1. Anatomy and Physiology of the Human Body11
Anatomy and Physiology of the Human Body

2. 2 The Nervous System U N I T
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3. The Two Main Divisions of the Nervous System
Central nervous system (CNS)
Made up of the brain and spinal cord
Peripheral nervous system (PNS)
Made up of all the nerves that connect the CNS to every organ and area of the body
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4. Two Types of Peripheral Nerves
12 pairs of cranial nerves
Connect the brain directly to the sensory organs (eyes, ears, tongue, nose, and skin)
31 pairs of spinal nerves that act as:
Motor nerves to permit movement
Sensory nerves to perceive stimuli
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5. Simple and Complex Reflex Actions
Simple reflex actions
No interpretation or decision is required; the nerve impulse travels only to the spinal cord and back
Complex reflex actions
The impulse is relayed through the spinal cord to the brain and the brain interprets the sensory impulse and sends it back down the spine
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6. Synapses
A synapse is a minute space between the axon of one neuron and the dendrite of another.
These impulses release chemicals called neurotransmitters that either speed up or slow down the transmission.
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7. The Effect of Various Substances on the Action of a Synapse
Alcohol slows down reactions.
Stimulants speed up reactions.
Diseases can invade the body and neurotoxins from the bacteria are released that can cause contraction or paralysis of muscle groups.
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8. The Purpose of the Automatic Nervous System
As part of the peripheral nervous system, these nerves are involuntary and unconsciously control breathing, heartbeat, and digestion.
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9. The Action of the Two Divisions of the Autonomic Nervous System
The sympathetic nervous system begins at the base of the brain and runs down the spinal cord.
These nerves extend to all vital organs and blood vessels, the eyes, and the sweat glands.
(continued)
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10. The Action of the Two Divisions of the Autonomic Nervous System
The parasympathetic nervous system contains the vagus nerve and the pelvic nerve, which are affected by emotions.
The vagus nerve extends from the brain to the upper abdominal organs.
The pelvic nerve branches into the lower abdominal and pelvic organs.
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11. The Main Parts of the Brain and Their Functions
(continued)
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12. The Main Parts of the Brain and Their Functions
Cerebrum
Controls sensory and motor activities and is divided into lobes
Frontal lobe
Located behind the forehead; related to emotion and personality
Occipital lobe
Located at the far back of the cerebrum; related to vision
(continued)
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13. The Main Parts of the Brain and Their Functions
Temporal lobe
Located on the side of the cerebrum; associated with hearing and smell
Parietal lobe
Located between the frontal and occipital lobes; associated with movement in the hands, feet, and tongue as well as sensations of pain, heat, and cold
(continued)
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14. The Main Parts of the Brain and Their Functions
Cerebellum
Found beneath the cerebrum; responsible for smooth muscle movement and coordination
The medulla oblongata
Adjoins the spinal cord; influences the function of the heart and lungs, stomach secretions, and opening of blood vessels
(continued)
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15. The Main Parts of the Brain and Their Functions
Pons
Located just above the medulla; regulates breathing and is responsible for chewing, tasting, and the secretion of saliva
Midbrain
Located superior to the pons; control center for reflex movements and pupil dilation of the eyes
Thalamus
Located between the cerebrum and the midbrain; acts as a relay station for impulses going to and from the brain
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16. The Hypothalamus Located just below the thalamus Responsible for:
Controlling the autonomic nervous system
Controlling blood pressure
Maintaining body temperature
Stimulating hormones to conserve water and maintain water balance
Assisting in appetite regulation
Increasing intestinal secretions and motility
Playing a role in emotions such as fear & pleasure
Maintaining state of wakefulness
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17. The Coverings of the Brain and Spinal Cord and Their Purpose
The meninges are the coverings on the brain and the spinal cord
Made up of 3 layers:
Pia mater: inner layer contains nerve tissue
Arachnoid: middle layer made of delicate, lacelike membranes
Dura mater: outer layer that protects CNS from damage from contact with bony surfaces of the skull and spine
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18. The Function of Cerebrospinal Fluid
Cerebrospinal fluid (CSF) acts as a watery cushion or shock absorber to provide additional protection for the CNS.
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19. Common Diagnostic Tests
Arteriography
A catheter is inserted into an artery and then threaded up to the carotid artery in the neck.
A dye is injected to detect aneurysms, hemorrhage, arteriosclerosis, or to check for signs of a stroke.
