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- Central nervous system
- Nervous system questions
- GK Questions and Answers on Nervous System
- GK Questions and Answers on Nervous System
The Nervous system is like the manager inside our body. Its function is to control and coordinate the parts of our body so that they work together, doing their job at the right time. The human nervous system receives information from the surroundings, processes it, interprets it and then responds accordingly.
Learn endocrine system, receptors in humans, human nervous system, human receptors, central nervous system test prep for online certificate courses. Free biology student portal for online learning coordination and control quiz questions for online certifications. MCQ : The nervous system which consists of all the nerves arisen from the central nervous system is called.
Central nervous system
The central nervous system CNS is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because it integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric animals —i. The CNS also includes the retina  and the optic nerve cranial nerve II ,   as well as the olfactory nerves cranial nerve I and olfactory epithelium  as parts of the CNS, synapsing directly on brain tissue without intermediate ganglia.
As such, the olfactory epithelium is the only central nervous tissue in direct contact with the environment, which opens up for therapeutic treatments. In vertebrates, the brain is protected by the skull , while the spinal cord is protected by the vertebrae. The CNS consists of the two major structures: the brain and spinal cord. The brain is encased in the skull, and protected by the cranium.
Microscopically, there are differences between the neurons and tissue of the CNS and the peripheral nervous system PNS. The white matter consists of axons and oligodendrocytes , while the gray matter consists of neurons and unmyelinated fibers. Both tissues include a number of glial cells although the white matter contains more , which are often referred to as supporting cells of the CNS.
Different forms of glial cells have different functions, some acting almost as scaffolding for neuroblasts to climb during neurogenesis such as bergmann glia , while others such as microglia are a specialized form of macrophage , involved in the immune system of the brain as well as the clearance of various metabolites from the brain tissue.
Upon CNS injury astrocytes will proliferate, causing gliosis , a form of neuronal scar tissue, lacking in functional neurons.
The brain cerebrum as well as midbrain and hindbrain consists of a cortex , composed of neuron-bodies constituting gray matter, while internally there is more white matter that form tracts and commissures.
Apart from cortical gray matter there is also subcortical gray matter making up a large number of different nuclei. From and to the spinal cord are projections of the peripheral nervous system in the form of spinal nerves sometimes segmental nerves . The nerves connect the spinal cord to skin, joints, muscles etc. All in all 31 spinal nerves project from the brain stem,  some forming plexa as they branch out, such as the brachial plexa , sacral plexa etc.
The spinal cord relays information up to the brain through spinal tracts through the "final common pathway"  to the thalamus and ultimately to the cortex. Reflexes may also occur without engaging more than one neuron of the CNS as in the below example of a short reflex. Apart from the spinal cord, there are also peripheral nerves of the PNS that synapse through intermediaries or ganglia directly on the CNS. These 12 nerves exist in the head and neck region and are called cranial nerves. Cranial nerves bring information to the CNS to and from the face, as well as to certain muscles such as the trapezius muscle , which is innervated by accessory nerves  as well as certain cervical spinal nerves.
Two pairs of cranial nerves; the olfactory nerves and the optic nerves  are often considered structures of the CNS. This is because they do not synapse first on peripheral ganglia, but directly on CNS neurons. The olfactory epithelium is significant in that it consists of CNS tissue expressed in direct contact to the environment, allowing for administration of certain pharmaceuticals and drugs. Rostrally to the spinal cord lies the brain. It is often the main structure referred to when speaking of the nervous system in general.
The brain is the major functional unit of the CNS. While the spinal cord has certain processing ability such as that of spinal locomotion and can process reflexes , the brain is the major processing unit of the nervous system. The brainstem consists of the medulla , the pons and the midbrain. The medulla can be referred to as an extension of the spinal cord, which both have similar organization and functional properties. Regulatory functions of the medulla nuclei include control of blood pressure and breathing.
Other nuclei are involved in balance , taste , hearing , and control of muscles of the face and neck. The next structure rostral to the medulla is the pons, which lies on the ventral anterior side of the brainstem. Nuclei in the pons include pontine nuclei which work with the cerebellum and transmit information between the cerebellum and the cerebral cortex. The midbrain, or mesencephalon, is situated above and rostral to the pons.
It includes nuclei linking distinct parts of the motor system, including the cerebellum, the basal ganglia and both cerebral hemispheres , among others. Additionally, parts of the visual and auditory systems are located in the midbrain, including control of automatic eye movements. The brainstem at large provides entry and exit to the brain for a number of pathways for motor and autonomic control of the face and neck through cranial nerves,  Autonomic control of the organs is mediated by the tenth cranial nerve.
Such functions may engage the heart , blood vessels , and pupils , among others. The brainstem also holds the reticular formation , a group of nuclei involved in both arousal and alertness. The cerebellum lies behind the pons. The cerebellum is composed of several dividing fissures and lobes. Its function includes the control of posture and the coordination of movements of parts of the body, including the eyes and head, as well as the limbs.
Further, it is involved in motion that has been learned and perfected through practice, and it will adapt to new learned movements. These connections have been shown by the use of medical imaging techniques, such as functional MRI and Positron emission tomography.
