Biology

Nervous System and Neurons

1,164 Questions

The nervous system and neurons section covers the structural and functional aspects of the human nervous system. Topics include nerve fibers, the myelin sheath, and sympathetic nervous system functions. This material is crucial for general science preparation in various competitive exams.

Neuron structureMyelin sheath productionSympathetic nervous systemCranial and spinal nervesParasympathetic functions

Nervous System and Neurons Questions

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

Axon is characterised by

  1. Transformation of energy

  2. Receiving the impulse

  3. Providing energy for impulse

  4. Conduction of impulse
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Axon is the long slender part of the neuron. It conducts nerve impulse from the dendron towards the synapse. So, option D is the correct answer.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

The gap between two neuron is _____

  1. 2-20 nm

  2. 25-30nm

  3. 150-200nm

  4. 50-60nm
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The gap between 2 neurons is called synapse. This signal between two neuron is passes when this synapse is filled with neurotransmitter. The size of the synapse ranges from 2-20 nm.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

Which one of the following is a correct match?

  1. Nerve impulses - Transmitted from axon towards dendron

  2. Synaptic knob - Dendron

  3. Neuron - Endocrine system

  4. Nerve - Excretory system
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The nerve impulses are generated at the sensory receptor and are carried towards the CNS through the sensory neuron. The The nerve impulse is transmitted through the axon of one neuron to the dendrite of the other neuron. At the axonic end, there are telodendrons which release the neurotransmitters which flow through the synapse to the dendrite of the other neuron. 

Thus, the correct answer is option A. 

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

A spinal nerve takes nerve impulses:

  1. to the CNS

  2. away from the CNS

  3. both to and away from the CNS

  4. only inside the CNS
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body.  We have 31 pairs of spinal nerves and they are named after the section of the spine they come out of.

8 pairs of cervical nerves (C1-C8)
12 pairs of thoracic nerves (T1 – T12)
5 pairs of lumbar nerves (L1-L5)
5 pairs of sacral nerves (S1-S5)
1 pair of coccygeal nerves (Co1)

So, the correct answer is 'both to and away from the CNS'.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

The nervous system uses .............. to transmit messages.

  1. Chemical impulses

  2. Electrical impulses

  3. Mechanical impulses

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The nervous system uses electrical impulses to transmit messages. Neurons conduct electrical impulses by generating the action potential. Action potential is generated through the flow of positively charged ions across the neuronal membrane.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

An axon terminal passes the electrical stimulus to a dendrite of next neuron through .............. reaction.

  1. Chemical

  2. Electrical

  3. Mechanical

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A nerve impulse travels in a form of electrical charge from a neuronal axon end to the synapse. Here, the electrical impulse is converted to the chemical impulse in the synaptic cleft. Further, this nerve impulse flows from synaptic cleft to dendritic tips, converting the chemical impulse to electrical impulse. The neurotransmitters required is synthesised only by axon terminals and the receptors required to detect these chemical transmitters are only present on the dendritic ends. Thus, the impulse always flows from one axonal end of a neuron to another dendron head of a neuron. 

So, the correct answer is option A.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

A nerve impulse leaves a neuron via the

  1. Dendrites

  2. Cyton

  3. Axon

  4. Nucleus
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Dendrites are the small extension of nerve cells that receives signals from sensory receptors or other neurons.

The long extension of the cell body of the nerve cell is called as axon that serves to conduct the nerve impulse away from the cell body. 
Cyton /soma is the metabolic center of the nerve cell where the metabolic contents are manufactured. It is not involved in nerve impulse conduction. The nucleus is present in the soma. 
Therefore, the correct answer is option C.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

There are certain special nerves which are insulated by myelin sheaths around them. The nerve impulse travels very fast along these nerves because it "leaps" along certain special points on these nerves. What is this special mode of conduction known as?

  1. Superconduction

  2. Saltatory conduction

  3. Ultrasonic conduction

  4. Hyperconduction
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Saltatory conduction is the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.

