Our Nervous System Chapter Notes | Eureka Plus Class 5: Book Solutions, Notes & Worksheets PDF Download

Nervous System

The human nervous system consists of the brain, spinal cord, and a vast network of nerves. It is responsible for controlling various essential functions in the body, including:

• Heartbeat
• Breathing
• Digestion of food
• Memory
• Speech
• Every movement of the body

The nervous system is crucial for activities such as writing, reading, thinking, and remembering. Essentially, it regulates and controls every function of the body.

Clear all your Class 5 doubts with EduRev Join for Free

Join for Free

The Brain

• The brain is a soft and delicate organ, which is why it is protected within the skull. The skull is made up of several strong and hard bones.
• The space between the brain and the skull bones is filled with a fluid. The fluid in the skull that surrounds the brain protects it from jerks and shocks. The brain has three parts- cerebrum, cerebellum and medulla oblongata.
• The skull protects the brain.

Cerebrum

The cerebrum is the largest and the uppermost part of the brain. It helps us to think, remember and learn. It also controls the functions of the eyes, ears, nose and tongue.

Cerebellum

The cerebellum controls movements and maintains the balance of the body. It enables a person to stand, walk, run, swim, jump and sit.

Medulla Oblongata

The medulla oblongata is the lowest part of the brain and is responsible for regulating vital functions such as heartbeat, blood circulation, and breathing.

Spinal Cord

The spinal cord serves as a link between the brain and the rest of the body. It begins in the medulla oblongata and extends along the back. Like the brain, the spinal cord is soft and delicate. It is protected by the bones of the vertebral column and surrounded by a fluid that shields it from jolts and impacts.

Download the notes Chapter Notes: Our Nervous System

Download as PDF

Download as PDF

Nerves

Nerves are thin, thread-like structures that are branched and present throughout the body. They are connected either to the brain or the spinal cord and are responsible for transferring messages. There are different types of nerves, each serving various functions in the body.

Types of Nerves

• Sensory Nerves: These nerves are responsible for carrying information, in the form of impulses, from various parts of the body, including sense organs, muscles, and internal organs, towards the brain or spinal cord.
• Motor Nerves: Motor nerves transmit messages from the brain or spinal cord to different body parts such as sense organs, muscles, and glands.

How does the nervous system work?

The brain and spinal cord receive information through nerves. This information comes from all parts of the body and from our surroundings. When the brain or spinal cord gets this information, they produce a suitable response or message. The responses from the brain allow us to see, hear, smell, taste, feel, think, and remember.

Reflex Action and Its Importance

• Reflex Action is a quick and automatic response to a stimulus, usually to protect the body from harm. When something harmful happens, like stepping on a thorn or touching something hot, the sensory nerves send a message to the spinal cord, which immediately sends a message back to the muscles to take action, like moving away from the danger. This process happens very fast, without involving the brain, to ensure a speedy reaction.
• Example of Reflex Action: When a finger is pricked by a pin, the sensory nerves in the finger send a pain signal to the spinal cord. The spinal cord quickly relays a message back through motor nerves to the arm muscles, causing the hand to move away from the pin. In this case, the pin prick is the stimulus, and moving the hand away is the reflex action.
• Reflex Action Involving Eyes: An example of reflex action involving the eyes is when a bright light suddenly shines in your eyes. The sensory nerves in the eyes detect the bright light and send a signal to the brain, which quickly sends a message to the eye muscles to constrict the pupils, reducing the amount of light that enters the eyes. This reflex action happens automatically to protect the eyes from excessive brightness.

How does the Nervous System Work?

The nervous system sends messages at an incredible speed, almost 100 times per second, from the brain to the toes. Some reflex actions, like blinking when something comes close to the eyes, involve the brain directly.

How do Sense Organs Function?

The sense organs include the eyes, ears, nose, tongue, and skin.  

Ears

• The eardrum, a thin membrane inside the ear, plays a crucial role in the hearing process. When sound waves enter the ear, they cause the eardrum to vibrate. This vibration is then converted into an impulse by the nerves in the ear and sent to the brain. The brain processes this information, allowing us to recognize and understand the sound.
• Ears are essential for the sense of hearing.

Nose

• Inside the nose, there are specialized nerves that detect smells. When we inhale, these nerves pick up the scent and convert it into an impulse, which is then sent to the brain. The brain processes this information and helps us identify the specific smell.
• The nose is responsible for the sense of smell.

Tongue

• The tongue is covered with many tiny sensors called taste buds. When we eat food, these taste buds detect the flavor and send a signal to the brain through the nerves connected to them. The brain then interprets this signal, helping us understand the taste of the food.
• Tongue  helps us to taste.

Skin

• Our skin is full of nerves, which is why we can feel things like pain, temperature, and textures with our fingertips. It plays a crucial role in helping us sense the world around us.
• Skin helps us to feel.

Care of Sense Organs

To take care of your sense organs, follow these tips:

Eyes:

• If something gets into your eye, don’t rub it. Rinse your eyes with clean water instead.
• When using a computer or watching TV, make sure the screen is at eye level to avoid strain.
• Eat foods rich in Vitamin A, like spinach, carrots, sweet potatoes, and fish, to keep your eyes healthy.

Ears:

• After a bath, gently wipe your ears with a clean cotton cloth.
• Avoid using sharp objects to clean your ears, as this can cause damage.
• Stay away from loud noises, such as loud music and firecrackers, to protect your hearing.

Nose:

• Use a clean handkerchief to wipe your nose.

Tongue:

• Use a tongue cleaner to clean your tongue in the morning and at night.

Body:

• After a bath, pat your body dry with a clean towel.
• Drink at least six glasses of water a day to stay hydrated.
• Eat foods like fruits, vegetables, and fish, and get some morning sunlight to keep your skin healthy.