Chapter 9: Wakefulness and Sleep Flashcards
functions of endogenous rhythms and our difficulty with altered rhythms
- endogenous circadian rhythms last about a day
- difficult to sleep on anything far from 24 hour schedule
- have rhythms for eating, drinking, urination, secretion of hormones, sensitivity to drugs, temperature, mood
- trend is that we sleep less as we get older
- jet lag due to mismatch between internal circadian clock and external time
describe the anatomical location of the biological clock and its biochemical and hormonal signals
light=critical for resetting
- in hypothalamus it is called suprachiasmatic nucleus (SCN)
- SCN provides main control of circadian rhythms for sleep and body temperature
- SCN generates circadian rhythm in genetically controlled, unlearned manner
how light can reset the biological clock
- retinohypothalamic path to SCN comes from special population of retinal ganglion cells that have their own photopigment called melanopsin that receive some input from rods and cones (but without this input they respond directly to light)
- located mainly near nose
- respond to light slowly and turn off slowly when light ceases not instantaneous changes in light
- retinohypothalamic path conveys info about light to SCN, axons comprising what path originates from special ganglion cells that respond to light by themselves, even without input from rods and cones
characteristics of the stages of slow-wave sleep
- stages 3 and 4 together
- neuronal activity is highly synchronized
- sensory input to cerebral cortex is greatly reduced
- few remaining sources of input can synchronize many cells
describe biological clock and its biochemical and hormonal signals
-genes known as period and timeless produce proteins PER and TIM that promote sleep and inactivity
-oscillate throughout the day based on feedback
-PER and TIM=low @ start of day
= high @ end of day
-light activates a chemical that breaks down TIM
-pineal and endocrine glands release melatonin mostly at night
characteristics of the stages of REM sleep
- paradoxical sleep because it is deep light in some ways and light in others
- EEG shows irregular, low voltage fast waves that indicate increased neuronal activity (light sleep)
- Postural muscles are relaxed (deep sleep)
- HR, HP, and breathing rate are more variable in REM
- has intermittent characteristics such as facial twitches and eye movements
Stages of Sleep
Stage 1 Stage 2 Stage 3 Stage 4 Stage 3 Stage 2 REM
brain areas and neurotransmitters that promote REM sleep
- activity increases in pons and limbic system
- decrease activity in primary visual cortex, motor cortex, and dorsolateral cortex
- increase activity in parietal and temporal cortex
- depends on relationship between serotonin and acetylcholine
Locus coeruleus
- in pons
- inactive during sleep but release bursts of impulses when meaningful event occurs resulting in emotional arousal
- axons release norepinephrine
- stimulation strengthens storage of recent memories and increases wakefulness
Histamine
- NT released
- excitatory effects during arousal and alertness
Histamine
- NT released
- excitatory effects during arousal and alertness
Orexin or Hypocretin
- peptide NTs
- from axons extending to basal forebrain
- responsible for staying awake
Acetylcholine
-released during wakefulness and REM sleep
GABA
-responsible for sleep
Insomina
- inadequate sleep
- feel tired during the day because you are not sleeping enough at night
- causes: noise, uncomfortable temperature, stress, pain, diet, medications, epilepsy, Parkinson’s, brain tumour, depression, anxiety, neurological or psychiatric condition
