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Central Nervous System

The brain and the spinal cord are the central nervous system, and they represent the main organs of the nervous system. The spinal cord is a single structure, whereas the adult brain is described in terms of four major regions: the cerebrum, the diencephalon, the brain stem, and the cerebellum. The regulation of homeostasis is governed by a specialized region in the brain. The coordination of reflexes depends on the integration of sensory and motor pathways in the spinal cord.

The iconic gray mantle of the human brain, which appears to make up most of the mass of the brain, is the cerebrum [link]. The wrinkled portion is the cerebral cortex , and the rest of the structure is beneath that outer covering. There is a large separation between the two sides of the cerebrum called the longitudinal fissure. It separates the cerebrum into two distinct halves, a right and left cerebral hemisphere.

Deep within the cerebrum, the white matter of the corpus callosum provides the major pathway for communication between the two hemispheres of the cerebral cortex. Many of the higher neurological functions, such as memory, emotion, and consciousness, are the result of cerebral function.

The complexity of the cerebrum is different across vertebrate species. The cerebrum of the most primitive vertebrates is not much more than the connection for the sense of smell. The basal nuclei are responsible for cognitive processing, the most important function being that associated with planning movements. The basal forebrain contains nuclei that are important in learning and memory. The limbic cortex is the region of the cerebral cortex that is part of the limbic system , a collection of structures involved in emotion, memory, and behavior.

The cerebrum is covered by a continuous layer of gray matter that wraps around either side of the forebrain—the cerebral cortex. This thin, extensive region of wrinkled gray matter is responsible for the higher functions of the nervous system.

The pattern of these folds of tissue indicates specific regions of the cerebral cortex. The head is limited by the size of the birth canal, and the brain must fit inside the cranial cavity of the skull. Extensive folding in the cerebral cortex enables more gray matter to fit into this limited space. If the gray matter of the cortex were peeled off of the cerebrum and laid out flat, its surface area would be roughly equal to one square meter. The folding of the cortex maximizes the amount of gray matter in the cranial cavity.

The surface of the brain can be mapped on the basis of the locations of large gyri and sulci. Using these landmarks, the cortex can be separated into four major regions, or lobes [link]. The lateral sulcus that separates the temporal lobe from the other regions is one such landmark.

Superior to the lateral sulcus are the parietal lobe and frontal lobe , which are separated from each other by the central sulcus. The posterior region of the cortex is the occipital lobe , which has no obvious anatomical border between it and the parietal or temporal lobes on the lateral surface of the brain. From the medial surface, an obvious landmark separating the parietal and occipital lobes is called the parieto-occipital sulcus.

The fact that there is no obvious anatomical border between these lobes is consistent with the functions of these regions being interrelated. Different regions of the cerebral cortex can be associated with particular functions, a concept known as localization of function. In the early s, a German neuroscientist named Korbinian Brodmann performed an extensive study of the microscopic anatomy—the cytoarchitecture—of the cerebral cortex and divided the cortex into 52 separate regions on the basis of the histology of the cortex.

Areas 17 and 18 in the occipital lobe are responsible for primary visual perception. That visual information is complex, so it is processed in the temporal and parietal lobes as well. Because regions of the temporal lobe are part of the limbic system, memory is an important function associated with that lobe. Even memories of movement are really the memory of sensory feedback from those movements, such as stretching muscles or the movement of the skin around a joint.

Structures in the temporal lobe are responsible for establishing long-term memory, but the ultimate location of those memories is usually in the region in which the sensory perception was processed. The main sensation associated with the parietal lobe is somatosensation , meaning the general sensations associated with the body.

All of the tactile senses are processed in this area, including touch, pressure, tickle, pain, itch, and vibration, as well as more general senses of the body such as proprioception and kinesthesia , which are the senses of body position and movement, respectively. Anterior to the central sulcus is the frontal lobe, which is primarily associated with motor functions. The precentral gyrus is the primary motor cortex.

