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Nervous System

Nervous System. CHAPTER 8. 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. Nervous System Divisions.

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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

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