Nervous System MCQ Quiz in मल्याळम - Objective Question with Answer for Nervous System - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

The correct answer is 25 cm. Key Points

• 25 cm is the average minimum distance of distinct vision for a young adult person with no defect in eyes.
• The minimum distance of distinct vision is the closest distance at which a person can see an object clearly.
• The distance varies for each individual and can change with age or eye defects.

Additional Information

• The nearest object that a person with "normal" vision (20/20 vision) can comfortably stare at is known as the least distance of distinct vision (LDDV) or reference seeing distance (RSD) in optometry.
• Stated differently, LDDV is the smallest reasonable distance that may be found between a visible item and the unaided eye.
• When viewed with the human eye, a lens's magnifying power (M) with a focal length (f in millimeters) can be computed as follows:
  • M = 250/f

Concept:

• The brain is a complex and vital organ in an animal's body that controls several activities.
• Memory, motor skills, breathing, vision, hunger, libido, etc. are some of the various processes in an animal's body that are regulated by the brain.
• The brain along with the spinal cord forms the Central Nervous System.
• A brain is made up of fats, carbohydrates, water, protein and salts.
• It comprises blood vessels and nerves.
• The brain carries out several functions of the body by sending and receiving chemical and electrical signals throughout the body.
• The brain is divided into three parts:
  • Forebrain (Prosencephalon)
  • Midbrain (Mesencephalon)
  • Hindbrain (Rhombencephalon)

Explanation:

• Option 1: Medulla oblongata - INCORRECT​
  • The medulla oblongata is located in the hindbrain. 
  • It is located at a point where the brain and spinal cord connect.
  • Functions:
  1. Controls heartbeats
  2. Controls breathing as well as blood pressure
  3. Produces reflective actions such as sneezing, coughing, vomiting, etc.
• Option 2: Midbrain - INCORRECT
  • ​Midbrain comprises two parts - Tectum and Tegmentum.
  • Midbrain consists of neuron clusters that facilitate various functions.
  • Functions:
  1. Facilitates visual reflexes
  2. Hearing
  3. Determines movements concerning responses and changes in the environment.
• Option 3: Cerebrum - INCORRECT
  • Cerebrum is the largest part of the brain.
  • It is part of the forebrain that is further divided into Frontal lobe, Parietal lobe, Occipital lobe and Temporal lobe.
  • Functions:
  1. Regulates temperature
  2. Enables speech
  3. Involved in thinking, reasoning and problem-solving
  4. Co-ordinates movements
  5. Controls emotions and learning, etc.
• Option 4: Cerebellum - CORRECT
  • The cerebellum is also known as the little brain.
  • The cerebellum is located in the hindbrain above the brainstem.  
  • Functions:
  1. Controls voluntary muscular movement like walking, posture, etc.
  2. Responsible for the maintenance of posture, balance and equilibrium.

So the correct answer is option 4 (Cerebellum).

Concept:

• Neurons are elongated nerve cells that conduct nerve impulses in the body.
• The human CNS comprises several billion neurons that control the movement of muscles and conducts the information from the sense organs to the CNS.
• Each neuron is made up of a cyton, axon and dendrites.
• Dendrites may be one to many but there is always one axon in a neuron.
• Impulses are transferred from the axon of one neuron to the dendrites of another neuron at the synapse. ​

Explanation:

