Human Brain

The brain is the largest and most complex organ in the body. It has more than 100 billion neurons or brain cells that form numerous synapses in the body for communication. It acts as a controlling centre and manages our thoughts, emotions, movement, vision, breathing, touch, temperature, hunger, and every vital function. The brain and the spinal cord make the CNS or central nervous system.

Any damage to the brain or spinal cord due to a sudden jerk, accident, trauma, or disease may hamper their functioning and can lead to death in severe cases. Therefore, we have the skull outside the brain, which acts as a shock absorber and protects it from damage. 

Human Brain 

What is the Human Brain Composed of? 

The human brain weighs around 3 pounds (1.4 kilograms) in an average adult. It is composed of organic matter. Two-thirds of the brain is made of fat, and the remaining is a combination of proteins, water, salts, and carbohydrates. It contains nerves and blood vessels. 

How does the Brain Work? 

The human brain collects and sends electrical and chemical signals throughout the body. Each signal determines a different process, and our brain interprets it. Some make us feel tired, while others may cause pain.

However, the interesting fact is that it keeps some messages within itself, and others are spread throughout the body through nerves. These messages are conveyed by neurons or nerve cells. These are responsible for collecting sensory input from the outer environment and sending commands to muscles to perform functions. 

What are the Main Parts of the Brain and their Functions? 

The human brain has three main parts; cerebrum, brainstem, and cerebellum. Let us understand these using the brain parts diagram given below.

Human Brain Parts

Cerebrum

The cerebrum is the frontal and the largest part of the brain. It regulates temperature and initiates and coordinates movements. Other parts of the cerebrum control speech, problem-solving, reasoning and thinking abilities, judgement, vision, hearing, touch and learning, and emotions. 

Refer to the cerebrum diagram for better understanding. 

Cerebrum

Brainstem 

The brainstem is the middle part of the brain that connects the cerebrum and the spinal cord. The brainstem is classified into the midbrain, the pons, and the medulla as shown in the brainstem diagram.

Brainstem 

1. Midbrain: The midbrain is a complex structure and has different types of neurons, layers, and other structures. It facilitates functions from movement and hearing to analysing environmental changes and responses. 

2. Pons: It is the second-lowest structure of the brainstem and lies above the medulla. It contains nerves that are connected directly to the brain. These nerves are important and help in controlling the senses and various parts of the mouth and face. The pons enables different functions, such as sleep, tear production, blinking, chewing, focusing vision, hearing, pain management and feeling, control and coordination, and facial expressions. 

3. Medulla: It is at the bottom of the brainstem. It is the meeting point for the brain and the spinal cord. Functions of the medulla include; managing and controlling heart rate, breathing, blood pressure, carbon dioxide, and oxygen levels. It produces reflexive actions or involuntary movements that occur after exposure to a stimulus. These can include sneezing, coughing, swallowing, and vomiting. 

Cerebellum 

It is a structure situated at the back of the brain. It is divided into two hemispheres that control muscular activities, such as walking, balance, posture, speech and learning motor behaviours. 

The Spinal Cord

The spinal cord runs at the back of the body from the bottom of the medulla through a large opening at the bottom of the skull. It is supported by the vertebral bones, which prevent it from external jerks or damages. It helps in receiving and sending signals to and from the brain to other body parts. It enables reflex actions, balance and coordination, mobility, and sensory functions. 

Spinal Cord

Sample Questions

State whether the statements mentioned below are correctly stated or not:

1.The cerebrum is divided into two hemispheres by a deep groove. 

Ans: True.

2.The cerebellum is the main part of the forebrain. 

Ans: False, the cerebrum is the main part of the forebrain. 

3.The brain is protected inside the skull.

Ans: True

4.The brainstem connects the brain to the spinal cord. 

Ans: True

Learn by Doing

Complete the the statements that follow by filling in the blanks:

1.The forebrain is classified into ________ lobes. 

Ans: four

2.The brain is covered by a ______ layered meninges. 

Ans: three

Segregate the given parts of the brain into the given categories:

1. Forebrain

2. Midbrain

3. Hindbrain 

• Cerebrum

• Cerebellum

• Thalamus

• Pons

• Medulla

• Hypothalamus

• Lobes for vision

• Lobes for hearing

Ans: Forebrain: cerebrum, thalamus, hypothalamus

Midbrain: lobes for vision, lobes for hearing

Hindbrain: cerebellum, pons, medulla.

Summary 

The brain is the vital organ of the human body. It is like an intelligent machine that controls different functions ranging from managing movements to sensory activities. It consists of billions of neural cells that help in receiving and processing information.