Chapter 8 Flashcards
endogenous circannual rhythm and
endogenous circadian rhythm
endogenous: coming from inside the animal/ not necessarily triggered by outside stimuli
circannual: yearly (birds flying north)
circadian: daily
processes that follow the circadian rhythm in humans
sleep, body temperature, mood, hormones, and much more
zeitgeber
stimuli that help setting and resetting the biological clock. Light is the important one for humans, other factors like activity, or food intake play a minor role. Lack of or problematic zeitgeber (e.g. in Antarctica) can lead to bad sleep and feeling unrested
jet lag
disruption of circadian rhythms due to crossing time zones. Jet lag is stressful –> more cortisol –> long term repeated jet lag damages the hippocampus
shift work
people often cannot adjust to working in the night
To improve adjustment the sleeping room must be very dark and the work place must have bright blueish light
morning and evening types
the body temperature rhythm differs for people, some have their peek of activity in the midday, some have it later in the afternoon
middle of sleep at different ages
the middle of sleep gets later and later until age 20, from which it starts to get earlier and earlier again
social jet lag
teenagers that are evening types suffer under the early times school starts and get worse grades than pupils with comparable IQ
the biological clock
the biological clock is endogene and works even when a person is deprived of light, food, has brain damages, takes drugs etc. It is quite robust. It slowly gets out of phase though when people do not get any indication of the day time
main brain structure for rhythms of sleep and body temperature
Add to dictionary nucleus (SCN)
properties of suprachiasmatic nucleus
lies just above the optic chiasm, works independent of the rest of the body,
how does light influence the SCN
there are special ganglion cell at the eye, which slowly respond to light, and transmit the average light intensity right into the SCN. These ganglion cells even work with little information, for example for nearly blind people
what are PER and TIM, and how do they work
They are proteins which promote sleep. Their production follows a negative feedback loop. Concentration is low in the morning, so they get produced. We (or flies actually) have the most of them in the night. A lot of PER and TIM sends messages to stop producing them. Therefore, the PER and TIM levels lower towards the morning. Light activates chemical to destroy these proteins
melatonin
is a hormone that promotes sleep and thereby also influence circadian rhythms. It get released by the pineal gland, which in turn is controlled by the SCN
distinction sleep and coma
sleep: actively produced by the brain, characterized by decreased responsibility to stimuli, but a loud noise still can wake people up
coma: extended period of unconsciousness caused by head trauma or the like. People cannot be woken up with a loud noise. Usually leads to death or recovery within
vegetative state
alternate between sleep and moderate arousal, but never with awareness of surroundings or purposeful behavior. Can last a long time
minimally conscious state
occasional brief periods of purposeful actions and limited amounts of speech and comprehension. Can last a long time
brain death
no sign of brain activity or response to stimuli, for 24 hours
EEG measurements
the eeg measures activity when most cells do the same thing, so no slight or small regional variations
polysomnography
a combination of eeg and eye movements
alpha waves
characteristic of relaxation, not of full wakefulness, frequency of 8 to 12 per second
sleep spindle
12 to 14 hz waves during a birst that lasts at least half a second, results out of interactions between thalamus and cortex
k-complex
a sharp wave associated with temporary inhibition of neuronal firing
stage 1 sleep
irregular, jagged low voltage waves