Chapter 18: Neural Control and Coordination Application Questions | biology Class 11 CBSE

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Chapter 18: Neural Control and Coordination Application Questions | biology Class 11 CBSE | ByteNotes.in

Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 1

Applied Concept

A sprinter begins a 100-metre race. With reference to neural coordination, explain how the body's organ systems are rapidly adjusted to meet the sudden increase in energy demand.

At the start of the race, the neural system rapidly detects the increased muscular activity and sends efferent impulses from the CNS to increase heart rate and breathing rate to enhance oxygen and glucose supply to muscles.
The sympathetic division of the autonomic neural system is activated, stimulating the heart and dilating blood vessels to muscles, while the somatic neural system continuously relays impulses to coordinate voluntary skeletal muscle contractions.
The hypothalamus regulates thermoregulation during the race, triggering sweating to dissipate the heat generated by increased metabolism.
After the race ends, impulses from the CNS gradually return all organ activities (nerves, lungs, heart, kidneys) to normal, illustrating the coordinated and reversible nature of neural regulation.

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Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 2

Applied Concept

With reference to the resting potential of a neuron, explain why a nerve fibre is described as being in a 'polarised' state when at rest.

In the resting state, the axonal membrane maintains a differential charge: the outer surface is positively charged and the inner surface is negatively charged, due to unequal distribution of ions.
This charge separation arises because the axonal membrane is more permeable to K+ and nearly impermeable to Na+ and intracellular negatively charged proteins, keeping K+ and negative proteins inside and Na+ outside.
The sodium-potassium pump actively transports 3 Na+ outward and 2 K+ inward, sustaining the ion gradients that maintain this charge difference.
Because there is a clear separation of positive and negative charges across the membrane, similar to the poles of a battery, the membrane is said to be polarised, and the resulting electrical potential difference is called the resting potential.

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Application Question

Hard difficulty • Concept in a practical situation

Hard

Question 3

Applied Concept

A patient is diagnosed with damage to the medulla oblongata following an accident. Predict the physiological consequences and justify your answer based on the functions of the medulla.

The medulla oblongata contains vital reflex centres that control respiration, cardiovascular reflexes, and gastric secretions.
Damage to the medulla would therefore impair the automatic regulation of breathing (respiratory centres), potentially causing respiratory failure.
Cardiovascular reflexes such as heart rate regulation and blood pressure control would also be compromised, potentially causing cardiac arrest or dangerous fluctuations in blood pressure.
Since the medulla is connected to the spinal cord and forms part of the brain stem, its damage would also disrupt the relay of signals between the brain and the spinal cord, affecting a wide range of reflex and voluntary functions.

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Application Question

Hard difficulty • Concept in a practical situation

Hard

Question 4

Applied Concept

A patient with a lesion in the cerebellum shows poor balance and uncoordinated movements. Relate these symptoms to the normal functions of the cerebellum.

The cerebellum is a part of the hindbrain with a highly convoluted surface to accommodate many neurons; it integrates information received from the semicircular canals of the ear and the auditory system.
Normally, the cerebellum coordinates voluntary movements and maintains body balance by continuously adjusting motor commands based on sensory feedback.
When the cerebellum is damaged, the integration of proprioceptive and vestibular signals is disrupted, leading to uncoordinated (ataxic) movements and poor balance.
The patient's symptoms — poor balance and uncoordinated movements — directly reflect the loss of the cerebellum's integrative and fine-motor coordination functions.

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Application Question

Hard difficulty • Concept in a practical situation

Hard

Question 5

Applied Concept

During neuroscience research, a scientist blocks the sodium channels in a neuron's membrane experimentally. With reference to the chapter, what effect will this have on nerve impulse generation?

At rest, the axonal membrane is nearly impermeable to Na+; when a stimulus is applied, the membrane becomes freely permeable to Na+, causing rapid Na+ influx that depolarises the membrane and generates an action potential.
If sodium channels are blocked, Na+ cannot enter the axon when a stimulus is applied, so depolarisation cannot occur.
Without depolarisation, no action potential (nerve impulse) can be generated at the stimulated site.
Consequently, impulse conduction along the axon would fail entirely, as the propagation of the action potential depends on sequential Na+ influx at successive sites along the axon.

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Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 6

Applied Concept

A student observes that after a stimulus is applied to a nerve fibre, the fibre briefly becomes unresponsive before becoming excitable again. Explain this observation using the concept of repolarisation.

When a stimulus generates an action potential, the axonal membrane at that site becomes depolarised (outer surface negative, inner surface positive) due to rapid Na+ influx.
The depolarised region is temporarily in a refractory state and cannot generate another action potential immediately.
The rise in Na+ permeability is extremely short-lived and is quickly followed by increased K+ permeability; K+ diffuses outward, restoring the resting potential (repolarisation) within a fraction of a second.
Once repolarisation is complete and the resting potential is restored, the fibre once more becomes responsive to further stimulation, explaining the brief period of unresponsiveness followed by recovery.

