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Nervous System

Nervous System

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Nervous System

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  1. Nervous System CHAPTER 8

  2. Nervous System Overview • Nervous System • Brain • Spinal cord • Nerves • Functions of nervous system • Regulates and coordinates all body activities • Center of all mental activity, including thought, learning, and memory

  3. Nervous System Divisions • Central Nervous System (CNS) • Brain • Spinal Cord • Processes and stores sensory and motor information • Controls consciousness

  4. Nervous System Divisions • Peripheral Nervous System (PNS) • 12 Pairs of Cranial Nerves • 31 Pairs of Spinal Nerves • Transmits sensory and motor impulses back and forth between CNS and rest of body

  5. Nervous System Divisions

  6. Peripheral Nervous System • Afferent (sensory) nerves • Carry impulses from the body to the central nervous system • Efferent (motor) nerves • Carry impulses from the central nervous system to muscles and glands • Cause the target organs to do something in response to commands

  7. Peripheral Nervous System • Somatic Nervous System (SNS) • Provides voluntary control over skeletal muscle contractions • Autonomic Nervous System (ANS) • Provides involuntary control over smooth muscle, cardiac muscle, and glandular activity and secretions in response to the commands of the central nervous system

  8. Autonomic Nervous System • Sympathetic nerves • Increase heart rate • Constrict blood vessels • Raise blood pressure • Fight-or-flight response • Parasympathetic nerves • Slow heart rate • Increase peristalsis of intestines • Increase glandular secretions • Relax sphincters

  9. Cells of the Nervous System • Neuron • Cell body • Contains the nucleus and cytoplasm • Axon • Conducts impulses away from the cell body • Some axons are covered with a myelin sheath • Dendrite • Conducts impulses toward the cell body • Synapse • Space between two nerves which the impulse must cross

  10. Cells of the Nervous System

  11. Cells of the Nervous System • Neuroglia • Connective tissue • Support system for neurons • Do not conduct impulses • Protect nervous system through phagocytosis • Types of Neuroglia Cells • Astrocytes • Microglia • Oligodendrocytes

  12. Central Nervous System • Brain • Surrounded by bone for protection • Enclosed in cranium • Spinal cord • Surrounded by vertebrae for protection • Surrounded by meninges and cerebrospinal fluid

  13. Meninges • Dura mater • Outermost layer of meninges • Tough, white connective tissue • Epidural space • Located outside of the dura mater • Contains supporting cushion of fat and connective tissue • Subdural space • Located beneath the dura mater • Cavity is filled with serous fluid

  14. Meninges • Arachnoid membrane • Middle layer of the meninges • Resembles a spider web • Subarachnoid space immediately beneath • Contains cerebrospinal fluid • Pia mater • Innermost layer of the meninges • Tightly bound to the surface of the brain and spinal cord

  15. Structures of the Brain • Cerebrum • Largest and uppermost portion of the brain • Controls consciousness, memory, sensations, emotions, voluntary movements • Cortex = outer surface • Gyri = elevations • Sulci = grooves • Longitudinal fissure divides cerebrum into two hemispheres

  16. Structures of the Brain • Cerebellum • Attached to the brain stem • Maintains muscle tone • Coordinates normal movement and balance • Diencephalon • Located between cerebrum and midbrain • Consists of thalamus, hypothalamus, and pineal gland

  17. Structures of the Brain • Brain Stem • Region between diencephalon and spinal cord • Consists of midbrain, pons, and medulla oblongata • Serves as pathway for impulses between brain and spinal cord • Controls respiration, blood pressure, and heart rate

  18. Spinal Cord • Pathway for impulses traveling to and from brain • Carries 31 pairs of spinal nerves • Affects limbs and lower part of body

  19. PATHOLOGICAL CONDITIONS Nervous System

  20. Alzheimer’s Disease • Pronounced • (ALTS-high-merz dih-ZEEZ) • Defined • Progressive and extremely debilitating deterioration of a person’s intellectual functioning

  21. Amyotrophic Lateral Sclerosis (ALS) • Pronounced • (ah-my-oh-TROFF-ik LAT-er-al skleh-ROH-sis) • Defined • Severe weakening and wasting of the involved muscle groups • Usually begins with hands • Progresses to shoulders, upper arms, then legs

  22. Anencephaly • Pronounced • (an-en-SEFF-ah-lee) • Defined • Absence of the brain and spinal cord at birth • Condition is incompatible with life

  23. Bell’s Palsy • Pronounced • (BELLZ PAWL-zee) • Defined • Temporary or permanent unilateral weakness or paralysis of muscles in the face

  24. Brain Abscess • Pronounced • (BRAIN AB-sess) • Defined • Accumulation of pus located anywhere in the brain tissue

  25. Carpal Tunnel Syndrome • Pronounced • (CAR-pal TUN-el SIN-drom) • Defined • Pinching or compression of median nerve within the carpal tunnel • Inflammation and swelling of tendons cause intermittent or continuous pain

  26. Cerebral Concussion • Pronounced • (seh-REE-bral con-KUSH-un) • Defined • Brief interruption of brain function usually with loss of consciousness lasting for a few seconds

  27. Cerebral Contusion • Pronounced • (seh-REE-bral con-TOO-zhun) • Defined • Small, scattered venous hemorrhages in the brain • Bruise of the brain tissue • Occurs when brain strikes the inner skull

