Brain

The human brain is a complex internal organ responsible for controlling an individual’s memory, emotions, perceptions, thoughts, sense of touch (proprioception), motor skills and cognition, vision, hunger, breathing and other processes that regulate our body. On average, the human brain weighs about 3 pounds, where 60% of it contains fat, and the rest is a combination of water, protein, carbohydrates and essential salts. The human body has a central nervous system that comprises the brain and the spinal cord together. The brain comprises more than 100 billion nerves that communicate in more than 100 trillion connections, known as synapses.

Parts of the brain

The human brain comprises three distinct parts – the cerebrum, cerebellum and brainstem.

Cerebrum

This is considered the largest part of the human brain. It is divided into left and right hemispheres. It is responsible for higher primate functions and sensory actions like vision, hearing, touch, taste and smell; speech; logical reasoning; emotions; learning; memory and spatial orientation.

Cerebellum

This is under the cerebrum. It functions as a medium to coordinate muscles and their movements to maintain individual posture and balance.

Brainstem

This part of the brain connects the cerebrum and cerebellum to the spine. It acts as a messenger or relay centre. It helps in automatic bodily functions such as regulating heart rate and body temperature, maintaining the circadian rhythm and regulating sleep and wake cycles, digestion, sneezing and coughing, peristalsis and reverse-peristalsis.

Right and left hemispheres

The cerebrum of the brain is divided into two halves or hemispheres. A bundle of nerves called the corpus callosum connects both hemispheres. These nerve fibres transmit chemical and electrical messages from one hemisphere to the other. A proven study shows that each half of the brain controls the opposite part of the body.

The left hemisphere controls speech, comprehension, statistical analysis and subject matter-related functions such as arithmetic and writing. The right hemisphere controls an individual’s creative, artistic and musical skills. It is also responsible for analysing direction and spatial orientation. 

Lobes of the brain

The cerebral hemisphere has distinct nervous fissures that divide the brain into four separate lobes: frontal, temporal, parietal and occipital lobes. However, the brain lobes do not function alone. They form very complex relationships with other brain lobes and between the left and right hemispheres.

Frontal Lobe

The frontal lobe of the brain is responsible for the following functions:

• Maintaining the personality, behaviour and emotions of an individual
• Take an active part in judgement, planning and solving problems using logic
• Broca’s area – speaking and writing (speech functions)
• The motor strip is responsible for maintaining body movement
• Also responsible for intelligence, cognition and self-awareness

Parietal Lobe

The parietal lobe of the brain is responsible for the following functions:

• It interprets the language and its words.
• It contains the sensory strip responsible for the somatic senses such as pain, temperature, proprioception.
• It is also responsible for interpreting signals that are received from the special senses, such as vision, hearing, motor skills, sensory and memory signals.
• It also controls the visual and spatial perception of an individual.

Occipital Lobe

It is responsible for interpreting vision and visual signals like colour (rods and cones), light (photoreceptors) and movement.

Temporal Lobe

The temporal lobe of the brain is responsible for the following functions:

• Wernicke’s area – responsible for understanding speech and language
• Maintaining sequence and organisational skills
• Memory encoding and retrieval
•  Auditory functions

Deep structures of the brain

Hypothalamus: This deep structure is located at the base of the brain’s third ventricle. It is called the master gland that controls the body’s autonomic system. It controls particular behaviours such as sleep, sexual responses and hunger and thirst needs. It also regulates body temperature, blood pressure, emotions and secretion of various hormones essential for body processes.

Pituitary Gland: It connects to the hypothalamus via the pituitary stalk. It is called the “master gland” and controls the other endocrine glands of the body. It is responsible for stress response, secreting growth-regulating hormones and controlling sexual development.

Pineal Gland: This is located behind the third ventricle and helps regulate the body’s internal biological clock. It regulates the circadian rhythm by secreting a hormone called melatonin. It also helps in sexual development.

Thalamus: It is the relay station that relays almost all information from and to the brain’s cortex. It also has a vital role in attention span, regulating pain tolerance, alertness and awareness and memory.

Conclusion

The brain is one of the largest and most complex internal organs in the human body responsible for various functions in our body. It is divided into four distinct lobes – frontal, temporal, parietal and occipital lobes – with specific regions that actively participate in various functions and processes of the body. Some of the main functions include processing sensory information, regulating blood pressure and respiratory actions and releasing hormones. The cerebrum of the brain is divided into two halves or hemispheres. A bundle of nerves called the corpus callosum connects both hemispheres. These nerve fibres transmit chemical and electrical messages from one hemisphere to the other.