year 3 physiology Flashcards
main function of ependymal cells
production of CSF as part of the choriod plexus
what cells degeneraet in MS
oligodendrocytes
where is CSf contained
within subarachnoid space and the central canal of the spinal cord
what cells form the blood cerebral spinal fluid barrier
ependymal
what cells regualte the compostion of CSF
ependymal
foramen from 4th venricle to subarahnoid space or central canal
luschka and megendie
where does csf get drained to
superior saggital venous sinus through arachnoid villi
communicating hydrocephalus is casued by
imbalance in csf production and absorption - most commonly inaqdeqaute reasbsorption into teh dural venous sinuses as the fucntion of teh arachnoid villi is impaired
non communicating hydrocephalus is due to
obstruction of CSf outflow - most likely to occur at the foramens, cerebal aqueduct etc
glutamate and GAba are what
amino acids
acetylocholine plays a role in
attention
what drugs can cause memory loss and have the potential to become addicitve hence they are only prescribed for short term use
Benzodiazepines
what is a ganglion
collection of neuronal cell bodies in the PNS
parasympathetic system only uses
acetylocholine where symapthetic used actelycholien and noraderenalien
what ion has greates influence of the resting membrane potential
K
what is not involved in the repolarisation process following an action potential
Na/K ATPase
action potentials can only occur where
nodes of ranvier
how does myelin sheath speed up conduction
increaseing the membrane resistance and reducing memebrane capacitance
does dopamine exert an excitatory or inhibitoryy effect
both!
glutamate and gaba both act on inotropic but gaba also works on what receptors
metabotropic
electroencephalogram measure what in epilepsy
excitatory or inhibitory transmission
schwan cell is ony able to myelinate
one single axon
what has a high memebrane resistance and reduces teh capitance of the axon
myelin
long term potentiation is also know as
tetanus - requires strong activity in both presynatpic and postsynaptic neurones
induction of long term potenitation requires activation of
glutamate NMDA receptors
abnormal synaptic plasticity can lead to
intellectual disability
long term potentitatio is synapse…
specific
acetlycholinsterase inhibitors eg pyridostigmine and donezpezil inhibit the activity of acetylocholinesterase so increases cholinergic transmission so more acetlycjoline is in the synaptic cleft for longer
- these drugs can cause side effects which activate the parasympathetic system eg bradycardia, excessive salivation, hypotension
is dorsum column tract consious
yes
what ascending tract is unconscious
spinocerebellar
second order neurones from DCLM decussate where
medulla
where are third order neurones
thalamus
what spinothalamic tract carries pain and temperature
lateral
second order neurones in the spinothalamic tract decussate where
within the spinal cord
3rd order neurones carry signals from thalamus to where
ipsilateal primary sensory cortex of the brain
if DCLM affected sensory loss will be
ipsilateral
spinothlamic tract affected, the sensory loss will be
contralateral
think decussation - spinothalamic decussates at
SPinal cord
spinocerebellar pathway likely to be affected if what is injured
descending motor tracts
main pathway for audiory
Lemniscal
most hearing decussate at
superior olivary nuclei
what sleep do you dream
Rem
sympathetic innervation is more related to what sleep
REM
and paraympathetic more linked to non rem
remeber in rem you get rapid eye movement so think sympathetic
what system is regulator for sleep wake cycle
RAS - reticular activating system
hypocretin affects what sleep
REM
nucleus thats major circaidan clock
suprachiasmatic nucleus
levels of hypocretin becoem very low in what
narcolepsy
what receptros respond do pressure, touch, vibration and stretch
mechanoreceptors
what plays a key role in differentation textures
merkels discs
what detects initial contact with objects
meissners corpuscles
what is involved with proprioception
muscle spindles and golgi tendon organs
finger tips have smaller receptive fields but larger density of free nerve endings - allows for greater acuiting in detectig a sensory stimulus
smaller the receptive field, the greater the sensoryy acuity
morphine and other opiods acts on what receptros
G protein coupled receptors
lateral inhibition allows for better
sensory acuity
smaller the receptive field the better the
sensory acuity
lateral genicuale nucleus involved in
vision
temporal lobe affects what quadrants
superior
- lower optic radiations
what tracts are responsible for voluntary control
pyramidal
what tract is responsible for involunatry and autonomic control of musculature eg muscle tone, balance, posture and locomotion
extrapyramidal
are there synapses in the desending tracts
no
pyramidal tracts consist of
corticospinal and corticobulbar
one of the first things the descending tract goes through is the
internal capsule - particualrly susceptible to compression from haemorrhagic bleeds
what corticospinal tract remains ipsialteral
anterior
upper motor neurones for what nerves dont innervate bilaterally
facial and hypoglossal
lower quadrants of the face (below teh eyes) has what innervation from facial
contralateral
upper motor neurones for what nerve only provide contralateral innervation
hypoglossal
what extrapyramidal tracts provide contralateral innervatoon
rubrospinal and tectospinal
what extrapydramidal tracts do not decussate and therefore provide ipsilateral innervation
vestibulospinal and reticulospinal
what tract involved with balance and psoture by innervating anti gravity muscles
vestibulspinal
what tract facilatates / inhibits voluntary movemtns
reticulospinal
rubro spinal tract involves
fine control of hand movements - red nucleus
tectospinal tract
coordinates head in relation to vision stimuli
what pyramidal tract is susceptible to damage becasue tehy extend almsot the wholw length of teh CNS and pass through internal capsule - common site of cerebrovascular accidents
corticospinal
corticospinal lesions affect what side
contralateral
corticospinal lesions cause what symptoms
upper motor neurone eg hypertonia, hyperreflexia , clonus, babinski
motor unit is
combination of the LMN and muscle fibres
difference in roles between alpha and gamma (lmns)
alpha - contraction
gamma- muscle tone and unconscious proprioception
what is often described as having a bag of worms under the skin
fasciculations
checking for reflexes uses what motor neurones
gamma
UMN signs seen in the descending motor tracts eg
corticospinal and corticobulbar ( also side note: also seen in extrapyradminal)
positive babinski - upper or lower motor neurone lesion
upper
postive babinksi is normal if
under 2 as the corticospinal tracts are not fully developed yet
clonus - rhymic movemtns as its as series of contractions
most common cause of ischaemic strokes
atherothromboembolii from the carotids
strokes cause what signs
UMNs
after strokes can regain sme fucntion in limb due to what tract
rubrospinal tract - is able to compensate for the loss of corticospainl fibres to a certain extent
