Autonomic Nervous System Drugs

Question 1

Two major components of Nervous System

Answer 1

Central nervous system (CNS)

Peripheral nervous system (PNS)

Question 2

Central Nervous System

Answer 2

• composed of the brain and the spinal cord.

Question 3

Peripheral Nervous System

Answer 3

• includes nerves outside the brain and spinal cord and consists of sensory neurons and motor neurons.

Question 4

What is Afferent/sensory and Efferent/motor?

Answer 4

Afferent (sensory) - sends impulses to the CNS
Efferent (motor) - receives impulses; transmits through the spinal cord to effector organ cells.

Question 5

Autonomic and Somatic Nervous System

Answer 5

Autonomic NS/ Visceral system - involuntary; controls and regulates the heart, GI, respiratory system, bladder, eyes, and glands.
Somatic NS - voluntary; innervates the skeletal muscles.

Question 6

What is the two divisions of ANS?

Answer 6

Sympathetic division - the SNS contains alpha and beta receptors
Parasympathetic division - the PNS contains nicotinic and muscarinic receptors

Question 7

SNS and PNS functions and homeostasis

Answer 7

• The sympathetic system is associated with the “fight-or-flight” response, and parasympathetic activity is often referred to as “rest and digest.” And homeostasis is the balance between two systems.
  For example, the heart receives connections from both the sympathetic and parasympathetic divisions. SNS stimulation causes the heart rate to increase, whereas PNS stimulation causes the heart rate to decrease.

Question 8

2 Neuron Chain

Answer 8

Neurons - conduct impulses to the synapse of a target organ.

1. Preganglionic neurons, release acetylcholine (ACh) onto nicotinic receptors on the postganglionic neuron.
2. Postganglionic neurons, of the PNS branch are classified as cholinergic, meaning that acetylcholine (ACh) is released, whereas postganglionic neurons of the SNS are classified as adrenergic, meaning that norepinephrine (NE) is released.

Question 9

Synaptic transmission

Answer 9

Synapse - a connection between the neuron and its target cell.

Question 10

What is Sympathetic NS?

Answer 10

• SNS receptors include Alpha-1, Alpha-2, Beta-1, and Beta-2 receptors. Epinephrine and norepinephrine stimulate these receptors, causing the overall fight-or-flight response in various target organs.

Question 11

Adrenergic agonists

Answer 11

• Adrenergic agonists stimulate Alpha-1, Alpha-2, Beta-1, or Beta-2 receptors.
  > Alpha-1 receptor agonists (causes vasoconstriction in the periphery, which increases blood pressure)
  > Alpha-2 receptor agonists (reduces CNS stimulation and is primarily used as an antihypertensive or a sedative)
  > Beta-1 receptor agonists (primarily affects the heart by increasing heart rate and contractility)
  > Beta-2 receptor agonists ( causes relaxation in smooth muscle in the lungs, GI, uterus, and liver)

Question 12

Adrenergic antagonists

Answer 12

• Adrenergic antagonist medications inhibit the Alpha-1, Alpha-2, Beta-1, and Beta-2 receptors.
  > Alpha-1 antagonists (primarily used to relax smooth muscle in the bladder and cause vasodilation)
  > Alpha-2 antagonists
  > Beta-1 antagonists (primarily block receptors in the heart, causing decreased heart rate and decreased blood pressure)
  > Beta-2 antagonists (Nonselective beta blockers block Beta-1 receptors and Beta-2 receptors in the lungs)

Question 13

What is Parasympathetic NS?

Answer 13

• Acetylcholine (ACh) stimulates nicotinic and muscarinic receptors. Drugs that stimulate nicotinic and muscarinic receptors are called cholinergics. Medications are primarily designed to stimulate muscarinic receptors. Nicotine stimulates pre- and post-ganglionic nicotinic receptors, causing muscle relaxation and other CNS effects.

Question 14

Muscarinic agonists

Answer 14

• also called parasympathomimetics and primarily cause smooth muscle contraction, resulting in decreased heart rate, bronchoconstriction, increased gastrointestinal/genitourinary tone, and pupillary constriction. There are two types of muscarinic agonists: direct-acting and indirect-acting.

Question 15

Two types of Muscarinic agonists

Answer 15

• Direct-acting agonists bind to the muscarinic receptor.
• Indirect-acting muscarinic agonists work by preventing the breakdown of ACh, thus increasing the amount of acetylcholine available to bind receptors.

Question 16

Muscarinic antagonists

Answer 16

• referred to as anticholinergics or “parasympatholytics.” Anticholinergics inhibit ACh and allow the SNS to dominate, creating similar effects as adrenergics. Their overall use is to relax smooth muscle.

Question 17

Nursing process with ANS medication

Answer 17

Assessment - Medications that stimulate ANS receptors often impact the heart, lungs, and blood vessels, so the nurse must often monitor blood pressure, heart rate, and lung sounds carefully for expected therapeutic effects and side effects. Anticholinergics cause muscle relaxation and can cause urinary retention, constipation, and dry mouth.

Question 18

Nursing process

Answer 18

Planning
Common goals include:
> Patient will adhere to the drug regimen.
> Patient’s vital signs will be within the desired range.

Question 19

Nursing process

Answer 19

Implementation of Interventions
> Report any marked vital signs changes or suspected adverse effects.
> Implement fall precautions, when needed, based on anticipated side effects of ANS medications.

Question 20

Nursing process

Answer 20

Evaluation - It is always important for nurses to know the reason why a medication is ordered for a specific patient, so evaluation of therapeutic effectiveness can be documented. Otherwise, the side effects may not warrant the use of the medication.