L22- Organisation of the CNS, PNS and ANS Flashcards
central nervous system made up of
brain and spinal cord
peripheral nervous system made up of
Somatic and Autonomic nervous system
somatic
skeletal movement - voluntary - conscious perception
autonomic
autonomous - sympathetic - parasympathetic - enteric
sympathetic NS
Flight or fight response Either on or off
why called sympathetic
All body parts become activated in sympathy with each other - ganglions synapse in sympathetic chain, also called the paravertebral ganglia
parasympathetic NS
Rests and digest
how does parasympathetic work differently to the sympathetic NS
Much more focussed- modulates discrete body systems- very fine tuned - ganglions synapse in specific tissue
enteric NS
intrinsic nervous system within the gut - contains a huge number or neurones - most of the serotonin in your body made in the gut
major function of enteric system
move food from mouth to anus
spinal cord split into how many segments and how many nerves
31 segments 31 nerves
connected to each spinal cord segment
• Ventral root- motor (if damaged just motor problems) • Dorsal root- sensory (if damaged just sensory problems) Come together to form a spinal nerve - both sensory and motor
segments of the spinal cord
cranial cervical throacic lumbar sacral coccygeal
cervical
C1-8
thoracic
T1-12
lumbar
L1-5
sacral
S1-5
coccygeal
fused- C1
white and grey matter in the spinal cord
grey matter- central part white matter- outside
white and grey matter in the brain
grey matter- on outside white matter- on inside
spinal cord cannot
regnerate
sensory input —>
processing
processing –>
motor output
draw:
sensory input –> processing –> motor output in the spinal cord
dorsal root contains
sensory neurone
- if damaged just sensory problems
ventral root contains
motor neurone
if damage jus tmotor problems
how is the ANS motor systme different to the somatic nervous system
it has a chain of two neurones between the CNS and the target organ
1) preganglionic
2) postganglionic
synapse between preganglionic and postganglionic neurone called
autonomic ganglion
NT of autonomic glanglion
ACh
preganglionic neurone cells bodies found in the
CNS
postganglionic neuroen cell body is found in
autonomic ganglion
sympathetic pre and post ganglionic neurone length
short preganglionic
long post ganglionic
parasympathetic pre and post ganglionic neurone length
long pre
short post
where are the sympathetic preganglionic neurone cell bodie sfound in the CNS
lateral horn in T1 -L2 cofrd segments
where are the parasympathetic preganglionic neurone cell bodie found in the CNS
located in the brainstem and in the sacral (S2-4)
myelination always on
short preganlionic axon and not post ganglionic
sympathetic chain is the same as the
paravertebral ganglia
paravertebral ganglia/ sympasthetic chain
where all symparthetic ganglia are found –> mean that symapthetic innvervation is a much more systemic response than parasympathetic innevration (where ganglions are found in specific tissues)
long parasympatheti preganglionic axon
project almost all the way to the target tissue
short parasympathetic pstganglionic axon
cell body for the post ganglionic axon is in the wall of the organ its targeting e.g. the bladder wall
Makes it much more discrete
draw a diagram showing how a motro neurone causes a response in target tissue
The sympathetic nervous system: Distribution to skin
Sympathetic preganglionic arising in the T1- L2 cord segments supply the skin via one of the following 3 routes
outline the 3 routes that sympathetic preganglionic neurones arising in the T1-L2 segments supply the skin
-
Synapse at the level of entry
- To supply dermatomes at the T1-L2 level
- Postganglionic get to their targets through the T1-L2 spinal nerves
-
Ascend the chain then synapse
- Typically supply the head and neck
- Postganglionic get to their targets along the walls of blood vessels
-
Descend the chain
- Typically supply the lower limbs
- Postganglionic get to their targets through the spinal nerves at levels L3 and below
The sympathetic nervous system: Distribution to abdominal viscera
- Sympathetic preganglionic can also traverse the chain then synapse in a pre-aortic ganglion (to supply abdominal viscera)
- Post ganglionic get to their targets along blood vessels
- Sensory fibres also travel along sympathetic destined for the abdomen and relay pain back from viscera back to the CNS
Parasympathetic preganglionic neurones typically synapse in ganglia that sit
close to their target organ
major source of parasympathetic preganglionic input to the thoracic and abdominal viscera is
the vagus nerve
The head of the vagus nerve has 4 spedcilaiased parasymapthetic ganglia
Ciliary ganglion
Pterygopalatine ganglion
Submandibular ganglion
Otic ganglion
Ciliary ganglion
receives parasympathetic preganglionic from the oculomotor nerve and distributes parasympathetic postganglionic to they eyes
Pterygopalatine ganglion
receives parasympathetic preganglionic from the facial nerve and distributes parasympathetic postganglionic to the lacrimal gland
Submandibular ganglion:
receives parasympathetic preganglionic from the facial nerve and distributes parasympathetic postganglionic to the submandibular and sublingual salivary glands
Otic ganglion:
receives parasympathetic preganglionic from the glossopharyngeal nerve and distributes parasympathetic postganglionic to the parotid gland
