Autonomic Nervous System Flashcards
Pathway of a typical reflex arc is:
AP from periphery → afferent neuron → dorsal root of spinal cord → ventral root of spinal cord → efferent neuron (motoneuron) → AP to periphery
Nociceptors are what kind of receptors?
Pain receptors
Smooth muscle does or does not have motorneurons?
Does not
Autonomic Nervous System reflexes happen within what regions of the brain?
Lower regions (brainstem, hypothalamus)
The ANS is used to control what part of the body?
The viscera - the autonomic system
Sensory information travels along a what and goes to where?
Afferent neuron to the CNS
The efferent side of the ANS relays messages to what?
Effectors
What are effectors for the ANS?
Smooth muscle, glands
What are not effectors for the ANS?
Skeletal muscle
What are the two divisions of the ANS?
The sympathetic and parasympathetic system
The sympathetic division does:
fight or flight
The parasympathetic division does:
rest and digest
The ANS always has how many neurons in its pathway to an effector?
Two
The ANS always has how many synapses in its pathway to an effector?
Two
The first neuron in the ANS pathway is called the what?
Pre-ganglionic neuron
Where does the pre-ganglionic neuron start?
The CNS
Map the pathway of a pre-ganglionic neuron:
CNS. Leaves CNS. Travels to ganglion. Synapses on second neuron in pathway.
What is a ganglion?
Cluster of neuronal cell bodies. Is the location where the pre-ganglionic axon synapses on the post-ganglionic neuron.
Where does the post-ganglionic neuron travel after the ganglion?
To the target organ to synapse all over it
What are three ways of distinguishing between parasympathetic and sympathetic systems?
Where the pre-ganglion leaves the CNS, the location of the ganglion and the lengths of the pre and post ganglionic axons
Where do the parasympathetic pre-ganglionic axons leave the CNS?
from the cranial and sacral divisions of the CNS
Where is the parasympathetic ganglion located?
In or on the target tissue
If the parasympathetic ganglion is located in or on the target tissue, then the parasympathetic PRE-ganglionic axon must be: short or long?
LONG
If the parasympathetic ganglion is located in or on the target tissue, then the parasympathetic POST-ganglionic axon must be: short or long?
SHORT
Where do the sympathetic pre-ganglionic axons leave the CNS?
thoracic and lumbar divisions of the CNS
What is PLS?
PLS = Parasympathetic, long then short
Where is the sympathetic ganglion?
Either: the sympathetic chain (paravertebral) OR the mesenteric OR the celiac ganglia
If the sympathetic ganglion is located so close to the vertebral column, then the sympathetic PRE-ganglionic axon must be: short or long?
SHORT
If the sympathetic ganglion is located so close to the vertebral column, then the sympathetic POST-ganglionic axon travel a short or long distance to its target tissue?
LONG
What is SSL?
Sympathetic, Short, Long
What is the NT from the parasympathetic pre-ganglion?
Acetylcholine
Acetylcholine binds to what receptor in post-synaptic parasympathetic ganglia?
nicotinic acetylcholine receptors
Nicotinic acetylcholine receptors allow what ion to pass through? This results in IPSP or EPSP in the post-synaptic ganglioc cell?
Sodium and EPSPs. Producing an AP
ANS nerves have what kind of junctions that differ from skeletal muscle junctions?
Varicosities
If I was a varicosity on the pre-synaptic, parasympathetic axon, I would have what NT inside me?
Acetylcholine
How much NT leakage into systemic circulation do we have with varicosities in the ANS?
Substantial
What kind of acetlycholine receptor is found on the effector cell following the post-synaptic neuron?
Muscarinic acetlycholine receptors
Muscarinic acetlycholine receptors differ from nicotinic acetylcholine receptors how?
mAchRs are serpentine receptors or G-protein coupled receptors
Muscarinic receptor 2 (M2) is where and does what?
M2 is a cardiac receptor and is Gi-coupled, which means it decreases cAMP concentration, which in turn increases K+ conductance (K+ out)
Muscarinic receptor 3 (M3) is where and does what?
M3: (widely distributed in body): Gq coupled, which means it produces IP3 and DAG which ultimately increases intracellular Ca++
Muscarinic receptor 4 (M4) are where and do what?
M4 (autoreceptors on neurons): Gi-coupled -decrease
cAMP which leads to a decrease Ach release
What NT is released by pre-ganglionic fiber in sympathetic nervous system?
Acetylcholine
What NT is released by POST-ganglionic fiber in sympathetic nervous system?
Norepinephrine = adrenaline
How many receptor types are there for norepinephrine?
Two types, alpha-adrenergic (with several subdivisions) and beta-adrenergic receptors (with three subdivisions)
α-adrenergic receptors have a higher or lower affinity for norepinephrine than epinephrine
Higher affinity for norepinephrine
β-adrenergic receptors have a higher or lower affinity for norepinephrine than epinephrine
Higher affinity for epinephrine
Where is epinephrine produced?
Within the chromaffin cells of the adrenal medulla
Chromaffin cells in the adrenal medulla secrete epinephrine in response to what NT from what system (parasympathetic or sympathetic)?
acetylcholine from sympathetic signaling
The Radial muscle (iris) has what receptor?
α-adrenergic (contracts muscle to dilate pupils)
The Ciliary muscle (lens) has what receptor?
β2-adrenergic (relaxes muscle flattens lens = allow distant vision)
The heart has what kind of receptor?
β2-adrenergic (increases strength/rate of contraction)
In general, α receptors cause contraction of vascular
smooth muscle and lead to vasoconstriction, true or false
True
In general, β receptors cause relaxation of vascular
smooth muscle and lead to vasodilation, true or false
True
Bronchial SM has what receptors which increase or decrease bronchodilation?
β2-adrenergic receptors to relax the SM and allow more air intake. Causes bronchodilation
Bronchial glands have what receptors which increase or decrease mucal secretions?
β2-adrenergic receptors which increase secretions and increase humidified air intake
The sphincters in the GI tract have what receptors in order to increase sphincter tone?
Alpha-1 adrenergics
The liver has what receptors in order to increase glucose release?
alpha 1 and beta-2 adrenergics
Adipose tissue has what receptors in order to increase free fatty acide release?
alpha-1, beta-1, and beta-3 adrenergics
If no effect is seen in parasympathetics this is because we:
don’t have parasympathetic receptors there
Action of parasympathetic system is signaled through what receptors?
muscarinic acetlycholine receptors