Cells from this region of the cerebral cortex are the upper motor neurons that instruct cells in the spinal cord to move skeletal muscles. Anterior to this region are a few areas that are associated with planned movements. The premotor area is responsible for thinking of a movement to be made. The frontal eye fields are important in eliciting eye movements and in attending to visual stimuli. Anterior to these regions is the prefrontal lobe , which serves cognitive functions that can be the basis of personality, short-term memory, and consciousness.

The prefrontal lobotomy is an outdated mode of treatment for personality disorders psychiatric conditions that profoundly affected the personality of the patient. Beneath the cerebral cortex are sets of nuclei known as subcortical nuclei that augment cortical processes. The nuclei of the basal forebrain serve as the primary location for acetylcholine production, which modulates the overall activity of the cortex, possibly leading to greater attention to sensory stimuli.

The hippocampus and amygdala are medial-lobe structures that, along with the adjacent cortex, are involved in long-term memory formation and emotional responses. The basal nuclei are a set of nuclei in the cerebrum responsible for comparing cortical processing with the general state of activity in the nervous system to influence the likelihood of movement taking place.

For example, while a student is sitting in a classroom listening to a lecture, the basal nuclei will keep the urge to jump up and scream from actually happening. The basal nuclei are also referred to as the basal ganglia, although that is potentially confusing because the term ganglia is typically used for peripheral structures.

The major structures of the basal nuclei that control movement are the caudate , putamen , and globus pallidus , which are located deep in the cerebrum. The caudate is a long nucleus that follows the basic C-shape of the cerebrum from the frontal lobe, through the parietal and occipital lobes, into the temporal lobe. The putamen is mostly deep in the anterior regions of the frontal and parietal lobes. Together, the caudate and putamen are called the striatum. The globus pallidus is a layered nucleus that lies just medial to the putamen; they are called the lenticular nuclei because they look like curved pieces fitting together like lenses.

The globus pallidus has two subdivisions, the external and internal segments, which are lateral and medial, respectively. These nuclei are depicted in a frontal section of the brain in [link]. The basal nuclei in the cerebrum are connected with a few more nuclei in the brain stem that together act as a functional group that forms a motor pathway.

Two streams of information processing take place in the basal nuclei. All input to the basal nuclei is from the cortex into the striatum [link]. The direct pathway is the projection of axons from the striatum to the globus pallidus internal segment GPi and the substantia nigra pars reticulata SNr.

The direct pathway causes the disinhibition of the thalamus inhibition of one cell on a target cell that then inhibits the first cell , whereas the indirect pathway causes, or reinforces, the normal inhibition of the thalamus. The thalamus then can either excite the cortex as a result of the direct pathway or fail to excite the cortex as a result of the indirect pathway. The switch between the two pathways is the substantia nigra pars compacta , which projects to the striatum and releases the neurotransmitter dopamine.

Dopamine receptors are either excitatory D1-type receptors or inhibitory D2-type receptors. The direct pathway is activated by dopamine, and the indirect pathway is inhibited by dopamine.

When the substantia nigra pars compacta is firing, it signals to the basal nuclei that the body is in an active state, and movement will be more likely. When the substantia nigra pars compacta is silent, the body is in a passive state, and movement is inhibited. To illustrate this situation, while a student is sitting listening to a lecture, the substantia nigra pars compacta would be silent and the student less likely to get up and walk around.

Watch this video to learn about the basal nuclei also known as the basal ganglia , which have two pathways that process information within the cerebrum. As shown in this video, the direct pathway is the shorter pathway through the system that results in increased activity in the cerebral cortex and increased motor activity. What does disinhibition mean?

What are the two neurons doing individually to cause this? As shown in this video, the indirect pathway is the longer pathway through the system that results in decreased activity in the cerebral cortex, and therefore less motor activity. The indirect pathway has an extra couple of connections in it, including disinhibition of the subthalamic nucleus. What is the end result on the thalamus, and therefore on movement initiated by the cerebral cortex?

There is some lateralization of function, in which the left side of the brain is devoted to language function and the right side is devoted to spatial and nonverbal reasoning.

