1. CHAPTER 8
Nervous System

2. Nervous System Overview
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 Pia mater 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 Defined (ALTS-high-merz dih-ZEEZ)
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 Defined (an-en-SEFF-ah-lee)
Absence of the brain and spinal cord at birth
Condition is incompatible with life

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

24. Brain Abscess Pronounced Defined (BRAIN AB-sess)
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 Defined (seh-REE-bral con-KUSH-un)
Brief interruption of brain function usually with loss of consciousness lasting for a few seconds

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

28. Cerebral Palsy Pronounced Defined (seh-REE-bral PAWL-zee)
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 Ataxic Damage to cortex of the brain
Tense muscles
Very irritable muscle tone
Ataxic
Damage to cerebellum
Affects equilibrium

30. Cerebral Palsy Athetoid Rigidity Mixed cerebral palsy
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 Defined (deh-JEN-er-ah-tiv disk)
Deterioration of the intervertebral disk
Usually due to constant motion and wear on the disk

34. Encephalitis Pronounced Defined (En-seff-ah-LYE-tis)
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 Defined (EP-ih-lep-see)
Syndrome of recurring episodes of excessive irregular electrical activity of the central nervous system, called seizures

36. Grand Mal Seizure Pronounced Defined (grand MALL SEE-zyoor)
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 Defined (pet-EE MALL SEE-zyoor)
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-RAY SIN-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 Defined (MY-grain headache)
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 Defined (KLUSS-ter headache)
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 Defined (TEN-shun headache)
Headache that occurs from long, endured contraction of the skeletal muscles around the face, scalp, upper back, and neck

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

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

45. Herniated Disk Pronounced Defined (HER-nee-ay-ted disk)
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 Defined (HUNT-ing-tonz koh-REE-ah)
Inherited neurological disease characterized by rapid, jerky, involuntary movements and increased dementia
Progressive, degenerative disease

47. Hydrocephalus Pronounced Defined (high-droh-SEFF-ah-lus)
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 Defined (in-trah-KRAY-nee-al TOO-morz)
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