So, the correct option is 'Saltatory conduction'.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

When the direction of nerve impulse is reversed, the condition is

  1. Axo - Axonic synapse

  2. Axo - Dendritic synapse

  3. Both of the above

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

There are different forms of synapse depending on the position of the synapse. When the synapse occurs in the axon, the synapse is known as the axoaxonic synapse. The nerve impulse conduction takes place from one axon to the other axon. The nerve impulse is transferred from the axon of one neuron to the axon of the other neuron. In this process, the direction of nerve impulse is reversed from axon to dendron to the axon to axon. 

Thus,l the correct answer is option A. 

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

Which of the following statements about the transmission of the nerve impulse is correct? 
(a) A nerve impulse travels from the dendritic end towards the axonal end.
(b) At the dendritic end, electrical impulses bring about the release of some chemicals which generate an electrical impulse at the axonal end of another neuron.
(c) The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in a dendrite of another neuron.
(d) A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells.

  1. (a) and (c)

  2. (b) and (d)

  3. (a), (c) and (d)

  4. (b), (c) and (d)
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A nerve impulse is a way nerve cells (neurons) communicate with one another. Nerve impulses are mostly electrical signals along the dendrites to produce a nerve impulse or action potential. The action potential is the result of ions moving in and out of the cell.
A nerve impulse travels from the dendritic end towards the axonal end. The chemicals released from the axonal end of one neuron cross the synapse and generate a similar electrical impulse in a dendrite of another neuron. A neuron transmits electrical impulses not only to another neuron but also to muscle and gland cells.

Therefore, the correct answer is option C.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

The rate at which a nerve impulse travels along a nerve fiber is dependent up on 

  1. Length of the nerve fibre

  2. Diameter of the nerve fibre

  3. Presence of connective tissue sheath

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Increased axon diameter in axons leads to increase action potential velocity. As there is an increase in diameter of a fibre, its internal resistance decreases. The internal resistance decreases faster relative to the membrane resistance - therefore the distance the membrane potential can travel is increased by an increased diameter. So, the correct answer is option B.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

If myelin sheath is continued in myelinated nerve fibre then what will happen in a neuronal conduction?

  1. Velocity will be increased.

  2. Conduction will be slow.

  3. Conduction will be stopped.

  4. No effect is seen.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Myelin is an insulating layer or sheath, that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty substances. The purpose of the myelin sheath is to allow electrical impulses to transmit quickly and efficiently along the nerve cells. Nerve impulses cannot pass through the myelination, so they jump from one node of Ranvier to the next. If the whole nerve becomes myelinated then the conduction will be stopped.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control
The speed of nerve impulse depends on the diameter of the axon.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The speed with which the nerve impulse is conducted by axon is known as nerve conduction velocity. The speed of nerve conduction does not depend on the diameter of axon only rather it depends on the diameter of the nerve fibre. The diameter of nerve fibre is axon, neurilemma, and myelin sheath in myelinated axons while axon and neurilemma in unmyelinated fibre. Conduction velocity is high in myelinated nerve fibre with the greater diameter. So, the given statement is false.

Multiple choice biology control and co-ordination in plants and animals voluntary and involuntary movements impulse and its transmission coordination in human beings- nervous control

The propagation of a nerve impulse is due to changes in the permeability of the nerve cell membrane that allow for a voltage difference across the membrane.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Neurons send messages through electrical impulses called as nerve impulses. The nerve impulse is due to the changes occurring across the cell membrane. Cell membranes contain a sodium-potassium pump. The concentration of sodium and potassium ions is different across the membrane. This difference causes a voltage difference between the inside of the neuron and its surroundings. This is called as the resting membrane potential. The membrane potential is always negative inside the cell. The sodium and potassium channels in the cells are voltage-gated, meaning they can open and close depending on the voltage across the membrane. During action potential, permeability of the nerve cell membrane changes for both sodium and potassium ions. During depolarization, there is influx of sodium ions which makes inside of the cell positive. Depolarization is followed by repolarization during which the outflux of potassium ions takes place which makes inside of the cell negative. The whole process results in the propagation of a nerve impulse.

Thus, the correct answer is option A.