Text Book Back Questions and Answers - Chapter 15 Nervous System 10th Science Guide Samacheer Kalvi Solutions - SaraNextGen [2024-2025]

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Chapter 15 - Nervous System - 10th Science Guide Samacheer Kalvi Solutions

I. Choose the Correct Answer.
Question $1 .$
Bipolar neurons are found in
(a) retina of eye
(b) cerebral cortex
(c) embryo
(d) respiratory epithelium
Answer:
(a) retina of eye
 

Question $2 .$
Site for processing of vision, hearing, memory, speech, intelligence and thought is:
(a) kidney
(b) ear
(c) brain
(d) lungs
Answer:
(c) brain
 

Question $3 .$
In reflex action, the reflex arc is formed by
(a) brain, spinal cord, muscle
(b) receptor, muscle, spinal cord
(c) muscle, receptor, brain
(d) receptor, spinal cord, muscle
Answer:
(b) receptor, muscle, spinal cord

Question $4 .$
Dendrites transmit impulse_______cell body and axon transmit impulse_______cell body.
(a) away from, away from
(b) towards, away from
(c) towards, towards
(d) away from, towards
Answer:
(b) towards, away from
 

Question $5 .$
The outer most of the three cranial meninges is_______
(a) arachnoid membrane
(b) piamater
(c) duramater
(d) myelin sheath
Answer:
(c) duramater
 

Question 6.
There are_______pairs of cranial nerves and_______pairs of spinal nerves.
(a) 12,31
(b) 31,12
(c) 12,13
(d) 12,21
Answer:
(a) 12,31

Question $7 .$
The neurons which carries impulse from the central nervous system to the muscle fibre:
(a) afferent neurons
(b) association neuron
(c) efferent neuron
(d) unipolar neuron
Answer:
(c) efferent neuron
 

Question 8.
Which nervous band connects the two cerebral hemispheres of brain?
(a) thalamus
(b) hypothalamus
(c) corpus callosum
(d) pons
Answer:
(c) corpus callosum
 

Question $9 .$
Node of Ranvier is found in
(a) muscles
(b) axons
(c) dendrites
(d) cyton
Answer:
(b) axons
 

Question $10 .$
Vomiting centre is located in:
(a) medulla oblongata
(b) stomach
(c) cerebrum
(d) hypothalamus
Answer:
(a) medulla oblongata

Question $11 .$
Nerve cells do not possess
(a) neurilemma
(b) sarcolemma
(c) axon
(d) dendrites
Answer:
(b) sarcolemma
 

Question 12.
A person who met with an accident lost control of body temperature, water balance, and hunger. Which of the following part of brain is supposed to be damaged?
(a) Medulla oblongata
(b) cerebrum
(c) pons
(d) hypothalamus
Answer:
(d) hypothalamus
 

II. Fill in the blanks.
Question 1.
______is the longest cell in our body.
Answer:
Axon
 

Question 2.
Impulses travels rapidly in______neurons.
Answer:
Myelin sheath of

Question $3 .$
A change in the environment that causes an animal to react is called______
Answer:
reactions or responses
 

Question $4 .$
______carries the impulse towards the cell body.
Answer:
Dendrites
 

Question $5 .$
The two antagonistic components of the autonomic nervous system are______and______
Answer:
Sympathetic, Parasympathetic
 

Question $6 .$
A neuron contains all cell organelles except______
Answer:
Golgi apparatus in axon
 

Question 7.
______maintains the constant pressure inside the cranium.
Answer:
Cerebrospinal fluid
 

Question $8 .$
______and______increases the surface area of cerebrum.
Answer:
Gyri and Sulci

Question $9 .$
The part of the human brain which acts as a relay centre is______
Answer:
Thalamus
 

III. State whether True or False, if false write the correct statement.
Question $1 .$
Dendrons are the longest fibres that conduct impulses away from the cell body.
Answer:
False
Correct Statement: Axons are the longest fibres that conduct impulses away from the cell body.
 

