Lectures 11-15 Flashcards
What is neuropraxis?
Injury to the myelin sheath (neurone can’t function)
What is axonotmesis?
axpn is damaged, but endoneurium, perineurium, and epineurium remain intact.
How does the axon heal from axonotmesis?
The various layers provide guidance to the nerve sprouts on where to attach
What is neurotmesis?
when the entire nerve fibre is severed (complete recovery doesn’t occur)
What happens soon after a severe neurone injury?
it would stop conducting AP’s, and the cut ends would leak intracellular fluid. The ends will split apart, swell, and seal
What would happen hours after a severe neurone injury?
synaptic terminals degenerate
neurofilaments accumulate
astroglia cause terminals to be pulled away from the postsynaptic cell
What happens days after a severe neurone injury?
Cell body of the proximal segment undergoes chromatolysis
The distal stump undergoes Wallerian Degeneration
What is chromatolysis?
Cell body produces repairing hormones, injured nerve forms a neuroma seal, allowing it to regenerate
What happens in Wallerian Degeneration?
distal segment dies, although protective sheathing may be preserved, leaving behind a hollow tube
What has the degeneration of fibres allowed us to do?
trace neural pathways
How would you divide the fate of a denervated muscle?
Acute phase
Chronic phase
What is a Reperfusion injury?
crushing injury to large muscle masses, causing fluid loss, hematuria, and traumatic Rhabdomylosis.
What are the sympathetic neurotransmitters and receptors?
Ganglionic, nACh(r)
Effector, alpha/beta adrenoreceptors
What are the parasympathetic neurotransmitters and receptors?
ganglionic, nACh(r)
effector, mACh(r)
Which main nerves are parasympathetic?
CN 3, 7, 9, 10 (only autonomic ones)
SN S2, S3, S4
where does sympathetic outflow leave the CNS?
T1 to L2/L3
What is the prevertebral chain?
lies anterior to the vertebral bodies in relation to the carotids
What 3 fibres are formed from sympathetic outflow?
White rami (myelinated) communicans Grey rami (unmyelinated) communicans Splanchic nerves
What is the difference in structure of somatic and autonomic neurones?
Somatic signals are more discrete, innervating specific fibres
Autonomic neurones have many swellings along the axon, each of which contains neurotransmitters in vesicles (broadcast messages)
Why are sweat glands unusual?
They recieve single innervation sympathetically, but they only use nACh!
What are the effects of SympNS and ParaNS on heart rate
SympNS increases
ParaNS decreases
Which of the SympNS and ParaNS increase motility?
ParaNS
Which of the dilator papillae and the constrictor papillae recieve sympathetic innervation?
dilator papillae
What sort of innervation do blood vessels recieve?
single, sympathetic innervation
EXCEPT THOSE SUPPLYING THE HEAD AND GONADS
