Question 1

Question 1Define the following terms:(a) Neuron(b) Nerve(c) Stimulus(d) Synaptic cleft(e) Reflex action(f) Corpus callosum

Accepted Answer

(a) Neuron — Neuron (nerve cells) are the fundamental units of the nervous system specialized to transmit information in the form of electrical impulses to different parts of the body.(b) Nerve — Nerve is a bundle of nerve fibres (axons) of separate neurons, enclosed in a tubular sheath.(c) Stimulus — An agent or the sudden change of the external or internal environment that results in a change in an organism or any of its body parts is called a stimulus.(d) Synaptic cleft — The gaps between the axon terminals and the dendrites of another one or more neurons are called synaptic clefts.(e) Reflex action — Reflex action is an automatic or quick or immediate involuntary action in the body brought about by a stimulus.(f) Corpus callosum — Corpus callosum is a sheet of fibres connecting the two cerebral hemispheres.

Question 2

Question 2Distinguish between the following pairs:(a) Cerebrum and cerebellum (function)(b) Sympathetic nervous system and parasympathetic nervous system (location and role)(c) Sensory nerve and motor nerve (direction of impulse carried)(d) Cerebrum and spinal cord (arrangement of cytons and axons of neurons)(e) Cranial nerves and spinal nerves (number in pairs)(f) Nerve impulse and flow of electricity (transmission and speed)(g) Medulla oblongata and cerebellum (function)

Accepted Answer

(a) Difference between cerebrum and cerebellum (function)CerebrumCerebellumThe cerebrum is the seat of intelligence, consciousness and will-power. It controls all voluntary actions. It enables us to think, reason, plan and memorize.The cerebellum maintains balance of the body and coordinate muscular activity.(b) Difference between sympathetic nervous system and parasympathetic nervous system (location and role)Sympathetic Nervous SystemParasympathetic Nervous SystemSympathetic nervous system is located between the neck and the waist region.Parasympathetic nervous system is located in the head and neck region and in sacral region.It prepares the body for violent action against the abnormal condition.It is concerned with re-establishing normal conditions after the violent act is over.(c) Difference between sensory nerve and motor nerve (direction of impulse carried)Sensory NerveMotor NerveSensory nerve brings impulses from the receptors i.e. sense organs to the brain or spinal cord.Motor nerve carries impulse from the brain or spinal cord to effector organs such as muscles or glands.(d) Difference between cerebrum and spinal cord (arrangement of cytons and axons of neurons)CerebrumSpinal CordThe grey matter containing cytons lies in the cortex (outer region) while the white matter containing axons lies in the medullary region (inner region).The grey matter containing cytons lies in the medullary region i.e. inner side while the white matter containing axons lies in the cortex i.e. the outer region.(e) Difference between cranial nerves and spinal nerves (number in pairs)Cranial NervesSpinal NervesThere are 12 pairs of cranial nerves.There are 31 pairs of spinal nerves.(f) Difference between nerve impulse and flow of electricity (transmission and speed)Nerve impulseFlow of electricityHere, neither any substance nor any electrons or ions move along the nerve fibre.Here, electrons actually move along the wire.Nerve impulses travel at a speed of about 100 metres per second.Electricity is conducted at a speed of about 150,000 km per second.(g) Difference between medulla oblongata and cerebellum (function)Medulla OblongataCerebellumMedulla oblongata controls the activities of internal organs, for example, peristaltic movement of the alimentary canal, movement of breathing and many other involuntary actions.The cerebellum maintains balance of the body and coordinates muscular activity.

Question 3

Question 7What is the difference between reflex action and voluntary action?

Accepted Answer

Reflex ActionVoluntary ActionInitiated by some stimulus (touch, pain, pressure, heat, light)Initiated by a willing thought.Mainly self-protective due to environment.Fulfilment of a desired goal.Commands originate mostly in the spinal cord and autonomic nervous system and a few in the brain as well.Commands originate in brain.Involve muscles and glands.Involve only muscles.

Question 4

Question 8Any factor that can bring a change in the body of an organism is called:ResponseStimulusReflexImpulse

Accepted Answer

StimulusReason — A stimulus is any agent or an environmental change which initiates a response in the body.

Question 5

Question 9Gyri and sulci are richly found in :Renal cortexCerebral cortexSpinal cortexAdrenal cortex

Accepted Answer

Cerebral cortexReason — In the cerebral cortex, the folds of gray matter are called gyri and the grooves are called sulci.

Question 6

Question 10The white matter of cerebrum mainly consists of :CytonsDendronsAxonsDendrites

Accepted Answer

AxonsReason — Axons are covered with myelin sheath which gives it white colour.

