Human Neural System Questions in English

(D) In the $Peripheral \ Nervous \ System$ $(PNS)$,bundles of axons are enclosed in connective tissue sheaths to form structures known as nerves.
In the $Central \ Nervous \ System$ $(CNS)$,bundles of axons are referred to as tracts,not nerves.
Therefore,axons form nerves specifically within the $PNS$.

(A) The human brain and the entire nervous system develop from the $Ectoderm$,which is the outermost germ layer of the developing embryo. During neurulation,the ectoderm folds to form the neural tube,which eventually differentiates into the brain and spinal cord.

(B) The stimulation of the parasympathetic nervous system is responsible for the 'rest and digest' response.
$1.$ It increases gastro-intestinal $(GI)$ secretions,such as salivary,gastric,and pancreatic juices.
$2.$ It increases $GI$ motility,which includes processes like peristalsis to move food through the digestive tract.
Therefore,the correct option is $B$.

(A) The nervous system,including the brain and spinal cord,is derived from the ectoderm. During embryonic development,the neural plate forms from the ectoderm,which then folds to form the neural tube,eventually giving rise to the central nervous system.

(A) The $Sympathetic$ nervous system is responsible for the 'fight-or-flight' response,which increases the body's defense mechanisms against adverse conditions.
It is activated during stress conditions,such as pain,fear,and anger.

(D) The autonomic nervous system $(ANS)$ regulates and coordinates involuntary activities such as heart beating,homeostasis,body temperature,breathing,gut peristalsis,and the secretion of glands. It primarily controls the smooth muscles and glands of the internal organs.

(A) The parasympathetic nervous system is responsible for the 'rest and digest' activities of the body.
It stimulates the activity of the digestive tract,including increasing the peristaltic movements and mobility of the small intestine to facilitate digestion and absorption.
In contrast,it decreases the heart rate,unlike the sympathetic nervous system which increases it.

(A) The human neural system is divided into the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
The $PNS$ is further divided into the Somatic Neural System and the Autonomic Neural System $(ANS)$.
The $ANS$ transmits impulses from the $CNS$ to the involuntary organs and smooth muscles of the body.
The $ANS$ is classified into the Sympathetic and Parasympathetic neural systems.
These systems regulate the activities of visceral organs,which are not under the conscious control of the individual,meaning they are under involuntary action.

(B) The correct answer is $(b)$.
In mammals, including rabbits and humans, there are $12$ pairs of cranial nerves.
These nerves are: $I$ (Olfactory), $II$ (Optic), $III$ (Oculomotor), $IV$ (Trochlear), $V$ (Trigeminal), $VI$ (Abducens), $VII$ (Facial), $VIII$ (Vestibulocochlear/Auditory), $IX$ (Glossopharyngeal), $X$ (Vagus), $XI$ (Spinal accessory), and $XII$ (Hypoglossal).

(B) The nerves that carry impulses from the receptor organs to the $CNS$ (Central Nervous System) are known as afferent or sensory nerves. These nerves consist exclusively of sensory nerve fibers that transmit sensory information toward the brain and spinal cord.

(C) The $Autonomic$ $nervous$ $system$ $(ANS)$ is the part of the peripheral nervous system that controls visceral functions, which occur below the level of consciousness. It is often referred to as the self-governing or involuntary nervous system because it regulates internal organs such as the heart, digestive system, and respiratory tract without conscious effort.

(A) The autonomic nervous system $(ANS)$ is a part of the peripheral nervous system that controls involuntary bodily functions. It consists of a network of nerves and ganglia,including the sympathetic and parasympathetic divisions. The sympathetic nervous system is characterized by a pair of sympathetic chain ganglia located along the spinal cord. Therefore,the presence of paired chain ganglia is a key feature of the autonomic nervous system.

(A) The $VI$ cranial nerve is the Abducens nerve.
It is a motor nerve that supplies the external rectus muscle of the eye,which is responsible for the lateral movement of the eyeball.

