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Structure Of Brain And Its Functions Pdf

structure of brain and its functions pdf

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The Lobes of the Brain and Their Functions

The brain is a remarkably complex organ comprised of billions of interconnected neurons and glia. It is a bilateral, or two-sided, structure that can be separated into distinct lobes. Each lobe is associated with certain types of functions, but, ultimately, all of the areas of the brain interact with one another to provide the foundation for our thoughts and behaviors.

It can be said that the spinal cord is what connects the brain to the outside world. Because of it, the brain can act. The spinal cord is like a relay station, but a very smart one. It not only routes messages to and from the brain, but it also has its own system of automatic processes, called reflexes.

The top of the spinal cord merges with the brain stem, where the basic processes of life are controlled, such as breathing and digestion. In the opposite direction, the spinal cord ends just below the ribs—contrary to what we might expect, it does not extend all the way to the base of the spine.

The spinal cord is functionally organized in 30 segments, corresponding with the vertebrae. Each segment is connected to a specific part of the body through the peripheral nervous system. Nerves branch out from the spine at each vertebra. Sensory nerves bring messages in; motor nerves send messages out to the muscles and organs. Messages travel to and from the brain through every segment.

Some sensory messages are immediately acted on by the spinal cord, without any input from the brain. Withdrawal from heat and knee jerk are two examples. When a sensory message meets certain parameters, the spinal cord initiates an automatic reflex.

The signal passes from the sensory nerve to a simple processing center, which initiates a motor command. In matters of survival, the spinal reflexes allow the body to react extraordinarily fast. The spinal cord is protected by bony vertebrae and cushioned in cerebrospinal fluid, but injuries still occur. When the spinal cord is damaged in a particular segment, all lower segments are cut off from the brain, causing paralysis.

Therefore, the lower on the spine damage is, the fewer functions an injured individual loses. The surface of the brain, known as the cerebral cortex , is very uneven, characterized by a distinctive pattern of folds or bumps, known as gyri singular: gyrus , and grooves, known as sulci singular: sulcus , shown in Figure 1.

These gyri and sulci form important landmarks that allow us to separate the brain into functional centers. The most prominent sulcus, known as the longitudinal fissure, is the deep groove that separates the brain into two halves or hemispheres: the left hemisphere and the right hemisphere. Figure 1. The surface of the brain is covered with gyri and sulci. A deep sulcus is called a fissure, such as the longitudinal fissure that divides the brain into left and right hemispheres.

There is evidence of some specialization of function—referred to as lateralization —in each hemisphere, mainly regarding differences in language ability. Beyond that, however, the differences that have been found have been minor this means that it is a myth that a person is either left-brained dominant or right-brained dominant.

The two hemispheres are connected by a thick band of neural fibers known as the corpus callosum , consisting of about million axons. The corpus callosum allows the two hemispheres to communicate with each other and allows for information being processed on one side of the brain to be shared with the other side. Normally, we are not aware of the different roles that our two hemispheres play in day-to-day functions, but there are people who come to know the capabilities and functions of their two hemispheres quite well.

In some cases of severe epilepsy, doctors elect to sever the corpus callosum as a means of controlling the spread of seizures Figure 2. While this is an effective treatment option, it results in individuals who have split brains. After surgery, these split-brain patients show a variety of interesting behaviors. However, they are able to recreate the picture with their left hand, which is also controlled by the right hemisphere.

When the more verbal left hemisphere sees the picture that the hand drew, the patient is able to name it assuming the left hemisphere can interpret what was drawn by the left hand.

Figure 2. Much of what we know about the functions of different areas of the brain comes from studying changes in the behavior and ability of individuals who have suffered damage to the brain. For example, researchers study the behavioral changes caused by strokes to learn about the functions of specific brain areas. A stroke, caused by an interruption of blood flow to a region in the brain, causes a loss of brain function in the affected region. The damage can be in a small area, and, if it is, this gives researchers the opportunity to link any resulting behavioral changes to a specific area.

The types of deficits displayed after a stroke will be largely dependent on where in the brain the damage occurred. Consider Theona, an intelligent, self-sufficient woman, who is 62 years old. Recently, she suffered a stroke in the front portion of her right hemisphere. As a result, she has great difficulty moving her left leg. Theona has also experienced behavioral changes.

For example, while in the produce section of the grocery store, she sometimes eats grapes, strawberries, and apples directly from their bins before paying for them.

This behavior—which would have been very embarrassing to her before the stroke—is consistent with damage in another region in the frontal lobe—the prefrontal cortex, which is associated with judgment, reasoning, and impulse control. Figure 3. The brain and its parts can be divided into three main categories: the forebrain, midbrain, and hindbrain. The four lobes of the brain are the frontal, parietal, temporal, and occipital lobes Figure 4. The frontal lobe is located in the forward part of the brain, extending back to a fissure known as the central sulcus.

The frontal lobe is involved in reasoning, motor control, emotion, and language. For example, Padma was an electrical engineer who was socially active and a caring, involved mother.

She completely lost the ability to speak and form any kind of meaningful language. There is nothing wrong with her mouth or her vocal cords, but she is unable to produce words. She can do routine tasks like running to the market to buy milk, but she could not communicate verbally if a situation called for it. Figure 5. Probably the most famous case of frontal lobe damage is that of a man by the name of Phineas Gage.

On September 13, , Gage age 25 was working as a railroad foreman in Vermont. Although lying in a pool of his own blood with brain matter emerging from his head, Gage was conscious and able to get up, walk, and speak. But in the months following his accident, people noticed that his personality had changed. Many of his friends described him as no longer being himself. Before the accident, it was said that Gage was a well-mannered, soft-spoken man, but he began to behave in odd and inappropriate ways after the accident.

