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Flashcards in physiology Deck (289):
1

what 2 cortexes are decisions made about what actions/ movements to make

prefrontal
parietal (converge at area 6)

2

what part of the brain does the procedural/ reflective/ implicit memory rely heavily on

cerebellum

3

if there is a lesion in the corticospinal tract, why may activity reappear after a few months

activity taken over by rubrospinal tract

4

what is the cerebral blood flow

55-60 mL/ 100g brain tissue / min
(75mL grey matter/ 45mL whit matter)

5

what makes up the vestibular system

series of fluid filled membranous tubes in the inner ear, embedded in the temporal bone
3 semi- circular canals
Utricle
saccule

6

when does area 6 fire neurones

when movement is made
when movement is imagines
when others make the same movement

7

how do thermoreceptors/ nocireceptors (Adelta and C) transmit sensory information

synapse in dorsal horn
cross at midline of spinal cord
project up through contralateral spirothalmic tract --> reticular formation --> thalamus --> cortex

8

what happens on the ipsilateral and contralateral side in the flexor withdrawal reflex

pain side - activation of flexors, inhibition of extensors
contralateral - inhibition of flexors, activation of extensors

9

why does cognition require motivation

requires an ability to remember events and learn form them

10

How much CSF is present in adults

150 cc

11

what is the highest order of brain function

cognition

12

what does each long term memory stored have

a well established, well rehearsed pattern of neuronal firing unique to that particular memory

13

what chemical changes occur in intermediate long term memory

increased Ca entry to presynaptic terminals, increases neurotransmitter release

14

what happens when critical volume of the cranium is reached

intracranial hypertension

15

what is interstitial oedema (ISF)

increase water due to poor absorption of CSF (increased CF)
Due to obstructive or communicating hydrocephalus

16

what do ventromedial between the brain and spinal cord control

posture and locomotion

17

what is the execution function of motor control

activation of motor neuron and interneuron pools to generate goal - directed movement

18

which area stores memories

cortex

19

where do the 5 patterns that run in the vestibular nerve to the brain come from

3 from cristae in semi circular canals
2 from maculae in otolith organs

20

why are the vestibular and visual apparatus so closely linked

- afferent fibres from semicircular canals project and connect to afferent fibres travelling to the extra-ocular nuclei
- vestibulocochlear fibres synapse to the nucleus of abducens, trochlear and occulomotor nerve

21

what type of pathways are sent from the reticular formation to their projections in REM sleep

cholinergic

22

what is the name of the huge projection that connects the cortex, pontine nucleus and cerebellum

cortico- ponto- cerebellar projection

23

describe the reapsorption pathway of CSF

lateral ventricles --> foramen of monro --> 3rd ventricle --> cerebral aqueduct --> 4th ventricle --> 2 foramina lushka/ foramen of megendie --> subarachnoid space --> venous system via arachnoid granulations laong dural venous sinuses

24

are descending pathways upper or lower motor neurones

upper

25

what is chorea (huntingotns)

spontaneous, uncontrolled rapid flicks and major movements with no purpose

26

what is procedural/ reflective/ implicit memory

acquired slowly through repetition, includes motor memory for acquired motor skills and rules based driving

27

what are the 2 types of cilia hair cells

kinocilium
stereocilia

28

what test method is used to measure ICP

Lundberg waves

29

what are the 3 functions in the hierarchy of motor control

strategy
tactics
execution

30

at what level and by what structures does the execution function of motor control occur

low - spinal cor, brain stem

31

what is spasticity

increased muscle tone, hyperactive stretch reflex,

32

where does the active inhibitory process of sleep originate and go to

reticular formation of the pons - to thalamus/ cerebral cortex

33

at what level and by what structures does the strategy function of motor control occur

high - basal ganglia , association neocortex

34

what is labyrinthitis

acute interference with normal vestibular function as a result of an infection

35

which planes are the semicircular canals in

all at right angles - coronal, transverse, saggital

36

where do sensory fibres terminate

somatosensory cortex of post central gyrus

37

what are inputs to the basal ganglia

frontal, prefrontal and parietal cortex

38

what structures are involved in the middle level of motor controls

motor cortex, cerebellum

39

What do C primary afferent fibres pick up

warmth (skin), slow pain (nociceptive)

40

why is the reabsorption of CSF passive

driven by the pressure gradient between the intracranial space (ICP) and the venous system (CVP)

41

when are beta waves shown on an EEG

alert, awake state (high frequency, low amplitude)

42

how is a somatotropin map organised

greatest control over areas with the most sensory receptors (fingers, lips etc.)

