Week 1 Flashcards
Sympathetic NS rhyme
Fight or flight
HR increased
Guy activity decreased
Parasympathetic rhyme
Rest and digest
Each part of symp and para consists of two types of neuron?
Pre ganglionic and post ganglionic
Cell body in CNS - axon enters PNS …
Cell body in PNS - inner aged target organ …
Preganglionic
Post ganglionic
Where is postganglionic cell located
In a ganglion
Where are preganglionic neurons
Symp- in thoracic and upper lumber spinal cord ( leave in spinal nerves T1 - L3
Para - brainstorm (leave in some cranial nerves) and sacral spinal cord ( leave in spinal nerve S2-S4 )
Where are the ganglia
Symp ganglia are mainly found in sympathetic chain(trunk) located next to vertebral column
Para ganglia are located in the Walls of the viscera they innervate
meninges
tough connective tissue surrounding and protecting the CNS
total segments of the spinal cord
31 total 8 12 5 5 1
cervical nerves C1 to 7 pass through the intervertebral foramen at what point?
above their appropriate vertebrae
C8 to coc 1 pass through the intervertebral foramen at what point?
below their appropriate vertebrae
where is the lower limit of the spinal cord in an adult ?
L1/L2 border
what does the neural tube develop from
from a flat plate of cells - neuro-ectoderm
plate forms a tube central canal surrounded by nervous tissue - grey and white matter.
Alar plate ?
Basal plate?
aspects of the spinal
Dorsal (sensory)
ventral( motor outputs to periphery)
(cord at time of development )
different types of SB
occulta, lipomeningocele, meningocele, myelomeninggocele (increasing in severity)
Main features of the grey matter?
Dorsal horn
immediate horn (connects dorsal horn to central horn )
ventral horn
dorsal and ventral aspects are bigger in which segments of the spinal cord?
cervical and lumbar.
innervating the limbs (accommodation of muscles to consider)
the outermost layer of spinal cord?
Dura mater.
a think inelastic membrane, fuses with the endosteum of cranium at the level foramen magnum .
guves rise to the epidural space
MIDDLE meningeal layer?
Arachnoid mater
- much thinner than dura mater, thin fibrous membrane , bridges the subarachnoid space
CSF
a filtrate of blood made in the choroid plexus within the ventriculatr system of the brain . Affords mechanical and immunological protection to the brain and SC.
500 ml produced a day
subarachnoid space contains …
trabeculae, veins and CSF
what plexus of veins exits in the epidural space?
vertebral/baston venous plexus - major rote in spread of cancer from deep pelvic regions
what is the Artery of Adamkiewicz?
-supplies loew 1/3 of spinal cord
-typically arises from left post. intercostal artery
asscoiated with spinal artery syndrome ( loss of urinary and or faecal continence , impaired motor function of legs / spasticity)-
what is found in the ganglions?
cell bodies of the sensory fibres
lowest portion of the spinal cord
conus medullaris
filum terminale
thin filament attaches the spinal cord in place
site of epidural injections ?
lumbar cistern - L3/4 L4/5 vertebral level ( supracristal line passes through body of L4 )
4 main classes of axons
A alpha (largest myelin sheath -emminate from motor neurons, proprioceptors ) A beta (mechanoreceptors of skin) A delta (pain and temperature) C fibres - unmyelinated( temperature , pain and itch)
what does a myelin sheath do ?
speeds up conduction of electrical impulses
Tracts of myelinated axons
ascending (sensory) and descending ( modulate activity
Ascending pathways
discriminative touch - dorsal column pathway
pain - spinothalamic pathway
descending pathways
motor
- muscle tone
- voluntary ( corticospinal corticobulbar)
what is a neuron
communicating unit of the NS
- highly specialised to transmit info from one cell to another.
• Electrically excitable → ability to signal to other
cells
• Communicates via action potentials and
synaptic transmission
what is the resting membrane potential?
Arises due to a difference in charge (due to
ions) between the inside and outside of the
neuron at rest
• More +ve ions outside cell / more –ve ions
inside cell
• Measured in relation to outside, therefore RMP
is a –ve value
• Typical RMP of neurons -60mV to -70mV
what is the distribution of ions across the membrane of a typical neuron
extracellular - Na (high) K (low) Cl (high)
intracellular - opposite
what is the equilibrium potential ?
membrane potential where No
ions entering cell =
No
ions leaving cell (no net gain or loss of ions). concentration gradient and electrical gradient cancel each other out.
what does the opening and closing of voltage gated channels depend on?
membrane potential
what does the opening of a ligand gated channels depend on?
= opened in response to binding /
activation by neurotransmitter or drug
what is an action potential?
• An action potential is
a very brief, but
dramatic change in
membrane potentia
what is depolarisation related to?
Depolarisation related to
increased permeability
to Na+
ions
Repolarisation and
hyperpolarisation due to….
Repolarisation and
hyperpolarisation due to
increased permeability
to K+ ions
Action potential summary?
• Very brief, but dramatic change in membrane
potential
• All or nothing response
• Changes in membrane permeability to Na+ & K+
• Depolarisation: fast opening of voltage-gated Na
channels (Nav
)
• Repolarisation / hyperpolarisation: slow opening
of voltage-gated K channels (Kv
)
what is the propagation of the action potential?
Opening of voltage-gated Na channels during action potential → depolarises axon either
side of depolarised zone reaching threshold → opening of voltage-gated Na channels
how can a positive charge travel?
- along axon or 2. out of axon via
membrane