Whereas these functions are predominantly associated with those sides of the brain, there is no monopoly by either side on these functions. Many pervasive functions, such as language, are distributed globally around the cerebrum. Some of the support for this misconception has come from studies of split brains.

A drastic way to deal with a rare and devastating neurological condition intractable epilepsy is to separate the two hemispheres of the brain. After sectioning the corpus callosum, a split-brained patient will have trouble producing verbal responses on the basis of sensory information processed on the right side of the cerebrum, leading to the idea that the left side is responsible for language function.

However, there are well-documented cases of language functions lost from damage to the right side of the brain. The deficits seen in damage to the left side of the brain are classified as aphasia, a loss of speech function; damage on the right side can affect the use of language.

Right-side damage can result in a loss of ability to understand figurative aspects of speech, such as jokes, irony, or metaphors. The diencephalon is the one region of the adult brain that retains its name from embryologic development. The rest of the brain, the spinal cord, and the PNS all send information to the cerebrum through the diencephalon. Output from the cerebrum passes through the diencephalon. The single exception is the system associated with olfaction , or the sense of smell, which connects directly with the cerebrum.

In the earliest vertebrate species, the cerebrum was not much more than olfactory bulbs that received peripheral information about the chemical environment to call it smell in these organisms is imprecise because they lived in the ocean.

The diencephalon is deep beneath the cerebrum and constitutes the walls of the third ventricle. The two major regions of the diencephalon are the thalamus itself and the hypothalamus [link]. There are other structures, such as the epithalamus , which contains the pineal gland, or the subthalamus , which includes the subthalamic nucleus that is part of the basal nuclei.

The thalamus is a collection of nuclei that relay information between the cerebral cortex and the periphery, spinal cord, or brain stem. All sensory information, except for the sense of smell, passes through the thalamus before processing by the cortex. Axons from the peripheral sensory organs, or intermediate nuclei, synapse in the thalamus, and thalamic neurons project directly to the cerebrum. It is a requisite synapse in any sensory pathway, except for olfaction.

The Central Nervous System Structure and Function

What exactly is the peripheral nervous system and what role does it play in the body? First, it is important to realize that the nervous system is divided into two parts: the central nervous system and the peripheral nervous system. The central nervous system includes the brain and spinal cord, while the peripheral nervous system includes all of the nerves that branch out from the brain and spinal cord and extend to other parts of the body including muscles and organs. Each part of the system plays a vital role in how information is communicated throughout the body. The peripheral nervous system PNS is the division of the nervous system containing all the nerves that lie outside of the central nervous system CNS.


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Central Nervous System

If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Please consult the latest official manual style if you have any questions regarding the format accuracy. The central nervous system is composed of the cerebral hemispheres, brain stem, cerebellum, and spinal cord.

The central nervous system CNS , working in tandem with the peripheral nervous system, allow the body to control and react to stimuli. In this article, we will look at the function, structure and clinical conditions associated with the central nervous system. The brain is responsible for generating our thoughts as well as interpreting information from the PNS and responding appropriately. This process is made possible by tracts of nerve cells in the Spinal Cord which connect the brain to the PNS. The tracts each have a different function and can be broadly split into Ascending and Descending.

Central nervous system

The brain and the spinal cord are the central nervous system, and they represent the main organs of the nervous system. The spinal cord is a single structure, whereas the adult brain is described in terms of four major regions: the cerebrum, the diencephalon, the brain stem, and the cerebellum. The regulation of homeostasis is governed by a specialized region in the brain. The coordination of reflexes depends on the integration of sensory and motor pathways in the spinal cord. The iconic gray mantle of the human brain, which appears to make up most of the mass of the brain, is the cerebrum [link].