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Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 7

Applied Concept

With reference to the structure of the cerebral cortex, explain why it is called 'grey matter' and what functional significance this greyish appearance has.

The cerebral cortex is the outer layer of cells covering the cerebral hemisphere; it appears greyish because neuron cell bodies are concentrated there, giving it the characteristic colour.
This concentration of cell bodies is what gives the cortex its grey appearance and also its designation as 'grey matter', in contrast to the underlying white matter formed by myelinated fibre tracts.
The grey matter contains motor areas (for voluntary movement), sensory areas (for processing sensory input), and association areas (for complex functions like memory and communication).
The cortex is thrown into prominent folds (gyri and sulci), which greatly increases its surface area and thus the total number of neuron cell bodies it can accommodate, enabling high cognitive capacity.

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Application Question

Hard difficulty • Concept in a practical situation

Hard

Question 8

Applied Concept

A researcher is studying the effect of a drug that prevents neurotransmitter release from synaptic vesicles. Predict the effect on synaptic transmission and explain your reasoning with reference to chemical synapses.

At chemical synapses, when an action potential arrives at the axon terminal, synaptic vesicles fuse with the pre-synaptic membrane and release neurotransmitters into the synaptic cleft.
If the drug prevents neurotransmitter release, the synaptic vesicles would fail to release their contents into the synaptic cleft despite the arrival of an action potential.
Without neurotransmitters in the synaptic cleft, no binding to post-synaptic receptors can occur, so ion channels on the post-synaptic membrane would not open.
Consequently, no new potential would be generated in the post-synaptic neuron, effectively blocking all synaptic transmission and preventing the propagation of nerve impulses from the pre-synaptic to the post-synaptic neuron.

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Application Question

Hard difficulty • Concept in a practical situation

Hard

Question 9

Applied Concept

A person suffers a stroke affecting the hypothalamus. Based on the functions of the hypothalamus described in the chapter, list the physiological disturbances that are likely to occur.

The hypothalamus contains centres that control body temperature; damage would impair thermoregulation, causing the person to be unable to maintain a stable body temperature (dysregulation of sweating, shivering).
Centres controlling urge for eating and drinking are also located in the hypothalamus, so damage could cause loss of appetite regulation (abnormal hunger or satiety) and disrupted thirst sensation.
The hypothalamus contains neurosecretory cells that secrete hypothalamic hormones; damage would disrupt hormonal control and affect the activities of several endocrine glands.
Since the hypothalamus along with the limbic system regulates sexual behaviour and emotional reactions, the person may also experience disturbances in motivation, emotional responses, and sexual behaviour.

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Application Question

Medium difficulty • Concept in a practical situation

Medium

Question 10

Applied Concept

With reference to the classification of neurons, explain why different types of neurons are suited to their specific locations in the body.

Multipolar neurons, with one axon and two or more dendrites, are found in the cerebral cortex where they receive inputs from many neurons simultaneously, enabling complex integration of signals.
Bipolar neurons, with one axon and one dendrite, are found in the retina of the eye, where a simple two-process structure efficiently transmits visual information from photoreceptors to the visual processing pathway.
Unipolar neurons, with only one axon, are typically found in the embryonic stage, where their simple structure may reflect the early, undifferentiated state of neural development.
This distribution shows that neuronal morphology is adapted to functional requirements: more dendrites allow greater convergence of inputs (multipolar), while simpler structures suffice for relay functions (bipolar) or developmental contexts (unipolar).

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Chapter sections

Chapter 18: Neural Control and Coordination | Application Questions

A sprinter begins a 100-metre race. With reference to neural coordination, explain how the body's organ systems are rapidly adjusted to meet the sudden increase in energy demand.

With reference to the resting potential of a neuron, explain why a nerve fibre is described as being in a 'polarised' state when at rest.

A patient is diagnosed with damage to the medulla oblongata following an accident. Predict the physiological consequences and justify your answer based on the functions of the medulla.

A patient with a lesion in the cerebellum shows poor balance and uncoordinated movements. Relate these symptoms to the normal functions of the cerebellum.

During neuroscience research, a scientist blocks the sodium channels in a neuron's membrane experimentally. With reference to the chapter, what effect will this have on nerve impulse generation?

A student observes that after a stimulus is applied to a nerve fibre, the fibre briefly becomes unresponsive before becoming excitable again. Explain this observation using the concept of repolarisation.

With reference to the structure of the cerebral cortex, explain why it is called 'grey matter' and what functional significance this greyish appearance has.

A researcher is studying the effect of a drug that prevents neurotransmitter release from synaptic vesicles. Predict the effect on synaptic transmission and explain your reasoning with reference to chemical synapses.

A person suffers a stroke affecting the hypothalamus. Based on the functions of the hypothalamus described in the chapter, list the physiological disturbances that are likely to occur.

With reference to the classification of neurons, explain why different types of neurons are suited to their specific locations in the body.

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