Question $2 .$
The sympathetic nervous system is a part of the central nervous system.
Answer:
False
Correct Statement: Sympathetic nervous system is a part of the autonomic nervous system.
 

Question $3 .$
Hypothalamus is the thermoregulatory centre of the human body.
Answer:
True
 

Question $4 .$
The cerebrum controls the voluntary actions of our body.
Answer:
True
 

Question $5 .$
In the central nervous system, myelinated fibres form the white matter.
Answer:
False
Correct Statement: In the central nervous system, two types of matter such as white matter or grey matter, is formed, with respect to the presence or absence of myelin sheath.

Question 6 .
All the nerves in the body are covered and protected by meninges.
Answer:
False
Correct Statement: The brain is covered by three connective tissue membrane or meninges.
 

Question 7.
Cerebrospinal fluid provides nutrition to brain.
Answer:
True
 

Question 8.
Reflex arc allows the rapid response of the body to a stimulus.
Answer:
True
 

Question $9 .$
Pons helps in regulating respiration.
Answer:
True
 

IV. Match the following
Question $1 .$

Answer:
1. (c) Cyton
2. (a) Forebrain
3. (d) Hindbrain
4. (b) Peripheral Nervous system
 

V. Understand the assertion statement. Justify the reason given and choose the correct choice.
(a). Assertion is correct and Reason is wrong
(b). Reason is correct and the assertion is wrong
(c). Both assertion and reason are correct
(d). Both assertion and reason are wrong
 

Question 1.
Assertion: Cerebrospinal fluid is present throughout the central nervous system.
Reason: Cerebrospinal fluid has no such functions.
Answer:
(a) Assertion is correct and Reason is wrong
 

Question 2.
Assertion: Corpus callosum is present in space between the dura mater and pia mater. Reason: It serves to maintain constant intracranial pressure.
Answer:
(d) Both assertion and reason are wrong
 

VI. Short Answer Questions.

Question $1 .$
Define the stimulus.
Answer:
The changes in the environmental condition, that are detected by receptors present in the body are called stimulus.
 

Question $2 .$
Name the parts of the hind brain.
Answer:
Hind brain consists of cerebellum, pons and medulla oblongata.
 

Question 3 .
What are the structures involved in the protection of the brain?
Answer:
The brain is covered by three connective tissue membrane or meninges.
- Dura mater, which is the outermost thick fibrous membrane.
- Arachnoid membrane, which is the middle thin vascular membrane providing a web-like cushion.
- Pia mater, which is the innermost, thin delicate membrane richly supplied with blood. Meningeal membranes protect the brain from mechanical injury.
 

Question $4 .$
Give an example for conditioned reflexes.
Answer:
Common examples of conditioned reflexes are playing a musical instrument, tying shoelaces or the neck-tie without being attentive, watering of the mouth after seeing or smelling favourite food.

Question $5 .$
Which acts as a link between the nervous system and the endocrine system?
Answer:
The hypothalamus controls the secretion of hormones from the Anterior Pituitary gland and is an important link between the nervous system and the endocrine system.
 

Question $6 .$
Define reflex arc.
Answer:
The path along which the reflexive impulse travel is called reflex arc.
(OR)
The path way taken by nerve impulse to accomplish reflex action is called reflex arc.
 

VII. Differentiate between
Question $1 .$
Voluntary and involuntary actions.
Answer:

VIII. Long Answer Questions.
Question $1 .$
With a neat labelled diagram explain the structure of a neuron
Answer:
Structure of Neuron: A neuron consists of three basic parts namely Cyton, Dendrites and Axon.