(C) In mammals,there are $12$ pairs of cranial nerves. Among these,the purely sensory nerves are the olfactory $(I)$,optic $(II)$,and vestibulocochlear/auditory $(VIII)$ nerves. Therefore,there are $3$ pairs of purely sensory cranial nerves.

(C) The $Autonomic \text{ } Nervous \text{ } System$ $(ANS)$ is a part of the peripheral nervous system that controls visceral functions which occur automatically without conscious effort.
These functions include the contraction of involuntary (smooth) muscles, the secretion of digestive glands, and the regulation of the heart rate.
The $ANS$ is further divided into the sympathetic and parasympathetic nervous systems, which work antagonistically to maintain homeostasis.

(D) The human neural system consists of the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
Afferent nerve fibres transmit impulses from tissues/organs to the $CNS$.
Efferent nerve fibres transmit regulatory impulses from the $CNS$ to the concerned peripheral tissues/organs.
Therefore,nerve impulses are brought to the $CNS$ by afferent fibres and carried away from the $CNS$ by efferent fibres.

(B) The peripheral nervous system is divided into two types of nerve fibres: afferent and efferent.
Afferent nerve fibres transmit impulses from tissues or organs (receptors) to the central nervous system $(CNS)$.
Efferent nerve fibres transmit regulatory impulses from the central nervous system to the concerned peripheral tissues or organs (effectors).
Therefore,the correct option is $B$.

(A) Motor nerves consist of efferent nerve fibers.
These fibers are responsible for conducting nerve impulses from the $CNS$ (Central Nervous System) to the peripheral tissues or organs known as effectors (such as muscles or glands).
Therefore,the correct pathway is $CNS$ to effectors.

(B) The parasympathetic nervous system is responsible for 'rest and digest' activities.
$1$. It promotes the constriction of the pupil (miosis).
$2$. It decreases the heart rate,whereas the sympathetic nervous system increases it.
$3$. Stimulation of sweat glands and contraction of arrector pili muscles are functions of the sympathetic nervous system.
Therefore,the correct function of the parasympathetic nervous system among the given options is the constriction of the pupil.

(A) The human brain is derived from the ectoderm,which is the outermost germ layer formed during embryonic development. The neural tube,which eventually develops into the central nervous system (including the brain and spinal cord),originates from the ectodermal tissue.

(B) Histiocytes are generally defined as tissue macrophages. In the central nervous system,the specialized macrophages that perform phagocytosis and immune surveillance are known as microglial cells. These cells are derived from the yolk sac during embryonic development and act as the resident immune cells of the brain.

(B) The human neural system is divided into two parts: the $CNS$ (Central Nervous System) and the $PNS$ (Peripheral Nervous System).
The $CNS$ includes the brain and the spinal cord.
The $PNS$ comprises all the nerves of the body associated with the $CNS$ (cranial nerves and spinal nerves).
Therefore,the cranial and spinal nerves are components of the $PNS$.

(A) The human neural system is divided into two main parts: the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
The $PNS$ is further divided into the Somatic Neural System and the Autonomic Neural System $(ANS)$.
The Autonomic Neural System transmits impulses from the $CNS$ to the involuntary organs and smooth muscles of the body.
The $ANS$ is classified into two divisions: the Sympathetic Neural System and the Parasympathetic Neural System.
Therefore,the autonomic neural system is composed of sympathetic and parasympathetic nerves.

(C) The human neural system is divided into two parts: the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
The $PNS$ is further divided into the Somatic Neural System and the Autonomic Neural System.
The Somatic Neural System relays impulses from the $CNS$ to skeletal muscles.
The Autonomic Neural System transmits impulses from the $CNS$ to the involuntary organs and smooth muscles of the body.
Therefore,the correct answer is the Autonomic nervous system.

(C) The human neural system is divided into two parts: the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
The $PNS$ is further divided into the Somatic Neural System and the Autonomic Neural System $(ANS)$.
The Somatic Neural System relays impulses from the $CNS$ to skeletal muscles.
The Autonomic Neural System transmits impulses from the $CNS$ to the involuntary organs and smooth muscles of the body,collectively known as visceral organs.
Therefore,the $ANS$ controls the functions of visceral organs.

