NEUROPHYSIOLOGY Flashcards
Action potential
initiated?
numbers?
- resting membrane potential
- threshold potential
- positive level
what in and out when?
At the axonal hillock
resting membrane - -70
threshold- -55
NA channels go IN
+40
K GO out
hyperpolarised
3 types of snapses
–> chemical- excitatory or inhibitory
sometimes just help build up but not release an actual (facilitaton) - spatial summation when several other help cause AP. Temporal summation when just one cuases AP
–> electrical
–> cojoint
Eating
full?
hungry?
outside CNs?
- ventromedial =. sateity centre
- lateral hypothalamus = feeding centre
ghrelin + neuropetite Y = increase appetite - leptin, cholecystokinin and seretonin = feel full
ghrelin only of these subtences produced outside CNS
food increase dopaminergic activity in nucelus accumbens (reward centre)
Temperature
hypothalamus has 2 centres controlling body temp
1) pre-optic anterior hypothalamus = hypothermic centre –> parasympathetic mediated sweating and vasodilation.
2) posterior hypothalamus = hyperthermic –> sympathetic drive, shivers + vasoconstriction
diurnal variation = median eminence (lesions here damage it)
Pain
where detects
which fibres
FAST?
SLOW?
receptors modulates?
thalamus - perception
cortical centres- localisation
C fibres. / A delta fibres carry pain to dorsal horn spinal cord
fast –> LATERAL SPINOTHALAMIC - localisation
slow –> reticulothamaic - subjective
receptors modulate- opioid in dorsal horn + descending fibres in seretonergic raphe nuceli (explains TCA help pain)
Thirst
areas ?
neurotransmitter?
subfornical organ + organum vasculosum of lamina terminalis - perception of thirst
+ hypothalamic paraventricular nuceleus
Angiotensin 2 + (hypotension stimulates via baroreceptiors)
Kluver-Bucy syndrome
Bilateral lesions of amygdala and hippocampus –> placidity with decreased aggressive
behaviour. oral exploratory behaviour + hypersexuality. Hypermetamorphosis
(objects are repeatedly examined as if novel)
LaurenceMoon-Biedl Syndrome
Obesity and hypogonadism along with low IQ, retinitis pigmentosa, and polydactyly. Diabetes insipidus
Autosomal recessive with genetic locus at 11q13
No hypothalamic lesions have been found.
Prader-Willi Syndrome
Hypotonia, obesity with hyperphagia, hypogenitalism, mental retardation, short stature, impaired glucose tolerance.
Abnormal control of body temperature and daytime
hypersomnolence is related to hypothalamic disturbances.
A reduction in oxytocin neurons and satiety neurons is noted. Associated with paternal deletion
Kleine-Levin Syndrome
Compulsive eating behaviour with hyperphagia, hypersomnolence, hyperactivity,
hypersexuality and exhibitionism. A hypothalamic abnormality sometimes preceded by a viral illness; often resolves by the third decade of life.
Psychogenic polydipsia
Psychogenic
polydipsia Excessive water consumption in the absence of hypovolemia or hypernatremia. May lead to water intoxication and serious electrolyte imbalance
Neurogenesis
where zones start?
- where continuous
Subventricular zone - neruones migrate out from here to cortical plate
- axons project to subplate neurones + detatch in development but in schizphrenia abnormal persistence of subplate neurones
- continuous at dentate gyrus of hippocampus and olfactory bulb
neuronal migration (begins first 6 months gestation)
2 types
myelination = beings 4th gestational month + complete by 2 yrs
1) Radial migration (form scaffolding)- form radial stacks of cells (Dakics cortical columns)
2) Tangential migration
failure of migration = heterotopia
Synaptogensis
synaptic pruning
occurs 2nd trimester –> 10 yrs old (mainly 2yrs)
pruning- commences early teen years
can measure neuronal numbers by d2 receptor density
d2 receptor loss faster men than women, fastest in schizophrenics
excessive pruning in schizophrenia, under pruning in autism
pituitary
- anterior
- posterior
pituitary
anterior - GH, LH, FSH, ACTH, TSH, prolactin
posterior
- Vasopressin (ADH)
- oxytocin (synthesised in magnocellular cells of supraoptic nuceli + paraventricular nuceli)