Biology

Nervous System and Neurons

1,224 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

The stimulus required to open enough Na+ channels to initiate depolarization is called _____.

  1. quick stimulus

  2. threshold stimulus

  3. membrane stimulus

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

The minimum stimulus required to open enough voltage-gated Na+ channels to initiate depolarization is called the threshold stimulus (or threshold potential). This critical value must be reached for the all-or-nothing action potential to be triggered.

Multiple choice

Multipolar nerve cells are present in

  1. pyramidal cells in cerebral cortex

  2. retina of the eye

  3. dorsal root ganglion

  4. All of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Multipolar neurons have one axon and two or more dendrites (i.e. more than two processes arise from cell body, hence multipolar). Cells of retina have bipolar neurons with one axon and one dendtrite (i.e. 2 processes in total, hence bipolar). Unipolar neurons have only an axon attached to the cell body and are usually found in the embryonic stage.

Multiple choice

Which of the following is/are spike?

  1. Nerves

  2. Axons

  3. Dendrites

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

A spike refers to the nerve impulse or action potential itself - the rapid, transient change in membrane potential that propagates along a neuron. While nerves, axons, and dendrites are anatomical structures, the spike is the electrical signal that travels through them.

Multiple choice

When interior of the cell is more negatively charged, the neuron is said to be

  1. at work

  2. at rest

  3. at charge

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

A neuron at resting membrane potential has a negatively charged interior relative to the exterior. This resting potential is typically around -70mV and is maintained by ion concentration gradients and selective membrane permeability. The neuron is not actively firing (at work) during this state.

Multiple choice

Goose pimples are innervated by

  1. cranial nerves

  2. spinal nerves

  3. sympathetic nervous system

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

Goose pimples (piloerection) are caused by contraction of arrector pili muscles, which are innervated by the sympathetic nervous system. This is an involuntary response to cold or emotional stimuli. Cranial nerves primarily innervate head and neck structures, while spinal nerves innervate body regions - but the specific autonomic control is sympathetic.

Multiple choice

Which part of the body receives messages transmitted by nerve cells located throughout the body?

  1. Lungs

  2. Heart

  3. Brain

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

The brain is the central processing unit of the nervous system and receives all messages transmitted by nerve cells throughout the body. Neurons carry electrical signals from sensory receptors and other body parts to the brain for processing and response generation. The lungs, heart, and liver perform vital functions but do not serve as the central message-receiving center.

Multiple choice

Match the following:

 
a. Sensory neurons 1. They serve as a link between other neurons.
b. Motor neurons 2. They transmit impulses from the central nervous system, i.e. spinal cord and brain towards effectors.
c. Relay neurons 3. They transmit impulses from receptors towards central nervous system, i.e. spinal cord and brain.

  1. a - 3, b - 2, c - 1

  2. a - 3, b - 1, c - 2

  3. a - 1, b - 3, c - 2

  4. a - 2, b - 3, c - 1

  5. a - 1, b - 2, c - 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is the correct option. 

Multiple choice

Match the following:

 
a. The cranial nerves 1. They mostly connect the internal organs of the body to spinal cord, though some also connect to brain.
b. The spinal nerves 2. They connect parts of the body like muscles, skin etc. to the spinal cord.
c. The visceral nerves 3. They connect all the parts in the head directly to the brain.

  1. a - 3, b - 2, c - 1

  2. a - 3, b - 1, c - 2

  3. a - 2, b - 3, c - 1

  4. a - 1, b - 3, c - 2

  5. a - 1, b - 2, c - 3
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is the correct option. The cranial nerves connect all the parts in the head directly to the brain. The spinal nerves connect parts of the body like muscles, skin etc. to the spinal cord. The visceral nerves mostly connect the internal organs of the body to spinal cord, though some also connect to brain.

Multiple choice

Match the following:

 
a. Sensory neurons 1. They transmit impulses from the receptors towards the central nervous system i.e. towards the spinal cord and the brain.
b. Motor neurons 2. They occur in the central nervous system i.e. the brain and the spinal cord, where they serve as a link between other neurons.
c. Relay neurons 3. They transmit impulses from the central nervous system i.e. the spinal cord and the brain, towards the muscle cells.

  1. a - 1, b - 2, c - 3

  2. a - 2, b - 1, c - 3

  3. a - 3, b - 1, c - 2

  4. a - 2, b - 3, c - 1

  5. a - 1, b - 3, c - 2
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct option. Sensory neurons transmit impulses from the receptors towards the central nervous system, i.e. towards the spinal cord and the brain. Motor neurons transmit impulses from the central nervous system, i.e. the spinal cord and the brain, towards the muscle cells. Relay neurons occur in the central nervous system, i.e. the brain and the spinal cord, where they serve as a link between other neurons.