The concept of the nervous system

The concept of the nervous system

The nervous system is a system in our body that helps us respond to things around us. It is like a communication system that sends signals to different parts of our body so that we can react to different situations.

It controls both

1. voluntary actions (actions we choose to do, like eating, playing, or talking)
2. involuntary actions (actions that happen automatically, like breathing or the heartbeat).

Why do we close our eyes when moving from a dim light to a bright light?

When we move from a dim light area to a bright light area, our eyes need to adjust to the brightness. The light is too much for our eyes to handle at once, so we close our eyes to protect them. This helps to avoid discomfort and allows our eyes to slowly adjust to the new light.

Why do we sweat when the temperature rises?

Sweating is the body's way of cooling down. When the temperature outside gets hot, our body works hard to keep itself cool. Sweating helps by releasing moisture on the skin, which cools the body when it evaporates. This helps us stay at a safe body temperature.

Human nervous system

Parts of the Central Nervous System and Their Functions

The central nervous system (CNS) is made up of two main parts: the brain and the spinal cord. Both are important for controlling the body's actions and responses to different situations.

The Brain

The brain is the largest and most important part of the central nervous system. It is protected by the skull to prevent injury. The brain receives information from all the senses (like sight, touch, and hearing) through nerves. Its main job is to coordinate the body's actions and make decisions.

Human Brain

The brain is divided into three main parts:

1. Cerebrum
2. Cerebellum
3. Medulla Oblongata

The Cerebrum

1. The cerebrum is the largest part of the brain and is folded to help it work more efficiently.
2. The cerebrum is divided into two halves:
   • The left side controls the right side of the body.
   • The right side controls the left side of the body.
3. The cerebrum helps with many important activities, such as:
   • Thinking
   • Learning
   • Remembering
   • Deciding
   • Movement
4. It also processes the senses of sight, hearing, taste, touch, and smell. For example, if the cerebrum is damaged, a person may not be able to see or hear, even though their eyes or ears are fine.

The Cerebellum

1. The cerebellum is located below the cerebrum.
2. Its main job is to coordinate muscle movement.
3. The cerebellum helps with balance and controls voluntary movements like:
   • Walking
   • Picking up objects
   • Riding a bicycle
   • Swimming
4. These actions become smoother and more efficient the more we practice them.

The Medulla Oblongata

1. The medulla oblongata is a small part of the brain that is connected to the spinal cord.
2. It controls involuntary actions, which are actions your body does automatically without thinking, such as:
   • Breathing
   • Heart rate
   • Body temperature regulation
   • Digestion
   • Coughing, sneezing, vomiting, and swallowing
3. It also helps to send messages between the brain and the spinal cord.

The Spinal Cord

The spinal cord is an important part of the central nervous system and is connected to the brain, specifically the medulla oblongata. It runs through a hollow space in the vertebral column (the backbone) and stretches from the neck to the waist. The spinal cord is soft and delicate, which is why it is protected by the vertebral column (the series of interlocking bones that make up the spine).

A section of spinal cord

Structure and Function of the Spinal Cord

1. The spinal cord is protected inside the vertebral column and acts like a canal for nerves.
2. It has two types of nerves:
   • Motor nerves, which carry signals from the brain to the muscles to make them move.
   • Sensory nerves, which carry signals from the body back to the brain to help you feel sensations like touch, heat, and pain.

Role of the Spinal Cord

1. The spinal cord is the main communication pathway between the brain and the rest of the body. It helps to transmit information from the brain to other body parts and vice versa.
2. If the spinal cord is injured, it can disrupt communication between the brain and the body, causing loss of feeling or movement in certain areas.

Involuntary Actions Coordinated by the Spinal Cord

The spinal cord also helps with involuntary actions—actions that happen automatically without conscious control. These include:

1. Knee jerk reaction: If you tap the lower part of your knee, your leg will automatically jerk.
2. Urinary bladder function: The spinal cord helps to control when the bladder contracts or relaxes.
3. Reflex actions: If you touch something sharp or hot, your body will immediately pull away from the painful stimulus.