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MD4001 Physiology > Sleep, Wakefullness and the ECG > Flashcards

Sleep, Wakefullness and the ECG Flashcards

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1
Q

What are the three states of consciousness

A

wakefullness

core consciousnes- wakefullness plus emotional responses, simple memory

extended consciousness- all of the above plus self awareness, autobiographical memory, language and creativity

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2
Q

are brain neurones active during sleep

A

yes but have a different activity

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3
Q

what are the two main phases of sleep

A

REM and non REM/ slow wave or deep sleep

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4
Q

what signals can be picked up from the EEG

A

post synaptic activity of synchronised dendritic activity but not individual neurons

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5
Q

what determines the size of the peak on the EEG

A

the number of neurons that are synchronised

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6
Q

what causes neurons to synchronise

A

neuronal interconnections or by pacemaker

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7
Q

describe how EEGs are performed

A

electrodes are arranged in 19 pairs on the surface of the head

comparison between pairs of electrodes provides a pictures of neuronal activity in areas of the brain

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8
Q

what happens during stage one sleep

A

slow rolling eye movements, theta waves

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9
Q

what happens during stage 2

A

K complexes and sleep spindles, no eye movements, body movement remains possible

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10
Q

what happens during stage 3 sleep

A

slow frewuency delta waves

harder to rouse

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11
Q

what happens in stage 4 sleep

A

deepest sleep hardest to rouse
heart rate and blood pressure lower

synchronised firing of large groups of neurons

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12
Q

what happens in REM sleep

A

fast beta waves and REM, easier to rouse than in stage 4

dreaming and low muscle tone

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13
Q

how long does it take to get from drowsy to deep sleep

A

one hour

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14
Q

describe sleep cycles throughout the night

A

stage 4 is only reached in the initial cycles, thereafter the deepest sleep atained is stage 3

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15
Q

what are the characteristics of REM sleep

A

increase in heart rate, neural activity, respiration and oxygen consumption, erection

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16
Q

what are the subtypes of alpha waves

A

visual cortex (classic)
sensory motor cortex (mu)
auditory( kappa)

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17
Q

what is the function of slow waves

A

thought to be involved with inhibiting sections of the relevant cortex

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18
Q

during what stage of sleep is the body paralysed, and body temperature drops

A

REM

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19
Q

what is the reticular formation

A

a diffuse collection of at least 100 neuromodulatory neurones spanning all three divisions of the brainstem

pathways in the brainstem connecting the spinal cord, cerebrum, and cerebellum, and mediating the overall level of consciousness.

it is not homogenous and has diverse functions

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20
Q

what are the functions of the reticular formation

A

posture, respiration, sleep, heart rate

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21
Q

where does the reticular formation project to

A

the thalamus, hypothalamus, brainstem nuclei, cerebellum, spinal cord and cerebral cortex

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22
Q

what does the reticular formation recieve input from

A

cerebra, visual and auditory systems, sensory spinal systems, cerebellum, certain brainstem nuclei

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23
Q

what structure is required for consciousness

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A

release of neurotransmitters from neurones of the reticular formation (norepinephrin, serotonin, acetylcholine)

24
Q

what neurotransmitters are required for consciousness

Study These Flashcards
A

norepinephrin, serotonin, acetylcholine

25
what structure modulates arousal in the cerebral cortex
thalamus
26
what inputs go to the thalamus
``` midbrain reticular formation vestibulocochlear nuclei spinal nucleus 5 spinoreticular pathway nucleus basalis thalamus ```
27
how can excitability of the thalamus be controlled
reticular formation
28
what is the effect of lesions to the thalamus on the eeg
most synchronous eeg waves are abolished
29
what stimulates stage 4 sleep
rhythmic stimulation of the thalamus induces stage 4 sleep
30
how can EEG wave types can be changed
activation of the reticular formation and so the thalamus- increasing stimulation of the thalamus increases alertness
31
what 3 structures are most concerned with wakefulness and are interconnected
thalamus, reticular formation, cerebral cortex
32
describe the effect of excitation on the reticular formation
depolarisation of the thalamus causes non rhythmic output to the cortex this causes increase arousal (alpha and beta waves)
33
describe the effect of inhibition to the reticular formation
this causes hyperpolarisation of the thalamus which causes rhythmic output to the cortex this causes slow EEG waves in the cerebral cortex so deeper sleep
34
how is deeper sleep achieved
inhibition of the reticular formation
35
what is non rem sleep characterised by
slow synchronised cortex waves, caused by a hyperpolarised thalamus and decreased activity in the arousal centres of the reticulum
36
what causes sleep spindles and K complexes (stage 2)
inherent rhythmicity of thalamic neurons as they hyperpolarise due to reduced ascending reticular formation input
37
describe the effect as thalamic cells hyperpolarise further
they develop slow wave rhythmicty due to thalamic interconnections which blocks ascending sensory input this rhythmicity is transmitted to the cortex and the waves become synchronised
38
what does the locus coeruleus block during rem sleep
descending motor output
39
describe the oxygen consumption of the brain during rem sleep
uses more than awake and engaged in a complex problem
40
what does the midbrain reticular formation do during rem
excites the thalamus and provides descending inhibitory stimuli to the motor pathways
41
describe the passage from wakefullness to sleep
midbrain reticulum projects cholinergic excitation onto the thalamus pathway is on except for NREM sleep direct cortical excitation is quiescent during REM sleep (lesions cause coma)
42
what is the ventrolateral pre optic nuceus
the centre of NREM sleep promotion it has inhibitory projections to all the major arousal centres and is active during sleep
43
what structures inhibit the ventrolateral pre optic nucleus
arousal centres
44
what are orexinergic neurons
normally acitve during wakefullness (lateral hypothalamus) they project to the cerebra, the arousal nuclei and the VLPO this causes indirect inhibition of the VLPO via reciprocal inhibition pathways
45
what hormone is pivotal in sleep awake switch circuitry
orexin
46
what happens when orexin is released
stimulates arousal centres and so causes inhibition of the VPLO shifts the balance towards wakefulness
47
what happens when the VPLO fires
inhibits orexinergic neurons and the arousal centres | this causes sleep
48
where is the suprachiasmatic nucleus located
hypothalamus
49
what does the suprachiasmitic nucleus control
circadian cycles, physiolical and behavioural rhythms including sleep wake cycle
50
what resets the SCN clock
zeitgebers (time givers) e.g. the light/ dark cycle
51
what do receptors in the retina contain
melanopsin which reacts to light and resets the clock gene
52
what are the two forms of permanent insomnia
rare inherited neurodegenerative process affecting the thalamus and the rostral hypogenic sleep centres stroke resulting in blockade of the basilar artery causing locked in sydrome, if this includes the loss of the pontine hypogenic centre the result can include insomnia
53
what causes narcolepsy
loss of orexinergic neurons in the lateral hypothalamus inherited autoimmune
54
what are the symptoms of narcolepsy
repeatedly falling asleep during the day limb weakness during emotional episodes (cataplexy) night time or morning wakening accompanied by muscular paralysis vivid dream recollection caused by pontine influence of muscle tone during REM
55
What is the term for sleep walking
somnambulance
56
what is REM sleep behaviour disorder
n the descending pontine reticular formation fails to properly immobilise the body. Characterised by rapid/violent movement and behaviour
57
what is somnambulance
during non-REM sleep. Often the same as REM sleep behaviour disorder but there is no memory of the dreams enacted. Occurs in NREM sleep which is why there is no memory, and happens when the midbrain reticular formation fails to paralyse the body

MD4001 Physiology (19 decks)

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