(C) The cranial nerves are classified as sensory,motor,or mixed based on their function.
$1$. The $Auditory$ (vestibulocochlear) nerve is a sensory nerve involved in hearing and balance.
$2$. The $Abducens$ nerve is a motor nerve that controls eye movement.
$3$. The $Optic$ nerve is a sensory nerve responsible for vision.
$4$. The $Trigeminal$ nerve is a mixed nerve (both sensory and motor).
Since both $Auditory$ and $Optic$ are sensory nerves,in the context of standard biology multiple-choice questions where only one answer is expected,$Optic$ is the primary sensory nerve associated with vision. However,both $A$ and $C$ are sensory. Given the standard classification,$Optic$ is the most commonly cited pure sensory nerve.

(A) The peripheral nervous system $(PNS)$ is divided into two types of nerve fibers: afferent and efferent.
$1$. Afferent nerve fibers transmit impulses from tissues or organs towards the Central Nervous System $(CNS)$.
$2$. Efferent nerve fibers transmit regulatory impulses from the Central Nervous System $(CNS)$ to the concerned peripheral tissues or organs.
Therefore,the nerve that carries impulses towards the $CNS$ is known as an afferent nerve.

(C) The $ANS$ (Autonomic Neural System) is a part of the peripheral nervous system that controls involuntary bodily functions. It transmits impulses from the central nervous system to the involuntary organs,smooth muscles,and glands of the body. Therefore,it primarily affects the internal organs.

(D) The autonomic nervous system is divided into two main divisions: the $Sympathetic$ nervous system and the $Parasympathetic$ nervous system.
These two systems work in an antagonistic manner to maintain homeostasis in the body.
The $Sympathetic$ nervous system is responsible for the '$fight-or-flight$' response,increasing heart rate and dilating pupils.
Conversely,the $Parasympathetic$ nervous system is responsible for the '$rest-and-digest$' response,decreasing heart rate and promoting digestion.
Therefore,they act in opposition to each other.

(A) The nerves that originate directly from the brain are known as $Cranial \text{ nerves}$.
In humans, there are $12$ pairs of cranial nerves.
Spinal nerves originate from the spinal cord, while the sciatic nerve is the largest nerve in the body, originating from the sacral plexus.

(D) The human neural system is divided into two parts: the Central Neural System $(C.N.S.)$ and the Peripheral Neural System $(P.N.S.)$.
The $P.N.S.$ comprises all the nerves of the body associated with the $C.N.S.$ (brain and spinal cord).
The nerve fibers of the $P.N.S.$ are of two types: afferent fibers and efferent fibers.
Afferent nerve fibers transmit impulses from tissues/organs to the $C.N.S.$,while efferent nerve fibers transmit regulatory impulses from the $C.N.S.$ to the concerned peripheral tissues/organs.
The efferent system is further divided into the Somatic Neural System and the Autonomic Neural System.
Therefore,both the Somatic and Autonomic neural systems are components of the $P.N.S.$ that transmit impulses from the $C.N.S.$ to peripheral organs.

(A) The brain is the most metabolically active organ in the human body,consuming approximately $20\%$ of the body's total oxygen supply. Because neurons have a very high metabolic rate and limited capacity for anaerobic respiration,they are extremely sensitive to hypoxia (oxygen deficiency). Even a brief interruption in oxygen supply can lead to irreversible damage or death of brain cells,making the brain the primary organ affected by oxygen deficiency.

(B) The $Parasympathetic$ $nervous$ $system$ is responsible for the conservation of energy.
It promotes 'rest and digest' activities, which slow down the heart rate, increase intestinal and glandular activity, and relax sphincter muscles in the gastrointestinal tract.
This system helps the body conserve energy and maintain homeostasis during periods of rest.

(D) The $Brain$ is the most metabolically active organ in the human body, consuming approximately $20\%$ of the total oxygen supply.
Because the $Brain$ has very limited capacity for anaerobic respiration and cannot store oxygen, it is extremely sensitive to hypoxia (shortage of oxygen).
Even a brief interruption in oxygen supply can lead to irreversible damage to neurons, making it the organ most affected by oxygen deprivation.

