Your nervous system consists of the brain, spinal cord, and nerves that run throughout your body. The nervous system carries messages to your muscles and organs. These messages tell your body what to do.
Your spinal cord is made of bundles of nerves. It starts in your neck and goes down your back. Nerves go out from the spinal cord to other parts of your body. Nerves from the spinal cord extend to the tips of your fingers and toes. Your spine, or backbone, protects your spinal cord.
The central nervous consists of the brain and spinal cord, which occupy the dorsal body cavity and act as the integrating and command centers of the nervous system. They interpret incoming sensory information and issue instructions based on past experience and current conditions.
The central nervous system (CNS) represents the largest part of the nervous system, including the brain and the spinal cord.
The brain is the largest and most complex mass of the nervous tissue in the body, its four major regions – cerebral hemispheres, diencephalons, brain stem and cerebellum.
Your brain is made of about 100 billion nerve cells. It looks like a lump of pinkish-gray jelly. Your brain is protected by bone called your skull. Liquid and skin like tissues also protect your brain.
paralysis agitans , Parkinson's , Parkinson's disease , Parkinson's syndrome , Parkinsonism , shaking palsy - a degenerative disorder of the central nervous system characterized by tremor and impaired muscular coordination
cerebral palsy, spastic paralysis - a loss or deficiency of motor control with involuntary spasms caused by permanent brain damage present at birth
agnosia - inability to recognize objects by use of the senses
CJD, Creutzfeldt-Jakob disease , Jakob-Creutzfeldt disease - rare (usually fatal) brain disease (usually in middle age) caused by an unidentified slow virus; characterized by progressive dementia and gradual loss of muscle control
Reye's syndrome - acquired encephalopathy following acute viral infections (especially influenza or chicken pox) in young children; characterized by fever, vomiting, disorientation, coma, and fatty infiltration of the liver
Thus, it conveys to higher centers information brought to it by peripheral nerves from many parts of the body; in addition, it is acted on by impulses from the brain itself. The spinal cord relays impulses also to the muscles, blood vessels, and glands by means of outgoing nerves, either in response to incoming stimuli or to signals from higher levels.
The PNS consists of all other nerves and neurons that do not lie within the CNS. The large majority of what are commonly called nerves (which are actually axonal processes of nerve cells) are considered to be PNS. The peripheral nervous system can be further classified either by direction of neurons and by function.
Effects of the Sympathetic and Parasympathetic divisions to Autonomic Nervous System Constricts blood vessels in viscera and skin ; increases blood pressure No effect on most blood vessels Blood vessels Increases rate and force of heartbeat Decreases rate; slows and steadies Heart Decreases urine output No effect Kidneys Constricts sphincters (prevent voiding) Relaxes sphincters (allows voiding) Urinary bladder/ urethra Dilates bronchioles Constricts bronchioles Lungs Causes glucose to be released to blood No effect Liver Decreases activity of digestive system ad constricts digestive system sphincters Increases smooth muscle mobility (peristalsis) and amount of secretion by digestive system glands; relaxes sphincters Digestive system Sympathetic effects Parasympathetic effects Target organ/system
Inhibits; result is dry mouth and dry eyes Stimulates; increases production of saliva and tears Glands – salivary, lacrimal Stimulates dilator muscles; dilates pupils Stimulates constrictor muscles; constricts pupils Eye (iris) Inhibits; decreases bulging of lens; prepares for distant vision Stimulates to increase bulging of lens for close vision Eye (ciliary muscle) Stimulates medulla cells to secrete epinephrine and norepinephrine No effect Adrenal medulla Stimulates to produce perspiration No effect Sweat glands of skin Stimulates; produces “ goose bumps” No effect Arrector pili muscles attached to hair follicles Causes ejaculation (emission of semen) Causes erection due to vasodilation Penis Increases metabolic rate; increases blood sugar levels; stimulates fat breakdown No effect Cellular metabolism