Question

Discuss the brain as a “functional whole”. Further, discuss the functions of the brain and explain hemispheric dominance and aplasias. Discuss the seat of stress and emotions in the brain and how it functions. Indicate whether the RAS is a functional or a structural entity of the brain.

Answer 1

Brain is one of the central organ of the body.It is the key organ of central nervous system.The brain is divided into cerebrum,cerebellum and medula oblongota.Brain controls,integrates,process and coordinate almost all the activities of the body.The structural and functional unit of brain is neurons.The brain is protectes by skull bones.Brain recieves all the stimulus from the sense organs,it processes it and provide response information to rest of the body through neurons.All the activities of our body are directly or indirectly guided by the brain.The cerebrum is the largest part of the brain.The surface is foldede into ridges and grooves.It performs functions like self control,planning,reasoning,abstract thought etc.Problem solving ability,behaviour,attention,perception,thought,visual reception,colour recongnizing ability,ability of speech etc are controlled by this cerebrum.Cerebellum controls and regulates muscular movements,posture,balance of the body.It is the center of cardiac and respiratory movements.Medulla oblongota controls the involuntary actions of the body like breathing,omiting,heart rate,swalloing etc.It transfers the message to and from the brain and spinal cord.Limbic system controls opur emotions.Pituitary gland releases many hormones necessory for growth,metabolism etc.Thus as a whole,brain functions and coordinates all the activities of the body.

The frontal lobe is separated into two:left and right brain and there is separation of function between the two sides .This is called lateralization.Both the sides are independent of each other and performs different functions.Hemispheric dominant theory states that amomg the two sides(right and left)one side of the brain is dominant over the other in an individual and has more influence over an individual's learning,creativity,personality etc.It is a right brain versus left brain theory.Both the sides of brain process stimulus in different ways and we choose one type of thinking only.Thus one side dominate over the other.If left side is dominant,the person will be more logical and methodological in thinking.If right side is dominant,the person is creative and emotional.

Aplasias is a disorder called aplasia cutis congenita which is a scalp defect .The skin in scalp will be absent resulting in the exposure of dura or even brain.

Limbic system is the seat of stress and emotions.Hypothalamus,thalamusHippocampus and amygdala are part of limbic system.It is involved in emotion,memory,stress,learning etc.Amygdala and hippocampus togetherly regulate the emotions and stress.When any stress or emotion occurs ,the amygdala gets stimulated followed by hypothalamus.Hypothalamus sends signals to the adrenal gland that releases hormones such as adrenaline and cortisol..These hormones enter bloodstream and reduces the stress and emotions.

RAS is Reticular Activating System.It is a network of neurons that mediate behaviour.It is the functional entity of brain.It is checks or is the gatekeeper of information between conscious mind and sensory system.