(a) Cyton: Cyton is called cell body or perikaryon. It has a central nucleus with abundant cytoplasm called neuroplasm. The cytoplasm has a large granular body called Nissl's granules and the other cell organelles like mitochondria, ribosomes, lysosomes, and endoplasmic reticulum. Neurons do not have the ability to divide. Several neurofibrils are present in the cytoplasm that help in the transmission of nerve impulses to and from the cell body.
(b) Dendrites: These are the numerous branched cytoplasmic processes, that project from the surface of the cell body. They conduct nerve impulses, towards the cyton. The branched projections increase the surface area for receiving the signals from other nerve cells.
(c) Axon: The axon is a single, elongated, slender projections. The end of axon terminates as fine branches, which terminate into knob like swellings called synaptic knob.
The plasma membrane of axon is called axolemma, while the cytoplasm is called axoplasm. It carries impulses away from the cyton. The axons may be covered by a protein sheath called myelin sheath, which is further covered by a layer of Schwann cells called neurilemma.

Myelin sheath breaks at intervals, by depressions called Nodes of Ranvier. The region between the nodes is called an internode. Myelin sheath acts as an insulator and ensures the rapid transmission of nerve impulses.

A junction between synaptic knob of the axon of one neuron and dendron of next neuron is called Synaptic Junction. Information from one neuron can pass to another neuron through these junctions, with the release of chemicals known as neurotransmitters, from the synaptic knob.

Question $2 .$
Illustrate the structure and functions of the brain.
Answer:
A human brain is formed of three main parts forebrain, midbrain and hindbrain.
1. Forebrain: The forebrain is formed of Cerebrum and Diencephalon. The diencephalon consists of dorsal thalamus and ventral hypothalamus.
(a) Cerebrum: It is the largest portion and nearly forms two-third of the brain. The cerebrum is longitudinally divided into two halves, as of right and left cerebral hemispheres by a deep - cleft called median cleft. The two cerebral hemispheres are interconnected by thick band of nerve fibres called corpus callosum. The outer portion of each cerebral hemisphere is formed of grey matter and is called cerebral cortex.
The inner or deeper part is formed of white matter and is called cerebral medulla. The cortex is extremely folded forming elevations called gyri, with depressions between them termed as sulci, that increase the surface area. Each cerebral hemisphere is divisible into a frontal lobe, a parietal lobe, a temporal lobe and an occipital lobe. These lobes are also known as cerebral lobes.
(b) Thalamus: Thalamus present in the cerebral medulla is a major conducting centre for sensory and motor signalling. It acts as a relay centre.
(c) Hypothalamus: It lies at the base of the thalamus. It controls the secretions of hormones from the anterior pituitary gland.
2. Midbrain: It is located between thalamus and Hindbrain. The dorsal portion of the midbrain consists of four rounded bodies called corporaquadrigemina, that control visual and auditory (hearing) reflexes.
3. Hindbrain: It is formed of three parts Cerebellum, Pons and Medulla Oblongata.

- Cerebellum: It is the second-largest part of the brain formed of two large-sized hemispheres and middle vermis.
- Pons: It is a bridge of nerve fibre that connects the lobes of the cerebellum. It relays signals between the cerebellum, spinal cord, midbrain and cerebrum.
- Medulla Oblongata: It is the posterior-most part of the brain, that connects the spinal cord and various parts of the brain.
Functions of Brain:

Question $3 .$
What will you do if someone pricks your hand with a needle? Elucidate the pathway of response with a neat labelled diagram.
Answer:

The pathway taken by nerve impulse to accomplish reflex action is called the reflex arc.
- When the hand is pricked by a needle, the stimulus is the prick (touch) pain, which is sensed by a receptor called touch or pain receptors in the skin in our hand. This stimulus in tum triggers an impulse in a sensory neuron.
- The sensory neuron transmits or conveys the message to the spinal cord.
- The spinal cord interprets the stimulus and the impulse is passed on to the relay neuron, which in tum transmits it to a motor neuron.
- Motor neurons carry command from the spinal cord to our arm.
- The muscle in our arm contracts and we withdraw our hand immediately from the needle prick. Muscle is the effector organ which has responded to the prick (pain).
 

