Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
CONCEPT MAP
Vocabulary : Neuron, Spinal cord, Reflex action, Reflex arc, Cornea, Pupil,
Retina, Iris, Pinna, Eardrum, Stimulus.
The Nervous
system and
sense organs
Nervous System Sense Organs
Brain Nerves Spinal
cord
Reflex
Action Eyes
Ears
Nose
Skin
Tongue
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
The system used to send, receive and process messages to and from
the various organs and organ systems inside the body is called as
Nervous System.
It consists of:-
Brain
Spinal cord
Nerves
Brain
Functions of brain:-
It is the main control centre of the body.
Brain monitors and regulates the body’s action and reactions.
It continuously receives information, rapidly analyzes this data
and then responds.
It also controls bodily actions and functions.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
Parts of Brain:-
1. Cerebrum
It collects information from all sense organs and controls
thinking and reasoning.
Centre of thinking, learning and memory.
2. Cerebellum
It helps in coordinating body movements.
Also responsible for the body balance and posture.
Centre responsible for creativity.
3. Brainstem
It lies below the cerebellum.
Connects brain to the spinal cord
It controls breathing and heart rate.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
Nerves
Nervous system consists of billions of nerve cells called neurons.
Nerves acts as carriers of signals to and from the brain to all parts of the
body.
There are three main types of nerves:-
Sensory nerves- They carry messages from different parts of
body to the brain or the spinal cord.
Motor nerves- they carry messages from the brain or spinal cord
to different parts of the body.
Mixed Nerves- works as both ways like sensory and motor
nerves.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
Spinal cord
Spinal cord is a long, thin, tube-like
structure.
It extends from the brain down the
spinal column.
Acts as bridge between the brain and
the rest of the body to transmits signals
to and from the brain.
Plays a major role in our reflex actions.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
Time please
A. Match the columns.
Heart-Four chambers
Blood-Red coloured fluid
Cerebellum-Balance
Blood vessels-Pipelines
Cerebrum-Thinking
B. Give one word for the following:-
1. A medium that carries vital gases within the human body:
Blood
2. A muscular organ that helps to pump blood to all parts of the
body: Heart
3. The thickest blood vessels: Artery
4. The part of brain that controls the heart rate: Brainstem
5. The main control centre of the body: Brain
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
Reflex Action
A reflex action is an immediate and rapid response to a stimulus.
Reflex actions are not directly controlled by the brain.
In humans, reflexes occur through a pathway called the
reflex arc.
A reflex action occurs very quickly.
Signals are directly sent from spinal cord without involving
the brain.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
The reflex arc works as follows:-
The sensory neuron carries the message from the point of
stimulus to the spinal cord.
The spinal cord receives the message, processes it and gives the
response.
The motor neuron then carries the message to the point where
the reflex occurs.
Spinal cord sends reflex messages in less than a second.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
Sense organs our body has five sense organs.
1. Eyes:-
We see with our eyes.
Eyes are located in the eye sockets of the skull.
Eyelids and eyelashes protect the eyes from dust.
Structure of the eye:-
Cornea- A thin, transparent layer covering the front part of the
eye is called cornea.
Iris- The round, coloured part of the eye, located behind the
cornea, is called iris.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
Pupil- The opening at the centre of the iris is called the pupil. Light
enters through the pupil.
Lens- A lens located just behind the pupil helps to focus the light.
Retina- Light passes through the lens and falls on a lining, called
the retina, which is sensitive to light. The retina sends messages to optic nerve, which carries the
message to the brain.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
2. Ears :-
We hear with our ears.
We have a pair of ears
Structure of the ear:-
There are three main parts of ear- outer, middle and inner ear.
Outer ear- The part of ear that can be seen from outside is called
outer ear or pinna. Outer ear receives sound.
Middle ear- It consists eardrum, the sound travels to the middle
ear and hits the eardrum.
Eardrum-
It is a thin, membrane like structure.
It vibrates like a stretched rubber band when you release
it.
Inner ear- the vibrations are then passed on to the inner ear.
Inner ear transforms the sound into a nerve signal, which is sent
to the brain via nerves.
3. Nose :-
We smell with our nose.
It helps to detect different odours.
It helps us in breathing.
Structure of nose:-
It has two nostrils that are lined with hair and mucus to trap dirt
from the air.
Nasal cavity that is lined with cells that are sensitive to smell.
These cells detect smell and send the messages to brain though
nerves.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
4. Skin :-
It helps us to feel, touch and sense heat, cold, pressure and
pain.
