Samacheer Kalvi 10th Science Guide Chapter 15 Nervous System

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Tamilnadu Samacheer Kalvi 10th Science Solutions Chapter 15 Nervous System

Samacheer Kalvi 10th Science Nervous System Text Book Back Questions and Answers

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.
The 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:
(d) receptor, spinal cord, muscle

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 Ranvler 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) sareolemma
(c) axon
(d) dendrites
Answer:
(b) sareolemma

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

II. Fill in the blanks:

1. ……….. is the longest cell in our body.
2. Impulses travels rapidly ……….. in ……….. neurons.
3. A change in the environment that causes an animal to react is called ………..
4. ………. carries the impulse towards the cell body.
5. The two antagonistic component of autonomic nervous system are ……….. and ……….
6. A neuron contains all cell organelles except …………
7. ………. maintains the constant pressure inside the cranium.
8. ………… and ………… increases the surface area of cerebrum.
9. The part of human brain which acts as relay center is ………….

Answer:

1. Nerve cell or neuron
2. sensory
3. stimulus
4. Dentrites
5. sympathetic and parasympathetic system
6. Nucleus
7. Cerebro Spinal Fluid (CSF)
8. Gyri and sulci
9. thalamus

III. State whether true or false, if false write the correct statement:

1. Dendrons are the longest fibres that conducts impulses away from the cell body.
2. Sympathetic nervous system is a part of central nervous system.
3. Hypothalamus is the thermoregulatory centre of human body.
4. Cerebrum controls the voluntary actions of our body.
5. In the central nervous system myelinated fibres form the white matter.
6. All the nerves in the body are covered and protected by meninges.
7. Cerebrospinal fluid provides nutrition to brain.
8. Reflex arc allows the rapid response of the body to a stimulus.
9. Pons helps in regulating respiration.

Answer:

1. False – Axons are the longest fibres that conducts impulses away from the cell body.
2. False – Autonomic nervous system is a part of central nervous system.
3. True
4. False – Cerebellum controls the voluntary actions of our body.
5. True
6. False – Brain is covered and protected by meninges.
7. True
8. True
9. True

IV. Match the following:

Answer:
A. (iii)
B. (i)
C. (iv)
D. (ii)

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.
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.

2. Assertion: Corpus callosum is present in space between the duramater and . piamater.
Reason: It serves to maintain the 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 the receptors present in the body is called stimulus.

Question 2.
Name the parts of the hindbrain.
Answer:
The hindbrain is formed of three parts. Cerebellum, Pons and Medulla Oblongata.

Question 3.
What are the structures involved in the protection of brain?
Answer:
Cranium (skull) and three connective tissue membrane meninges – Duramater, Arachnoid membrane and piamater protect the brain.

Question 4.
Give an example for conditioned reflexes.
Answer:
The conditioned reflexes are the result of practice and learning. Playing the harmonium by striking a particular key, on seeing a music note is an example of conditioned reflexes.

Question 5.
Which acts as a link between the nervous system and endocrine system?
Answer:
Hypothalamus is the link between nervous system and endocrine system as it controls the secretion of hormones from anterior pituitary gland.

Question 6.
Define reflex arc.
Answer:
The path taken by nerve impulse to accomplish reflex action is called a Reflex arc.

VII. Differentiate between:

Question 1.
Voluntary and involuntary actions.
Answer:

Question 2.
Medullated and non-medullated nerve fibre.
Answer:

VIII. Long Answer Questions:

Question 1.
Illustrate the structure and functions of brain.
Answer:
The human brain is divided into 3 major parts. Fore brain, Mid brain and Hind brain.
Fore brian consists of Cerebrum, Thalamus and Hypothalamus.

Mid brain
Parts of the brain is Corpora quadrigemina
Function is control visual and auditory reflexes.

Hind brain consists of Pons, Cerebellum and Medulla Oblongata.

Question 2.
What will you do if someone pricks your hand with a needle? Elucidate the pathway of response with a neat labelled diagram.
Answer:
If we touch a sharp pointed object, we immediately withdraw our hand.
Here the skin is the receptor and it receives the stimulus, that is the pain. This stimulus (pain) in turn triggers an impulse in sensory neuron. The sensory neuron transmits or convey the message to the spinal cord. Spinal cord interprets the stimulus and the impulse is passed on to the relay neuron which in turn transmits it to a motor neuron. Motor neuron carry command from the spinal cord to our arm. Muscle in our arm contracts and we withdraw our hand immediately

Question 3.
With a neat labelled diagram explain the structure of a neuron.
Answer:

A neuron is the basic structural and functional unit of the nervous system. A neuron consists of Cyton, Dendrites and Axon.
Cyton : It has a central nucleus with abundant cytoplasm called neuroplasm. The cytoplasm has large granular body called Nissl’s granules and the other cell organelles like mitochondria, ribosomes, lysosomes, and endoplasmic recticulum.

Dendrites : These are the numerous branched cytoplasmic processes that project from the surface of the cell body. They conduct nerve impulses towards the cyton.