The body of the cerebellum holds more neurons than any other structure of the brain, including that of the larger cerebrum , but is also more extensively understood than other structures of the brain, as it includes fewer types of different neurons.
The two structures of the diencephalon worth noting are the thalamus and the hypothalamus. The thalamus acts as a linkage between incoming pathways from the peripheral nervous system as well as the optical nerve though it does not receive input from the olfactory nerve to the cerebral hemispheres.
Previously it was considered only a "relay station", but it is engaged in the sorting of information that will reach cerebral hemispheres neocortex. Apart from its function of sorting information from the periphery, the thalamus also connects the cerebellum and basal ganglia with the cerebrum.
In common with the aforementioned reticular system the thalamus is involved in wakefullness and consciousness, such as though the SCN. The hypothalamus engages in functions of a number of primitive emotions or feelings such as hunger , thirst and maternal bonding.
This is regulated partly through control of secretion of hormones from the pituitary gland. Additionally the hypothalamus plays a role in motivation and many other behaviors of the individual. The cerebrum of cerebral hemispheres make up the largest visual portion of the human brain. Various structures combine to form the cerebral hemispheres, among others: the cortex, basal ganglia, amygdala and hippocampus.
The hemispheres together control a large portion of the functions of the human brain such as emotion, memory, perception and motor functions. Apart from this the cerebral hemispheres stand for the cognitive capabilities of the brain. Connecting each of the hemispheres is the corpus callosum as well as several additional commissures. Functionally, the cerebral cortex is involved in planning and carrying out of everyday tasks. The hippocampus is involved in storage of memories, the amygdala plays a role in perception and communication of emotion, while the basal ganglia play a major role in the coordination of voluntary movement.
Both act to add myelin sheaths to the axons, which acts as a form of insulation allowing for better and faster proliferation of electrical signals along the nerves. Axons in the CNS are often very short, barely a few millimeters, and do not need the same degree of isolation as peripheral nerves.
Some peripheral nerves can be over 1 meter in length, such as the nerves to the big toe. To ensure signals move at sufficient speed, myelination is needed. The way in which the Schwann cells and oligodendrocytes myelinate nerves differ. A Schwann cell usually myelinates a single axon, completely surrounding it. Sometimes, they may myelinate many axons, especially when in areas of short axons.
They do this by sending out thin projections of their cell membrane , which envelop and enclose the axon. During early development of the vertebrate embryo, a longitudinal groove on the neural plate gradually deepens and the ridges on either side of the groove the neural folds become elevated, and ultimately meet, transforming the groove into a closed tube called the neural tube.
At this stage, the walls of the neural tube contain proliferating neural stem cells in a region called the ventricular zone. The neural stem cells, principally radial glial cells , multiply and generate neurons through the process of neurogenesis , forming the rudiment of the CNS.
The neural tube gives rise to both brain and spinal cord. The anterior or 'rostral' portion of the neural tube initially differentiates into three brain vesicles pockets : the prosencephalon at the front, the mesencephalon , and, between the mesencephalon and the spinal cord, the rhombencephalon. By six weeks in the human embryo the prosencephalon then divides further into the telencephalon and diencephalon ; and the rhombencephalon divides into the metencephalon and myelencephalon.
The spinal cord is derived from the posterior or 'caudal' portion of the neural tube. As a vertebrate grows, these vesicles differentiate further still.
The telencephalon differentiates into, among other things, the striatum , the hippocampus and the neocortex , and its cavity becomes the first and second ventricles. Diencephalon elaborations include the subthalamus , hypothalamus , thalamus and epithalamus , and its cavity forms the third ventricle. The tectum , pretectum , cerebral peduncle and other structures develop out of the mesencephalon, and its cavity grows into the mesencephalic duct cerebral aqueduct. The metencephalon becomes, among other things, the pons and the cerebellum , the myelencephalon forms the medulla oblongata , and their cavities develop into the fourth ventricle.
Diagram depicting the main subdivisions of the embryonic vertebrate brain, later forming forebrain , midbrain and hindbrain. Tectum , Cerebral peduncle , Pretectum , Mesencephalic duct. Pons , Cerebellum. Planarians , members of the phylum Platyhelminthes flatworms , have the simplest, clearly defined delineation of a nervous system into a CNS and a PNS. In arthropods , the ventral nerve cord , the subesophageal ganglia and the supraesophageal ganglia are usually seen as making up the CNS.
Arthropoda, unlike vertebrates, have inhibitory motor neurons due to their small size. The major trend that can be observed is towards a progressive telencephalisation: the telencephalon of reptiles is only an appendix to the large olfactory bulb , while in mammals it makes up most of the volume of the CNS. In the human brain, the telencephalon covers most of the diencephalon and the mesencephalon.
Indeed, the allometric study of brain size among different species shows a striking continuity from rats to whales, and allows us to complete the knowledge about the evolution of the CNS obtained through cranial endocasts. Mammals — which appear in the fossil record after the first fishes, amphibians, and reptiles — are the only vertebrates to possess the evolutionarily recent, outermost part of the cerebral cortex known as the neocortex.