It forms a continuous, covering layer around our entire
body
There are several nerves under the surface of skin.
These nerves detect touch and send messages to brain.
5. Tongue :-
It helps us to sense different tastes like sweet, sour, bitter
and salty.
There are several taste buds located over the entire surface
of tongue
These taste buds detect taste and send messages to the
brain through the nerves.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
Let’s Practise
A. Fill in the blanks with the correct words:-
1. Brain controls all the organs of the body.
2. The spinal cord is involved in the reflexes of the body.
3. The spinal cord acts as a bridge between the brain and the rest
of the body.
4. Reflex actions are not directly controlled by the brain.
5. The outer or external ear is called the pinna.
B. Tick the correct option.
1. Which of these is not a part of the nervous system?
a. Brain b. nerves c. Spine d. Spinal cord
2. The nervous system consists of billions of nerve cells, called
a. Neurons b. vessels c. veins d. arteries
3. It is responsible for body balance.
a. Cerebellum b. Cerebrum c. Spinal cord d. Brainstem
4. The long, thin, tube-like structure that extends from the brain
down the spinal column is called the ----------------.
a. Relex arc b. Cerebellum c. spinal cord d. neuron
5. Which of these is not a sense organ?
a. Tongue b. Skin c. Nose d. Hair
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
C. Short answer questions
1. List the main organs of the nervous system?
Ans1. The Brain, spinal cord, and the nerves make up the nervous
system.
2. State two functions of the cerebellum.
Ans2. The cerebellum is responsible for controlling body balance and
posture.
3. Where is the spinal cord located?
Ans3. The spinal cord acts as a bridge between the brain and the rest
of the body and it extends from the brain down the spinal column.
4. What is reflex arc?
Ans4. In human beings, reflexes occur through a pathway called the
reflex arc.
5. List the three types of nerve found in our body.
Ans5. Three types of nerves are sensory, motor and mixed.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
6. What is retina? State its functions.
Ans6. Retina is a light-sensitive lining behind the lens, at the back of
our eye. It sends messages to the optic nerve, which carries the
message to the brain.
D. Long answer questions
1. What is brain? Draw a labelled diagram of the human brain and
state the functions of the major parts.
Ans1. Brain is the main control centre of the body, protected by the
skull. The brain monitors and regulates the body’s actions and
reactions. It continuously receives information, rapidly analyzes this
data and then responds. It also controls bodily actions and functions.
For diagram—refer page no.79/ lesson notes.
Functions of the major parts of brain:-
Cerebrum- It collects information from all sense organs and controls
thinking and reasoning. It is the centre of thinking, learning and
memory.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
Cerebellum- It helps in coordinating body movements. It is also
responsible for the body balance and posture and is the centre
responsible for creativity.
Brainstem- It lies below the cerebellum. It connects brain to the spinal
cord and It controls breathing and heart rate.
2. List the three types of nerves and mention their functions.
Ans 2. The three main types of nerves are-
Sensory nerves- They carry messages from different parts of
body to the brain or the spinal cord.
Motor nerves- they carry messages from the brain or spinal cord
to different parts of the body.
Mixed Nerves- they carries messages from different parts of the
body to the brain or spinal cord, as well as from the brain or
spinal cord to different parts of the body.
3. With the help of labelled diagram, explain the reflex arc.
Ans3. In humans, reflexes occur through a pathway called the
reflex arc. ( for diagram refer figure on page no.81 of textbook)
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
A reflex action occurs very quickly because signals are directly
sent from spinal cord without involving the brain.
The reflex arc works as follows:-
The sensory neuron carries the message from the point of
stimulus to the spinal cord.
The spinal cord receives the message, processes it and gives the
response.
The motor neuron then carries the message to the point where
the reflex occurs.
Spinal cord sends reflex messages in less than a second.
Sub: Science Lesson Note Grade: V
Chapter: 8 Human Body: Nervous System and Sense Organ
4. Draw a labelled diagram of the structure of the ear and state
the function of cochlea.
Ans4. Please refer the given fig. in lesson notes and page no. 83
of coursebook
Function of cochlea (inner ear):-
The outer ear receives sound. This sound travels to the middle
ear and hits the eardrum. The eardrum is a thin, membrane like
structure. It vibrates like a stretched rubber band when you
release it. The vibrations are then passed on to the inner ear
(cochlea). The inner ear transforms the sound into a nerve
signal, which is sent to the brain via nerves.