What went wrong when the king rode under the arch?

It was too low and knocked off his crown

How does the chain of blame unfold in the poem?

Each accused person blames another, ending with the king's own changes

How is the human neural system divided?

It is divided into the central neural system (brain and spinal cord) and the peripheral neural system (afferent and efferent fibres, with somatic and autonomic divisions).

What are the three major parts of a neuron?

The cell body, the dendrites and the axon.

Why is the neuron membrane said to be polarised?

Because the sodium-potassium pump and selective ion permeability keep the outer surface positive and the inner surface negative, creating a resting potential.

Explain depolarisation of a nerve fibre.

When a stimulus makes the membrane permeable to sodium, sodium rushes in and reverses the polarity, making the outer surface negative and the inner surface positive, generating an action potential.

What is an action potential or nerve impulse?

It is the electrical potential difference produced across the membrane at a stimulated site due to the reversal of polarity, which travels along the axon.

How is a nerve impulse transmitted across a chemical synapse?

The arriving impulse causes synaptic vesicles to release neurotransmitters into the synaptic cleft, which bind to receptors on the post-synaptic membrane and open ion channels to generate a new potential.

Differentiate between electrical and chemical synapses.

At electrical synapses current flows directly between closely placed neurons and transmission is faster, while at chemical synapses neurotransmitters carry the signal across a synaptic cleft.

Name the three major parts of the brain.

The forebrain, the midbrain and the hindbrain.

What does the hypothalamus control?

It controls body temperature, the urge for eating and drinking, and secretes hypothalamic hormones; with the limbic system it regulates sexual behaviour and emotions.

What are the parts and functions of the hindbrain?

The hindbrain has the pons (interconnecting fibre tracts), the cerebellum (coordination and balance) and the medulla oblongata (controls respiration, cardiovascular reflexes and gastric secretions).

Neural Control and Coordination

Class 11 Biology · Biology · Chapter 18

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CBSE Class 11 · Biology

19 chapters: every table, cycle and pathway

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CBSE Class 11 · Biology

19 chapters: every table, cycle and pathway

Marks booster + cheatsheet: key concepts in 2 lines each, common traps
18 marks: Unit V, breathing to hormones
15 marks each: Units I and III
Common traps, corrected
Five kingdoms classification table
Physiological numbers, with page numbers

Page 1 free about 8 min read, Full kit about 55 min read

₹159See the full kit

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Summary

This chapter explains how the neural system coordinates and integrates the activities of the body. Coordination is the process by which organs work together, achieved jointly by the neural system, which gives rapid point-to-point control, and the endocrine system, which gives chemical integration through hormones. The human neural system is divided into the central neural system (brain and spinal cord) and the peripheral neural system, whose afferent fibres carry impulses to the central system and efferent fibres carry them away; the peripheral system includes the somatic and autonomic (sympathetic and parasympathetic) divisions. The neuron, the structural and functional unit, has a cell body, dendrites and an axon, which may be myelinated or non-myelinated. Neurons are excitable because their membranes are polarised, maintained by the sodium-potassium pump giving a resting potential; a stimulus causes sodium influx and depolarisation, generating an action potential or nerve impulse that travels along the axon. Impulses pass between neurons at synapses, mostly chemical synapses using neurotransmitters released across the synaptic cleft. The brain, protected by the skull and meninges, has three parts: the forebrain (cerebrum, thalamus, hypothalamus and limbic system), the midbrain, and the hindbrain (pons, cerebellum and medulla oblongata), each controlling specific functions of the body.

Neural system and its divisionsNeuron as the structural and functional unitGeneration and conduction of nerve impulseTransmission of impulses across synapsesCentral neural system and the brainForebrain, midbrain and hindbrain functions

Key terms

Neuron

The structural and functional unit of the neural system, composed of a cell body, dendrites and an axon.

Resting potential

The electrical potential difference across the polarised membrane of a resting neuron.

Action potential

The reversal of membrane polarity at a stimulated site, constituting the nerve impulse.

Synapse

The junction between two neurons across which an impulse is transmitted, usually by neurotransmitters.

Neurotransmitter

A chemical such as acetylcholine released at a chemical synapse to transmit an impulse to the next neuron.

Cerebrum

The major part of the forebrain, divided into two hemispheres connected by the corpus callosum.

Extra questions & answers

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The structural and functional unit of the neural system is the:

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