Test: Nervous System - UPSC MCQ

The correct statement about the cerebellum is that it regulates muscular movement for locomotion and it is a part of the brain.

The correct answer is D. Glial cells. Glial cells, also known as neuroglia or glia, are non-neuronal cells that provide support, nourishment, and protection to neurons in the nervous system. They play important roles in maintaining the structural integrity of the nervous system, regulating the chemical environment around neurons, and assisting in neuronal communication.

A synapse is a microscopic gap or junction between two adjacent neurons where nerve impulses pass from one neuron to the next. It is the site of communication between neurons, where neurotransmitters are released from the presynaptic neuron, cross the synaptic gap, and bind to receptors on the postsynaptic neuron, transmitting the nerve impulse.

The pons, cerebellum, and medulla are all structures located in the hindbrain, which is the posterior part of the brain. The hindbrain is responsible for controlling vital functions such as breathing, heart rate, and coordination of movement. It is one of the three major divisions of the brain, along with the forebrain and midbrain.

The cranial nerves are a set of twelve pairs of nerves that emerge directly from the brain and exit through openings in the skull. These nerves are responsible for carrying sensory and motor information to and from various regions of the head, neck, and visceral organs. They control a wide range of functions, including vision, hearing, smell, taste, facial movements, and internal organ regulation.

Elastic connective tissue is not a component of the peripheral nervous system (PNS). The PNS consists of the nerves and ganglia outside the brain and spinal cord. It includes cranial nerves (which emerge from the brain), spinal nerves (which emerge from the spinal cord), and ganglia (clusters of cell bodies of neurons). Elastic connective tissue, on the other hand, is a type of connective tissue that provides elasticity and support to various organs and structures in the body, but it is not directly involved in the functioning of the nervous system.

The speed of a nerve impulse, also known as the conduction velocity, can vary depending on various factors such as the type of nerve fiber and its myelination. However, option B, which states a range of 0.5 - 130 m/s, is a reasonable approximation for the speed of nerve impulses in the human body. Different types of nerves have different conduction velocities, with larger, myelinated fibers typically conducting impulses faster than smaller, unmyelinated fibers. For example, motor neurons responsible for muscle control can transmit impulses at speeds around 60-130 m/s, while sensory neurons transmitting touch or pain signals can range from 1-30 m/s. Keep in mind that these values are general estimates and can vary depending on the specific nerve and individual circumstances.

The endoplasmic reticulum (ER) is not typically found in the axon. The ER is an organelle involved in protein synthesis and lipid metabolism, and it is mainly found in the cell body of a neuron rather than in the axon. The axon is a long, slender extension of a neuron responsible for transmitting electrical impulses away from the cell body to other neurons or target cells.

On the other hand, neurofibrils, mitochondria, and microtubules are all components that can be found in the axon:

• Neurofibrils: These are thread-like structures made of protein called neurofilaments. They provide structural support and are involved in maintaining the shape and integrity of the axon.
• Mitochondria: These are energy-producing organelles found throughout the neuron, including the axon. Mitochondria generate adenosine triphosphate (ATP), the molecule used for cellular energy, which is essential for the axon to function properly.
• Microtubules: These are cylindrical structures composed of proteins called tubulins. They play a crucial role in providing structural support and facilitating the transport of various molecules, including neurotransmitters and vesicles, within the axon.

Interneurons are multipolar neurons that are located entirely within the central nervous system (CNS). They serve as connectors or relay neurons, facilitating communication between sensory neurons and motor neurons. Interneurons receive information from sensory neurons and transmit signals to motor neurons, allowing for the integration and processing of information within the CNS. They play a crucial role in coordinating and regulating complex neural activities, such as reflexes and higher-order cognitive functions.

The nervous system consists of the brain, spinal cord, and nerves. These components work together to process and transmit information throughout the body, allowing for the coordination of various bodily functions and responses.

The brain is the central control center of the nervous system. It receives, interprets, and processes sensory information, initiates voluntary movements, and regulates numerous physiological processes.

