TASK 6 Flashcards
_circadian rhythms
– animal and human’s daily routine (24h)
_zeitgeber
– A stimulus (usually the light/dark) that resets the biological clock that is responsible for circadian rhythms
_The control of seasonal rhythms and circadian rhythms involves another part of the brain (WHICH?)
the pineal gland. This structure sits on top of the midbrain, just in front of the cerebellum. The pineal gland secretes a hormone called melatonin
_melatonin
– A hormone secreted during the night by the pineal body; plays a role in circadian and seasonal rhythms
_diurnal
– being active during the daylight
_nocturnal
– being active during the night
Most animals attend diurnal/nocturnal rhythms because of their biological clock, humans have clocks but otherwise they would follow it as well, even if ….
It is regulated (usually) by endogenous factors (light/dark)
_free running
– animal that maintains its own cycle, not caring about the daily routine
_entrainment
– synchronizing a biological rhythm to an environmental stimulus
_suprachiasmatic nucleus (SCN)
– region of the hypothalamus above the optic chiasm where the circadian oscillator is located, it produces circadian rhythms
_melanopsin
– A photo pigment present in ganglion cells in the retina whose axons transmit information to the SCN and the thalamus – photo pigment found within particular retinal ganglion cells that project to the suprachiasmatic nucleus
_retinal ganglion cells send their axons along the _______________________??
retinohypothalamic pathway (RHT)
_infradian
– referring to a rhythmic biological event whose period is longer than that of a circadian rhythm – that is, longer than a day
_circannual
– occurring on a roughly annual basis
_ultradian
– referring to a rhythmic biological event whose period is shorter than that of a circadian rhythm , usually from several minutes to several hours long
_retinohypothalamic tract (RHT)
– it is a photic neural input pathway involved in the circadian rhythms of mammals. The origin of the retinohypothalamic tract is the intrinsically photosensitive retinal ganglion cells (ipRGC), which contain the photo pigment melanopsin. It splits off at the optic chiasm to synapse directly within the SCN. These retinal ganglion cells contain melanopsin
We have an endogenous circadian clock (dark-light) proved with an experiment with people in a cave with no light for few weeks who showed ??different or not different?? circadian rhythms
differeny
_electroencephalography (EEG)
– provides a way to define and describe stages of sleep and arousal. Supplemented with _electromyography (EMG) _electro-oculography (EOG)
_electromyography (EMG)
– measures muscle tension
_electro-oculography (EOG)
– records eye movement
SLEEP PERIODS
Adults usually show repeated cycles (4-5 periods per night) of about 90-110 minutes each. The REM periods are longer in the last periods (40 min) and shorter in the first periods. Teenager should wake up after, they have different circadian rhythms compared to adults Each period has STAGES. REM occurs in stage 1 from the second period on, usually preceded by stage 2 . So stage 1, 2, 3 then back to the 2 and then 1 (which is REM)
_Waking
– awake human’s EEG is desynchronized. It is a mix of high frequencies with low amplitude. Also called beta activity
_alpha activity
– Smooth electrical activity of 8–12 Hz recorded from the brain; generally associated with a state of relaxation
_betha activity
– Irregular electrical activity of 13–30 Hz recorded from the brain; generally associated with a state of arousal
_tetha activity
– EEG activity of 3.5–7.5 Hz that occurs intermittently during early stages of slow-wave sleep and REM sleep
_delta activity
– Regular, synchronous electrical activity of less than 4 Hz recorded from the brain; occurs during the deepest stages of slow-wave sleep
_stage 1
NREM – alpha rhythms appear during relaxation, meaning reduction of muscle tension and slow heart rate. Also eyes may roll slowly. Vertex spikes (sharp waves) start this stage
_stage 2
NREM – defined by sleep spindles (waves of 12-14 Hz) and K complexes. If awakened during these first two stage of sleep, many participants deny that they were asleep, even though they failed to respond to signals while in those stages
_stage 3 and 4
NREM – defined by large-amplitude, very slow waves also defined as SWS – slow waves sleep, widespread synchronization of cortical activity . People in this stage would recognize one person speaking, but if more people are talking then they would hear just a buzz. Neurons tend to do synchronized activity, instead of doing different jobs (as when you are awake) _down state _up state
_down state
– A period of inhibition during a slow oscillation during slow-wave sleep; neurons in the neocortex are silent and resting