43

what is the function of the tonic labyrinth reflex

keep the axis of the head in a constant relationship with the rest of the body (uses information from maculae ad neck proprioreceptors)

44

what is stage 2 of the sleep cycle

eye movements stop
EEG shows sleep spindles - clusters of rhythmic waves

45

what happens if the SCN nucleus is destroyed

lose circadian rhythm of sleep

46

what is the normal plantar response in Babinski's sign

flexion

47

what happens to experiences the brain deems insignificant

they are forgotten

48

what movements cause the putamen and caudate to fire

putamen - before limb/ trunk movements
caudate - before eye movements

49

when are delta waves seen on an EEG

deep sleep (very low frequency, high amplitude)

50

what do cerebral arterioles do if CPP is low

dilate to allow adequate flow at the decreased pressure

51

how do venous systems cope with a rise in ICP

collapse easily and squeeze blood out through jugular veins or emissary/ scalp veins

52

which direction does the utricle and saccule detect

utricle - back / front tilt
saccule - vertical movement

53

what is narcolepsy

patients enter directly into REM sleep with little warning - very dangerous

54

where is the choroid plexus primarily located

lateral ventricles, posterior 3rd ventricle roof, caudal 4th ventricle roof

55

how do you over ride a reflex (e.g if holding something important)

descending pathways from brain voluntary excite alpha motor neurones to override the inhibition from the GTO and maintain contraction

56

where is the utricle

swelling at base that connects the semicircular canals

57

what is the function of the supplementary motor area

innervates distal motor units directly

58

when are theta waves seen in an EEG

children sleep and adults during times of emotional stress and frustration

59

define 'asleep'

state of unconsciousness from which and individual can be aroused by normal stimuli - light, tough, sound etc

60

what does korsakoff's syndrome lead to (chronic alcoholism)

Vit B1 deficiency leads to damage of the limbic system structures and impaired ability to consolodate memories

61

how long does immediate long term memory last

hours to weeks
e.g what you did at the weekend

62

what is the function of the cupula in the christae

stretches across entire width of ampulla and responds to movement of the endolymph fluid within the canals (cilia hair cells stretch width)

63

how are the eye muscles in REM sleep

rapid eye movements

64

what type of neurones are the ones within the reticular formation

seratogernic

65

which part of the brain deems an experience significant enough to be remembered

frontal cortex and its associations with the reward/ punishment centres in limbic system.

66

what cord segment is the biceps jerk

C6

67

what structures are involved in the low level of motor controls

brain stem, spinal cord

68

what is kinetosis

motion sickness - powerful maintained stimulation of vestibular system causes nausea/ vomitting, low BP, dizziness, sweating

69

what is the immediate/ sensory memory

ability to hold experiences in mind for a few seconds

70

what is nociceptive pain

a sensory experience that occurs when specific peripheral sensory neurones (nociceptors) respond to noxious stimuli
localised site of injury and time limited

71

where are new memories stored

coded for and stored in the sensory association areas of the cortex alongside existing memories the brain deems similar

72

where does integration of inputs of sensory receptors take place

cerebellum, unconsciously

73

what movement are initiated by the cortex

voluntary movements in response to visual, olfactory, auditory, emotional and intellectual cues

74

how do neurones produce ATP

oxidative metabolism of glucose (some ketones)

75

what are cristae

sensory receptors inside the ampulla, which have a flexible gelatinous structure called the cupula

76

what is retrograde amnesia

can't access old memories
no events leading up to the injury but can recall events that happened a long time ago as they are better rehearsed and more deeply ingrained

77

what factors regulate cerebral blood flow

CPP
Concentration of arterial CO2
Arterial O2

78

what do the otolith organs detect (utricle and saccule)

linear acceleration

79

how does the limbic system form a memory

giving events emotional significance

80

what produces CSF

choroid plexus

81

what is cognition

the integration of all sensory information to make sense of a situation

82

If ICP rises, does CPP increase or decrease

decrease

83

what happens if there is bilateral hippocampal damage

intact immediate/sensory and long term memory but unable to form new long term memories

84

is the flexor reflex monosynaptic or polysynaptic

polysynaptic

85

where is the saccule

swelling underneath utricle

86

what 2 somatic motor maps are found in area 6

Premotor area (PMA) and supplementary motor area (SMA)