The spinal cord is a long, cylindrical bundle of nerves that extends from the brain down the vertebral column. It serves as a communication pathway between the brain and the rest of the body. The spinal cord relays signals between the brain and peripheral nerves, and it also carries out reflex actions independently of the brain.

Nerves are bundles of specialized cells called neurons that transmit electrical signals throughout the body. They connect the central nervous system to various organs, muscles, and sensory receptors, allowing for the transmission of sensory information to the brain and the initiation of motor responses.

Together, the brain, spinal cord, and nerves form the complex network of the nervous system, enabling the body to interact with its environment and regulate its internal functions.

The basic structural and functional unit of the nervous system is the neuron. Neurons are specialized cells that transmit electrical and chemical signals in the nervous system. They are responsible for processing and transmitting information throughout the body. Neuroglia, also known as glial cells, are another type of cell in the nervous system that provide support and protection to neurons, but they are not the basic unit of the nervous system. Perikaryon refers to the cell body of a neuron, which contains the nucleus and other organelles, but it is not the basic unit of the nervous system either. Therefore, the correct answer is C) Neurons.

Nissl bodies, also known as Nissl substance or Nissl granules, are clusters of rough endoplasmic reticulum (ER) found in the cell bodies of neurons. They are named after the German neuropathologist Franz Nissl, who first described them.

Nissl bodies consist of stacked layers of rough ER, which are composed of ribosomes attached to the ER membrane. The rough ER plays a crucial role in protein synthesis. In neurons, Nissl bodies are particularly abundant and are involved in the production of proteins needed for the growth, maintenance, and functioning of the neuron.

These clusters of rough ER give Nissl bodies a granular appearance when stained, and they are especially prominent in the cell bodies of neurons. However, Nissl bodies are not present in the axons and dendrites of neurons.

It's important to note that Nissl bodies should not be confused with other cellular components such as Golgi bodies, lysosomes, or mitochondria, as these structures have different functions and characteristics.

The medulla oblongata, located in the hindbrain, is responsible for controlling many involuntary actions in the body. It is a vital part of the brainstem and serves as a pathway for nerve fibers traveling between the spinal cord and higher brain regions. The medulla plays a crucial role in regulating essential functions such as breathing, heart rate, blood pressure, swallowing, and other autonomic processes. Therefore, option A) Medulla in Hindbrain is the correct choice for the control of involuntary actions in our body.

The number of ganglia does not affect the speed of conduction of a nerve impulse. Ganglia are collections of nerve cell bodies located outside the central nervous system. They are involved in coordinating and integrating signals within specific regions of the peripheral nervous system. However, they do not directly influence the speed of nerve impulse conduction.

On the other hand, the factors that do affect the speed of conduction of a nerve impulse are the presence of a myelin sheath, the diameter of the axon, and the temperature. The myelin sheath is a fatty substance that surrounds and insulates certain axons, allowing for faster transmission of electrical signals. A larger axon diameter also contributes to faster conduction as it provides less resistance to the flow of electrical signals. Additionally, temperature affects the speed of nerve impulse conduction, with higher temperatures generally resulting in faster transmission.

Therefore, among the given options, A) No. of ganglia does not affect the speed of conduction of a nerve impulse.

The rhombencephalon, also known as the hindbrain, is one of the three primary vesicles that develop during embryonic brain development. It is responsible for controlling vital functions and regulating motor coordination. The medulla, or medulla oblongata, is a part of the hindbrain located at the base of the brainstem, and it is considered an extension of the spinal cord. The medulla plays a crucial role in regulating involuntary functions such as breathing, heart rate, blood pressure, and reflex actions.

The other options mentioned are not part of the rhombencephalon.

A) Temporal lobe: The temporal lobe is one of the four lobes of the cerebral cortex, which is part of the forebrain.

B) Thalamus: The thalamus is a structure located in the diencephalon, which is a part of the forebrain. It serves as a relay station for sensory information.

