Autonomic nervous system Flashcards
functions of the nervous system
regulate bodily activities by:
-detecting and interpreting changes and organising responses
cells in the nervous system
neurons
glial cells
afferent neurons
receive and integrate incoming information form sensory receptors
efferent neurons
transmit information to other neurone or effector organs/tisuses
what can neurones be
pre or post synaptic
two divisions of the nervous system
peripheral and central nervous system
divisions of peripheral nervous system
examples are cranial and spinal nerves
splits into somatic and autonomic and sensory
somatic
motor innervation of all skeletal muscles
autonomic
motor innervation of smooth muscle, cardiac muscle and glands
divisions of autonomic
sympathetic
parasympathetic
describe peripheral nervous system
31 pairs of spinal nerves
8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
12 pairs of cranial nerves
somatic nervous system
innervate structures derived from somites
-skin and skeletal muscles
can be motor or sensory
repsond to information from external environment and associated with production of voluntary movement
autonomic nervous system
innervate the viscera and glandular and smooth muscle cells
motor or sensory
receive signal via visceral afferent and response via visceral efferent
system responds to information from internal environment and associated with control of involuntary processes
when does the sympathetic nervous system stimulate
to act in times of stress as it governs flight or fight
effects of the sympathetic nervous system
increases heart rate and blood pressure
decreasing blood flow to extremities and GI tract through vasoconstriction
increasing blood flow to heart and muscles through vasodilation
dilating the pupils
when is the parasympathetic nervous system stimulated
most commonly active
rest and digest
functions during non-stressful times
effects of the parasympathetic nervous system
decreasing heart rate and force of contraction to lower the blood pressure
increasing blood flow to the extremities and GI tract
decreasing blood flow to the heart and muscles
constricting the pupils
homeostasis
based upon achieving balance between opposing systems
degree to which each system is active is referred as sympathetic or parasympathetic
structure of a typical spinal nerve
dorsal root and ventral root
Dr smith is very mean
dorsal root
formed by solely sensory neurones which synapse in the dorsal horn of grey matter
ventral root
formed by solely motor neurone which synapse in the ventral horn of grey matter
structure of typical spinal nerve
contains all fibres trailing out of into the ventral and dorsal roots
then split into dorsal and ventral rami
what does ventral ramus innervate
anterior and lateral aspects
what does dorsal ramus innervate
posterior aspects of the body
pathway of somatic sensory nerve
afferent from receptor
along ventral/dorsal ramus
into spinal nerve
through dorsal root
into spinal cord to synapse in dorsal horn of grey matter
pathway of somatic motor nerve
efferent from ventral horn of grey matter
through ventral root
into spinal nerve
along dorsal/ ventral ramus
and synapse at the effector muscle
somatic nerves neurotransmitter
acetylcholine
cell bodies of motor/efferent lie where
in the ventral horn of grey matter in spinal cord
cell bodies of sensory/afferent lie where
in the dorsal root ganglion (DRG)
autonomic nervous system
sympathetic from spinal nerves T1-L2
ASNS described as having thoracolumbar outflow
parasympathetic arise from brainstem and S2-4
APNS has craniosacral outflow
ANS visceral efferent
innervate smooth, cardiac muscle, glandular cells and viscera
ANS motor pathways comprised of what
pre-synaptic (pre-ganglion) fibre
post-synaptic (post-ganglion) fibre
site of synapsis always lie in ganglia
pathway of sympathetic efferent
The pre-ganglionic sympathetic fibre,
will originate in lateral horn of grey
matter.
* The neuron will then travel through the
ventral root and mixed spinal nerve and
into the white ramus communicans.
This is ‘white’ as pre-ganglionic fibres
are myelinated.
The pre- and post-ganglionic neurons
synapse in the sympathetic ganglion.
* The post-ganglionic sympathetic fibre,
will then exit the ganglion through the
grey ramus communicans and travel to
the target tissue.
This is ‘grey’ as post-ganglionic fibres
are unmyelinated.
In some cases, fibres will travel up or
down to different levels of the
sympathetic trunk before passing
through the grey ramus communicans
and distributing to their target tissues.
exception to the rule
splanchnic nerves
splanchnic nerves
travel through the sympathetic chain
do not synapse within
synapse in the pre vertebral ganglia instead
targets of splanchnic nerves
organs
what is sympathetic distribution to most organs through
splanchnic nerves
exceptions
thoracic organs
pulmonar plexus
Pre-ganglionic sympathetic fibres
innervating the lungs synapse in
the sympathetic chain at levels T1-
4
cardiac plexus
Pre-ganglionic sympathetic fibres
innervating the heart synapse in
the sympathetic chain at levels T1-
4, as well as from the cervical
ganglia.
neurotransmitter in sympathetic ganglion between pre and post ganglionic fibres
acetylcholine
neurotransmitter in post ganglion in sympathetic
noradrenaline
pathway of parasympathetic efferent
efferent through ventral horn of grey matter
through ventral root
into spinal nerve
along dorsal/ventral ramus
to synapse within ganglion before reaching the target tissue
Pre-ganglionic fibres will pass from the brainstem
or sacral spinal cord to the target tissues.
* Parasympathetic autonomic ganglia lie near to or
within the lining of the target tissue or organ.
* All parasympathetic innervation from the neck
down to the midgut is provided by the vagus nerve
(CN X).
parasympathetic efferents
between pre and post and at post is acetylcholine
visceral afferents
transmit sensations of visceral pain and distension back to the CNS
follow same pathway as somatic afferents
cell bodies also lie in the dorsal root ganglia DRG
summary sympathetic division
Fight or flight.
‘Thoracolumbar’ outflow.
Ganglia lie along the sympathetic chain.
Short preganglionic neurons.
Long postganglionic neurons.
Postganglionic neurons signal using
noradrenaline.
summary sympathetic division
Fight or flight.
‘Thoracolumbar’ outflow.
Ganglia lie along the sympathetic chain.
Short preganglionic neurons.
Long postganglionic neurons.
Postganglionic neurons signal using
noradrenaline.
summary parasympathetic division
Rest and digest.
‘Craniosacral’ outflow.
Ganglia lie close to/within the target tissue.
Long preganglionic neurons.
Short postganglionic neurons.
Postganglionic neurons signal using
acetylcholine.