Question $4 .$
Describe the structure of the spinal cord.
Answer:
The spinal cord is a cylindrical structure lying in the neural canal of the vertebral column. It is also covered by meninges. It extends from the lower end of medulla oblongata to the first lumbar vertebra. The posterior-most region of spinal cord tapers into a thin fibrous thread-like structure called Filum terminate.

Internally, the spinal cord contains a cerebrospinal fluid-filled cavity, known as the central canal. The grey matter of the spinal cord is ' $H$ ' shaped. The upper end of the letter, ' $H$ ' forms posterior horns and lower end forms anterior horns. A bundle of fibres pass into the posterior horn forming the dorsal or afferent root. Fibres pass outward, from the anterior horn forming the ventral or efferent root. These two roots joins to form spinal nerves. The white matter is external and has a bundle of nerve tracts. Spinal cord conducts sensory and motor impulses to and from the brain. It controls the reflex actions of the body.
 

Question $5 .$
How nerve impulses are transferred from one neuron to next neuron?
Answer:

All the information from the environment is detected by the receptors, located in the sense organs such as the eyes, nose, skin and etc. Information from the receptors is transmitted as electrical impulse and is received by the dendritic tips of the neuron. This impulse travels from the dendrite to the cell body and then along the axon to its terminal end. On reaching the axonal end, it causes the nerve endings to release a chemical (neurotransmitter) which diffuses across a synapse and starts a similar electrical impulse in the dendrites of the next neuron, then to their cell body to be carried along the axon.

The electrical signal reaches the brain or spinal cord. The response from the brain (or spinal cord) is similarly passed on to the effector organs such as the muscle or gland cell, that undergoes the desired response.
 

Question $6 .$
Classify neurons based on its structure.
Answer:
The neurons are classified, based on their structures:

(a) Unipolar neurons: Only one nerve process arises from the cyton, which acts as both axon and dendron. It is found in early embryos, but not in the adult.
(b) Bipolar neurons: The cyton gives rise to two nerve processes, of which one acts as an axon, while another acts as a dendron. Bipolar neurons are found in the retina of the eye and olfactory epithelium of nasal chambers.
(c) Multipolar neurons: The cyton gives rise to many dendrons and an axon. Multipolar neurons found in the cerebral cortex of the brain.
 

IX. Higher Order Thinking Skills (HOTS) Questions
Question $1 .$
' $A$ ' is a cylindrical structure that begins from the lower end of medulla and extend downwards. It is enclosed in bony cage ' $\mathrm{B}^{\prime}$ and covered by membranes ' $\mathrm{C}$ ' $\mathrm{As}$ many as ' $\mathrm{D}$ ' pairs of nerves arise from the structure ' $A$ '.
1. What is $A$ ?
2. Name (a) bony cage ' $B$ ' and (b) membranes ${ }^{\prime} \mathrm{C}$ '
3. How much is D?
Answer:
1. $A$ is spinal cord.
2. (a) Bony cage is Vertebral column
(c) is Meninges
3. $\mathrm{D}$ is 31 pairs of spinal nerve.
 

Question $2 .$
Our body contains a large number of cells ' $\mathrm{L}$ ' which are the longest cells in the body. L has a long and short branch called as ' $M$ ' and ' $N$ ' respectively. There is a gap ' $O$ ' between two ' $L$ ' cells, through which nerve impulse transfer by the release of chemical substance ' $\mathrm{P}$ '.

