SPECIALIZED FUNCTIONS OF BRAIN ::
SLEEP :;
Sleep is defined as a state of unconsciousness from which one can be aroused by harmless stimuli and is refreshing in nature There is a popular notion that sleep is a uniformly quiescent and peaceful state and therefore devoid of stress it is however not correct many physiological changes occur during sleep in general there is decrease in blood volume blood -pressure heart rate respiration various secretions and muscle tone however rhythmically at a regular interval in sleep there is increase in activity sleep rhythm can be divided into various stages main stage are (1) Slow wave sleep or non rapid eye movement (NREM) Sleep and (2) rapid eye movement (REM) sleep The sleeping habbit and rhythm may differ from individual to individual and depend upon age Normal sleep requirement is 7-9 hours for adults for the new born baby it is 16-20 hours and it decreases as the age advances old people require 5-6 hours sleep only REM stage of sleep occurs at a regular interval of 90 minutes in adults it occupies about 20% of total sleep in adults children have about 40-50% of REM sleep
During slow wave (NREM) Sleep there are characteristic changes in EEG This phase can be divided into four stages phase I is drowsines followed by phase II the light sleep and phase III and IV as profound and deep sleep respectively During NREM sleep secretion of growth hormone is the greatest there is relaxation of skeletal museles and decrease in various physiological activites This NREM sleep is needed for bodily repair Deep sleep is followed by REM sleep As the name suggests eye-ball shows movements The individual may report that they have been dreaming in males penile erections may occur There is an increase in pulse blood pressure and respiration during this stage patients of angina peectoris migraine duodenal ulcers etc have exacerbations of their symptoms Although it appears that REM sleep is disturbing stage but it has been established that it is concerned with repair of mental tiredness it is necessary for the mental well -being and deprivation of this stage may cause irritation and other psychological disturbances
The causes of sleep although not very clear may be instinct fatigue parasympathatic predominance etc it was proposed that inhibition of reticular formation or removal of external stimulation can cause sleep But it has been found to be wrong of late various neurotransmitters such as serotonin catecholamines etc have been proposed to be involved in sleep mechanisms
SPEECH :::
Speech is a motor activity involving control of labial lingual pharynegeal palatal and respiratory muscles Motor area 44 is the speech area in the cerebral cortex that integrates with visual and audiopsychic area Thalamus cerebellum and basal ganglia are also involved in speech writing and reading are also the forms of speech speech is unique amongst motor acitvities in that its
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