Test: Neuron, Types of Neuron & Neuroglia - NEET MCQ

The myelinated nerve fibres are enveloped with Schwann cells, which form a myelin sheath around the axon. The gaps between two adjacent myelin sheaths are called nodes of Ranvier.

Nissl bodies found in the cell body of the neurons are the granules of rough endoplasmic reticulum (RER) with rosettes of free ribosomes.The main function of Nissl bodies within neurons is to aid in the production and dispersal of chemical substances such as proteins and peptides. 

The resting membrane potential of a cell is defined as the electrical potential difference across the plasma membrane when the cell is in a non-excited state. Traditionally, the electrical potential difference across a cell membrane is expressed by its value inside the cell relative to the extracellular environment. It is found in both nerves and muscle cells.

The node of Ranvier is a periodic gap in the insulating sheath on the axon of certain neurons that serves to facilitate the rapid conduction of nerve impulses. These interruptions in the myelin covering were first discovered in 1878 by French histologist and pathologist Louis Antoine Ranvier, who describes the nodes as constrictions. They are present in myelinated nerves.

The sensory (afferent) division carries sensory signals by way of afferent nerve fibers from receptors in the central nervous system (CNS). It can be further subdivided into somatic and visceral divisions. The somatic sensory division carries signals from receptors in the skin, muscles, bones and joints.

Based on the number of axon and dendrites, the neurons are divided into three types, i.e., multipolar (with one axon and two or more dendrites; found in the cerebral cortex), bipolar (with one axon and one dendrite, found in the retina of eye) and unipolar (cell body with one axon only; found usually in the embryonic stage).

• On the outer side of the plasma membrane, there is a positive charge while the inner side carries a negative charge.


• This is due to the distribution of ions such as sodium (Na+) and potassium (K+) across the membrane.


• Na+ concentration is higher outside the cell, while K+ concentration is higher inside the cell.


• These concentration gradients contribute to the establishment of the resting potential.


• Electrically, the resting potential is not neutral but rather exhibits a polarized state with a voltage difference across the membrane.

Therefore, option D is correct as it accurately describes the distribution of charges and ions associated with the resting potential of a cell.

A Nissl body, also known as Nissl or tigroid substance is a large granular body found in neurons. These granules are rough endoplasmic reticulum (RER) with rosettes of free ribosomes and are the sites of protein synthesis.
Hence, the correct answer is Option A.

The neuron is the structural and functional unit of the nervous system. The neuron or the nerve cell has three main parts-the cell body, the axon and the dendrites. Glomerulus is a part of nephron.

• Resting potential is the membrane potential of a neuron when it is not being stimulated.


• It is typically around -70mV in neurons.


• This resting potential is maintained by the sodium-potassium pump that actively transports ions across the neuron membrane.

• Action potential is a brief reversal of the membrane potential that occurs when a neuron is stimulated.


• It is a rapid change in membrane potential that allows for the transmission of signals along the neuron.


• Action potential involves a depolarization phase followed by repolarization and hyperpolarization phases.

• Repolarization is the phase of the action potential where the membrane potential returns to its resting state after depolarization.


• This process involves the closing of voltage-gated sodium channels and opening of voltage-gated potassium channels.


• Repolarization ensures that the neuron is ready to fire another action potential if it receives another stimulus.

• Depolarization is the phase of the action potential where the membrane potential becomes less negative or even positive.


• It is caused by the influx of sodium ions into the neuron through voltage-gated sodium channels.


• Depolarization is essential for the propagation of the action potential along the neuron.

Action potentials are generated by special types of voltage-gated ion channels in a cell's plasma membrane. When the channels open (in response to depolarization in transmembrane voltage), they allow an inward flow of sodium ions, which changes the electrochemical gradient, which in turn produces a further rise in the membrane potential. This then causes more channels to open, producing a greater electric current across the cell membrane. The process proceeds until all of the available ion channels are open, resulting in a large upswing in the membrane potential. The rapid influx of sodium ions causes the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate. As the sodium channels close, sodium ions can no longer enter the neuron, and then they are actively transported back out of the plasma membrane. Potassium channels are then activated, and there is an outward current of potassium ions, returning the electrochemical gradient to the resting state.

Brain cells remain in the beginning stage of interphase of cell reproduction for their life, and never divide, and instead develop by forming new synapses with other neurons. They lack cellular machinery for cell division. So, the correct answer is option A. 

Neurons are the structural and functional unit of the nervous system. Each neuron consists of dendrites, axon, and soma. Dendrites are the small extension of nerve cells that receive 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. A nephron is the anatomical and functional unit of kidney and thus is the part of the excretory system. Thus, the correct answer is option A.

