Neurotransmitters and Drugs Affecting the Autonomic Nervous System

These flashcards review the divisions of the nervous system, functions of autonomic branches, catecholamines, adrenergic receptors, pharmacologic agents, therapeutic uses, side effects, and nursing considerations.

What two main divisions make up the nervous system?

The Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

Which structures compose the CNS?

The brain and spinal cord.

How many pairs of cranial and spinal nerves are in the PNS?

12 pairs of cranial nerves and 31 pairs of spinal nerves.

What is the primary function of the Somatic Nervous System (SNS)?

Voluntary control of skeletal muscle contractions.

Which branch of the PNS provides involuntary control over smooth muscle, cardiac muscle, and glands?

The Autonomic Nervous System (ANS).

List three classic sympathetic (fight-or-flight) responses.

Increased heart rate, vasoconstriction/raised blood pressure, and bronchodilation.

Give three typical parasympathetic (rest-and-digest) effects.

Slowed heart rate, increased intestinal peristalsis, and relaxation of sphincters.

What are catecholamines?

Substances (endogenous or synthetic) that produce sympathomimetic responses.

Name the three endogenous catecholamines.

Epinephrine, norepinephrine, and dopamine.

Which synthetic catecholamine is commonly used as a bronchodilator?

Isoproterenol (also acceptable: albuterol is a synthetic β2 agonist but not a catecholamine).

Which additional adrenergic receptor is stimulated specifically by dopamine?

Dopaminergic receptors.

Stimulation of dopaminergic receptors primarily causes dilation of which four vascular beds?

Renal, mesenteric, coronary, and cerebral blood vessels.

Alpha-adrenergic receptors respond primarily to which neurotransmitter?

Norepinephrine (NE).

Beta-adrenergic receptors respond primarily to which neurotransmitter?

Epinephrine (EPI).

Where are α1 receptors located and what is a key effect of their activation?

Smooth muscle, heart, and liver; activation causes vasoconstriction (smooth-muscle contraction).

What is a primary action of α2 receptor activation?

Inhibition of norepinephrine release and insulin secretion, plus vasoconstriction and platelet aggregation.

Where are β1 receptors mainly found and what do they do when stimulated?

Primarily in the heart; they increase heart rate, force of contraction, and AV conduction.

List three major sites of β2 receptors.

Lungs, vascular smooth muscle, and uterus (also GI tract and liver).

Why are β2 agonists used in asthma therapy?

They relax bronchial smooth muscle, causing bronchodilation.

Which receptor class do drugs like propranolol block?

β-adrenergic receptors (non-selective beta blockers).

What therapeutic effect do α1 antagonists have on blood pressure?

They cause vasodilation, lowering peripheral vascular resistance and blood pressure.

State one example of an adrenergic anorexiant and its role.

Phentermine; used as a short-term adjunct for weight loss by suppressing appetite.

How do topical adrenergic agents act as nasal decongestants?

They constrict dilated nasal arterioles, reducing nasal blood flow and congestion.

Name two vasoactive sympathomimetics used to support the heart in shock.

Dobutamine and dopamine (others: epinephrine, isoproterenol, fenoldopam).

List two common CNS side effects of alpha-adrenergic stimulation.

Headache and restlessness (also excitement, insomnia, euphoria).

What cardiovascular side effect can β-adrenergic stimulation cause?

Palpitations or dysrhythmias due to increased heart rate.

Before giving an adrenergic agent, which three baseline assessments should a nurse perform?

Vital signs, peripheral pulses/skin perfusion, and renal/hepatic/cardiac function history.

How do cardioselective (β1) beta blockers reduce myocardial oxygen demand?

They decrease heart rate, prolong SA node recovery, slow AV conduction, and lessen contractility.

What condition can α-blockers help relieve by decreasing resistance to urinary outflow?

Benign prostatic hyperplasia (BPH).

Which receptor’s activation leads to mydriasis (pupil dilation) and is used in treating open-angle glaucoma?

α-adrenergic receptor activation (via drugs like epinephrine or dipivefrin).