The Human Brain

The human brain is the nerve center for all biochemical processes and activities of the body's organs. The nervous system, which is in charge of communicating information to and from the brain, facilitates contact between the brain and the body organs. The brain absorbs input from the body organs from the nervous system, processes it, and then sends the output to the organ's muscles, which contract and expand based on the impulse obtained, influencing movement or action execution. The anatomy of the human brain is similar to that of animals, the only distinction is that the human brain is a bit large in size. It is very complex with about 86 billion neurons, also called grey matter, which records and store every information in the brain and that is how a person is able to remember an event in the past. These neurons are interconnected by multitudes of links referred to as synapses (Raznahan et l., 1592-95)

Anatomy of the Human Brian

The human brain can be dissected in a number of ways. The main human brain parts are the forebrain, midbrain, and hindbrain. The three divisions contain a lot of other parts of which are going to be discussed in detail together with their functions.

_x0095_ The forebrain also called prosencephalon is comprised of the thalamus, cerebrum, hypothalamus, the pineal gland, and other parts. The region where the cerebrum resides is referred as the telencephalon by Neuroanatomists whereas the area occupied by the thalamus, hypothalamus and the pineal gland is called diencephalon.

_x0095_ The midbrain also knew as mesencephalon, is the part of the brain which is located in the central region or rather between the hindbrain and the interbrain. It covers a larger portion of the brainstem

_x0095_ The hindbrain which is termed as rhombencephalon comprises of the remaining portion of the brainstem and also contains the cerebellum and the pons.

The Brain cells

The human brain contains millions of brain cells which facilitate processing of data and interpretation. Some of these cells include;

_x0095_ Neurons are responsible for performing all communication functions within the brain. They are composed of the sensory neurons which transmit information from the peripheral nervous system to the brain. This data carries with it information about the body biological and physical conditions. The brain_x0092_s grey matter is made up of the interneurons which receive information brought by the sensory neurons and process it then sends back the output in the form of signals via the motor neurons which transmit to the body glands and muscle organs for execution (Binkofski, Ferdinand & Laurel 222-229).

_x0095_ Neuroglia which is also referred as glial cells act as the supportive cells to the brains neurons. They are classified into four categories which are; Astrocytes which are responsible for neurons protection through preventing leaving of pathogens and chemicals out of the brain capillaries. They also serve in extracting nutrients from the blood. Oligodendrocytes provide an insulation to the axon of neurons called myelin. This enables neurons in transmitting data in the forms of signals in a fast manner when insulated than when not insulated. Generally, Oligodendrocytes increase the rate of speed of communication within the brain. Microglia is more similar to lymphocytes, they prevent entry of pathogens into the brain system. Ependymal cells are responsible for the formation of the cerebrospinal fluid. The brain can further be divided into two divisions; Gray matter and White matter. Gray matter is mostly composed of the interneurons which are unmyelinated. It is the region for processing of information. White matter is made of the rest of the neurons, motors and sensory neurons which are connected to the rest of the body. The neurons in this regions are myelinated to enable fast movement of information to and from the brain.

The Hindbrain

As cited earlier, this part of the brain is made of the cerebellum, the pons and the remaining part of the brainstem. Each of these will be discussed in detail.

_x0095_ Brainstem

The brainstem connects the brain to the spinal cord of the brain. It is termed as the most delicate part of the brain and responsible for controlling the brain_x0092_s functions. The brainstem is made up of three parts; the pons, the medulla oblongata and the midbrain. The three regions are covered by reticular formation which is a mixer of the gray and the white matter of the brain. The reticular formation performs a very vital function in the brain of regulating and controlling sleeping and regaining of consciousness of the brain (Miller & Jeffrey 78).

The medulla oblongata is cylindrical in shape and connects to the spinal cord on its rear end and the pons on its front part. The medulla oblongata mainly contains a large portion of the white matter which carries signals towards the brains and out of the brains. In other words, it houses majority of the unmyelinated neurons. Also within the medulla oblongata are a number of gray matter parts which are responsible for executing the normal body functions or rather a homeostasis. The medulla oblongata is also responsible for regulating the blood pressure and oxygen levels in the brain via the cardiovascular center. It is also responsible for controlling the heartbeat rate to ensure that enough and sufficient oxygen is supplied to all parts of the body. The region also contains the medullary rhythmicity center also regulate the breathing rate for oxygen supply in the body. Reflex actions like vomiting, coughing and sneezing are also effected by this part of the brain (Messe et al., 45-48).

The pons is the part within the brainstem located at the inferior to the midbrain, superior to the oblongata and anterior to the cerebellum. The pons have are only responsible for coordinating the transfer of signals in and out of the cerebellum

Cerebellum

This is the wrinkled region of the brain located adjacent to the brainstem. It is made up of the cerebellar cortex, which is the outer covering of cerebellum which enhances the processing capability of the cerebellum. In the interior of the cerebellar cortex is arborvitae which performs the function of connecting the cerebellar cortex to the body.