(continued)
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20. Common Diagnostic Tests
Glasgow coma scale
Tool used to determine the level of unconsciousness
Assesses eye movement, verbal response, and motor response
Computerized axial tomography
Series of x-rays of the layers of the brain; makes a three-dimensional picture
Can identify tumors, bleeding, blood clots, disease, and edema
(continued)
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21. Common Diagnostic Tests
Electroencephalography
A brain wave test that measures the brain’s electrical signals, both normal and abnormal
Can detect abnormalities caused by epilepsy, tumors, strokes, head injuries, or infections
(continued)
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22. Common Diagnostic Tests
Electromyography
Uses electrical stimulation passed through small needles inserted into the muscle to demonstrate the electrical activity of peripheral muscles
Can diagnose disorders such as diabetic neuropathy and carpal tunnel syndrome
(continued)
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23. Common Diagnostic Tests
Lumbar puncture
A spinal needle is inserted into a small space in the lower back to remove small amounts of cerebrospinal fluid
Can help diagnose bleeding or infection and can measure fluid pressure in the spine
Myelography
After a lumbar puncture is performed, dye is instilled to outline the structures of the spinal cord to detect abnormalities of the spinal cord
(continued)
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24. Common Diagnostic Tests
Positron emission tomography
Uses agents, such as glucose or hormones; agents are mixed with chemicals and injected into the blood; records images of where the material ends up in the body
Can help diagnose epilepsy and Alzheimer’s disease
Skull x-rays
X-ray images of the bony structure of the skull to identify tumors and fractures
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25. Common Diseases and Disorders
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26. Alzheimer’s Disease
Progressive, degenerative disease that attacks the brain
Results in impaired memory, thinking, and behavior, as well as memory loss
8th leading cause of death in the United States
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27. Amyotrophic Lateral Sclerosis (Lou Gehrig’s Disease)
Fatal, progressive neurological disease that causes degeneration of motor neurons in the brain and spinal cord
Usually occurs between ages 40 and 70
Death occurs within 2 to 5 years of diagnosis
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28. Bell’s Palsy Disease that affects the 7th cranial nerve of the face
It occurs spontaneously and will usually subside spontaneously within 1 to 9 weeks.
Causes weakness or paralysis on one side of the face
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29. Cerebral Palsy
Nonprogressive brain injury that occurs during fetal development, perinatally, or in early infancy; affects muscle and brain development
Four forms of cerebral palsy include:
Spastic (50% to 75%)
Athetoid (15% to 20%)
Atonic (10%)
Mixed
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30. Encephalitis
Severe brain inflammation that causes edema and nerve cell destruction
Onset of fever, headache, vomiting, and stiffness in the neck and back is sudden and acute
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31. Epilepsy Seizure disorder that affects 1% to 2% of the population
Generally associated with abnormal electrical impulses from the neurons
Causes uncontrollable convulsions, loss of control of bodily functions, and unconsciousness
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32. Essential Tremor Most common movement disorder of the nervous system
Causes involuntary shaking of the hands and head, which is made worse by action or movement
Often confused with Parkinson’s disease
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33. Headache
Often classified as vascular, muscle contractions (tension), or traction (inflammatory)
Causes dull, persistent aching, and a feeling of a tight band around the head
Can be caused by stress, fatigue, or environment
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34. Migraine Headache Headache that causes severe throbbing pain
Beginning symptoms may include fatigue, visual disturbances, or sensory symptoms
Triggers that may initiate migraines are chocolate, red wine, and bright lights
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35. Herpes Zoster
Acute unilateral inflammation of the dorsal root ganglion
Causes fluid-filled vesicle lesions on the skin and severe pain from the affected nerves
The vesicles erupt in about 2 weeks
Episodes can last from 1 to 4 weeks.
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36. Hydrocephalus
Excess accumulation of cerebrospinal fluid within the ventricles of the brain
Occurs most commonly in newborns
Increase in fluid compresses the brain tissue against the skull and results in brain damage
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37. Meningitis Inflammation of the meninges of the brain and spinal cord
May be caused by a virus or bacteria
If untreated, mortality is 70% to 100% if it is bacterial meningitis.
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38. Multiple Sclerosis
Demyelinating disorder of the nervous system that affects the central nervous system; usually first diagnosed between ages 20 and 40
The disease attacks the myelin sheath of the nerves and destroys patches of tissue, which are replaced by scar tissue.
(continued)
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39. Multiple Sclerosis
The scar tissue distorts or interrupts the passage of the nerve impulse.
