Human Brain

Introduction to The Human Brain

The human brain is the main Central Nervous System organ, situated in the head, protected by the cranium. Human brain has the same overall construction and anatomy as other mammalian brains, but it has a more developed cerebral cortex. The human brain is particularly complex and extensive. It embodies 2% of body mass, but it takes approximately 25% of all the blood pumped by the heart.

The brain splits in left and right hemispheres. It is a distributed set of billions of cells. Bigger animals, such as elephants and whales, have larger brains, but when they are measured via encephalization coefficient (which compensates the body size), the human brain coefficient is practically twice as large as the common dolphin coefficient and three times bigger than the chimpanzee coefficient. Most of the development is due to the cerebral cortex, specifically the frontal lobes, which are connected to executive functions such as reasoning, scheduling, abstract thinking and self-control.

What is and Where is The Human Brain Located?

The brain role, as part of the Central Nervous System is to regulate most functions of human body, including vital functions such as heart rate or breathing, basic functions like being hungry, sleeping, or sexual instinct, also complex functions like speaking, thinking, remembering etc. The human brain is the most complex of all living constructions, processing sensory information while organizes and preserves the organism’s vital functions. One trillion primary cells, i.e. neurons, work together over electrical compulsions in order to organize physical activities and mental processes that differentiate the human being from others animal species. The brain is a gelatinous mass, approximately 1.4 kg in weight, depending on the body weight and sex of each individual. There is no connection between a person’s brain weight and his/her intellectual capacity.

The human brain and spinal cord are components of the Central Nervous System. The cranium and the three membranes with cerebrospinal fluid, named meninges, allow the brain to stay protected from impacts/ knocking on its four lobes:

human brain

Picture 1: Parts of the Human Brain

  • The frontal lobe is located behind the forehead, and is responsible for considerable of the complex cognitive function: Reasoning, imagination, planning, values and behavior.
  • The parietal lobe is located in the upper back of the frontal lobe. It covers the sensitive cortex (processing those messages related to touch, palate and body temperature), and the motor cortex (controlling the movement).
  • The temporal lobe is located behind the temple, sheltering the auditory cortex, taking care of the language comprehension, and acting over emotions and memory.
  • The occipital lobe is located behind the head, controlling the visual cortex in charge of handing out what the individual sees.


The anatomy of the human brain it is characterized by the following parts:

structure of human brain

Picture 2: Structure of Human brain

Cerebral cortex

Cerebral cortex is a tissue layer that forms the brain’s outer covering, whose thickness fluctuates from 2 to 6 millimeters. In intellectually superior mammals, such as humans, the cerebral cortex has protuberances and grooves that supply additional space to store relevant information about the organism. The left and right cerebral hemispheres are linked by the rough corps located into the cerebral cortex.


Cerebellum is an area located at the cranium base, below the occipital lobe. Cerebellum is small size (like a walnut), and coordinates significant functions such as movement, coordination equilibrium, and language learning.


Thalamus takes information from the body and several sensory organs. The information received is filtered before transferring it to the cerebral cortex, in order to prevent a brain overload. On the other side, the cortex sends information to the thalamus, so it can be diffused to other brain and spinal cord areas.


Hypothalamus is the gland that monitors the organism’s vital functions, such as thirst, body temperature, sleep, or pain states. Hypothalamus and the pituitary gland connect the nervous and hormonal systems.


Hippocampus is the area located within the temporal lobe. It is central for cognitive processes such as learning and memory.


Brainstem is located at the human brain radix, connecting to the spinal cord. Brainstem contains three areas: Mesencephalon, protuberance and medulla, which allow the brain to interconnect with the rest of the central and peripheral nervous system. The medulla bulb leads the reflex acts, i.e. those functions that body makes automatically, such as heart rate, breathing, swallowing, blood pressure, or digestion.


Hypophysis (pituitary gland) is responsible for liberating hormones. Together with the hypothalamus, the pituitary gland links the hormone-related organs, i.e. the endocrine organs: ovaries, mammary glands, thyroids, adrenals, and testes).

Spinal cord

Spinal cord is the central nervous system component that begins in the lower area of the brain, extending along the spine. The spinal cord links the brain with the nerves. The spinal cord’s nerve tissues are approximately 45 centimeters long, and nearly 2 centimeters bulk, and they conform the peripheral nervous system.

Function of the Brain

Physiological functions of human brain involves in reception of information from the body, understanding it (through cognitive process), and guiding the body’s reply. Brain is the maximum responsible of the thinking and motion the body generates. The human brain also mediates in vital actions such as: To breath, to control blood pressure, and to release hormones. The brain allows human being to interact successfully with the environment, by communicating and interacting with others.