Axon : The axon is a single, elongated, slender projection. 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 protective sheath called myelin sheath which is further covered by a layer of Schwann ceils called neurilemma. Myelin sheath breaks at intervals by depressions called Nodes of Ranvier. The region between the nodes is called as internode. Myelin sheath acts as insulator and ensures rapid transmission of nerve impulses.

Question 4.
Describe the structure of spinal cord.
Answer:
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 terminale.

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

Question 5.
How nerve impulses are transferred from one neuron to next neuron?
Answer:
The information from the environment are detected by the receptors located in our sense organs such as the eyes, the nose, the skin 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 (neuro transmitter) 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.

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

The flow of nerve impulses from axonal end of one neuron to dendrite of another neuron through a synapse is called synaptic transmission.

Question 6.
Classify neurons based on its structure.
Answer:
The neurons may be of different types based on their structure and functions. Structurally the neurons may be of the following types:

(i) Unipolar neurons: Only one nerve process arises from the cyton which acts as both axon and dendron.
(ii) Bipolar neurons: The cyton gives rise to two nerve processes of which one acts as an axon while another as a dendron.
(iii) Multipolar neurons: The cyton gives rise to many dendrons and an axon.

IX. Higher Order Thinking Skills: (HOTS)

Question 1.
‘A’ is a cylindrical structure that begins from the lower end of the medulla and extends downwards. It is enclosed in bony cage 4B’ and covered by membranes ‘C’. As many as ‘D’ pairs of nerves arise from the structure ‘A’.
(i) What is A?
(ii) Name (a) bony cage ‘B’ and (b) membranes ‘C’
(iii) How much is D?
Answer:
(i) Spinal cord
(ii) (a) Cranium
(b) Duramater, Arachnoid membrane, Piamater
(iii) 31 pairs of Spinal nerves

Question 2.
Our body contains a large number of cells ‘L’ which are the longest cells in the body.
L has 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 release of chemical substance ‘P’.

1. Name the cells L.
2. what are M and N?
3. What is the gap O?
4. Name the chemical substance P.

Answer:

1. L is Nerve cell or Neuron
2. M is axon and N is dendrite
3. Gap O is synaptic junction
4. P is neuro transmitter – Acetylcholine

Samacheer Kalvi 10th Science Nervous System Additional Important Questions and Answers

I. Choose the correct answer:

Question 1.
Inner layer of Axon is:
(a) Myelin sheath
(b) Neurilemma
(c) Meninges
(d) Sarcolemma
Answer:
(b) Neurilemma

Question 2.
Which one is thin and vascularised?
(a) Piamater
(b) Duramater
(c) Arachnoid membrane
(d) Pleural membrane
Answer:
(b) Duramater

Question 3.
Uni polar neurons are found in:
(a) Adult nervous tissue
(b) Stem cells
(c) Embryonic stem cells
(d) Embryonic nervous tissue
Answer:
(d) Embryonic nervous tissue

Question 4.
Among the following which one controls our anger.
(a) Hypothalamus
(b) Cerebrum
(c) Cerebellum
(d) Thalamus
Answer:
(a) Hypothalamus

Question 5.
………. form the cerebral cortex of our brain.
(a) Grey neuron
(b) Fibrous tissue
(c) White neurons
(d) Ganglions
Answer:
(c) White neurons

Question 6.
……… is fitted with neuro transmitter.
(a) Synaptic knob
(b) Synaptic plate
(c) Synaptic cleft
(d) Synaptic branch
Answer:
(a) Synaptic knob

Question 7.
The functional connection between two neurons is called:
(a) Synapse
(b) Synapsis
(c) Chiasma
(d) Chiasmata
Answer:
(a) Synapse

Question 8.
Which of the following pair is correct?
(a) Sensory nerve – afferent
(b) Motor nerve – afferent
(c) Sensory nerve – ventral
(d) Motor nerve-dorsal
Answer:
(a) Sensory nerve – afferent

Question 9.
A healthy person got injured resulting in damage and death of a few cells. Which of the cells are least likely to be replaced by new cells:
(a) Liver cell
(b) Neuron
(c) Nephron
(d) Osteocytes
Answer:
(b) Neuron

Question 10.
The number of pairs of spinal nerves in human being is:
(a) 12
(b) 18
(c) 31
(d) 24
Answer:
(c) 31

II. Fill in the blanks:

1. ………lies at the base of the thalamus.
2. ………. transmit electrical impulses towards the cyton.
3. The sensory organs contain ………. neuron.
4. Mid brain with ………. together form the brain stems.
5. Chemical substances which take part in synaptic transmission is ……….
6. The membrane which cover the brain and the spinal cord is ………..
7. If the corpus collosum is removed in Mammalian brain then ……… will be affected.
8. Last end of spinal cord is called ………..
9. The …………. is the continuation of medulla oblongata.
10. ………. is the part of the brain which helps to maintain balance.
Answer:
1. Hypothalamus
2. Dendrites
3. Bypolar
4. Hind brain
5. acetycholine
6. Meninges
7. coordination of cerebrum
8. filum terminate
9. spinal cord
10. Cerebellum

III. State whether true or false, if false write the correct statement.

1. The gaps on the cyton are called Nodes of Ranvier.
2. Corpus callosum is a sheet of Nervous tissue that unites the right and left Cerebral Hemisphere.
3. Cerebral aqueduct is found in Mid brain.
4. Dendrites transmit chemical impulse towards the cyton.
5. The lower end of medulla oblongata is filum terminate.