There are many CNS diseases and conditions, including infections such as encephalitis and poliomyelitis , early-onset neurological disorders including ADHD and autism , late-onset neurodegenerative diseases such as Alzheimer's disease , Parkinson's disease , and essential tremor , autoimmune and inflammatory diseases such as multiple sclerosis and acute disseminated encephalomyelitis , genetic disorders such as Krabbe's disease and Huntington's disease , as well as amyotrophic lateral sclerosis and adrenoleukodystrophy.
Lastly, cancers of the central nervous system can cause severe illness and, when malignant , can have very high mortality rates. Symptoms depend on the size, growth rate, location and malignancy of tumors and can include alterations in motor control, hearing loss, headaches and changes in cognitive ability and autonomic functioning.
Specialty professional organizations recommend that neurological imaging of the brain be done only to answer a specific clinical question and not as routine screening.
From Wikipedia, the free encyclopedia. Brain and spinal cord. Main article: Neuroanatomy.
Nervous system questions
The nervous system is responsible for our thoughts, our emotions, our senses, and our movements. The brain, nerves, and spinal cord are all members of this important process. How much do you know about the nervous system? Do you know what happens when the system malfunctions? Find out by taking this multiple-choice quiz. Search Encyclopedia. Take the Nervous System Quiz The nervous system is responsible for our thoughts, our emotions, our senses, and our movements.
The central nervous system consists of the brain and spinal cord. This article gives a brief overview of the central nervous system CNS. We will look at the types of cells involved, different regions within the brain, spinal circuitry, and how the CNS can be affected by disease and injury. Here are some key points about the central nervous system. More detail and supporting information is in the main article. The brain is protected by the skull the cranial cavity and the spinal cord travels from the back of the brain, down the center of the spine, stopping in the lumbar region of the lower back. The brain and spinal cord are both housed within a protective triple-layered membrane called the meninges.
GK Questions and Answers on Nervous System
It seems that you're in Germany. We have a dedicated site for Germany. It is now known that the adult mammalian brain undergoes repair and renewal from pools of stem cells and that cell cycle alteration may cause a variety of neurological disorders ranging from autism to brain tumors. In The Cell Cycle in the Central Nervous System, prominent researchers, physicians, engineers, and pharmacologists join forces to delineate how the brain is a complex organ composed of widely varying cell types, including blood vessels, and what its cellular-based disorders may be. Topics covered range from the cell cycle during the prenatal development of the mammalian central nervous system CNS to future directions in postnatal neurogenesis through gene transfer, electrical stimulation, and stem cell introduction.
Jump to content. Top of the page Check Your Symptoms. The nervous system is a complex, highly specialized network. It organizes, explains, and directs interactions between you and the world around you. The nervous system controls:.
GK Questions and Answers on Nervous System
EDU - ЕТ? - спросила Сьюзан. У нее кружилась голова. - Энсей Танкадо и есть Северная Дакота.
Мидж… - Доброй ночи, Чед. - Она направилась к двери. - Ты уходишь. - Ты же знаешь, что я бы осталась, - сказала она, задержавшись в дверях, - но у меня все же есть кое-какая гордость.
Это было одним из крупнейших достижений Стратмора. С помощью ТРАНСТЕКСТА, взломавшего шифр, ему удалось узнать о заговоре и бомбе, подложенной в школе иврита в Лос-Анджелесе. Послание террористов удалось расшифровать всего за двадцать минут до готовившегося взрыва и, быстро связавшись по телефону с кем нужно, спасти триста школьников. - А знаешь, - Мидж без всякой нужды перешла на шепот, - Джабба сказал, что Стратмор перехватил сообщение террористов за шесть часов до предполагаемого времени взрыва. У Бринкерхоффа отвисла челюсть. - Так почему… чего же он так долго ждал.
A) Formulate responses to sensory stimulation. B) Send signals 7) ____ neuron transmits signals from the PNS to the central nervous system. A) Interneuron.
Фильтр Х-одиннадцать уничтожен, - сообщил техник. - У этого парня зверский аппетит. Смит начал говорить. Его комментарий отличался бесстрастностью опытного полевого агента: - Эта съемка сделана из мини-автобуса, припаркованного в пятидесяти метрах от места убийства. Танкадо приближается справа, Халохот - между деревьев слева. - У нас почти не осталось времени, - сказал Фонтейн. - Давайте ближе к сути дела.
Безвкусное золотое кольцо с надписью по-латыни. - Нет. - Он усмехнулся. - Я попросил Фонтейна передать его наследникам Танкадо. - Он взял ее руку и натянул что-то на палец. - Лжец, - засмеялась Сьюзан, открывая .
- Тут сказано, что сверхкритическая масса плутония составляет тридцать пять и две десятых фунта. - Вот именно! - крикнул Джабба. - Посмотрите уран. Его сверхкритическую массу.
Он просиял. - Второй раз за один вечер. Что подумают люди.
Меня зовут Северная Дакота. Нуматака подавил смешок. Все знали про Северную Дакоту.