Extensive of the physiological functions of the brain involve reception of information from the rest of the body, interpreting the information, and supervisory the body’s response. The main human brain functions are to keep the organism alive, so that it can interact with the environment. All the human being deliberates, feels and does is connected to specific functions of his/her brain:

  • Sensitive functions, reception and processing of data (information of the different perceived stimuli). The stimuli of external or internal origin are apprehended through different receptors. These relevant receivers transform the stimuli by energy indicators.
  • Motor functions: The brain controls voluntary and involuntary actions. The motor cortex is located in the frontal lobe, ahead the Rolando fissure, a cleft located in the upper brain of the higher mammals. This area is the central sulcus of the brain, and is characterized by separating the parietal lobe from the frontal lobe.
  • Integrative functions are mental activities such as learning, memory, attention, language etc. Most patients who suffer from a kind of brain damage lose some cognitive capability.
  • Cognitive functions are those mental processes that let individual to receive, interpretive, select, lay-up, transform, develop and recover information from the environment. Cognition allow people to understand and link to the world around them. The daily human activities involve millions of connections, also complex mental computations between different brain areas, to get a proper working in the surrounding world. Main cognitive functions:
    • Attention: Individual chooses between stimuli that arrive at the same time into the brain, both external (sound, smells or images) and internal (values, feelings or thoughts). Stimuli are useful and to perform a motor and mental activity.
    • Memory is in charge of information encoding, storing and recovery. People need the attention system to work correctly. If an individual does not pay attention to one given thing, he/she will not be able to cypher, to store and recover that information.
    • Executive are the most complex cognitive functions. It is the control of cognition and opinions and behavior guideline, done by different processes related to each other. Executive functions cover a set of skills, such as scheduling, paying attention, organizing, or validating intentional behavior. They are located in the frontal lobe.
    • Language is the symbolic human communication system, stating through languages. Language is not only significant for communicating with other people. It also structures the innermost thinking. In language processing, several brain areas mediate, acting in a cohesive way through numerous functional systems relating, particularly, the left hemisphere.
    • The visual perception functions allow individual to identify and categorize the stimuli. These functions help humans to interpret, assign and associate what they are watching with known categories, fit in into their knowledge field. The proper working of the visual perception allows, for example, to recognize the faces of relatives, also to identify if an object is a letter, a coat or a plant.
    • The visual spatial functions examine, recognize and manage the space in which human beings. We are talking about processes such as depth perception, logical navigation, or mental construction. The visual spatial functions include different skills, such as orientation through a given place, reading a map, to calculate how far is a car in order to decide whether or not to cross the street, to walk without tripping over the objects that are on our ride etc.

functions of human brain

Picture 3: Functions of Human Brain

The Brain Hemispheres

  • The leading hemisphere in 98% of humans is the left one, responsible for logical reasoning, different skills, and communication.
  • The right hemisphere is in charge for symbolic thinking and imagination. It is related to non-verbal expression, such as: Intuition, recognition of voices, faces or melodies. In the right hemisphere views and memories are manifested through images. In left-handed people roles are inverted.
  • The left hemisphere lean towards dominance because it is located in two specialized zones: the Broca area, the motor cortex that directs the speech, and the Wernicke area, responsible for verbal understanding. The left hemisphere is dominant in most people, related to the verbal section, as well as the ability to analyze, logical reasoning, or mathematical problem resolving.
  • The corpus callosum is located at the bottom of the interhemispheric fissure, in control for the connection between the two cerebral hemispheres. This frame, conformed by nerve fibers (involved in myelin), is responsible for information exchange among the different regions of the cerebral cortex.

Clinical Significance

The brain, spinal cord and nerves form the Human Nervous System. They control together all the body functions. When it is healthy, it works quickly and mechanically. However, when some problem happens, the results can be devastating. When something is wrong in a region of the nervous system, people may have difficulty to talk, move, breath, swallow, read, remember, feel etc. Over six hundred neurological diseases are threat for human. The most known categories include:

  • Diseases caused by malfunctioning genes, such as Huntington’s disease, and muscular dystrophy
  • Degenerative illnesses, in which nerve cells are serious damaged (or die), such as
  • Parkinson and Alzheimer
  • Difficulties with the nervous system development, such as spina bifida
  • Diseases in blood vessels that provide the brain, such as strokes
  • Infections, such as meningitis
  • Convulsive disorders, such as epilepsy disease
  • Cancer, such as brain tumors
  • Damages to the spinal cord and brain


Caring for the nervous system sometimes is not easy, as the brain functions are so complex, and there are many factors involved, making it complicated, but not impossible. The brain controls human body; Therefore, caring for it should be a priority in people’s life.

Nobody likes to get sick, but many times people act irresponsibly, putting their health at risk. The consequence can be critical diseases in the long term. However, as the health effects are not seen immediately, but generally when the problem is already much more severe, people do not start caring their health until it is too late.

Regarding main factors that protect the nervous system:

  • Self-esteem: self-confidence, to value life, and to strive to meet goals. Having high self-esteem favors facing and solving daily problems.
  • The development of personal values such as respect, tolerance, solidarity, and love, in order to maintain a high level of mental health.
  • Stay productive and healthy, through recommended behaviors and life habits.
  • Eating well, doing physical exercises, resting enough, and taking care of personal hygiene.
  • Establish healthy relationships with others is the basis of a quiet life in society. Envy, violence and resentment, or jealousy threaten mental health.
  • Avoid smoking, alcohol and other drugs that disturb the proper working of the nervous system, and can lead to critical mental illness, even death from brain damage.