Autonomic Nervous System (ANS) Review

PHRM 3550

What is the ANS?

a system of afferent & efferent nerves and reflexes that regulates smooth muscle, cardiac muscle, & glands

What does the ANS consist of?

afferent nerves, efferent nerves, & reflexes

What is the function of the ANS?

permits the body to adjust to alterations in the internal & external environment

What are the two divisions of the ANS?

Sympathetic Nervous System (SNS) & Parasympathetic Nervous System (PNS)

What does the SNS prepare the body for?

stressful situations (fight or flight)

What does the PNS maintain?

homeostasis & vegetative functions

What are the neurotransmitters of the SNS?

norepinephrine (NE) & epinephrine (EPI)

What is the neurotransmitter of the PNS?

acetylcholine (ACh)

What is the outflow of the SNS?

thoracolumbar

What is the outflow of the PNS?

craniosacral

What are the sympathetic receptor types?

Alpha-1, Alpha-2, Beta-1, & Beta-2

What is the general response of Alpha-1 receptors?

usually excitatory

What is the general response of Alpha-2 receptors?

usually inhibitory

What is the general response of Beta-1 receptors?

usually excitatory

What is the general response of Beta-2 receptors?

usually inhibitory

What is the receptor profile of norepinephrine?

acts equally on Alpha-1, Alpha-2, & Beta-1 receptors, but minimally on Beta-2 receptors

What is the receptor profile of epinephrine?

acts equally on Alpha-1, Alpha-2, Beta-1, & Beta-2 receptors

What is the discharge pattern of the PNS?

limited & discrete

What is the discharge pattern of the SNS?

discrete or massive

What is an example of discrete SNS discharge?

heat regulation & vasodilation to skeletal muscle blood vessels

What is an example of massive SNS discharge?

reaction to stress (fight or flight)

What happens to the heart during SNS stress reaction?

increased HR & contractile force via Beta-1

What happens to sweating during SNS stress reaction?

increased in apocrine glands activated by epinephrine

What happens to cutaneous (skin) blood vessels during SNS stress reaction?

constriction via Alpha-1

What happens to skeletal muscle & coronary blood vessels, & bronchi during SNS stress reaction?

dilation via Beta-2

What happens to the pupils during SNS stress reaction?

dilation (mydriasis) via Alpha-1 & Beta-2

What happens to glycogen during SNS stress reaction?

glycogenolysis (glycogen breakdown) mediated by Beta receptors

What does "cholinergic" mean?

it refers to acetylcholine-mediated signaling

What are the 2 types of cholinergic receptors?

muscarinic & nicotinic

What are the 2 types of nicotinic receptors?

Ng (ganglionic) & Nm (skeletal muscle)

What is Ng?

nicotinic receptor found in ganglia

What is Nm?

nicotinic receptor found at the neuromuscular junction of skeletal muscle

What is the neurotransmitter of the somatic nervous system?

ACh acting at Nm receptors

What is the transmitter at sympathetic ganglia?

ACh acting at nicotinic ganglionic receptors (Ng)

What is the transmitter at parasympathetic postganglionic endings?

ACh acting at muscarinic receptors