Different Parts of Human Brain and Its Functions
Published By mohansyam on 2009-12-20 1678 Views
A normal human brain weighs about 2% of the total body weight. Human brain grows up to 75-80% of the adult size with in the first two years and full size at the age of 6 years. It is situated in a bony case called cranium which protect it from injuries. Brain is covered with cranial meninges. Human brain is wrinkled surface and pinkish grey in colour. It is formed of more than 100 billion neurons. Since each neuron can connect with about 25,000 other cells there are about 2.5 million billions inter linked nerve connection in the brain. Human brain can be divided in to three regions, Fore brain, Mid brain and Hind brain..
Fore brain consists of cerebrum and diencephalons.
Cerebrum is the largest portion and occupies about 2/3 portions of human brain. It is divided by longitudinal fissures in to two cerebral hemispheres. Two hemispheres are connected by a horizontal sheet of nerve fibre called corpus callosum. It consists of long bundles of densely packed nerve fibre which are 10 cm long. There are about 200 millions of nerve fibres in the corpus callosum.
Each cerebral hemisphere is divided in to four lobes by three deep grooves called fissures. From the front to the back they are frontal lobe, temporal lobe, parietal lobe and occipital lobe. The left part of the brain controls the right part of body and right half controls the left part.
Functions of various lobes of cerebrum
It involves in the inner monitoring of complex thoughts and actions and creative ideas. It helps in the translation of perceptions and memories in to action. Will power and personality is affected by the development of this lobe. Abstracting ability and decision making ability is controlled by this lobe.
Temporal lobe helps in the decoding and interpretation of sounds. It helps in the language comprehension. It is the centre for memory and emotions.
It is the main area for feeling of touch, hot, cold and pain. It takes informations from surroundings and organizes it and communicates to the other part of the brain. It controls activities like reading a clock, dressing ourselves.
Occipital lobe decodes and interprets the visual informations such as shape and colour.
The outer surface of the cerebrum is called cerebral cortex. It is a layer of 2-4 mm thick. Cerebral complex has a grayish brown appearance . Hence it is referred to as gray matter. Surface of cerebral cortex is divided in to many number of folds. This increases the surface area of the brain.
Diencephlon is hidden by cerebrum. It consists of mainly subcortical nuclei, thalamus and hypothalamus.
Different collections of neurons are known as nuclei. Each nucleus has its own specific function. The nuclei has its own functions. The nuclei control different activities automatically. In the forebrain at the base of the cortex there is a collection of subcortical nuclei. It is called basal ganglia. Corpus striatum is the largest nucleus present in it. It regulates planning and execution of stereotyped movements.
Thalamus lies laterally posterior to the cerebrum. It is the important link between sense organs and cerebral cortex. Thalamus receives majority of the incoming signal from the sense organs. It determines the source of signals, evaluates their importance and integrates and passes them to the cerebrum.
Hypothalamus lies in the base of thalamus. It is a small vascularised structure weighs about 4 gm. It is only about 1/300 of the total brain mass.
Functions of hypothalamus
1) It integrate and control visceral activities. The nuclei present in the hypothalamus gives signal to the body to eat, drink, get angry, keep cool, make love etc
2) Through its connections to the brain stem it maintains homeostasis and internal equilibrium of the body.
3) It organizes behaviour related to the survival of the species such as fighting, feeding, fleeing and mating. A septum which is linked to the hypothalamus contains another emotion centre for sexual arousal.
4) It maintains body temperature at constant level by means of a complex thermostat system.
5) They correct the rate of heart beat and respiration if they are wrong.
It forms the middle portion of the brain. It controls the activity of voluntary muscles. It is also concerned with auditory and visual reflexes. Mid brain consists of four small lobes called corpora quadrigemina. The upper lobes are a pair of superior colliculi and lower lobes are called inferior colliculi. The superior part of colliculi receives sensory informations from eyes and muscles of the head. They control all visual reflexes by co-ordinating the movements of head and eyes. The inferior pair of colliculi receives sensory impulses from the ears and muscles of the head. They control all auditory reflexes.
Hind brain consists of cerebellum, medulla oblongata and pons varoli.
Cerebellum is the second largest part of the brain. It is placed between the cerebral hemispheres and brain stem. It is made up of two cerebral hemispheres.
Functions of cerebellum
A)It maintains of posture and equilibrium of the body is another function.
B)Cerebellum plays an important role in controlling all rapid muscular activities such as running, typing, talking etc
It is the posterior most part of the brain. It connects the various parts of the brain with spinal cord. Medulla controls important subconscious activities such as breathing, digestion, heart beat etc
Pons varoli forms the floor of the brain stem. It is a neural connection connecting the cerebral cortex with cerebellum. It relays the information between cerebrum and cerebellum.
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You have to give proper food for the working of brain. If not,