The cerebellum is responsible for regulating and controlling body balance, posture as well enhancing coordination of the body muscles. The cerebellum receives data from body muscles and joints and uses it to effect balance in the body.

The Midbrain

The midbrain is further divided into the tectum which is located in the posterior region of the midbrain. Tectum houses auditory and visual reflex relays including the pupillary reflex for light intensity, accommodation reflex for focus among others. Cerebral peduncles are the second midbrain subdivision which houses a majority of nerves tracts. The nerve tracts connect the cerebrum and the thalamus spinal cord. The region also contains substantia nigra which houses neurons with melanin for inhibiting movement.

The Forebrain

This forebrain holds a number of brain parts including the hypothalamus, the thalamus, and the pineal glands.

_x0095_ Thalamus acts as a switch for directing sensory neurons into the various parts of the cerebral cortex. The sensory neurons moving to the brain forms an array of relays with the neurons contained in the thalamus. Thalamus also facilitates the learning process in human beings through directing information into the memory centers located into the interior of the cerebrum (Mai, Milan & George 52)

_x0095_ Hypothalamus is located adjacent to the thalamus and the pituitary glands. The hypothalamus is majorly known as the temperature control center, blood pressure control, heart beat rate as well as hunger and thirst. In case of a change in these body conditions the hypothalamus responds by directing the signal to muscles and heart to act countering that change. For instance, in the case of a rise in body temperature, this part sends a signal to the sweat gland located in the skin to effect sweating. The same applies to when the body is having insufficient food and water signals are sent to the cerebral cortex where feelings of hunger and thirst are effected. The hypothalamus is also responsible for hormone production using the pituitary glands. Some of these hormones include antidiuretic hormone and oxytocin (Duvernoy 70-75).

_x0095_ The pineal gland is responsible for the synthesis of hormone melatonin which helps in inducing sleep.

Cerebrum

This is the largest portion of the human brain. It controls complex brain functions such as creativity, reasoning, logic, and language. The cerebrum is divided into left and right hemispheres by a longitudinal fissure which passes through its center. Each of the hemispheres is subdivided into temporal, occipital, parietal and frontal lobes. Cerebrum contains information processing center at its surface known as the cerebral cortex. This is where signals from the sensory neurons are directed for processing and interpretation.

Inside the cerebral cortex is the corpus callosum which enhances communication between the left and the right hemisphere. Cerebral cortex also contains regions of gray matter form two systems; the nuclei and limbic system.The nuclei in collaboration with the substantia nigra facilitate the movement of body muscles enhancing posture and skeletal balance. On the other

hand, the limbic system is involved in facilitating the body to respond to emergency and emotions in a quick manner.

Physiology of the human brain

Apart from the structure and functions, the brain like any other body organ is involved in physiological mechanisms like metabolism, sensory functions, and motor control and processing. These are basically the processing by which the brain performs its functions.

Metabolism

The human brain takes in approximately 20% of oxygen and nutrients. The reason for this large consumption of nutrients and oxygen is due to the massive energy that is used in the brain functions. For instance, the nervous tissues of the brain use a lot of energy in transmitting, processing and interpreting data in and out of the brain. During this process, the metabolic rate is very high. The brain also requires a lot of blood supply to ensure constant and healthy performance. Lack of enough blood, oxygen, and food often results in dizziness which may amount to unconsciousness (Diamond 40).

Sensory

This is the process through which the brain receives information from the body_x0092_s conditions via sensory receptors. This information is all fed to the central processing areas of the brain which in turn generate a signal that is sent back to designated muscles and glands which act to restore normal functioning of the body. Some of these conditions may include a change in body temperature, change in blood pressure as well as heartbeat rate variation (Song et al., 642).

Motor control

The human body has direct control over all the body movements. The regions responsible for this is called motor area contained in the cerebral cortex. It sends signals to the skeletal muscles which in turn produce movements. This is achieved with the help of the basal nuclei located in the brainstem Cerebellum also has a role to play in facilitating body movements.

Processing

When information has been fed into the brain, the responsible regions take the task of processing the information and producing output signals. This is mainly done by the cerebral cortex. The information is measured, evaluated, and compared with past conditions, which in turn produces an image of the output. The processing units then produce the actions signals which are sent to the brain motor areas which finally execute an action or movement via the body muscles and glands (Ernst et al., 1072-73).

Learning and Memory

The brain records and stores information regarding an event or an experience. The information is stored in different forms depending on its origin and how long it is to be stored. The brain keeps short-term memory that helps in to monitor and follow up the activities in which it is engaged in. Short-term memory is simply a loop formed by neurons within the brain to enhance temporal storage of information. The information is then immediately replaced by new and fresh information unless it gets transferred to the long-term memory. Long-term memory is stored by a part called hippocampus. The hippocampus is responsible for transferring short-term information from the temporal lobes to the long-term memory located in the cerebral cortex (Penfield 113).

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