(A) The human neural system is divided into two parts: the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
The $PNS$ is further divided into the Somatic Neural System and the Autonomic Neural System.
The Somatic Neural System relays impulses from the $CNS$ to skeletal muscles,which are under voluntary control.
In contrast,the Autonomic Neural System transmits impulses from the $CNS$ to the involuntary organs and smooth muscles of the body.

(B) The human neural system is divided into two main parts: the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
The $PNS$ is further divided into the Somatic Neural System and the Autonomic Neural System $(ANS)$.
The Autonomic Neural System is responsible for involuntary functions and is subdivided into the Sympathetic Neural System and the Parasympathetic Neural System.
Therefore,the sympathetic and parasympathetic systems are components of the Autonomic Neural System.

(A) The human neural system is divided into two parts: the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
$CNS$ includes the brain and the spinal cord.
$PNS$ comprises all the nerves of the body associated with the $CNS$. The $PNS$ is further divided into the Somatic neural system and the Autonomic neural system.
Therefore,the correct pair is $CNS = \text{Brain} + \text{Spinal cord}$.

(D) The parasympathetic nervous system is responsible for 'rest and digest' activities.
It promotes functions that conserve energy.
Constriction of the pupil (miosis) is a characteristic parasympathetic response.
In contrast,contraction of hair muscles (piloerection),stimulation of sweat glands,and increase in heart rate are functions associated with the sympathetic nervous system.

(B) The human neural system is divided into two parts: the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
$PNS$ consists of nerve fibers that are classified into two types: afferent nerve fibers and efferent nerve fibers.
Afferent nerve fibers transmit impulses from tissues/organs to the $CNS$.
Efferent nerve fibers transmit regulatory impulses from the $CNS$ to the concerned peripheral tissues/organs (such as muscles or glands).
Therefore,efferent nerve fibers carry impulses from the $CNS$ to the effector organs like muscles.

(D) The human neural system is divided into the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
The $PNS$ is further divided into the Somatic Neural System and the Autonomic Neural System $(ANS)$.
The Somatic Neural System relays impulses from the $CNS$ to skeletal muscles,which are under conscious control.
The Autonomic Neural System $(ANS)$ transmits impulses from the $CNS$ to the involuntary organs and smooth muscles of the body.
The $ANS$ consists of two divisions: the sympathetic neural system and the parasympathetic neural system.
These systems regulate the visceral organs (involuntary organs) and operate independently of conscious control.

(N/A) The neural system of all animals is composed of highly specialized cells called neurons.
It can receive,transmit,and detect various kinds of stimuli.
In lower invertebrates,the neural organization is very simple.
For example,in $Hydra$,it consists of a network of neurons. In insects,the neural system is better organized,where a brain is present along with a number of ganglia and neural tissues.
The vertebrates have a more developed neural system.
In higher organisms,the neural system performs three basic functions:
$(i)$ It receives sensory impulses from the external and internal environment and sends them to the brain.
$(ii)$ The brain analyzes the type of stimuli.
$(iii)$ Responses,according to the stimuli,are transported in the form of nerve impulses to various body parts or cells.

(N/A) The human neural system is divided into two main parts:
$(i)$ The Central Neural System $(CNS)$
$(ii)$ The Peripheral Neural System $(PNS)$
$(1)$ The $CNS$ includes the brain and the spinal cord. It is the site of information processing and control.
$(2)$ The $PNS$ comprises all the nerves of the body associated with the $CNS$ (brain and spinal cord). The nerve fibres of the $PNS$ are of two types:
$(a)$ Afferent nerve fibres: These transmit impulses from tissues/organs to the $CNS$.
$(b)$ Efferent nerve fibres: These transmit regulatory impulses from the $CNS$ to the peripheral tissues/organs.
The $PNS$ is further divided into two subdivisions:
$(i)$ Somatic Neural System: This relays impulses from the $CNS$ to skeletal muscles.
$(ii)$ Autonomic Neural System: This transmits impulses from the $CNS$ to involuntary organs and smooth muscles of the body. The autonomic neural system is further classified into the Sympathetic Neural System and the Parasympathetic Neural System.
Additionally,the Visceral Nervous System is a part of the peripheral nervous system that comprises the whole complex of nerves,fibres,ganglia,and plexuses by which impulses travel from the $CNS$ to the viscera and from the viscera to the $CNS$.

