Ch. 9 Wakefulness and Sleep Flashcards
- Some animals can generate, internal mechanism that operates on an annual or yearly cycle.
- Ex. Birds migratory patters; animals storing food for the winter.
Endogenous Circannual Rhythms
o All animals produce, internal mechanisms that operate on an approximately 24-hour cycle.
ο Animals generate endogenous 24-hour cycles of wakefulness and sleep.
ο Also regulates the frequency of eating and drinking, body temperature, secretion of hormones, and urination.
Endogenous Circadian Rhythms
- Stimulus that resets the circadian rhythm.
* LIGHT is a dominant ______ for land animals.
Zeitgeber
o A disruption in circadian rhythms due to crossing time zones.
o Travelers complain of sleepiness during the day, sleeplessness at night, depression and impaired concentration.
Jet Lag
- The biological clock depends on this part of the hypothalamus.
- It is located just above the optic chiasm, it provides the main control of the circadian rhythms for sleep and body temperature.
The Suprachiasmatic Nucleus
Light resets the SCN via a small branch of the optic nerve known as the
Retinohypothalmic Path
The Retinohypothalmic path comes from a special population of ganglion cells that have their own photo pigment called
Melanopsin
The pineal gland releases the hormone ______, which influences both circadian and circannual rhythms.
Melatonin
An extended period of unconsciousness caused by head trauma, stroke, or disease.
Coma
Alternates between periods of sleep and moderate arousal, although even during the more aroused state, the person shows no awareness of surroundings.
Vegative State
One step higher from a vegetative state, with occasional, brief periods of purposeful actions and limited amounts of speech comprehension.
Minimally Conscious State
A condition with no sign of brain activity and no response to any stimulus.
Brain Death
Records an average of the electrical potentials of the cells and fibers in the brain areas nearest each electrode on the scalp.
The Electroencephalograph
A combination of EGG and eye movement records.
Polysomnograph
Characteristic of relaxation, not of all wakefulness. .
Alpha Waves
Alpha waves are present.
Awake (Relaxation)
o When sleep has just begun
o The EGG is dominated by irregular, jagged, and low voltage waves.
o Brain activity begins to decline.
Stage 1 Sleep
characterized by the presence of Sleep Spindles and K-complex
Stage 2 Sleep
Stage 2 Sleep is characterized by the presence of
Sleep Spindles and K-Complex
o Together constitute slow wave sleep (SWS) and is characterized by:
• EGG recording of slow, large amplitude wave.
• Slowing of heart rate, breathing rate, and brain activity.
• Highly synchronized neuronal activity.
Stage 3 and Stage 4
o Are periods characterized by rapid eye movements during sleep.
o Also known as Paradoxical Sleep, but term used for non-humans.
o EGG waves are irregular, low voltage, and fast.
o Postural muscles of the body are more relaxed than other stages.
Rapid Eye Movement (REM)
Sleep stages other than rem.
NON-REM (NREM) Sleep
- A cut through the midbrain decreases arousal by damaging this area.
- A structure that extends from the medulla into the forebrain; controls motor areas of the spinal cord and selectively increases arousal and attention in various forebrain areas.
Reticular Formation
• Part of the Reticular Formation that contributes to cortical arousal.
• These neurons receive input from many sensory systems and generate spontaneous activity of their own.
• Their axons extend into the forebrain, releasing acetylcholine and glutamate, which excite cells in the hypothalamus, thalamus, and basal forebrain
PONTO
Pontomesencephalon