• Activation of Sodium-Potassium Pump: When the sodium-potassium pump is activated, it exchanges sodium ions (Na⁺) for potassium ions (K⁺).


• Number of Ions Exchanged: The pump exchanges three sodium ions for every two potassium ions.


• Specifics: For every cycle of the pump, one ATP molecule is used to pump three sodium ions out of the cell and two potassium ions into the cell.


• Ratio: Therefore, the ratio of sodium ions to potassium ions exchanged is 3:2.

Synapse, also called neuronal junction, the site of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector). A synaptic connection between a neuron and a muscle cell is called a neuromuscular junction

Conduction of nerve impulse is faster in myelinated fibres as myelin is an insulating layer or sheath, that forms around nerves, including those in the brain and spinal cord which protect and insulates the axons thus enhance the transmission of electrical impulses.

• Synaptic Knob: The swollen, structure present at the terminal end of each branch of a nerve cell is called the synaptic knob.

• Neurotransmitter Release: The synaptic knob contains synaptic vesicles filled with neurotransmitters that are released into the synaptic cleft.


• Communication: The synaptic knob is responsible for transmitting signals from one neuron to another at the synapse.

• Signal Transmission: The synaptic knob plays a crucial role in the transmission of nerve impulses across the synapse.


• Neuronal Communication: It facilitates communication between neurons, allowing for the relay of information throughout the nervous system.

• The synaptic knob is a vital component of the nervous system, enabling the transmission of signals between neurons and facilitating neuronal communication.

Both endocrine and nervous system are the integrative system in the body. 
The nervous system has three overlapping functions. These functions are based on the sensory input, integration and motor output. The nervous system is a highly integrated system, the control center of which is the brain.
Endocrine system has organs such as Thyroid, Pituitary glands that secrete hormones which regulate body functions. Hence, option D is correct.

• Axon: Axons transmit nerve impulses away from the cell body (cyton) towards other neurons or effector cells.


• Dendrite: Dendrites generally transmit nerve impulses from other neurons towards the cell body (cyton).


• Node of Ranvier: Nodes of Ranvier are small gaps in the myelin sheath of axons where action potentials are regenerated. They do not transmit nerve impulses to the cyton.


• Synaptic knob: Synaptic knobs are located at the end of axons and are responsible for transmitting signals to the next neuron at the synapse. They do not transmit nerve impulses to the cyton.

In the context of transmitting nerve impulses to the cyton, dendrites are the structures that play a crucial role. Dendrites are specialized extensions of the neuron that receive signals from other neurons and transmit these signals towards the cell body (cyton). This process is essential for integrating incoming signals and determining whether the neuron will generate an action potential.

While axons, nodes of Ranvier, and synaptic knobs are important components of the nervous system and play key roles in transmitting nerve impulses, they do not primarily transmit signals to the cyton. Axons carry impulses away from the cyton, nodes of Ranvier regenerate action potentials along the axon, and synaptic knobs transmit signals to the next neuron at the synapse.

An axon is also known as a nerve fiber. It is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body. The function of the axon is to transmit information to different neurons, muscles and glands.

Dendrites are a part of the nerve cell or the neuron. They are short fibers that project out from the cell body, but not the axon. They branch repeatedly and help in the transmission of impulses.

The body's various functions and processes are controlled by nervous system and endocrine system. But the nervous system plays a primary role in regulating the activities of organs of bodies and to act on the stimulus from outside also. The coordination of different parts of central nervous system and peripheral nervous system together regulate all voluntary as well as involuntary functions.

Neurotransmitters are the chemicals which help in the transmission of impulses from neuron to neuron and from to neuron the target tissue or cell. They are stored in the synaptic vesicles.

Axons are long fibers while dendrites are short fibers. Axons carry or transmit nerve impulses away from the cell body towards synapses. Their terminal ends are branched and end with synaptic knobs.

Neurons or nerve cells are classified into three types based on the number of axon and dendrites. The three types of neurons are namely, multipolar neurons, unipolar neurons and bipolar neurons.

The outer membrane has positive charge and inner membrane is negative. This is how the membranes of axon generally is. That is why the condition is known as resting potential. On stimulation by impulses, the membrane permeability changes resulting in negative outside and positive inside, that's action potential. 
Hence, the correct answer is Option B.

Correct answer is Nissl’s granules.
Non-myelinated neurons lack myelinated axons. Hence, myelin forming Schwan cells, which surround and form myelin, are absent. Nodes of Ranvier are also absent as they are the points between two adjacent myelin sheaths.