Anatomy and Pharmacology of the Autonomic Nervous System

A set of vocabulary flashcards covering the divisions of the nervous system, neurotransmitters, receptor subtypes, and pharmacological agents acting on the autonomic nervous system.

Central Nervous System (CNS)

The division of the nervous system made up of the brain and spinal cord.

Peripheral Nervous System (PNS)

A network of spinal nerves and cranial nerves outside the brain that carries information between the CNS and the rest of the body.

Autonomic Nervous System (ANS)

The division of the nervous system that controls vegetative functions such as circulation, respiration, digestion, and maintenance of body temperature.

Homeostasis

The process of maintaining a constant internal environment or a state of equilibrium.

Preganglionic neuron

A neuron with its cell body in the spinal cord or brain and myelinated fibers that originate before the ganglia.

Postganglionic neuron

A non-myelinated neuron that sends its axons directly from the ganglia to the effector organs.

Sympathetic Nervous System

The thoracolumbar division of the ANS that prepares the body for 'fight or flight' and involves expenditure of energy.

Parasympathetic Nervous System

The craniosacral division of the ANS that returns the body to a 'rest and digest' state and is associated with conservation of function.

Acetylcholine (ACh)

The chief neurotransmitter of the parasympathetic nervous system released at ganglia, postganglionic nerve endings to sweat glands, and neuromuscular junctions.

Choline acetyltransferase (CAT)

The enzyme responsible for synthesizing acetylcholine from acetyl coenzyme A and choline inside the cytoplasm of nerve fibers.

Acetylcholinesterase (AChE)

The enzyme that terminates the action of acetylcholine by hydrolyzing it into choline and acetate.

Muscarinic receptors (M)

Cholinergic receptors typically found in the peripheral visceral organs that respond to muscarine.

Nicotinic receptors (N)

Cholinergic receptors found in autonomic ganglia and skeletal muscle neuromuscular junctions.

Adrenergic receptors

Receptors that respond to noradrenaline and are subdivided into alpha ($\alpha$) and beta ($\beta$) types.

$\alpha_1$ Receptors

Adrenergic receptors located in most vascular smooth muscles (causing contraction), pupillary dilator muscle (causing mydriasis), and the heart.

$\beta_1$ Receptors

Adrenergic receptors located in the heart that increase the rate and force of contraction.

$\beta_2$ Receptors

Adrenergic receptors located in respiratory, uterine, and vascular smooth muscle that cause relaxation, and in the liver to promote glycogenolysis.

Sympathomimetics

Adrenergic drugs that mimic the effects of sympathetic nerve stimulation.

Parasympathomimetics

Cholinergic drugs that mimic acetylcholine or the effects of parasympathetic nerve stimulation.

Mydriasis

Dilation of the pupil of the eye.

Miosis

Constriction of the pupil of the eye.

Bethanechol

A synthetic choline ester similar to carbachol but with fewer side effects due to a lack of nicotinic actions.

Pilocarpine

A cholinergic alkaloid with chiefly muscarinic actions used primarily in the treatment of glaucoma.

Myasthenia Gravis

A chronic autoimmune disorder where antibodies destroy the communication between nerves and muscles, resulting in skeletal muscle weakness.

Neostigmine

A reversible cholinesterase inhibitor used to treat myasthenia gravis and paralytic ileus; it does not cross the blood-brain barrier.

Physostigmine

An anticholinesterase drug that is highly distributed throughout the body, can pass the blood-brain barrier, and is used for glaucoma or atropine overdose.

Atropine

The prototype muscarinic antagonist derived from Atropa belladonna that antagonizes acetylcholine and causes effects like tachycardia and bronchodilation.

Cycloplegia

Loss of the ability to accommodate for near objects due to the relaxation or weakening of the ciliary muscle.

Catecholamines

Direct-acting adrenergic drugs with a catechol nucleus, including adrenaline, noradrenaline, dopamine, and isoprenaline.

Adrenaline (Epinephrine)

A catecholamine produced by the adrenal medulla that stimulates all alpha ($\alpha$) and beta ($\beta$) receptor subtypes.

Noradrenaline (Norepinephrine)

A predominantly alpha ($\alpha$) receptor agonist used as a hypertensive agent in hypotensive states.

Prazosin

An alpha-adrenergic blocker with high affinity for $\alpha_1$ receptors, used for management of hypertension and benign prostatic hyperplasia.

Propranolol

A non-selective $\beta$ adrenergic blocker used for hypertension, cardiac arrhythmias, and prophylaxis against migraine and angina.