87

what is the most significant factor in determining cerebral blood flow

cerebral perfusion pressure (CPP)

88

Wha is the CPP

effective blood pressure gradient across the brain (CPP = MAP - ICP)

89

how many times id the CSF volume turned over each day

3/4 times

90

where are feedforward anticipatory adjustments made t

brainstem reticular formation

91

what does the spinal cord receive direct and descending input form

descending - brainstem
direct - corticospinal tract (pyramidal)

92

what is sensory memory based on

sensory modalities - visual decays fastest <1s and auditory slowest <4s

93

how do the autonomc, sympathetic and aortic baroreceptors respond in cushings reflex

autonomic - decreased cerebral blood flow
sympathetic - alpha 1 adrenergic receptors - hypertension and bradycardia
aortic baroreceptors - vagus nerve - bradycardia

94

what type of sleep is seen in the first few hors of sleep

Deep, slow wave sleep (stage 1-4)

95

how is balance maintained in the flexor withdrawal reflex

contralateral limb extends via excitatory interneurons which cross the spinal cord

96

how do both medial and lateral white matter tracts differ in origin and function

medial - brain stem - posture, balance and orienting
lateral - cortex - precise skilled voluntary movements

97

does chronic pain have a protective function

no - degrades health and function

98

how are amino acids and sugars transported across the capillary endothelium

by specific carrier mediated mechanisms

99

what percentages of brain, ISF, blood and CSF make up the total cranium volume (1700mL)

brain (70%) + ISF (10%) - 1400mL
blood (10%) - 150mL
CSF (10%) - 150mL

100

what is neuropathic pain

pain initiated or caused by a primary lesion or dysfunction in the somatosensory nervous system (not site of injury)
almost always a chronic condition - diabetic neuropathy, post herpatic neuralgia, MS

101

how does TENS work

electrical stimulation activates innocuous mechanoreceptive fibres from the same body segment as painful stimulus
release of endogenous opioid peptides from interneurones
activate mu receptors, inhibiting synaptic transmission between primary afferent fibres and 2nd order projection

102

What do Agamma primary afferent fibres pick up

cold (skin), fast pain (nociceptive), pressure

103

depending on whether the fluid is warm or cold, which direction will the nystagmus be

cold - opposite side
warm - same

104

where to medium spin neurones in basal ganglia project from and to

putamen and caudate nucleus to substantia nigra nad globus pallidus

105

how long must you be awake to have the same reaction time as a drink/ drive limit

18 hours

106

what stage of memory is associated with reverberating circuits

short term memory

107

list 6 things sleep supports

neuronal plasticity
learning and memory
cognition
clearance of waste products from CNS
conservation of whole body energy
immune function

108

what is stage 3 of the sleep cycle

high amplitude, very slow delta waves, interspersed with short episodes of faster waves

109

why do you not act out your dreams in REM sleep

inhibition of skeletal muscles from projections from pons to spinal cord

110

What do Abeta primary afferent fibres pick up

touch, pressure, vibration (30-70 m/s)

111

what nocioception does Adelta and C fibres pick up

Adelta - sharp / fast pain
C - dull/ slow pain

112

what areas of the brain are involved in consolidation

papez circuit
frontal cortex
sensory and association areas

113

what is an allodynia peripheral sensitisation response to pain

described threshold for response - respond to normally unpainful stimuli

114

why do people that don't have C nocioceptice fibres tend to die young

of injuries they don't know about

115

whats is stage 4 of the sleep cycle

exclusively delta waves

116

what is the function of the motor cortex

planning, initiating and directing voluntary movement

117

what substnaces can penetrate the blood brain barrier

lipid soluble

118

If ICP rises, is there more or less absorption of CSF

less

119

how long does long term memory last and why

can be lifelong - due to structural changes in synaptic connections

120

how does testing reflexes help detect level of spinal cord damage

can evoke reflexes above and not below

121

what information is facilitated by the lateral spinothalamic tract

spatial, temporal and intensity of painful stimuli

122

where is the cell body of primary afferent fibres

dorsal root ganglion

123

why do drugs that block serotonin formation inhibit sleep

neurones within reticular formation are seratogernic

124

what do christae detect

rotational acceleration

125

what things does testing the stretch reflex test

integrity of whole spinal circuit :
afferent nerves
balance of synaptic inputs to motorneurones
motorneuron health
Neuromuscular junction
muscles

