Each thought, each emotion, each action—all result from the activity of this system. Through its many parts, the nervous system monitors conditions both within and outside the body. It then processes that information and decides how the body should respond, if at all. Finally, if a response is needed, the system sends out electrical signals that spur the body into immediate action. Although one of the smallest of the body's systems in terms of weight, the nervous system is the most complex and versatile. DESIGN: PARTS OF THE NERVOUS SYSTEMThe nervous system is a collection of cells, tissues, and organs. It can be split into two separate divisions: the central nervous system and the peripheral nervous system. Diagnosis and treatment of chronic acquired demyelinating polyneuropathies. Norman Latov 1, Journal name: Nature Reviews Neurology Volume: 10, Pages. Disorders of malnutrition Chapter 12. Protein-energy malnutrition. Protein-energy malnutrition (PEM) in young children is currently the most important. The International Space Station (ISS) might be the perfect laboratory for developing antidotes to gases used in chemical warfare. Nerve agents such as sarin and VX. View our vast library of medical abbreviations & terminology, resources, articles, tips and other information about Tarlov Cyst Disease. ![]() The central nervous system (CNS) acts as the command center of the body. It interprets incoming sensory information, then sends out instructions on how the body should react. The CNS consists of two major parts: the brain and the spinal cord. The peripheral nervous system (PNS) is the part of the nervous system outside of the CNS. It consists mainly of nerves that extend from the brain and spinal cord to areas in the rest of the body. Cranial nerves carry impulses to and from the brain while spinal nerves carry impulses to and from the spinal cord. Electronic surveillance capabilities, extreme abuse of technology, securities and human rights. More than 100 years has passed since Charcot, Carswell, Cruveilhier, and others described the clinical and pathological characteristics of multiple sclerosis.1 This. The PNS can be divided into two systems: the somatic nervous system and the autonomic nervous system. The somatic nervous system controls the voluntary movements of the skeletal muscles. The autonomic nervous system control activities in the body that are involuntary or automatic. These include the actions of the heart, glands, and digestive organs and associated parts. The autonomic nervous system can be divided further into two subdivisions: the parasympathetic and sympathetic nervous systems. These two subdivisions work against each other. The parasympathetic nervous system regulates involuntary activities that keep the body running smoothly under normal, everyday conditions. The sympathetic nervous system controls involuntary activities that help the body respond to stressful situations. The Nervous System: Words to Know. Arachnoid (ah- RAK- noid): Weblike middle layer of the three meninges covering the brain and spinal cord. Autonomic nervous system (aw- toh- NOM- ik NERV- us SIS- tem): Part of the peripheral nervous system that controls involuntary actions, such as the heartbeat, gland secretions, and digestion. Axon (AK- son): Taillike projection extending out a neuron that carries impulses away from the cell body. Basal ganglia (BAY- zul GANG- lee- ah): Paired masses of gray matter within the white matter of the cerebrum that help coordinate subconscious skeletal muscular movement. Brain: Central controlling and coordinating organ of the nervous system. Cauda equina (KAW- da ee- KWHY- nah): Spinal nerves that hang below the end of the spinal cord. Central nervous system: Part of the nervous system consisting of the brain and spinal cord. Cerebral cortex (se- REE- bral KOR- tex): Outermost layer of the cerebrum made entirely of gray matter. Cerebrum (se- REE- brum): Largest part of the brain, involved with conscious perception, voluntary actions, memory, thought, and personality. Corpus callosum (KOR- pus ka- LOW- sum): Large band of neurons connecting the two cerebral hemispheres. Dendrites (DEN- drites): Branchlike extensions of neurons that carry impulses toward the cell body. Diencephalon (die- en- SEF- ah- lon): Rear part of the forebrain that connects the midbrain to the cerebrum and that contains the thalamus and hypothalamus. Dura mater (DUR- ah MAY- tur): Outermost and toughest of the three meninges covering the brain and spinal cord. Ganglion (GANG- glee- on): Any collection of nerve cell bodies forming a nerve center in the peripheral nervous system. Gray matter: Grayish nerve tissue of the central nervous system containing neuron cell bodies, neuroglia, and unmyelinated axons. Gyri (JYE- rye): Outward folds on the surface of the cerebral cortex. Hippocampus (hip- ah- CAM- pes): Structure in the limbic system necessary for the formation of long- term memory. Hypothalamus (hi- po- THAL- ah- mus): Region of the brain containing many control centers for body functions and emotions; also regulates the pituitary gland's secretions. Limbic system (LIM- bik SIS- tem): Group of structures in the cerebrum and diencephalon that are involved with emotional states and memory. Medulla oblongata (mi- DUL- ah ob- long- GAH- tah): Part of the brain located at the top end of the spinal cord that controls breathing and other involuntary functions. Meninges (meh- NIN- jeez): Membranes