(N/A)

Invertebrate Neural System	Vertebrate Neural System
$1$. The most primitive neural system is observed in $Hydra$, which is in the form of a nerve net.	$1$. The structural and functional unit of the neural system is the neuron.
$2$. It is highly developed in insects, consisting of ganglia and brain-like structures.	$2$. It is organized into a Central Neural System $(CNS)$ and a Peripheral Neural System $(PNS)$.

(N/A) The human neural system is divided into two main parts: the Central Neural System $(CNS)$ and the Peripheral Neural System $(PNS)$.
$1$. The $CNS$ consists of the brain and the spinal cord.
$2$. The $PNS$ is further divided into the somatic neural system and the autonomic neural system.
$3$. The brain is divided into the forebrain,midbrain,and hindbrain.
$4$. The autonomic neural system is further classified into the sympathetic neural system and the parasympathetic neural system.
Following the hierarchy:
- The box next to $CNS$ is $PNS$.
- Under $CNS$,the box next to Brain is Spinal cord.
- Under $PNS$,the box next to Autonomic neural system is Somatic neural system.
- Under Brain,the boxes are Forebrain,Midbrain,and Hindbrain.
- Under Autonomic neural system,the box next to Sympathetic neural system is Parasympathetic neural system.

(A) $(1)$ The cell body (cyton) contains typical cell organelles and Nissl's granules. Nissl's granules are rough endoplasmic reticulum with ribosomes,which are sites of protein synthesis.
$(2)$ The nervous system of Hydra is composed of a nerve net. It is a primitive type of nervous system consisting of a network of neurons spread throughout the body,lacking a centralized brain or ganglia.

(B) The $PNS$ (Peripheral Nervous System) consists of all the nerves of the body associated with the $CNS$ (Central Nervous System) comprising the brain and the spinal cord.
It includes two types of nerve fibers:
$(a)$ Afferent nerve fibers: These transmit impulses from tissues/organs to the $CNS$.
$(b)$ Efferent nerve fibers: These transmit regulatory impulses from the $CNS$ to the concerned peripheral tissues/organs.

(A) The $PNS$ (Peripheral Neural System) is divided into two main divisions: the Somatic Neural System and the Autonomic Neural System.
$1$. The Somatic Neural System relays impulses from the $CNS$ to skeletal muscles.
$2$. The Autonomic Neural System transmits impulses from the $CNS$ to involuntary organs and smooth muscles of the body.

(B) The visceral nervous system is a component of the peripheral nervous system $(PNS)$.
It facilitates the transmission of nerve impulses through nerves,ganglia,and plexuses (nerve networks).
It acts as a communication pathway between the central nervous system $(CNS)$ and the internal organs (viscera).
It consists of the entire complex of nerves and plexuses that regulate involuntary functions of the internal organs.

(C) In mammals,the three primary germ layers are the ectoderm,mesoderm,and endoderm.
$1$. The ectoderm gives rise to the nervous system,epidermis of the skin,hair,nails,and sensory organs.
$2$. The mesoderm gives rise to the muscular system,skeletal system,circulatory system,and reproductive system.
$3$. The endoderm gives rise to the lining of the digestive tract and respiratory system.
Therefore,the nervous system is derived from the ectoderm.

(C) The nervous system is divided into the central nervous system and the peripheral nervous system.
The peripheral nervous system is further divided into the somatic nervous system and the autonomic nervous system.
The somatic nervous system is responsible for relaying information from the central nervous system to the skeletal muscles,thereby controlling voluntary movements.
Therefore,skeletal muscles are under the control of the somatic nervous system.