126

if there is a lesion in the upper motor neuron, what will happen to tone

spasticity

127

what encodes the intensity and the location of the sensory stimulus

intensity - frequency of action potentials
location - receptive field

128

what is vasogenic oedema (EC)

increased capillary permeability causes plasma filtrate (from primary/ met tumour, abscess, infarction, trauma)

129

what is the difference between chronic (primary) and temporary (secondary) insomnia

chronic - no identifiable cause or pathology
temporary - response to pain, bereavement or other crisis

130

what is the long term potentiation that forms basis of learning and memory

increased amplitude in graded membrane potential (EPSP) in the post synaptic cell strengthens the synapse

131

what are the arachnoid villi in arachnoid granulations

one way valves that open when the ICP is 3-5cm H20 greater than the dural venous sinus pressure

132

what makes acute pain different from chronic pain

<1 month, usually obvious tissue damage

133

how do NSAIDs work

noxious stimulation of the skin releases bradykinin which stimulates nociceptive sensory terminals
prostaglandins sensitise the sensory terminal fibres to bradykinin
NSAIDs inhibit cyclo-oxygenase the enzyme which converts arachidonic acid --> prostaglandins
STOP SENSATION

134

what is cytotoxic oedema (ICF)

cellular swelling causes increased water and NA due to failure of membrane transport
(due to early infarction, water intoxication)

135

what is the difference between compliance and elastance

compliance - change in volume for a change in pressure (dV/ dP)
elastance - change in pressure observed for a given change in volume (dP/ dV)

136

what happens if a short term memory is significant

consolidation of memory into long term memory

137

what are the inputs to the posterior parietal cortex (area 5 and 7) to create a mental image of body in space

somatosensory, proprioceptive, visual

138

what is the function of the static reflex

image stays the right way up - when head tilts, eyes intort/ extort to compensate

139

what is nociception

the detection of tissue damage by specialised transducers connected to Adelta and C fibres
(respond to thermal, chemical, mechanical and noxious stimuli)

140

why is total asleep time greatest during development

brain maturation and synaptic formation occurring rapidly

141

in the stretch reflex, what muscles does the efferent impulse inhibit

antagonist

142

what cord segment is the patellar tendon

L4

143

how is LMN distribution somatotopic

medial - axial and proximal limb muscles
lateral - distal limb muscles eg fingers

144

how long does short term memory last

seconds- hours

145

what spinal layers are the wide dynamic range neurones

layer 5
receive input from Abeta mainly but also noxious via interneurones

146

what is contained in the otolith membrane

otoliths (CaCO3 crystals) denser than endolymph

147

how does the CSF cope with a rise in ICP

displaces from the ventricular system through the foramina of Luschka and magendie into the spinal subarachnoid space

148

what does the process of consolidation involve

selective strengthening of synaptic connections through repetition

149

what is the response in babinski's sign in a baby or if there is cortical damage

extension

150

what are the sensory cells of the semi circular canals called

ampulla

151

what is Parkinson's caused by

degeneration of neurones in substantial migration and their dopaminergic inputs to corpus striatum

152

what is the cause of Menieres disease

overproduction of endolymph causing an increase in pressure

153

what are the 4 stages of memory

intermediate/ sensory memory
short term memory
intermediate long term memory
long term memory

154

how long after spinal shock does it take for reflexes to return

2-6 weeks

155

why does alzheimers cause a severe memory loss

severe loss of cholinergic neurones throughout the brain , including the hypothalamus

156

what stage of sleep can you never be deprived of

REM

157

what is the function of the dynamic righting reflex

rapid postural adjustments that are made to stop you falling when you trip (long reflexes involving limb extensors)

158

what is cerebral oedema

state of increased brain volume as a result of an increase in water content (prominent cause of intracranial hypertension)

159

what is motor learning based on

predictions, calculations and experience to compare what is intended with actual actions and compensations

160

what is the normal MAP and how is it calculated

90 mmHg
2/3 DP + 1/3 SP

161

what happens if there is distortion towards and away from the kinocilium

towards - depolarisation and increased APs in vestibular nerve
away - hyper polarisation and decreased APs

162

what are night terrors

nightmares that occur in deep, delta sleep common in young children typically early in the night - they are not properly awake and don't remember in the morning

