L22 - Sleep Flashcards
(11 cards)
describe the changes that occur to our bodies during our normal circadian rhythm
Over night:
- vasopressin (EDH) highest at night
- metatonin high
- cortisol increasing throughout night
- growth hormone spikes at night, promote smooth eruption.
- thyrotropin highest at night, to do with metabolism
how does the circadian ryhtmn affect salivary flow rate
- salivary glands express clock genes that promote: water channel expression in salivary glands, high alpha-amylase expression at night
describe the hypothalamic circadian timing system (diagram on slides)
hypothalamus controls pituitary gland, but its also part of the brain proper and the top end of the endocrine system
- ventrolateral pre optic nuclei (is the sleep centre)
- suprachiasmatic nucleus (is the central clock)
- reticular formation (arousal centre)
- lateral hypothalamic area (contains orexin neurons)
suprachiasmatic nucleus: - drives melatonin via paraventricular nucleus
- drives body temperature via dorsal supra ventricular zone
- drives wake-sleep via ventral SPZ and dorsomedial hypothalamus
describe the brain regulation of wake/sleep state: reticular activating system (diagram on slides)
- suprachiasmatic nucleus (vasopressin and vasoactive intestinal peptide)
- pedunclopontine and laterodorsal tegmental nuclei (acetylcholine)
- ventrolateral preoptic nucleus (sleep centre; GABA)
- lateral hypothalamic area (orexin)
- reticular formation (noradrenaline, serotonin, histamine)
suprachiasmatic nucleus (SCN), negative energy balance and limbic system activity all activate orexin neurons in the lateral hypothalamic area.
orexin neurons activate monoaminergic neurons (reticular formation)
- which activates the thalamus and cortex
- and deactivates the sleep centre (ventrolateral pre optic nucleus)
describe the flip-flop switch for sleep
Awake:
- orexin neurones in the lateral hypothalamic area activate the reticular formation which blocks ventrolateral pre optic nucleus (sleep centre), meaning you are awake
If changes towards this… you get sleep
Sleep:
- reticular formation off and orexin neurone stimulating reticular formation
- sleep centre block orexin and reticular formation and you end up asleep
can’t be ‘falling’ asleep. its an immediate change from awake to asleep
describe the electroencephalogram assessment of sleep
records the different electrical signals/fields of the nuerons that are under the electrodes during the wake-sleep system
- beta rhythm: alert
- alpha rhythm: drowsy
- theta rhythm: Non-REM sleep
- delta rhythm: slow-wave sleep
- REM (paradoxical sleep) - similar to awake beta rhythm
what is the relationship between anaesthesia and sleep
anaesthesia does NOT equal sleep
because anaesthesia is the removal/reduction of function of the brain
- as sedation deepens, EEG frequency slows and EEG amplitude increases
what are the stages of normal sleep
normal sleep goes in cycles (shown on graph on slide)
- enter deep sleep, then dreaming (paradoxical) sleep, then deep, then dreaming etc. etc. in a cycle but each time the stages get longer
- difficult to function well if you cut your sleep cycle short
what are the symptoms of sleep bruxism (teeth grinding)
- (abfraction) loss of tooth matter at gum line
- (gum recession) gum tissue wears away or pulls back from teeth
- (attrition) mechanical heating of the incised or occlusal surfaces of teeth
masticatory muscles are involved with this, as they are what are used for teeth grinding. masseter is main muscle for this.
caused by SNS activation
cycle:
1. SNS gets triggered by something. get rise in autonomic cardiac sympathetic dominance
2. rise in brain activity (EEG)
3. tachycardia, big breath, rise in supra hyoid muscle tone
4. onset of RMMA (rhythmic masticatory muscle activity) with possible tooth grinding with rise in BP
5. swallowing (less than half of episode)
describe obstructive sleep apnea
occurs when throat muscles intermittently relax and block the airway during sleep (snoring!)
- obstructive sleep apnea is the most common sleep apnea
the gold standard for diagnosis of sleep apnea is nocturnal polysomnography ie. measurement of
- brain waves
- eye movements
- muscle activity
- chest movements (get stages of no breathing)
- air flow
- blood oxygen saturation (blood oxygen decreases)
describe the levels in the apnea-hypopnea index (AHI)
apnea severity, AHI events/hours of sleep
- normal: <5
- mild: 5<AHI<15
- moderate: 15<AHI<30
- severeL >30