1. Name the cells $L$
2. What are $M$ and $N$ ?
3. What is gap $\mathrm{O}$ ?
4. Name the chemical substance $P$ ?
Answer:
1. Neuron
2. Axon and Dendrites
3. Synaptic Junction (knob)
4. Neurotransmitter (Acetylcholine)
 

I. Fill in the blanks.
Question $1 .$
The condition needed for the coordination between the various cells and organ for the diverse activities is called______
Answer:
Homeostasis
 

Question $2 .$
A number of nerve fibres bundled up together to form______
Answer:
Nerves
 

Question $3 .$
The other name for cyton is cell body or______
Answer:
Perikaryon

Question $4 .$
______is an important neurotransmitter released by neurons.
Answer:
Acetylcholine
 

Question $5 .$
______membranes protect the brain from mechanical injury.
Answer:
Meningeal
 

Question $6 .$
The four rounded bodies of the midbrain are called______
Answer:
Corporaquadrigemina
 

Question 7.
The Posterior most region of spinal cord tapers into fibrous thread-like structures called______
Answer:
Filum terminale
 

II. Choose the incorrect statement and Write it as a correct statement.
Question $1 .$
Responses refer to the changes in the environmental conditions, which are detected by receptors.
Answer:
Incorrect Statement
Correct Statement: Stimulus refer to the changes in the environmental conditions, which are detected by receptors. .
 

Question $2 .$
The brain is the controlling centre of all the body activities.
Answer:
Correct Statement

Question $3 .$
Axon carries impulses towards the cyton.
Answer:
Incorrect Statement
Correct Statement: Axon carries impulses away from the cyton.
 

Question $4 .$
CNS consists of all nerves, which connect the brain and spinal cord to all parts of the body.
Answer:
Incorrect Statement
Correct Statement: CNS consists of all nerves, which connect the brain and spinal cord to all parts of the body.
 

Question $5 .$
A receptor is a cell or group of cells that receive the stimuli.
Answer:
Correct Statement
 

III. Match the following.
Question $1 .$

Answer:
1. (d) Do not conduct nerve impulses
2. (e) Information from the receptor
3. (b) Connects the lobe of the cerebellum
4. (c) Cerebrospinal fluid
5. (a) Conduct nerve impulses
 

IV. Answer the following in a word or with a Sentence.
Question $1 .$
What are Spinal Reflexes?
Answer:
Most of the reflex actions are monitored and controlled by the spinal cord. So it is called Spinal Reflexes.
 

Question $2 .$
Name the two enlargement found in spinal cord.
Answer:
The spinal cord has two enlargements.
Cervical plexus - found in neck region
Lumbar plexus - in Lumbar region.
 

Question 3 .
What is the function of Meningeai membranes in the brain?
Answer:
Meningeal membranes protect the brain from mechanical injury.
 

Question $4 .$
Write a function of glial cells.
Answer:
Glial cells or Neuroglia are non-exciting, supporting cells of nervous system.

Question $5 .$
Name the granules in the cytoplasm of Peyton.
Answer:
Nissl's granules.
 

Question $6 .$
Which is the controlling centre of all body activities?
Answer:
Brain
 

Question $7 .$
In which fluid, is the brain suspended?
Answer:
The brain is suspended in the cerebrospinal fluid.
 

Question $8 .$
Name the four rounded bodies in the dorsal portion of midbrain.
Answer:
Corpora quadrigemina
 

Question $9 .$
Which is the longest cell of the human body?
Answer:
The longest cell of the human body is axon.
 

Question $10 .$
Name the tapered spinal cord into a thin thread-like structure present in the posterior-most region.
Answer:
Filum terminate.

V. Draw a neat labelled diagram of the following.
Question $1 .$
(a) Brain
(b) Structure of Spinal Cord
(c) Nerve impulse transmission
Answer:
(a) Brain

(b) Structure of Spinal Cord

(c) Nerve impulse transmission

VI. Answer the following briefly.
Question $1 .$
What is the synaptic transmission?
Answer:
The flow of nerve impulses from the axonal end of one neuron to the dendrite of another neuron through a synapse is called synaptic transmission.
 

Question 2.
What is homeostasis?
Answer:
The coordination between the various cells and organs is essential for their diverse activities to maintain physiological balance called Homeostasis.
 