163

where does the lateral spinothalamic tract terminate

ventroposterior thalamic nuclei

164

what drugs increase time in REM sleep and cause more vivid dreams

anticholinesterases

165

what is the ampulla

swelling at base that contains sensory hair cells

166

what nucleus in the hypothalamus is responsible for the 24 hour circadian rhythm

suprachiasmatic uncle (SCN)

167

what types of sensory receptors are there

mechanoreceptors
chemoreceptos
thermoreceptors
nociceptors
proprioceptors

168

what is somnambulism

sleep walking

169

where does the corticospinal tract decussate

medulla

170

what is seratonin a precursor of

melatonin

171

how day light make you less sleepy

detectede by cells in retina --> axon to SCN --> less melatonin --> less sleepy

172

what does the vestibular system control

posture and balance

173

what spinal layers are the low threshold mechanoreceptive neurones

layer 3 and 4
receive inout from Abeta

174

what is anterograde amnesia

can't form new memories
inability to recall events that happen after the injury - can be short lived or permanent

175

what are the 4 classes of ventromedial pathways

tectospinal
vestbulospinal
pontine reticulospinal
medullary rectospinal

176

how does dreaming help to tidy up memory stores

forget memories that are no longer useful

177

what are the immediate sensory and autonomic effects that occur in spinal shock

loss of sensation
loss of bladder, bowel and sexual regulation

178

do putamen neurones inhibit or excite the globes pallidus at rest

inhibit (input from cortex releases inhibition)

179

how do opiates work (morphine)

activate mu receptors which inhibit transmission across the synapse in dorsal horn (epidural)
activate descending pathways from PAG (peri- aqueductal grey matter) in brainstem
inhibit action potential firing at nociceptive nerve terminals

180

what 3 foramina does CSF flow through from 4th ventricle to subarachnoid space

2 foramina of luschka
1 foramen of magendie

181

is the stretch reflex monosynaptic or polysynaptic

monoynaptic

182

what is the strategy function of motor control

the goal and the movement strategy to best achieve the goal (decision making)

183

what is the dynamic vestibular nystagmus reflex

series of saccadic eye movements that rotate the eye against the direction of rotation of the head and body so that the original direction of gaze is preserved despite head rotation (e.g roundabout)
direction of nystagmus = direction of rapid flick back

184

what structures are involved in the high level of motor controls

association neocortex, basal ganglion

185

what is the major ascending tract for nociception

spinothalamic
(sends impulses to thalamus)

186

what do the pontine/ medullary rectospinal tracts do

control trunk and antigravity muscles in limbs (use sensory information about balance, body position and incoming vision)

187

what occurs in the process of CSF synthesis

Na is pumped into subarachnoid space (using ATP) and water follows from blood vessels

188

what percentage of sleep is spent in REM sleep

25%

189

why are smells particularly powerful in evoking long term memories

olfactory stimuli relayed from olfactory tract through the amygdala and hippocampus to the prefrontal cortex

190

what produces the drag which bends the cupola and embedded cilia in the opposite direction of movement

inertia of endolymph

191

why does sleep increase when you are ill

supports immune function

192

what 3 structural changes take place at synapses in long term memory

Increase in ;
- NT release sites on presynaptic membrane
- number of NT vesicles stored and released
- number of presynaptic terminals

193

define 'coma'

stay of unconsciousness from which an individual can't be aroused and doesn't respond to stimuli

194

what does defective orexin signalling from hypothalamus cause

narcolepsy - individual suddenly falls asleep

195

what stage of sleep do dreams occur in and remembered

REM

196

at what level and by what structures does the tactics function of motor control occur

middle - cerebellum, motor cortex

197

what drives emotive behaviours

seeking reward - well being, euphoria, sexual arousal
avoiding punishment - terror, anger, pain

198

if there is damage to the dorsal column , what sensory stimulus will be lost on the ipsilateral side

touch, vibration, proprioception below lesion

199

what cord segment is the triceps jerk

C7

200

how long does chronic pain last

3-6 months +

201

what activates sensory signal transduction

low pH, heat
chemical mediators - bradykinin, histamine, prostaglandins

202

how are maculae orientated in the utricle and saccule

utricle - horizontal
saccule - verticle

203

what investigation can be done to assess consciousness

EEG - electro encephelogram

204

what does the electrical phenomenon of short term memory depend on

maintained excitation from reverberating circuits (constantly refreshed)

205

why is the stretch reflex highly localised

only affects alpha neurones of one/ two spinal segments

206

what spinal layers are the nociceptive specific neurones

layer 1 and 2
receive input from C and Adelta

207

what is the tactics function of motor control

the sequence of spatiotemporal muscle contraction to achieve a goal smoothly and accurately

