The Autonomic Nervous System Flashcards
(19 cards)
Where does the sensory information go?
Through the afferent neuron to the dorsal spinal cord.
How does the motor response go?
Through the ventral spinal cord to the efferent neuron (motor neuron)
Autonomic nervous system
Comes out of the ventral spinal cord.
Unlike the withdrawal reflex, most
of the integration of autonomic
reflexes occurs within the
brain
,
although at lower levels
(brainstem, hypothalamus) rather
than the cortex.
The Autonomic Nervous system has 2 parts, what are they?
- Sympathetic
- Parasympathetic
What is the structure of the ANS that goes to the effector cell?
Neuron #1 is Pre-ganglionic
•Starts in the CNS (so it gets the message from
the brain)
•Leaves the CNS*
•Travels to a ganglion
•Where it will synapse on the second neuron in
the pathway.
Neuron #2 is Post-ganglionic
What is a ganglion?
The ganglion is a cluster of neuronal cell bodies. The pre-ganglionic axon synapses on the post-ganglionic neuron here.
The post-ganglionic neuron then travels to the target organ and synapses
on it.
Where do the pre-ganglionic axons leave for the parasympathetic?
The axons of the parasympathetic pre-ganglionic axons leave the
CNS from the:
- Cranial
- Sacral
What is the length of the pre and post ganglion axons in Parasympathetic?
In the parasympathetic nervous system, the
ganglia are located on or near the target organs.
In the parasympathetic nervous system, the pre-ganglionic fiber is long,
while the post-ganglionic axon is short.
PLS
Where do the axons for the Sympathetic leave the CNS?
The axons of the sympathetic
pre-ganglionic axons leave the CNS from the:
• thoracic
• lumbar
What is the length of the pre and post ganglionic fibers of the Sympathetic ANS?
In the sympathetic nervous system, the ganglia are
located in the sympathetic chain, just outside the
vertebral column.
In the sympathetic nervous system, the pre-ganglionic
fiber is short, while the post-ganglionic axon is
long.
SSL
What are the neurotransmitters for pre and post ganglionic fibers in Parasympathetic?
In the parasympathetic nervous system, the
neurotransmitter released by the pre-ganglionic fiber
is Acetylcholine.
The nicotinic Ach receptor
is expressed on the post-
ganglionic cells’ dendrites.
We see a muscarinic receptor on the effector cell.
What are en passant synapses?
Instead of the specialized synaptic structure
we saw in the CNS, these synapses are en passant
(in passing).
It’s more like the mailman throwing your mail
out of the window as he/she goes by your
house…
Autonomic nerves have varicosities, little swellings
along the length of the axon.
What are the neurotransmitters released in the Sympathetic?
In the sympathetic nervous system, the
neurotransmitter released by the pre-ganglionic fiber
is Acetylcholine.
The nicotinic Ach receptor is expressed
on the post-ganglionic cells’ dendrites.
In the sympathetic nervous system, the neurotransmitter released
by the post-ganglionic fiber is norepinephrine.
What receptors can Norepinephrine bind to?
• alpha-adrenergic receptors (of which there
are several)
• beta-adrenergic receptors (of which there
are three…)
What type of receptors do NE/epi use?
• All of the NE/epi receptors are
serpentine receptors that connect to G-proteins.
• alpha-adrenergic
•beta-adrenergic: 3 subtypes, all raise cAMP
How is the adrenal medulla different (Sympathetic response)?
Innervated by a pre-ganglionic axon that has travelled through the
sympathetic chain ganglion without synapsing.
Within the medulla, we have chromaffin cells that produce
epinephrine…
Since this is a pre-ganglionic neuron coming
in, we have acetylcholine acting at nicotinic
receptors…
Epinephrine released to the blood
(some dopamine and
norepinephrine too)
What does the parasympathetic system do?
- *The parasympathetic system**
- *“rest and digest”**
- Have plenty of oxygen
- Heart beating slowly
- Blood Pressure is relatively low
- Digesting food, so intestine gets the blood
- Getting fuel from the GI tract
What does the Sympathetic system do?
The Sympathetic System
“Fight or Flight”
•Need lots of oxygen
•Get the O2 to the muscle
•Heart pumping fast, hard
•Aren’t going to worry about
digesting (since being
digested is much more
immediately on your
mind…)
•Need the fuel to run with.
What is the general rule of thumb with the adrenergic receptors?
• alpha-receptors cause contraction of vascular
smooth muscle and lead to vasoconstriction
•beta-receptors cause relaxation of vascular
smooth muscle and lead to vasodilation