Answer:

1. False – The gaps on the axon are called Nodes of Ranvier.
2. True
3. False – Cerebral aqueduct is found in fore brain.
4. False – Dendrites transmit electrical impulse towards the cyton.
5. True

IV. Match the following:

Answer:
A. (ii)
B. (iv)
C. (i)
D. (v)
E. (iii)

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.
1. Assertion: Medulla oblongata is very important for our body.
Reason: Medulla oblongata regulates all in voluntary activities.
Answer:
(c) Both assertion and reason are correct.

2. Assertion: With drawl reflex is controlled by spinal cord.
Reason: Initially cerebrum is involved and require alertness for perform this reflex.
Answer:
(a) Assertion is correct and reason is wrong.

3. Assertion: In human being, cerebrum is most developed part of brain. Reason: Cerebrum is having large surface area and analyzing centre for maintaining body activity.
Answer:
(c) Both assertion and reason are correct.

VI Answer in one or two Sentences.

Question 1.
List the components of Nervous system.
Answer:
The components of Nervous system are brain, spinal cord and brain.

Question 2.
What is Motor or efferent neuron?
Answer:
Motor or efferent neuron carries impulses from the Central Nervous System to effector organs such as muscle fibre or gland.

Question 3.
What is synapse?
Answer:
The paint of contract between the neighbouring nerve cells is called synapse.

Question 4.
Name the outermost fibrous membrane of the brain.
Answer:
Dura mater.

Question 5.
Name the two components, ANS (Autonomic Nervous System).
Answer:
The two antagonistic components of ANS are sympathetic and para sympathetic system.

VII. Short answer questions:

Question 1.
What is Coordination?
Answer:
The various organs working in a systematic controlled and efficient way to produce proper response to various stimuli is called coordination.

Question 2.
What are simple or basic reflexes? Give a few actions, as examples.
Answer:
These simple reflexes are inbuilt and unlearned responses. Many of the actions we perform in our day to day life are simple reflexes, eg. Winking of eyes, Sneezing, Coughing and Yawning. We perform these actions without thinking.

Question 3.
Name the second largest part of the brain. What is its functions?
Answer:
The cerebellum is the second largest part of the brain, formed of two large-sized hemispheres and middle vermis. Maintenance of posture and balance, co-ordinate voluntary muscle activity, are some of the functions of the cerebellum.

Question 4.
Differentiate simple reflexes and conditioned reflexes.
Answer:

VIII. Higher Order Thinking Skills: (HOTS).

Question 1.
Give two examples of conditional reflexion.
Answer:

• Applying the brake while driving, when a red or yellow traffic light appears. We do not have to think about pressing the brake.
• Producing saliva is a response of a dog naturally have, when they smell or see food or when a bell sound was followed by food.

Question 2.
Injury to medulla oblongata can cause death. Why?
Answer:
Medulla Oblongata emerges from the base of the brain and joins the brain to the spinal cord. It controls the involuntary functions.

IX. Long Answer Question:

Question 1.
Classify peripheral nervous based on the nerves arising from the brain and the spinal cord.
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. Nerves arising from spinal cord are called spinal nerves.

Cranial Nerves : In man, there are 12 pairs of cranial nerves. Some of the cranial nerves are sensory Eg: optic nerve which innervates the eye. Some are motor nerves which helps in rotation of eyeball. It also innervates the eye muscles, muscles of iris and tear gland.

Spinal Nerves : There are 31 pairs of spinal nerves. Each spinal nerve has a dorsal sensory root and the ventral motor root. The direction of impulses in dorsal spinal root is towards the spinal cord and in ventral spinal root away from the spinal cord.

Question 2.
List out the components of Nervous system and its function.
Answer:
The nervous system is formed of three distinct components namely the neurons, neuroglia and nerve fibres.
(i) Neuron or nerve cell : A neuron or nerve cell is the structural and functional unit of the nervous system. It is the longest cell of the human body with a length of over 100μm. These cells are highly specialised to detect, receive and transmit different kinds of stimuli. Information is conducted through neurons in the form of electrical impulses from one part of the body to another.

(ii) Neuroglia : Neuroglia are also called as glial cells. They are non¬exciting, supporting cell of the nervous system. They do not initiate or conduct nerve impulses.

(iii) Nerve fibres : The nerve fibres are the long slender processes of neurons. A number of nerve fibres are bundled up together to form nerves.

Question 3.
Explain Autonomic Nervous system.
Answer:
Autonomic Nervous System (ANS) is also called as visceral nervous system as it regulates the function of internal visceral organs of our body through its two antagonistic (opposite) components sympathetic and parasympathetic systems. They enable the body to perform rapid and specific visceral activities in order to maintain steady state. It controls the involuntary functions of the visceral organs.