The Nervous System Terminology PDF

The Nervous System Terminology  Overview of STRUCTURES, COMBINING FORMS, AND FUNCTIONS OF THE NERVOUS SYSTEM Brain, cerebr/o, encephal/o; Coordinates all body activities by receiving and transmitting messages throughout the body. Spinal Cord, myel/o; Transmits nerve impulses...

The Nervous System Terminology  Overview of STRUCTURES, COMBINING FORMS, AND FUNCTIONS OF THE NERVOUS SYSTEM Brain, cerebr/o, encephal/o; Coordinates all body activities by receiving and transmitting messages throughout the body. Spinal Cord, myel/o; Transmits nerve impulses between the brain, arms and legs, and lower part of the body. Nerves neur/i, neur/o; Receive and transmit messages to and from all parts of the body. Sensory Organs and Receptors ; Receive external stimulation and transmit these stimuli to the sensory neurons. (Eyes: Oculo, Ears: Oto, Nose: Naso, Skin(touch): dermato, Tongue (taste); Lingua 2 STRUCTURES OF THE NERVOUS SYSTEM The major structures of the nervous system ○ The nerves ○ Brain ○ Spinal cord ○ Sensory organs. 3 Divisions of the Nervous System Two primary parts: ○ Central nervous systems ○ Peripheral nervous systems The central nervous system (CNS); ○ the brain ○ spinal cord. The peripheral nervous system (PNS); ○ the 12 pairs of cranial nerves extending from the brain ○ the 31 pairs of peripheral spinal nerves extending outward from the spinal cord. 4 The Nerves A nerve; one or more bundles of neuronal extensions that connect the brain and the spinal cord with other parts of the body. A tract; a bundle or group of nerve fibers located within the brain or spinal cord. Ascending nerve tracts; carry nerve impulses toward the brain. Descending nerve tracts; carry nerve impulses away from the brain. 5 The Nerves A ganglion; a nerve center made up of a cluster of nerve cell bodies outside the central nervous system (plural, ganglia or ganglions). The term innervation; the supply of nerves to a specific body part. A reflex; an automatic, involuntary response to some change, either inside or outside the body. ○ Examples; Changes in the heart rate, breathing rate, and blood pressure Coughing and sneezing, Responses to painful stimuli, Deep tendon reflexes. 6 The Nerves A plexus; a network of intersecting spinal nerves (plural, plexuses) ○ Also, a network of intersecting blood or lymphatic vessels. Receptors; sites in the sensory organs (eyes, ears, skin, nose, and taste buds) that receive external stimulation. A stimulus; anything that excites (activates) a nerve and causes an impulse (plural,stimuli). An impulse; a wave of excitation transmitted through nerve fibers and neurons. Neurons; the basic cells of the nervous system ○ Allow different parts of the body to communicate with each other. 7 Neuron Parts The dendrites; the root-like processes that receive impulses and conduct them to the cell body. The axon; a process that conducts impulses away from the nerve cell. ○ Protected by a myelin sheath, which is a white fatty tissue covering. Terminal end fibers; the branching fibers at the end of the axon ○ Lead the nervous impulse from the axon to the synapse. A synapse; the space between two neurons or between a neuron and a receptor organ. Neurotransmitters; chemical substances that transmit the messages from a neuron to the target receptor. 8  Glial cells; support and protect neurons A myelin sheath; the protective covering made up of glial cells. The portion of the nerve fibers that are myelinated are known as white matter. The portion of the nerve fibers that are unmyelinated are known as gray matter. 9  THE CENTRAL NERVOUS SYSTEM The brain, spinal cord The Meninges The meninges; Membranes that enclose the brain and spinal cord (singular meninx). Cerebrospinal fluid; produced by special capillaries within the four ventricles located in the middle region of the cerebrum. ○ A clear, colorless, and watery fluid that flows throughout the brain and around the spinal cord. 10 Cerebrum Cerebrum; the largest and uppermost portion of the brain. ○ thought, judgment, memory, emotion, ○ also, controlling and integrating motor and sensory functions. Cerebral; pertaining to the cerebrum or to the brain Cerebral cortex; made up of gray matter, is the outer layer of the cerebrum and is made up of elevated folds and deep fissures Gyri (singular gyrus); the elevated folds in the cerebral cortex. Sulci; the fissures (grooves) of the cerebral cortex. 11 The Cerebral Hemispheres The left cerebral hemisphere controls the majority of functions on the right side of the body. The right cerebral hemisphere controls most of the functions on the left side of the body. The crossing of nerve fibers that makes this arrangement possible occurs in the brainstem. The Cerebral Lobes The frontal lobe controls skilled motor functions, memory, and behavior. The parietal lobe receives and interprets nerve impulses from sensory receptors in the tongue, skin, and muscles. The occipital lobe controls eyesight. The temporal lobe controls the senses of hearing and smell, and the ability to create, store, and access new information. 12  The cerebellum; the second largest part of the brain. ○ At the back of the head below the posterior portion of the cerebrum ○ Produce smooth and coordinated movements, to maintain equilibrium, and to sustain normal postures. The spinal cord; a long, fragile tube-like structure that begins at the end of the brainstem and continues down almost to the bottom of the spinal column ○ Contains all the nerves that affect the limbs and lower part of the body ○ Serves as the pathway for impulses traveling to and from the brain. 13 THE PERIPHERAL NERVOUS SYSTEM 12 pairs of cranial nerves that extend from the brain 31 pairs of spinal nerves that extend from the spinal cord. Peripheral; pertaining to body parts that are away from the center of the body. Three types of specialized peripheral nerves; autonomic, sensory, and somatic nerve fibers. Autonomic nerve fibers carry instructions to the organs and glands from the autonomic nervous system. Sensory nerve fibers receive external stimuli, such as how something feels, and transmit this information to the brain where it is interpreted. Somatic nerve fibers, which are also known as motor nerve fibers, convey information that controls the body’s voluntary muscular movements. 14 The Cranial Nerves The 12 pairs of cranial nerves originate from the under surface of the brain. The Peripheral Spinal Nerves The 31 pairs of peripheral spinal nerves are grouped together and named based on the region of the body they innervate. ○ C1–C8, the cervical nerves ○ T1–T12, the thoracic nerves ○ L1–L5, the lumbar nerves ○ S1–S5, the sacral nerves Spinal nerves sometimes join with others to form a plexus to innervate a certain area. ○ The lumbar plexus is made up of the first four lumbar nerves (L1–L4) and serves the lower back. 15 16 17  PATHOLOGY OF THE NERVOUS SYSTEM Cephalalgia; also known as a headache, is pain in the head. Hydrocephalus; a condition in which excess cerebrospinal fluid accumulates in the ventricles of the brain. Meningitis; an inflammation of the meninges Dementia; a slowly progressive decline in mental abilities ( memory, thinking, and judgment) ○ Senile dementia is dementia of the aged. Encephalitis; an inflammation of the brain Alzheimer’s disease; a group of disorders involving the parts of the brain that control thought, memory, and language. ○ The leading cause of dementia Parkinson’s disease (PD); a chronic, degenerative central nervous disorder characterized by fine muscle tremors, rigidity, and a slow gait. Amnesia; a memory disturbance characterized by a total or partial inability to recall past experiences. Syncope, also fainting; the brief loss of consciousness caused by the decreased flow of blood to the brain. 18 Strokes A stroke, or CVA, a cerebrovascular accident; the blood flow to the brain is disrupted because a blood vessel is either blocked or has ruptured. 19