  28. Cerebral Palsy • Pronounced • (seh-REE-bral PAWL-zee) • Defined • Collective term used to describe congenital brain damage that is permanent but not progressive • Characterized by the child’s lack of control of voluntary muscles

  29. Cerebral Palsy • Spastic • Damage to cortex of the brain • Tense muscles • Very irritable muscle tone • Ataxic • Damage to cerebellum • Affects equilibrium

  30. Cerebral Palsy • Athetoid • Damage to basal ganglia • Causes sudden jerking • Rigidity • Causes child to be in continual state of tension • Mixed cerebral palsy

  31. Cerebrovascular Accident (CVA) • Pronounced • (seh-REE-broh-VASS-kyoo-lar AK-sih-dent) • Defined • Death of a specific portion of brain tissue • Results from decreased blood flow to that area of the brain • Also called a stroke

  32. Cerebrovascular Accident • Causes • Transient ischemic attacks (TIAs) • Also known as mini strokes • Cerebral thrombosis • Occurs largely in individuals older than 50 • Cerebral embolism • Embolus causes an occlusion • Cerebral hemorrhage • Cerebral vessel ruptures

  33. Degenerative Disk • Pronounced • (deh-JEN-er-ah-tiv disk) • Defined • Deterioration of the intervertebral disk • Usually due to constant motion and wear on the disk

  34. Encephalitis • Pronounced • (En-seff-ah-LYE-tis) • Defined • Inflammation of the brain or spinal cord tissue • Virus enters CNS when person experiences viral disease such as mumps, measles, or through tick or mosquito bite

  35. Epilepsy • Pronounced • (EP-ih-lep-see) • Defined • Syndrome of recurring episodes of excessive irregular electrical activity of the central nervous system, called seizures

  36. Grand Mal Seizure • Pronounced • (grand MALLSEE-zyoor) • Defined • Epileptic seizure characterized by sudden loss of consciousness and generalized involuntary muscular contraction • Vacillates between rigid body extension and an alternating contracting and relaxing of muscles

  37. Petit Mal Seizure • Pronounced • (pet-EE MALL SEE-zyoor) • Defined • Small seizures in which there is a sudden, temporary loss of consciousness • Lasts only a few seconds • Also known as absence seizures

  38. Guillain-Bàrré Syndrome • Pronounced • (GEE-yon bah-RAYSIN-drom) • Defined • Acute polyneuritis of the peripheral nervous system • Myelin sheaths on the axons are destroyed • Decreased nerve impulses • Loss of reflex response • Sudden muscle weakness • Usually follows viral gastrointestinal or respiratory infection

  39. Headache (Cephalalgia) • Pronounced • (seff-ah-LAL-jee-ah) • Defined • Pain anywhere within the cranial cavity varying in intensity from mild to severe • May be chronic or acute • May occur as result of a disease process • May be totally benign

  40. Migraine Headache • Pronounced • (MY-grain headache) • Defined • Recurring, pulsating, vascular headache developing on one side of the head • Characterized by slow onset • May be preceded by an aura during which sensory disturbance occurs

  41. Cluster Headache • Pronounced • (KLUSS-ter headache) • Defined • Headache occurring typically two to three hours after falling asleep • Described as extreme pain around one eye that wakens the person from sleep

  42. Tension Headache • Pronounced • (TEN-shun headache) • Defined • Headache that occurs from long, endured contraction of the skeletal muscles around the face, scalp, upper back, and neck

  43. Epidural Hematoma • Pronounced • (eh-pih-DOO-ral hee-mah-TOH-mah) • Defined • Collection of blood located above the dura mater and just below the skull

  44. Subdural Hematoma • Pronounced • (sub-DOO-ral hee-mah-TOH-mah) • Defined • Collection of blood below the dura mater and above the arachnoid layer of the meninges

  45. Herniated Disk • Pronounced • (HER-nee-ay-ted disk) • Defined • Rupture or herniation of the disk center through the disk wall and into the spinal canal • Causes pressure on the spinal cord or nerve roots

  46. Huntington’s Chorea • Pronounced • (HUNT-ing-tonz koh-REE-ah) • Defined • Inherited neurological disease characterized by rapid, jerky, involuntary movements and increased dementia • Progressive, degenerative disease

  47. Hydrocephalus • Pronounced • (high-droh-SEFF-ah-lus) • Defined • Abnormal increase of cerebrospinal fluid in the brain that causes the ventricles of the brain to dilate • Results in increased head circumference in infant with open fontanel • Congenital disorder

  48. Intracranial Tumors • Pronounced • (in-trah-KRAY-nee-al TOO-morz) • Defined • Tumors occurring in any structural region of the brain • May be malignant or benign • Classified as primary or secondary • Named according to the tissue from which they originate

  49. Primary Intracranial Tumors • Pronounced • (PRIGH-mah-ree in-trah-KRAY-nee-al TOO-morz) • Defined • Tumors that arise from gliomas and the meninges • Gliomas = malignant glial cells that are a support for nerve tissue

  50. Primary Intracranial Tumors • Glioblastoma multiforme • Most rapidly growing of the gliomas • Astrocytomas • Tend to invade surrounding structures • Ependymomas • Occur more commonly in children and adolescents • Usually encapsulated and benign