Such changes in personality would be consistent with loss of impulse control—a frontal lobe function. With connections between the planning functions of the frontal lobe and the emotional processes of the limbic system severed, Gage had difficulty controlling his emotional impulses.

On the basis of extremely limited information about Gage, the extent of his injury, and his life before and after the accident, scientists tended to find support for their own views, on whichever side of the debate they fell Macmillan, Figure 6.

Specific body parts like the tongue or fingers are mapped onto certain areas of the brain including the primary motor cortex.

This strip running along the side of the brain is in charge of voluntary movements like waving goodbye, wiggling your eyebrows, and kissing.

It is an excellent example of the way that the various regions of the brain are highly specialized. Interestingly, each of our various body parts has a unique portion of the primary motor cortex devoted to it.

Each individual finger has about as much dedicated brain space as your entire leg. Your lips, in turn, require about as much dedicated brain processing as all of your fingers and your hand combined!

Figure 7. Spatial relationships in the body are mirrored in the organization of the somatosensory cortex. Because the cerebral cortex in general, and the frontal lobe in particular, are associated with such sophisticated functions as planning and being self-aware they are often thought of as a higher, less primal portion of the brain.

Indeed, other animals such as rats and kangaroos while they do have frontal regions of their brain do not have the same level of development in the cerebral cortices. The closer an animal is to humans on the evolutionary tree—think chimpanzees and gorillas, the more developed is this portion of their brain.

It contains the somatosensory cortex , which is essential for processing sensory information from across the body, such as touch, temperature, and pain. The somatosensory cortex is organized topographically, which means that spatial relationships that exist in the body are maintained on the surface of the somatosensory cortex.

For example, the portion of the cortex that processes sensory information from the hand is adjacent to the portion that processes information from the wrist. Figure 8. The types of deficits are very different, however, depending on which area is affected.

The auditory cortex , the main area responsible for processing auditory information, is located within the temporal lobe. The occipital lobe is located at the very back of the brain, and contains the primary visual cortex, which is responsible for interpreting incoming visual information.

You will learn much more about how visual information is processed in the occipital lobe when you study sensation and perception. Be suspicious of any statement that says a brain area is a center responsible for some function. The notion of functions being products of brain areas or centers is left over from the days when most evidence about brain function was based on the effects of brain lesions localized to specific areas.

Neurons in areas contribute because they are part of a system. The amygdala, for example, contributes to threat detection because it is part of a threat detection system. And just because the amygdala contributes to threat detection does not mean that threat detection is the only function to which it contributes.

Amygdala neurons, for example, are also components of systems that process the significance of stimuli related to eating, drinking, sex, and addictive drugs. Privacy Policy. Skip to main content. Module 3: Biopsychology. Search for:.

The Lobes of the Brain and Their Functions

The brain is a fascinating and complex organ. It is responsible for senses, movement and control, emotions and feelings, language and communication, thinking and memory. Research of the brain and understanding the inner workings of the brain will help us to learn about the mechanisms of certain neurological conditions, including hydrocephalus. Increasing our own knowledge of the brain helps us understand our own bodies better and helps us have informed conversations with our doctors, be it as a patient or a caregiver. To celebrate BAW we present a two-part blog to increase our understanding of the brain and how the brain is impacted by hydrocephalus. We hope you enjoy these blogs and find them both informative and useful. This global coalition of BAW partners includes more than universities, K schools, hospitals, patient groups, museums, government agencies, services organizations, and professional associations.

structure of brain and its functions pdf

The Central Nervous System

Although we now know that most brain functions rely on many different regions across the entire brain working in conjunction, it is still true that each lobe carries out the bulk of certain functions. In humans, the lobes of the brain are divided by a number of bumps and grooves.

The Human Brain: Anatomy and Function

A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head , usually close to the sensory organs for senses such as vision. It is the most complex organ in a vertebrate's body. In a human, the cerebral cortex contains approximately 14—16 billion neurons , [1] and the estimated number of neurons in the cerebellum is 55—70 billion. These neurons typically communicate with one another by means of long fibers called axons , which carry trains of signal pulses called action potentials to distant parts of the brain or body targeting specific recipient cells.

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The Temporal Lobes

It also integrates sensory impulses and information to form perceptions, thoughts, and memories. The brain gives us self-awareness and the ability to speak and move in the world. Its four major regions make this possible: The cerebrum , with its cerebral cortex, gives us conscious control of our actions. The diencephalon mediates sensations, manages emotions, and commands whole internal systems. The cerebellum adjusts body movements, speech coordination, and balance, while the brain stem relays signals from the spinal cord and directs basic internal functions and reflexes.

The Frontal Lobes are located in the front of the brain. They are very large and have many functions. The frontal lobes are considered to be our emotional control centre. They play a central role in our personality and how we act. They are also involved in attention skills and controlling movement. The frontal lobes manage skills known as Executive Functions.

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The brain is an amazing three-pound organ that controls all functions of the body, interprets information from the outside world, and embodies the essence of the mind and soul. Intelligence, creativity, emotion, and memory are a few of the many things governed by the brain. Protected within the skull, the brain is composed of the cerebrum, cerebellum, and brainstem. The brain receives information through our five senses: sight, smell, touch, taste, and hearing - often many at one time.

The brain is a remarkably complex organ comprised of billions of interconnected neurons and glia. It is a bilateral, or two-sided, structure that can be separated into distinct lobes.


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