• Option 1: more permeable to K+ - CORRECT
  • When a neuron is not conducting an impulse it is in resting potential (polarization).
  • In a resting state, there are more potassium ions (K⁺) in the intracellular fluid of the neuron.
  • Whereas, sodium ions (Na⁺) predominate the extracellular fluid.
  • Sodium ions are 10 times more outside the neuron and potassium ions are 25 times more inside the neuron.
  • This creates a potential difference across the membrane. This is known as resting potential.
  • The resting membrane (axonal membrane) of the neuron is more permeable to potassium than to sodium ions.
  • As a result, potassium ions leave the nerve fiber faster than sodium ions enter it.
• Option 2: more permeable to Na+ - INCORRECT
  • At resting potential, nerve fibers are more permeable to potassium ions than to sodium ions.
  • However, on being stimulated by an impulse, the nerve fiber gets depolarized.
  • A local excitatory state is observed at the site of stimulation.
  • At this point, the membrane becomes more permeable to sodium ions than to potassium ions.
  • As a result, more sodium ions enter the nerve fiber than potassium ions leave it.
  • This creates a potential difference across the membrane called an action potential.
• Option 3: more permeable to Ca++ - INCORRECT
  • ​At resting potential, nerve fibers are more permeable to potassium ions.
  • Calcium ions play an important role in the conduction of an impulse at the synapse.
  • On the arrival of an impulse at the presynaptic knob, calcium ions that are present in the synaptic cleft enter the cytoplasm of the presynaptic knob.
  • The calcium ions cause the movement of the synaptic vesicles to the surface of the knob.
  • The synaptic vesicles then fuse with the presynaptic membrane and rupture. 
  • The neurotransmitters present inside the vesicles are thus released in the synaptic cleft.
• Option 4: impermeable to ions in general - INCORRECT
  • ​At resting, potential nerve fibers are permeable to selective ions.
  • The axon membrane of the nerve fiber is more permeable to potassium ions that are present in the extracellular fluid of the fiber.

So the correct answer is option 1 (More permeable to K+).

The correct answer is No option is correct.

• At synapses of the Neuron, the information is transmitted in the chemical form, called as Neurotransmitter.

Key Points

• Synapse:
  • It is the junction between 2 neurons.
  • There is a very narrow gap of about 20nm between neurons called the synaptic cleft.
  • An action potential cannot cross the synaptic cleft, so nerve impulses are carried by chemicals called neurotransmitters.
• The structure of a synapse:
  • At the synapse, the presynaptic neuron communicates with the postsynaptic neuron.
  • At the end of the presynaptic neuron, there are synaptic knobs.
  • Synaptic knobs contain many mitochondria and large amounts of ER to manufacture neurotransmitters.
  • There is a tiny gap known as the synaptic cleft
• Functions of a synapse:
  • A single impulse is transmitted to a number of different neurons creating simultaneous responses.
  • A number of impulses are combined at a synapse allowing stimuli from different receptors to interact for a single response. 

The correct answer is Optic nerve

Explanation-

• The optic nerve is responsible for transmitting visual information from the retina of the eye to the brain.
• It consists of axons of retinal ganglion cells, which gather visual information from the photoreceptor cells (rods and cones) in the retina.
• Once these ganglion cell axons converge at the optic disc (also known as the blind spot), they form the optic nerve.
• The optic nerve carries the visual signals to the brain's visual centers, primarily to the thalamus and then to the visual cortex in the occipital lobe, where visual processing occurs.
• Cornea,Bipolar cell, and Rod and cone cell are all components of the visual system, but they are not directly responsible for transmitting nerve impulses from the eye to the brain.
• The optic nerve serves this crucial function in visual information transmission.

Conclusion-Nerve impulses are carried from the eye to the brain by the Optic nerve.

The correct answer is Multipolar neuron

Explanation-

• Multipolar neurons are a type of nerve cell characterized by having multiple dendrites and a single axon extending from the cell body.
• These neurons are the most common type found in the central nervous system.
• Multipolar neurons have a single axon and multiple dendrites arising from the cell body (soma).
• The dendrites receive incoming signals from other neurons or sensory receptors, while the axon conducts nerve impulses away from the cell body to other neurons or effector cells.
• The axon may have numerous branches (axon collaterals) along its length, allowing for communication with multiple target cells.
• Multipolar neurons are found throughout the central nervous system, including the brain and spinal cord, where they play various roles in sensory processing, motor control, and interneuronal communication.

Unipolar neurons  have a single process that divides into two branches, functioning as both an axon and a dendrite, and are typically found in sensory ganglia.

Bipolar neurons are a type of nerve cell characterized by having two processes (one dendrite and one axon) extending from the cell body.

Conclusion-A neuron with many short dendrites and a single long axon is a Multipolar neurons. 

The correct answer is A-III, B-IV, C-II, D-I

Explanation:

A. Pons - III. Connects different regions of the brain

• The pons is part of the brainstem and acts as a bridge between various parts of the nervous system, including the cerebellum and cerebrum. It helps relay messages from the cortex and the cerebellum. Pons consists of fibre tracts that interconnect different regions of the brain.