C) Substantia nigra: The substantia nigra is a structure located in the midbrain, which is part of the brainstem. It is involved in the production of dopamine and plays a role in movement control.

Therefore, the correct answer is D) Medulla.

The nervous system is responsible for controlling and coordinating every activity that you do. It is a complex network of specialized cells called neurons that transmit electrical and chemical signals throughout the body. The nervous system is divided into two main parts: the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which includes all the nerves that branch out from the CNS to the rest of the body.

The nervous system controls various activities such as movement, sensation, perception, thinking, memory, and the regulation of vital bodily functions like heart rate, breathing, digestion, and hormone release. It receives information from the environment and processes that information to produce appropriate responses or actions.

Therefore, the correct answer is A) Nervous System.

The neuron is the basic unit of the nervous system. Neurons are specialized cells that transmit electrical and chemical signals throughout the body, allowing for communication and coordination within the nervous system. They are responsible for processing and transmitting information, enabling various functions such as sensory perception, motor control, and cognitive processes.

While the brain and spinal cord (options A and B) are essential components of the nervous system, they are made up of a vast network of interconnected neurons. The nerves (option D) are bundles of axons (long extensions of neurons) that transmit signals between the central nervous system and the rest of the body.

Therefore, the correct answer is C) Neuron as the basic unit of the nervous system.

The correct answer is B) Cerebral reflexes.

Reflex actions that involve the brain are referred to as cerebral reflexes. These reflexes occur when sensory information is processed and integrated in the brain before a motor response is initiated. Unlike spinal reflexes (option C), which are mediated by the spinal cord alone, cerebral reflexes involve higher-level processing and decision-making in the brain.

The brain plays a crucial role in coordinating complex reflex actions and integrating sensory input with motor output. Examples of cerebral reflexes include the pupillary reflex (controlling the size of the pupil in response to light), the gag reflex (protective response to prevent choking), and the withdrawal reflex (removing a hand from a hot surface).

Options A and D are not correct:

A) Stimulus: A stimulus is any external or internal event that elicits a response from an organism. While stimuli can trigger reflex actions, the term "stimulus" does not specifically refer to reflex actions involving the brain.

D) Reflex arc: A reflex arc refers to the neural pathway that mediates a reflex action. It typically involves a sensory receptor, an afferent neuron, an interneuron in the spinal cord or brain, an efferent neuron, and an effector organ. While reflex arcs can involve the brain, the term "reflex arc" does not specifically describe reflex actions that involve the brain.

Therefore, the correct answer is B) Cerebral reflexes.

The spinal cord is a long, cylindrical bundle of nerve tissue that extends from the base of the brainstem to the lower back. It is a vital part of the central nervous system (CNS) and serves as a communication pathway between the brain and the rest of the body.

During embryonic development, the spinal cord originates from the neural tube, which is a structure that develops from the ectoderm. The neural tube gives rise to different regions of the central nervous system, including the brain and spinal cord.

Specifically, the spinal cord originates from the caudal part of the neural tube, which eventually differentiates into the medulla oblongata in the developing brainstem. The medulla oblongata, often referred to as just the medulla, is the lowest part of the brainstem and serves as a transitional region between the brain and the spinal cord.

Therefore, the correct answer is B) Medulla.

The system of the body that coordinates and controls its activities is known as the nervous system. The nervous system is a complex network of specialized cells called neurons that transmit electrical and chemical signals throughout the body. It is responsible for receiving sensory information, processing and integrating that information, and initiating appropriate responses or actions.

The nervous system is involved in controlling and coordinating various functions, including movement, sensation, perception, thinking, memory, and the regulation of vital bodily processes such as heart rate, breathing, digestion, and hormone release. It works in conjunction with other organ systems (option A), such as the muscular system (option B), to enable coordinated movement and bodily functions.

Nervous tissue (option C) is a component of the nervous system, consisting of specialized cells (neurons and glial cells) that make up the structure and function of the nervous system. However, the nervous system as a whole is responsible for coordinating and controlling the body's activities.