline (NA)

Neurotransmitter released by the sympathetic system. Causes Na+ inflow through adrenergic receptors and increased contraction strength via Ca2+ channels.

AV Node

The atrioventricular node that is affected by both the parasympathetic (increases conduction delay, reduces heart rate) and sympathetic systems (decreases conduction delay, increases heart rate).

Stroke Volume

The amount of blood ejected by the heart with each beat. Increased by sympathetic activation.

Adrenal Medulla

Releases noradrenaline and adrenaline (hormones) into the circulation, affecting the SA node, AV node, and ventricular myocardium.