B. Hypothalamus - IV. Neuro secretory cells

• Hypothalamus lies at the base of the thalamus. The hypothalamus contains a number of centres which control body temperature, urge for eating and drinking. It also contains several groups of neurosecretory cells, which secrete hormones called hypothalamic hormones.

C. Medulla - II. Controls respiration and gastric secretions

• The medulla of the brain is connected to the spinal cord. The medulla contains centres which control respiration, cardiovascular reflexes and gastric secretions.
• Three major regions make up the brain stem: mid-brain, pons and medulla oblongata.
• Brain stem forms the connections between the brain and spinal cord.

D. Cerebellum - I. Provides additional space for neurons, regulates posture and balance

• The cerebellum plays a crucial role in motor control. It does not initiate movement but contributes to coordination, precision, and accurate timing. It also regulates posture and balance. Cerebellum has very convoluted surface in order to provide the additional space for many more neurons.

Concept:

• Visceral organs are the internal organs of the abdominal, thoracic, and pelvic cavities.
• The internal organs are controlled by the visceral nervous system (VNS).
• This nervous system is also known as the autonomic nervous system.
• The autonomic nervous system controls involuntary functions but it can work with the somatic nervous system to provide voluntary control.

Explanation:

Sympathetic and Parasympathetic neural system - 

• The autonomic nervous system is divided into:
  • Sympathetic nervous system - “fight or flight" system
  • Parasympathetic nervous system - "rest and digest" or "feed and breed" system
  • Enteric nervous system
• The function of our visceral organs is controlled by the sympathetic and para-sympathetic neural systems.

So, the correct option is Option 2.

The correct answer is option 2.

Key Points

• The stereotyped sequence of depolarization and consequent repolarization of the membrane is called action potential.
• This happens when a stimulus have the potential to depolarize the membrane beyond its threshold potential.
• Cells that are capable of triggering an action potential are called excitable cells.
• Excitability is a property of muscle and nerve cells.
• The action potential has the following events: 
  • Resting potential of -70mV.
  • Depolarization of the membrane by the influx of sodium ions. 
  • An overshoot phase caused by exceeding the threshold potential. 
  • Repolarization caused by the efflux of K⁺.
  • Hyperpolarization is the further decrease in the membrane potential. It inhibits action potentials by increasing the stimulus required to move the membrane potential to the action potential threshold.
• The action potential follows an all-or-none principle.
• The action potential has a constant amplitude that is independent of the intensity of the stimulus.
• The only determining factor that ascertains the occurrence of an action potential is the stimulus potential.
• For an action potential to occur, the stimulus potential must exceed the threshold potential.

Explanation:

• Once the stimulus potential is greater than the threshold potential, depolarization occurs.
• As a result of depolarization beyond the threshold, the membrane conductance for sodium ions increases.
• Sodium influx occurs, leading to the membrane potential becoming +40mV.
• This change leads to the efflux of potassium ions (K⁺) due to the osmotic boost causing restoration of the original membrane potential and repolarizing it.  

The correct answer is Sympathetic nerves and epinephrine

Explanation:

• The autonomic nervous system (ANS) regulates involuntary physiological functions, including heart rate, blood pressure, respiration, and digestion.
• It comprises two main components: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS).
• The SNS is responsible for the "fight or flight" response, which prepares the body to respond to perceived threats by increasing heart rate, dilating airways, and releasing energy stores.
• Epinephrine (also known as adrenaline) is a hormone and neurotransmitter released by the adrenal glands during the activation of the sympathetic nervous system. It plays a critical role in accelerating heart rate and increasing cardiac output.

Other Options:

• Cranial nerves and acetylcholine - This is incorrect. Cranial nerves are part of the parasympathetic nervous system, which typically slows down the heart rate. Acetylcholine is the neurotransmitter associated with the parasympathetic nervous system and generally promotes relaxation and a decrease in heart rate.
• Adrenaline (epinephrine) can accelerate heart rate, cranial nerves are primarily associated with the parasympathetic system, which does not use adrenaline to regulate the heart rate.