208

what does the vestibulospinal tract do

stabilise head and neck

209

what things can be done to manage increased ICP

- head elevation (facilitate venous return)
- mannitol/ hypertonic saline
- hyperventilation (decrease CBF)
- barbiturate coma - decrease cerebral metabolic
- surgical decompression
- new - brain tissue O2 monitoring and micro- dialysis

210

what type of neurones directly control muscle

alpha motor neurones in the spinal cord

211

how does the flexor withdrawal reflex work

increased sensory AP from nociceptors
Interneurons have;
increased activity in flexor muscle of affected part
inhibit antagonist extensors

212

what is kinaesthesia

perception of movement and body position

213

when does kinetosis occur

when visual and vestibular inputs to cerebellum are conflicted

214

how is a bigger reaction achieved in the flexor withdrawal reflex in response to a lot of pain

alpha nociceptive fibres branch at multiple spinal levels to activate interneurons in several spinal segments

215

what type of receptors are used in the flexor withdrawal reflex

nociceptors (pain) in skinny, muscles and joints

216

what are the 3 key components for learning and memory

hippocampus, cortex and thalamus

217

is the flexor withdrawal ipsilateral or contralateral

ipsilateral flexion
contralateral extension

218

what cord segment is the achilles tendon

S1

219

what is useful in the treatment of cerebral oedema

mannitol

220

describe hypokinesia (in parkinson's)

slowness, difficulty making voluntary movements, increased muscle tone (rigidity), tremors of hand and jaw

221

what is lateral inhibition of neurones

activation of one sensory inout causes synaptic inhibition of neighbours (gives better definition of boundaries)

222

when are alpha waves shown on an EEG

relaxed, awake state (high frequency, high amplitude)

223

what is declarative/ explicit memory

abstract memory for events (episodic) and for words, rules and language (semantic)

224

what 4 things make up the papez circuit

hippocampus --> maxillary bodies --> anterior thalamus --> cingulate gyrus

225

what does the tectospinal tract do

ensure eyes remain stable as body moves

226

what are the 2 main types of memory

declarative/ explicit memory
procedural/ reflective/ implicit memory

227

if there is damage to the anterolateral column , what sensory stimulus will be lost on the contralateral side

loss of nocioceptive and temperature sensation below lesion

228

what is neurone convergence

several neurones synapse onto 1 (referred pain)

229

what is the function of the flexor withdrawal reflex

withdraw body part away from painful stimuli and in towards the body

230

what symptoms are seen in Huntington's disease

hyperkinesia, dementia, personality disorders

231

what are the 4 components of the limbic system

hypothalamus, hippocampus, cingulate gyrus and amygdala

232

what do cerebral arterioles do if CPP is high

constrict

233

what 4 systems control movement

descending control pathways
basal ganglia
cerebellum
local spinal cord/ brainstem circuits

234

where does major subcortical input to area 6 (premotor) come from

VLO - ventral lateral nucleus in dorsal thalamus

235

what are the signs of cushings reflex

hypertension, irregular breathing, bradycardia

236

what part of the brain does the declarative/ explicit memory rely heavily on

hippocampus

237

what form of oedema are steroids effective in treating

vasogenic oedema

238

why do depressed people have a disrupted sleep pattern

lack of seratonin

239

how long does the process of consolidation take (short term --> long term memory)

hours/ days (memories exist as electrical activity during this time and are vulnerable to being wiped out)

240

if there is a lesion in the lower motor neuron, what will happen to paralysis

flaccid (floppy)

241

what does activity in the SCN stimulate the release of

melatonin form the pineal gland (more melatonin in darkness)

242

where are upper motor neurones located

brainstem or cortex

243

what is the normal ICP and CPP

ICP - 5-15mmHg
CCP - 80 mmHg

244

what is the monro- kelly doctrine

the cranium is a rigid structure with brain, blood and CSF at a constant pressure
when a new intracranial mass is introduced, a compensatory change in volume must occur through a decrease in blood or CSF

245

what is the purpose of facilitation

increase the effects of sensory inputs

246

what are the 2 classes of lateral pathways

corticospinal
rubrospinal

247

what are the 3 components to central sensitisation response to pain

wind up - wind up response to the input
classical - open up new synapses
long term potentiation - mainly activated synapses

