Autonomic Nervous System Flashcards
What are the two major portions the autonomic nervous system is divided into?
Parasympathetic and Sympathetic
What is the third (not so major) portion of the autonomic nervous system?
Enteric (GI tract)
What is that parasympathetic system chiefly involved in?
Maintaining normal (resting) function of body
What is the sympathetic system chiefly involved in?
Regulating organ function during excitement or stress
T/F: When both systems act on the same organ, their actions are usually opposite
True
What would be a non-invasive way to assess autonomic function of a patient being rushed into the ER?
Shine a light into eyes to look for dilation or contraction of pupil
T/F: Both PNS and SNS innervate muscles in the iris
True (muscle contraction happen in both cases)
Sympathetic muscle contraction causes ____ in the iris
Mydraisis (dilation)
Parasympathetic muscle contraction causes ____ in the iris
Myosis (contraction)
How do neurons talk to each other or to other muscles/target organs in the ANS?
Neurotransmitters are released
What are the 5 events in the life of a neurotransmitter?
- Synthesis
- Storage
- Release
- Receptor binding
- Disposition (signal must be stopped in some way)
What are 2 major neurotransmitters in the ANS?
Acetylcholine (ACh): “Cholinergic” neurons/synapses
Epinephrine/Adrenalin (Epi)
Norepinephrin (NE): “adregergic” neurons/synapses
Where do the nerves originate in the PNS?
Medulla and sacral segments of spinal cord
What does the PNS innervate?
Cardiac and smooth muscle, gland cells, nerve terminals
What does the SNS innervate?
Sweat glangs, cardiac and smooth muscle, gland cells, nerve terminals, renal vascular smooth muscle in the kidney
Describe the preganglionic and postganglionic neurons in the PNS
Preganglionic neurons: long; synapse in peripheral ganglia near or in target organ
Postganglionic neurons: short; extend to targets; few postganglionic neurons for every preganglionic neuron
Describe the preganglionic and postganglionic neurons in the SNS
Preganglionic neurons: short; emerge from intermediolateral nuclei or thoraco-lumbar segments of spinal cord (T1-T3); synapse in paravertebral sympathetic ganglis, prevertebral ganglia, or adrenal medulla.
Postganglionic neurons: Several (as many as 20) for every preganglionic neuron; causes amplification and generalization of the signal
Targets of the SNS include:
Sweat and salivary glands, heart, lungs, pancreas, stomach, intestine, colon, sexual organs, kidneys, bladder
Targets of PNS include:
intrinsic eye muscles, salivary and lachrymal glands, heart, lungs, pancreas, stomach, intestine, colon, sexual organs, kidney, bladder
Preganglionic neurons of PNS signal through release of _____
ACh
What kind of receptors do Postganglionic neurons express in the PNS?
Nicotinic ACh (nAChR)
Postganglionic neurons of PNS signal the target through release of _____
ACh
What receptors do the target organs express in the PNS?
Muscarinic ACh (mAChR)
Preganglionic neurons of SNS signal through release of _____
ACh
What receptors do the postganglionic neurons express in the SNS?
Nicotinic ACh (nAChR)
Most postganglionic neurons of SNS signel the target through release of ___ or ___
Epi or NE
What receptors do the target organs of the SNS express?
alpha or beta adrenergic receptors
NE acts mainly as a _____
Neurotransmitter
Epi acts mainly as a ____
Neurohormone - signals humorally throughout body
What are the 2 types of cholinergic receptors?
- Nicotinic ACh receptors (nAChR)
2. Muscarinic ACh receptors (mAChR)
_____ receptors are ion channels that, when activated by agonist, allow influx of Na ions to excite the neuron.
nAChR
______ receptors are G protein-coupled receptors that signal through second messenger systems to excite the neuron.
mAChR