Question $3 .$
What are Neurotransmitters? Give an example.
Answer:
Neurotransmitters are chemicals, which allow the transmission of a nerve impulse from the axon terminal of one neuron to the dendron of another neuron or to an effector organ. Acetylcholine is the neurotransmitter released by neurons.
 

Question $4 .$
Name the three connective tissue membrane of Meninges.
Answer:
1. Duramater: Outermost thick fibrous membrane.
2. Arachnoid membrane : Middle thin vascular membrane provide web like cushion.
3. Piamater : Innermost thin oblicate membrane richly supplied with blood.

Question $5 .$
What are the types of nerve fibres?
Answer:
The two types of nerve fibres, based on the presence or absence of myelin sheath are
- Myelinated nerve fibre: The axon is covered with a myelin sheath.
- Non-myelinated nerve fibre: The axon is not covered by a myelin sheath.
Myelinated and non-myelinated nerve fibres from the white matter and grey matter of the brain.
 

Question $6 .$
Why is the Autonomic Nervous System called Visceral nervous system?
Answer:
The Autonomic Nervous System is also called Visceral Nervous System because it regulates the function of internal visceral organs of our body.
 

Question $7 .$
What are the cerebral lobes?
Answer:
Each cerebral hemisphere is divisible into a frontal lobe, a parietal lobe, a temporal lobe and an occipital lobe. These lobes are called cerebral lobes.
 

Question 8.
How are neurons categorized on the basis of functions?
Answer:
On the basis of functions the neurons are categorised as:
- Sensory or afferent neurons, which carry impulses from the sense organ to the central nervous system.
- Motor or efferent neurons, which carry impulses from the central nervous system to effector organs such as the muscle fibre and the gland.
- Association neurons, which conduct impulses between sensory and motor neurons.
 

Question 9.
What is cerebrospinal fluid? What is its functions?
Answer:
The brain is suspended in a special fluid environment called cerebrospinal fluid (CSF).
Functions:

- It acts as a shock-absorbing fluid and protects the brain from damage when it is subjected to a sudden jerk.
- It supplies nutrients to the brain.
- It collects and removes wastes from the brain.
- It is responsible for maintaining a constant pressure inside the cranium.
 

Question $10 .$
Explain the Peripheral Nervous System.
Answer:
Peripheral Nervous System is formed, by the nerves arising from the brain and the spinal cord. The nerves arising from the brain are called cranial nerves. In man, there are 12 pairs of cranial nerves. Some of the cranial nerves are sensory.
Nerves arising from the spinal cord are called spinal nerves. In man, there are 31 pairs of spinal nerves. Each spinal nerve has a dorsal sensory root and the ventral motor root.
 

VI. Higher Order Thinking Skills (HOTS) Questions
Question 1.
Raju got an injury on the head during motorbike accident on the road. Later he faced a problem in maintaining balance of the body while walking or sitting. Which part of the brain do you think is affected?
Answer:
Cerebellum in the brain is affected as it maintains the body balance.
 

Question 2.
What is Electroencephalogram (EEG)?
Answer:
Electroencephalogram (EEG) is an instrument, which records the electrical impulses of the brain. An EEG can detect abnormalities in the brain waves and help in diagnoses of epilepsy, brain tumours and head injuries, etc.

Question $3 .$
Name a few brain diseases.
Answer:
- Alzheimer's disease (develop, as we age)
- Parkinson's disease
- Amyotrophic Lateral Sclerosis (ALS)
 

Question $4 .$
What are brain injuries? Give examples.
Answer:
The damage of brain tissue, neurons and nerves. This damage affects our brain's ability to communicate with the rest of our body. Examples of Brain injuries include blood clots, hematomas, swelling inside the skull, strokes and etc.
 

Question $5 .$
What are the symptoms of brain injury?
Answer:
Vomiting, Nausea, Speech difficulty, bleeding from the ear, Numbness and etc.