In biology , the nervous system is a highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes that impact the body, then works in tandem with the endocrine system to respond to such events. The CNS consists of the brain and spinal cord. The PNS consists mainly of nerves , which are enclosed bundles of the long fibers or axons , that connect the CNS to every other part of the body. Nerves that transmit signals from the brain are called motor or efferent nerves, while those nerves that transmit information from the body to the CNS are called sensory or afferent. Spinal nerves serve both functions and are called mixed nerves. The PNS is divided into three separate subsystems, the somatic , autonomic , and enteric nervous systems.

Nervous system , organized group of cells specialized for the conduction of electrochemical stimuli from sensory receptors through a network to the site at which a response occurs. All living organisms are able to detect changes within themselves and in their environments. Changes in the external environment include those of light , temperature , sound , motion, and odour , while changes in the internal environment include those in the position of the head and limbs as well as in the internal organs. Once detected, these internal and external changes must be analyzed and acted upon in order to survive. As life on Earth evolved and the environment became more complex, the survival of organisms depended upon how well they could respond to changes in their surroundings. One factor necessary for survival was a speedy reaction or response.


A neuron has a cell body, dendrite, and axon. The cell body contains many of the organelles vital to maintain the cells structure and function, including the nucleus​.


The 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 the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric animals —i. It consists of a large nerve running from the anterior to the posterior, with the anterior end is enlarged into the brain. Not all animals with a central nervous system have a brain, although the large majority do. The rest of this article exclusively discusses the vertebrate central nervous system, which is radically distinct from all other animals.

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.

The nervous system controls bodily function by gathering sensory input, integrating that information internally, and communicating proper motor output. The nervous system allows organisms to sense, organize, and react to information in the environment. The basic unit of the nervous system is the neuron. Synapses form between the neurons, allowing them to communicate to other neurons or other systems in the body. The neurons responsible for taking information to the CNS are known as afferent neurons, while the neurons that carry the responses from the CNS to the PNS are known as efferent neurons. The human nervous system : The nervous system of the human body, including the brain and spinal cord central nervous system and all the nerves of the body peripheral nervous system.

The central nervous system CNS controls most functions of the body and mind. It consists of two parts: the brain and the spinal cord.

If your institution subscribes to this resource, and you don't have a MyAccess Profile, please contact your library's reference desk for information on how to gain access to this resource from off-campus. Please consult the latest official manual style if you have any questions regarding the format accuracy. The central nervous system is composed of the cerebral hemispheres, brain stem, cerebellum, and spinal cord.

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.

 А лучше еще быстрее.  - Стратмор положил трубку. Сьюзан стояла, завернувшись в мохнатое полотенце, не замечая, что вода капает на аккуратно сложенные веши, приготовленные накануне: шорты, свитер - на случай прохладных вечеров в горах, - новую ночную рубашку. Расстроенная, она подошла к шкафу, чтобы достать чистую блузку и юбку. Чрезвычайная ситуация.

Танкадо не собирался продавать свой алгоритм никакой компьютерной компании, потому что никакого алгоритма не. Цифровая крепость оказалась фарсом, наживкой для Агентства национальной безопасности. Когда Стратмор предпринимал какой-либо шаг, Танкадо стоял за сценой, дергая за веревочки.

Introduction to the Central Nervous System

 Это зашифрованный вирус, болван; ваше счастье, что вам не удалось его вскрыть. - Но… - Сделка отменяется! - крикнул Стратмор.  - Я не Северная Дакота. Нет никакой Северной Дакоты.

 Quiere Vd. Algo? - настаивал бармен.  - Fino.

Беккер оказался на прямом отрезке, когда вдруг улочка начала подниматься вверх, становясь все круче и круче.

Куда его понесло? - думала.  - Почему он не звонит. Вода из горячей постепенно превратилась в теплую и, наконец, холодную.

 - Стратмор уже солгал нам.  - Она окинула Бринкерхоффа оценивающим взглядом.  - У тебя есть ключ от кабинета Фонтейна. - Конечно.

Он крикнул парню: - Десять тысяч, если отвезете меня в аэропорт. Тот даже не повернул головы и выключил двигатель.

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That suggests it is made of two organs—and you may not even think of the spinal cord as an organ—but the nervous system is a very complex structure.

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