Anatomy SC: 1 and 3 Neurons, Sympathetic and PSympathetic Flashcards
Do the action potentials that pass through a dendrite travel towards or away from the cell body?
Towards
Are dendrites or axons longer?
Axons
What produces the myelin sheath in the PNS?
Schwann cells
What produces the myelin sheath in the CNS?
Oligodendrocytes
What are Schwann cells responsible for in the PNS?
Producing myelin sheaths
What are Oligodendrocytes responsible for in the CNS?
Producing myelin sheaths
What is the main function of the myelin sheath?
To greatly increase the speed of action potential along axon
What is a collection of nerve cell bodies called in the PNS?
Ganglion
What is a collection of nerve cell bodies called in the CNS?
Nucleus
All motor neurons of skeletal muscles and the ANS are (multi/uni)polar
Multipolar
What are unipolar neurons generally used for?
Sensory innervation
Define a nerve
A collection of axons surrounded by connective tissue and blood vessels
(Called a nerve in the PNS but a tract in the CNS)
Do tracts tend to be single or mixed modailty?
Single
Which division is said to be responsible for the ‘fight or flight’ response?
Sympathetic
Which division is said to be responsible for the ‘rest and digest’ response?
Parasympathetic
What is the sympathetic division also known as?
Thoracolumbar outflow
Presynaptic sympathetic cell bodies are only found between __ and __
T1 to L2
Lateral horns are only found from ___ to ___
T1 to L2
To join the sympathetic trunk, an action potential will exit the __ via the __ root into the __ nerve then into the __ rami then almost immediately leaves via the __ ramus (communicantes) to join the sympathetic trunk
To join the sympathetic trunk, an action potential will exit the SPINAL CORD via the ANTERIOR root into the SPINAL nerve then into the ANTERIOR rami then almost immediately leaves via the WHITE ramus (communicantes) to join the sympathetic trunk
Once an action potential has reached the sympathetic trunk (ST), it will do one of 4 things…
Ascend, then synapse
Synapse at level of entry
Descend, then synapse
Pass through ST without synapsing to enter at abdominopelvic splanchnic nerve
Neurotransmitter of PREganglionic sympathetic neurones is __
ACh
Neurotransmitter of POSTganglionic sympathetic cells is generally __ , or __ in sweat glands
Generally noradrenaline
ACh in sweat glands
Sympathetic innervation of the heart:
PREsynaptic axons synapse in __ or ___
POSTsynaptic axons pass in __ nerves to the __
PRE: T1 or cervical paravertebral ganglia
POST: cardiopulmonary splanchnic nerves to the SA and AV nodes and myocardium
Sympathetic innervation of the lungs:
PREsynaptic axons synapse in the __
POSTsynaptic axons pass in __ nerves to the __
PRE: upper thoracic paravertebral ganglia
POST: cardiopulmonary splanchnic nerves to the bronchiolar smooth muscle and mucous glands
Sympathetic innervation abdominopelvic organs:
PREsyanptic axons synapse in __ where they form __
Synapse in one of the many prevertebral ganglia where they form a plexus of nerves around arteries to travel to the target organ
Sympathetic innervation of adrenal medulla:
PREsynaptic axons pass through the __ to synapse __
…pass through the aorticorenal ganglion to synapse directly onto the adrenaline/noradrenaline secretory cells (the suprarenal medullary cells)
The adrenal medulla is an exception in that it is directly innervated by preganglionic sympathetic neurones
The parasympathetic innervation is also known as
The craniosacral outflow
Where are preganglionic parasympathetic neurones located?
In the brainstem and spinal cord
Presynaptic parasympathetic axons leave the CNS via
CN III, VII, IX and X
Sacral spinal nerves
Craniosacral outflow
How do the parasympathetic axons travel to the eye?
Cilliary ganglion
How do the parasympathetic axons travel to the hindgut, pelvis and perineum?
Sacral spinal nerves
What do the parasympathetic ganglia in the head supply?
Lacrimal and salivary glands
What does the vagus nerve supply?
Organs of neck, chest and abdomen as far as hindgut
Vagus nerve synapses in or at wall of target organ
In the sympathetic division, preganglionic neurones have __ (long/short) axons while post ganglionic fibres are relatively __ (long/short)
In the sympathetic division, preganglionic neurones have SHORT axons while post ganglionic fibres are relatively LONG.
This is due to the sympathetic chain that runs alongside the vertebral column made up of sympathetic ganglia
In the parasympathetic division, ganglia are located __
Close to the target organ
This means preganglionic neurones have long axons and postganglionic fibres are short
