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CHAPTER 8

CHAPTER 8. Nervous System. Nervous System Overview. Nervous system consists of: 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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CHAPTER 8

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  1. CHAPTER 8 Nervous System

  2. Nervous System Overview • Nervous system consists of: • 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. Question True or False: Basically, the central nervous system (CNS) is the command center, and the peripheral nervous system (PNS) is the messenger.

  7. 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

  8. 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

  9. Autonomic Nervous System • Sympathetic nerves • Increase heart rate • Constrict blood vessels • Raise blood pressure • Fight-or-flight response

  10. Autonomic Nervous System • Parasympathetic nerves • Slow heart rate • Increase peristalsis of intestines • Increase glandular secretions • Relax sphincters

  11. Question __________ nerves carry the impulses from the body to the CNS, while __________ nerves carry the impulses from the CNS to the body. • Somatic, autonomic • Afferent, efferent • Autonomic, somatic • Efferent, afferent

  12. 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

  13. Cells of the Nervous System • Neuron • Dendrite • Conducts impulses toward the cell body • Synapse • Space between two nerves which the impulse must cross

  14. Cells of the Nervous System

  15. Cells of the Nervous System • Neuroglia • Connective tissue • Support system for neurons • Do not conduct impulses • Protect nervous system through phagocytosis

  16. Cells of the Nervous System • Types of neuroglia cells • Astrocytes • Microglia • Oligodendrocytes

  17. 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

  18. 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

  19. Meninges • Dura mater • Subdural space • Located beneath the dura mater • Cavity is filled with serous fluid

  20. 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

  21. Structures of the Brain • Cerebrum • Largest and uppermost portion of the brain • Controls consciousness, memory, sensations, emotions, voluntary movements • Cortex = outer surface

  22. Structures of the Brain • Cerebrum • Gyri = elevations • Sulci = grooves • Longitudinal fissure divides cerebrum into two hemispheres

  23. 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

  24. 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

  25. Structures of the Brain

  26. Structures of the Brain

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

  28. Question Which part of the brain enables you to read this question and answer it correctly? • cerebrum • cerebellum • brain stem • meninges

  29. PATHOLOGICAL CONDITIONS Nervous System

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

  31. 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

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

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

  34. Brain Abscess • Pronounced • (BRAINAB-sess) • Defined • Accumulation of pus located anywhere in the brain tissue

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

  36. Question True or False: The breakdown of the word anencephaly is an = without or not, encephal– = skull, and –y makes it a noun.

  37. 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

  38. 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

  39. 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

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

  41. Cerebral Palsy • Athetoid • Damage to basal ganglia • Causes sudden jerking • Rigidity • Causes child to be in continual state of tension • Mixed cerebral palsy • Combination of the 3 types

  42. Question Why is the disease called cerebral palsy instead of cerebellar palsy? • It involves involuntary muscle. • It is all in the patient's head. • It doesn't sound as good. • It involves voluntary muscle.

  43. 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

  44. Cerebrovascular Accident • Causes • Transient ischemic attacks (TIAs) • Also known as mini strokes • Cerebral thrombosis • Occurs largely in individuals older than 50

  45. Cerebrovascular Accident • Causes • Cerebral embolism • Embolus causes an occlusion • Cerebral hemorrhage • Cerebral vessel ruptures

  46. 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

  47. 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

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

  49. 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

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

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