Functions Of Reticular Formation Flashcards
(33 cards)
PRF is located in…….
Midbrain & pons
Describe functions of ascending & descending fibers of PRF
A, go first to thalamus (intralaminar & reticular nuclei) which, in turn, project diffusely & non-specifically to almost all parts of cerebral cortex, responsible for arousal
D, increasing antigravity muscle tone
The activity of reticukar excitatory area is inhibited by…….
Reticular inhibitory area, inhibitory areas of cerebral cortex, paleocerebellum, basal ganglia (the same activate inhibitory reticulat formation)
Functions of medullary reticular nuclei
Decrease brain activity (inhibits PRF)
Decreasing antigravity muscle tone
Mention factors stimulating RAS
Sensory signals that enter the brain from periphery esp pain
Signals from cerebral cortex
Analeptic & symoathomimetic
Stress
Caffeine
Thyroid hormone
Mention factors inhibiting RAS
Lack of sensory input signals
Signals from sleep centers
General anesthesia
Damage by tumour/vascular lesion
Enumerate functions of reticular formation
- It is a vital link between higher centers in brain & lower centers in spinal cord
- Maintain posture & equilibrium and muscle tone (cont. facilitatory impulses from reticular formation & vestibular nuclei)
- Arousal & consciousness
- RF contains vital centers for heart rate, blood pressure, respiration & many digestive activities
- Pain modulation (raphe magnus nucleus)
- REM sleep
Compare 1ry & 2ry evoked potential
1ry, in the form of a +ve wave followed by a -ve wave, recorded from specific area of the brain (localised)
2ry, follows the 1ry evoked potentials & consists of large prolonged +ve wave, not localised, due to activation of cortical neurons by impulses arriving from non-specific thalamic nuclei
Mention uses of evoked potentials
Mapping of brain areas
Diagnosis of diseases
EEG is a measure of……
The summation of polysynaptic potentials of neurons in cerebral cortex
Describe conditions of performing EEG
In a calm room with comfortable temperature & the person should be in complete physical & mental rest
Compare alpha and beta waves
A, waves of adult, awake, relaxed person with closed eyes, recorder from occipital, parietal and frontal regions, amp 50 um, Frq 8-13 cycles/sec.
B, waves of awake person with open eyes, recorded from parietal and fronta regions, amp 25 um, frq 13-30 cycles/sec.
Compare theta and delta waves
T, It is wave of children and adults during light sleep and emotional stress, recorded from temporal and parietal regions, amp 100 um, frq 4-7 cycles/sec.
D, it is the wave of deep sleep, infants and in cases of brain damage and surgical anesthesia, recorded from all cortical areas, amp 100 um, frq 3.5 cycles/sec
Describe gamma waves
It is the wave of hyperaroused, higher mental activity and processing of complex tasks, it is recorded from all cortical areas, amp 0.5-2 uv, frq 30-80 Hz
Value of EEG
Non invasive test for brain func
Localization of tumours
Monitor sleep stages and diagnose disorders
Diagnose epilepsy
Indicates brain death
GR, occurrence of alpha block
Stimulation of ascending reticular activating system
Mention functions of sleep
- Provides brain with time to restore biochemical & physiological processes that have progressively decreased during wakefulness? Congition, metabolic-caloric balance, thermal equilibrium, immune competence
- Facilitation of learning & memory
- Neural maturation
Importance of NREM sleep is….., …..is released during it & ….activity is increased.
Physical rest
Growth hormone
Parasympathetic
In NREM, threshold for arousal is….., while in REM it is….
Low
High
REM is important for……, with increased…..activitu
Mental rest
Sympathetic
Mention two phenomena occuring in REM & another 2 in NREM
R, teeth gringing & penile erection
N, sleep walking & talking
Mention type of wave in REM
Rapid irregular low voltage B waves (desynchronized beta rhythm)
Describe waves of Stage 2
Sleep spindles (bursts of large alpha waves 12-24 Hz) and K complexes (large & slow potetial) are seen within theta waves
First NREM sleep lasts for……, there is less……and more…..towards the morning
Average 90 min
stage 3 & 4 sleep
REM