248

what neuronal changes occur in cognition (neuronal plasticity)

central neurones adapt their connections in response to learning experiences

249

what is a central sensitisation response to pain

response of 2nd order neurones in the CNS to normal input

250

where do 2/3 of the corticospinal tracts originate

area 4 and 6 of frontal motor cortex

251

what do higher order reflexes integrated by brain stem nuclei control

posture and balance

252

why must patients be distracted when testing reflexes

avoid voluntary input

253

where does the rubrospinal tract originate

red nucleus of midbrain (inputs form area 4 and 6)

254

which type of pain responds to conventional anaesthetics (nociceptive or neuropathic)

nocioceptive

255

what are the three types of primary afferent fibres that provide cutaneous sensation

Abeta - large myelinated
Adelta - small myelinated
C - unmyelinated fibres

256

where does the medial spinothalamic tract project to

cortical regions - anterior cingulate and ínsula cortex, limbic sytem
receives input from the ventral spinothalamic tract

257

which part of the reticular formation are the excitatory neurones which sustain wakefullness held

ascending reticular activity system

258

what percentage of CO/ O2 consumption does the brain receive

CO- 15%
O2 - 20%

259

how does REM sleep % decline through age

80% 10 week premature
50% full term
25% adulthood
may be absent by 80

260

what is disrupted in amnesia e.g head injury, infection

reverberation circuits disrupted - if hypothalamus/ thalamus memory loss occurs

261

what is the excitatory neurotransmitter required for wakefulness and where is it released from

orexin - from hypothalamus

262

what are present in dural venous sinuses to reabsorb CSF

arachnoid granulations

263

what are the sensory hair cells in the otolith organs called

maculae

264

what 2 types of primary afferent fibres mediate proprioception

Aalpha and Abeta in muscle spindle and gologi tendon organs

265

what happens if there is a lesion in the cerebellum

un-coordinates inaccurate movements (ataxia)
(similar to alcohol)

266

what is immediate long term memory associated with

chemical adaptation at the presynaptic terminal

267

what is the blood brain barrier composed of

astrocytic foot processes wrapping around capillary endothelium composed of tight junctions

268

what is stage 1 of the sleep cycle

slow wave, non REM sleep
slow eye movements, easily aroused
(high amplitude, low frequency theta waves)

269

why do beta waves on an EEG have low amplitude

high activity in brain means that opposing polarities of the signals cancel each other out so don't get recorded on EEG

270

how is the caloric stimulation test set up

outer ear rinsed with cold or warm fluid - temperature difference from core goes through thin bone which sets up convention current for endolymph

271

what is insomnia

chronic inability to obtain the necessary amount or quantity of sleep to maintain adequate daytime behaviour

272

why is the flexor withdrawal reflex slightly slower than the stretch reflex

done by interneurones so have a small synaptic delay

273

which is the largest most important lateral pathway

corticospinal tract

274

do globus pallidus neurones inhibit or excite the VLO at rest

inhibit

275

which area stores and accesses memories

thalamus

276

what causes the symptoms of huntingtons

profound loss of caudate, putamen and globus pallidus (inhibitory effects of basal ganglia)

277

what is pain

an unpleasant sensory and emotional experience which we primarily associate with tissue damage or be described in terms of such damage (different for everyone)

278

what is cerebral autoregulation

the ability to maintain a constant blood flow to the brain over a wide range of CPP (50 - 150 mmHg)

279

how do local anaesthetics work

block all NA action potential - stop all axonal transmission

280

what do lateral pathways between the brain and spinal cord control

voluntary movements of distal muscles

281

what do sleep deprived subjects demonstrate

impairment of cognitive function and physical performance, sluggishness, irritability

282

how long does REM last and how often does it occur

5-30 mins every 90 mins during a normal nights sleep

283

why is 24 hour circadian rhythm in line with light/ dark cycles

optic nerve fibres pass to SCN

284

what is the function of the basal ganglia

gating proper initiation of movement

285

how do mechanoreceptors (Aalpha and Abeta) transmit sensory information

project straight up through ipsilateral dorsal columns to synapse at cuneate and gracile nuclei
2nd order decussate at brainstem --> reticular formation --> thalamus --> cortex

286

how much CSF is produced each day

450 - 600ccs

287

what stage of sleep does sleep walking occur in most

stage 4

288

what is the function of the pre motor area

connect reticulospinal neurones innervating proximal units

289

which area forms memories

hippocampus