that cover the brain and spinal cord. Midbrain: Part of the brain between the hypothalamus and the pons that regulates visual, auditory, and rightening reflexes. Myelin (MY- ah- lin): Soft, white, fatty material that forms a sheath around the axons of most neurons. Nerve: Bundle of axons in the peripheral nervous system. Neuroglia (new- ROGUE- lee- ah): Also known as glial cells, cells that support and protect neurons in the central nervous system. Neuron (NUR- on): Nerve cell. Neurotransmitter (nur- oh- TRANS- mi- ter): Chemical released by the axon of a neuron that travels across a synapse and binds to receptors on the dendrites of other neurons or body cells. Node of Ranvier (NODE OF rahn- VEEAY): Small area between Schwann cells on an axon that is unmyelinated or uncovered. Oligodendrocyte (o- li- go- DEN- dro- site): Cell that produces the myelin sheath around the axons of neurons in the central nervous system. Parasympathetic nervous system (pair- ah- simpuh- THET- ik NERV- us SIS- tem): Division of the autonomic nervous system that controls involuntary activities that keep the body running smoothly under normal, everyday conditions. Peripheral nervous system (peh- RIFF- uh- ruhl NERV- us SIS- tem): Part of the nervous system consisting of the cranial and spinal nerves. Pia mater (PIE- ah MAY- tur): Delicate innermost layer of the three meninges covering the brain and spinal cord. Pons: Part of the brain connecting the medulla oblongata with the midbrain. Reflex (REE- flex): Involuntary and rapid response to a stimulus. Schwann cell (SHWAHN SELL): Cell that forms the myelin sheath around axons of neurons in the peripheral nervous system. Somatic nervous system (so- MAT- ik NERV- us SIS- tem): Part of the peripheral nervous system that controls the voluntary movements of the skeletal muscles. Spinal cord: Long cord of nerve tissue running through the spine or backbone that transmits impulses to and from the brain and controls some reflex actions. Sulci (SUL- sye): Shallow grooves on the surface of the cerebral cortex. Sympathetic nervous system (sim- puh- THET- ik NERV- us SIS- tem): Division of the autonomic nervous system that controls involuntary activities that help the body respond to stressful situations. Synapse (SIN- aps): Small space or gap where a nerve impulse passes between the axon of one neuron and a dendrite of the next neuron. Thalamus (THAL- ah- mus): Part of the brain behind the hypothalamus that acts as the brain's main relay station, sending information to the cerebral cortex and other parts of the brain. White matter: Whitish nerve tissue of the central nervous system containing bundles of myelinated axons. Neurons. The cells making up the brain, spinal cord, and nerves are called neurons. They are special cells capable of receiving a stimulus (nerve or electrical impulse), transmitting that stimulus throughout their length, and then delivering that stimulus to other cells next to them. The human body contains about 2. Almost half of them are located in the brain. A neuron consists of three main parts: the cell body, dendrites, and an axon (dendrites and axons are both referred to as nerve fibers). The cell body has most of the same structures found in typical body cells, such as a nucleus (the part of the cell that controls its activities). It is ball shaped, about 0. Dendrite comes from the Greek word dendron, meaning . Extensions of the cell body, they contain the same cytoplasm or cellular fluid found in the cell body. Dendrites are the points through which signals from adjacent neurons enter a particular neuron (the signal is then transmitted to the cell body). Since each neuron contains many dendrites, a neuron can receive signals from many other surrounding neurons. An axon is a taillike projection extending out of one end of the cell body. It ends in a cluster of branches called terminal branches or axon terminals. Axons have the opposite function of dendrites: they carry nerve impulses away from the cell body. Axons vary in length and diameter. Some (such as those in the central nervous system) are very short, no longer than 0. Others (such as those in the peripheral nervous system) can be 3 feet (1 meter) long. Most long axons are surrounded by a white, fatty material called myelin. The tubelike covering formed is known as a myelin sheath. It serves the same kind of function as the wrapping on a telephone line or an electrical cable. It protects the axon and prevents electrical impulses traveling through it from becoming lost. Special cells form the myelin sheath by wrapping themselves around the axons of neurons. In the CNS, the cells forming the myelin sheath are called oligodendrocytes. In the PNS, special cells known as Schwann cells form the myelin sheath. The gap or indentation on an axon where one Schwann cell ends and another begins is known as a node of Ranvier. The nodes are unmyelinated (lack a myelin sheath), and the nerve or electrical impulse jumps from node to node as it passes along an axon (in unmyelinated axons, the impulse travels continuously along the axon). Scientists believe Schwann cells produce a chemical that helps regenerate or restore damaged neurons in the peripheral nervous system. For example, if surgeons are able to reattach a person's severed hand, that person may regain some sensation and movement in that hand as neurons grow and make connections.
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