NURS 2042 - Autonomic Nervous System Overview (notes)

What are the two major divisions of the nervous system described in the lecture, and which one is the focus?

The nervous system divides into the central nervous system (brain and spinal cord) and the peripheral nervous system; the lecture focuses on the peripheral nervous system.

Within the peripheral nervous system, what are the two components and which one is involuntary?

The somatic division (voluntary) and the autonomic division (involuntary); the autonomic nervous system is involuntary.

Which two branches make up the autonomic nervous system and what are their neurotransmitter types?

The sympathetic (adrenergic) system and parasympathetic (cholinergic) system; adrenergic uses catecholamines, while cholinergic uses acetylcholine.

What catecholamines are naturally produced in the body and their common abbreviations?

Norepinephrine (NE or “nor-epi”), epinephrine (Epi), and dopamine (DA or “dopa”).

What primary roles does norepinephrine play in the body?

It acts mainly on blood vessels to increase heart rate, cause vasoconstriction, raise blood pressure, and increase blood glucose by inhibiting insulin.

What are the major actions of epinephrine?

It primarily acts on the heart to raise heart rate, elevate blood pressure, and increase blood glucose.

What are dopamine’s key functions in the sympathetic system?

It regulates movement, mood/pleasure, motivation, and affects renal perfusion leading to increased urine output.

Where are alpha-1 adrenergic receptors located and what do they do?

They are found in blood vessels, causing vasoconstriction, decreased GI motility, uterine contraction, and pupil dilation.

What are the primary actions of beta-1 adrenergic receptors?

Located in the heart, they increase heart rate, increase contractility, and cause uterine relaxation.

What do beta-2 receptors do in the lungs and other tissues?

They promote bronchodilation, smooth muscle relaxation, uterine relaxation, vasodilation, and decreased GI motility.

Which neurotransmitter binds dopaminergic receptors and what does stimulation cause?

Only dopamine binds; it increases renal perfusion, increases urine output, decreases blood pressure, and improves glucose availability.

What is the general role of the sympathetic nervous system?

It produces the “fight or flight” response, using catecholamines to increase heart rate, blood pressure, glucose, and redirect blood flow.

What is the general role of the parasympathetic nervous system?

It produces the “rest and digest” response using acetylcholine to promote digestion, urination, secretions, and calming of the body.

Which neurotransmitter activates the parasympathetic system?

Acetylcholine.

What are the two types of cholinergic receptors?

Nicotinic receptors and muscarinic receptors.

Where are nicotinic receptors located and what are their effects?

Located in ganglia; they increase blood pressure, raise heart rate, constrict pupils, increase GI/GU motility, relax sphincters, and increase muscle contraction.

Where are muscarinic receptors found and what do they cause?

Found in organs; they increase secretions, dilate vessels to lower blood pressure, constrict pupils, and increase GI/GU motility.

How do adrenergic and cholinergic systems compare in terms of heart rate?

Adrenergic increases heart rate (fight/flight), while cholinergic decreases heart rate (rest/digest).

How do both systems affect pupils and GI motility?

Both can cause constriction/dilation depending on receptor subtype; both influence GI motility — adrenergic decreases it, cholinergic increases it.

What happens when the sympathetic (adrenergic) system is “turned on”?

Catecholamines are released producing the fight-or-flight response: increased HR/BP, bronchodilation, glucose release, and vasoconstriction.

What happens when parasympathetic agonists are activated?

They enhance rest-and-digest functions such as digestion, secretions, urination, and decreased heart rate.

What happens when parasympathetic antagonists (anticholinergics) are used?

They “turn off” parasympathetic activity, causing a dry state: increased HR, decreased secretions, decreased GI motility, and pupil dilation.