Circuits Flashcards
Typical sympathetic nervous system circuit
Presynaptic neuron releases Ach –> binds nAchR on postsynaptic neuron –> Postsynaptic neuron releases NE –> binds AdR
Parasympathetic nervous system circuit
Presynaptic neuron releases Ach –> binds nAchR on postsynaptic neuron –> postsynaptic neuron releases Ach –> binds mAchR
Exceptions to the typical sympathetic nervous system circuit
Sweat glands (postsynaptic neuron releases Ach –> binds nAchR)
Adrenal medulla Chromaffin cells (presynaptic neuron releases Ach –> binds nAchR on chromaffin cell –> chromaffin cell releases E/NE directly into circulation)
Effects of sympathetic nervous system on heart? Parasympathetic?
SNS: Increased rate (SA), increased contractility (A/V), increased conduction velocity (AV)
PNS: Decreased rate (SA), decreased contractility (A), decreased conduction velocity (AV)
Effects of SNS on eye? PNS?
SNS: Mydriasis, relaxation of ciliary muscle = flattening lense (far vision)
PNS: Miosis, contraction of ciliary muscle = rounding of lense (AKA accomodation, near vision)
Effects of SNS/PNS on lacrimal glands?
SNS: None
PNS: Increased secretion
Effect of SNS/PNS on lungs?
SNS: bronchodilation
PNS: bronchoconstriction
Effects of SNS/PNS on sweat glands?
SNS: Increased secretion
PNS: None
Effects of SNS/PNS on Liver?
SNS: glycogenolysis
PNS: none
Effects of SNS/PNS on GI tract?
SNS: Inhibition of peristalsis and secretion
PNS: Stimulation of peristalsis and secretion
Effects of SNS/PNS on colon/bladder?
SNS: inhibition of peristalsis
PNS: contraction
Effects of SNS/PNS on Salivary glands?
SNS: some secretion
PNS: secretion
Effects of SNS/PNS on arterioles/veins?
SNS: vasoconstriction
PNS: none
What has predominantly sympathetic tone? Parasympathetic tone?
SNS: blood vessels, sweat glands
PNS: heart, GI/GU, salivary glands, eye
Where are presynaptic SNS/PNS neurons located?
SNS: lateral horn of T1-T12
PNS: brainstem and sacral