Question 7

Question 6Name the following:(a) Three types of neurons(b) Three types of nerves(c) Three main parts of the neuron(d) Two major divisions of the nervous system(e) Three layers of the meninges(f) Three main parts of the brain(g) Two parts of the autonomic nervous system(h) Two types of reflexes.

Accepted Answer

(a) Three types of neurons —Sensory neuronsMotor neuronsAssociation neurons(b) Three types of nerves —Sensory nervesMotor nervesMixed nerves(c) Three main parts of the neuron —CytonDendritesAxon(d) Two major divisions of the nervous system —Central nervous systemPeripheral nervous system(e) Three layers of the meninges —Dura materArachnoidPia mater(f) Three main parts of the brain —CerebrumCerebellumMedulla oblongata(g) Two parts of the autonomic nervous system —Sympathetic nervous systemParasympathetic nervous system(h) Two types of reflexes —Natural (inborn) reflexConditioned (acquired) reflex.

Question 8

Question 3The diagram given below shows the internal structure of spinal cord depicting a phenomenon. Study the diagram and answer the following questions.(a) Name the phenomenon shown in the figure and define the same.(b) Identify the parts labelled as 1 and 2. Write one functional difference between these two.(c) Name the bony protective covering and the membranous protective covering of the spinal cord.(d) Label the guidelines 3 and 4.(e) How is the labelled part 3 different from part 4 with respect to its composition (part of neuron)?(f) Give the technical term for the point of contact between the two nerve cells.(g) Name the fluid filled inside the central canal of spinal cord.(h) Name the term used for a small gap between two neurons.(i) Give one example of a neurotransmitter.(j) Draw a neat diagram of a nerve cell and label the parts : Perikaryon, Node of Ranvier, Myelin sheath and Axon terminals.

Accepted Answer

(a) The phenomenon shown in the figure is Spinal reflex.Spinal reflex is an automatic/quick/immediate, involuntary action in the body brought about by a stimulus.(b) The parts labelled 1 & 2 are:1 → Sensory nerve2 → Motor nerveOne functional difference between Sensory & Motor nerve is:Sensory nerveMotor nerveBrings impulse from receptors to brain or spinal cord.Carry impulse from brain and spinal cord to effector organs.(c) Back bone or vertebral column is the bony protective covering. Meninges (dura mater, arachnoid and pia mater) is the membranous protective covering.(d) Guidelines 3 and 4 are:3 → Gray matter4 → White matter(e) Gray matter is composed of cytons and white matter is composed of axons.(f) Synapse(g) Cerebrospinal fluid(h) Synapse(i) Acetylcholine(j) Diagram of nerve cell with the parts labelled is shown below:

Question 9

Question 4The figure given below is the basic structural and functional unit of the human nervous system. Study the diagram and answer the following questions:(a) Write the technical term for the diagram.(b) Name two organs of our nervous system where these cells are richly found.(c) How are these cells significant for us ?(d) Name the cell organelle that is absent in these cells and how does it affect our body metabolism ?(e) Redraw the same figure and label the following — Perikaryon, Axon, Dendrites, Myelin sheath and Node of Ranvier.

Accepted Answer

(a) Neuron(b) Brain and spinal cord(c) Neurons are the fundamental building blocks of the nervous system. They help us to process information, control our movements, allow us to perceive the world around us, and are involved in learning and memory.(d) Centrosome is the cell organelle absent in these cells. It is absent because the nerve cells have lost the ability to divide.(e) Below is the labelled diagram of neuron:

Question 10

Question 5It was a pleasant dark evening when Anuj saw a person clumsily walking towards him. The person, in his nonsensical and slurred speech, started talking to Anuj and Anuj realised he was possibly intoxicated. Answer the following questions:(a) How does alcohol consumption affect the brain ? State the part of the brain affected resulting in uncoordinated movements and speech.(b) In which part of the brain does the impulse for walking or speaking arise ?(c) How does part (a) differ with part (b) structurally?

Accepted Answer

(a) Alcohol slows down brain activity, which leads to delayed responses, poor coordination and slower thinking. It also affects hippocampus part of brain which can lead to blackouts.The part of brain which is affected resulting in uncoordinated movements and speech is Cerebellum.(b) Cerebrum(c) Differences between Cerebellum and Cerebrum:CerebellumCerebrumIt is a small, egg-shaped lobe located at the base under the cerebrum.It is the uppermost, largest and the most prominent part of the brain.It does not have convolutions, but has many furrows.It is highly convoluted in appearance with ridges and grooves.It coordinates the movement of voluntary muscles and maintains the balance of the body.It controls mental activities such as thinking and reasoning, memory, intelligence and perception of taste, pain and touch etc.

The Nervous System

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Multiple Choice Type

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Structured Application Skill Type