This results in paralysis, double vision, loss of balance, weakness, speech and hearing difficulties, foot dragging, numbness, and a sensation of pins and needles.
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40. Neuralgia Terms used to describe generalized nerve pain
Neuralgia causes severe pain along the course of the involved nerve or nerves.
Can be the result of pressure, nutrition, toxins, inflammation, or ganglial changes.
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41. Paralysis
Term used to describe temporary or permanent loss of voluntary function
Spastic paralysis
Caused by upper motor neurons
Flaccid
Caused by lower motor neurons
Can be caused by trauma or by the destruction of nerve tissue
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42. Hemiplegia
Term used to describe one-sided paralysis that results from brain damage
Damage to the left side of the brain will result in right-sided paralysis.
Damage to the right side of the brain will result in left-sided paralysis.
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43. Paraplegia
Term used to describe the loss of motor or sensory function in the lower extremities
Usually the result of trauma
Paralysis may be temporary or permanent, spastic or flaccid
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44. Quadriplegia
Devastating permanent paralysis that affects all body systems, the arms, the legs, and all of the body below the level of the injury to the spinal cord
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45. Parkinson’s Disease
Progressive, crippling disease that affects 1 in every 100 people over the age of 60
Parkinson’s disease affects more men than women
Main symptoms are muscle rigidity and hand tremors with a masklike facial expression
(continued)
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46. Parkinson’s Disease
Symptoms progress to include a peculiar gait, drooling, progressive tremors of the hands, and the head becomes bowed
Body bends forward and steps become faster and faster; often results in falling
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47. Reye’s Syndrome
Acute childhood illness characterized by fatty infiltration of the liver and increased intracranial pressure
Prognosis depends on the degree of CNS depression that results from the increased pressure
This syndrome almost always follows within 1 to 3 days of an acute viral infection, such as an upper respiratory infection or chickenpox.
A correlation exists with the use of aspirin in children and the flu and chickenpox.
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48. Sciatica
Term used to describe inflammation of the sciatic nerve of the leg
It is usually a unilateral pain that begins gradually and runs down the back of the thighs
Generally affects middle-age males
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49. Spinal Cord Defects
These defects result from the failure of the tissues of the spinal cord to properly close during the first trimester of pregnancy
Spina bifida occulta
Characterized by the incomplete closure of one or more vertebra without protrusion of the spinal cord or meninges
(continued)
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50. Spinal Cord Defects Spina bifida with meningocele Myelomeningocele
A sac protrudes from the opening that contains the meninges and cerebrospinal fluid
Myelomeningocele
In the sac that protrudes from the opening there is the meninges, CSF, and a portion of the spinal cord
(continued)
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51. Spinal Cord Defects
Treatment and prognosis depend on the location and extent of the spinal cord defect.
If CSF and meninges are involved, surgery is required to prevent further injury.
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52. Subarachnoid Hemorrhage
Term used to describe a collection of blood in the subarachnoid space usually caused be spontaneous rupture of a weakened blood vessel
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53. Subdural Hematoma
Term used to describe a collection of blood within the subdural space
This is generally a slow process in which the gradual accumulation of blood causes progressive symptoms of seizures, motor disturbances, and progressive weakness.
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54. Tourette Syndrome
Neurological disorder that is characterized by “tics,” involuntary, rapid, sudden movements that occur repeatedly
Onset is usually before the age of 21.
Some people may also vocalize unacceptable words or echo things just heard.
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55. Transient Ischemic Attacks
Recurring strokelike events that last from a few seconds to a few hours and then disappear after 12 to 24 hours
Considered to be a warning sign of an impending stroke
Characterized by double vision, slurred speech, dizziness, and falling
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56. Trigeminal Neuralgia
Disorder of the fifth cranial nerve on one side of the face
Produces episodes of excruciating pain on stimulation of a trigger zone
Frequently follows exposure to heat or cold
(continued)
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57. Trigeminal Neuralgia
Episodes may last from 1 to 15 minutes and recur from several times a day to a few times a year.
Occurs mostly in people over age 40 and affects more women than men
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58. Tumors
Abnormal masses that can occur anywhere in the body, but when the tumors are malignant and located in the brain, almost all limit life from 6 months to 6 years following diagnosis
Tumors are more common in men than in women.
Tumors are most prevalent between ages 40 and 60 in adults and ages 2 and 12 in children.
Symptoms vary with the size and location of the tumor.
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59. Unit Summary
Name the parts of the brain. What is the largest part of the brain?
What causes multiple sclerosis?
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