CNS Physiology-Critical thinking
1. Describe several mechanisms by which pain could theoretically be controlled medically or surgically.
2. At what two sites would central nervous system injuries interfere with the perception of heat applied to the right side of the body? At what single site would a central nervous system injury interfere with the perception of heat applied to either side of the body?
3. Damage to what parts of the cerebral cortex could explain the following behaviors? (a) A person walks into a chair placed in her path. (b) The person does not walk into the chair but does not know what the chair can be used for.
4. What changes would occur in the knee jerk reflex after destruction of the gamma motor neurons?
5. What changes would occur in the knee jerk reflex after destruction of the alpha motor neurons?
6. We have said that hypertonia is usually considered a sign of disease of the descending motor pathways, but how might it result from abnormal function of the alpha motor neurons?
7. Explain why patients given drugs to treat Parkinson’s disease sometimes develop symptoms similar to those of schizophrenia.
8. Explain how clinical observations of individuals with various aphasias help physiologists understand the neural basis of language.
9. Why is there very little white matter in the sacral spinal cord as compared to the cervical cord?
10. What is cordotomy? Why does it frequently fail to provide complete relief from pain?
11. What are tendon jerks and what is their physiological basis?
12. What is tone?
13. What is the difference between hypertonia and spasticity?
14. Explain how you can reach the tap in the bathroom even with your eyes closed.
15. Why is it more difficult to wake up a young person than an elderly person and a person during the first half of sleep than during the second half?
16. When Joni first stepped onto the sailboat, she smelled the tangy sea air and felt the motion of water beneath her feet. After a few minutes, she no longer noticed the smell, but unfortunately she was aware of the rolling motion for hours. What types of receptors are involved in smell and detection of motion? Why did her sensation of smell fade but the rolling sensation remain?
17. Monique sticks her left hand into a hot tub heated to about 43C (110F) in order to decide if she wants to enter. Trace the pathway involved in transmitting the sensation of heat from her left hand to the somatosensory area in the cerebral cortex.
18. Marvin has had trouble sleeping. Last night his mother found him sleepwalking and gently led him back to his bed. When Marvin was awakened by his alarm clock the next day, he had no recollection of sleepwalking and, in fact, told his mother about the vivid dreams he had. What specific stages of sleep did Marvin undergo during the night? What neurological mechanism awakened Marvin in the morning?
19. Smelling salts can sometimes help restore consciousness after a person has fainted. The active ingredient of smelling salts is ammonia, and it acts by irritating the lining of the nasal cavity. Propose a mechanism by which smelling salts would raise a person from the unconscious state to the conscious state.
20. A police officer has just stopped Bill on suspicion of driving while intoxicated. The officer asks Bill to walk the yellow line on the road and then to place the tip of his index finger on the tip of his nose. How would these activities indicate Bill’s level of sobriety? Which part of the brain is being tested by these activities?
21. Colleen falls down a flight of stairs and bumps her head several times. Soon after, she develops a headache and blurred vision. Diagnostic tests at the hospital reveal an epidural hematoma in the temporoparietal area. The hematoma is pressing against the brain stem. What other signs and symptoms might she experience as a result of the injury?
22. Cerebral meningitis is a condition in which the meninges of the brain become inflamed as the result of viral or bacterial infection. This condition can be life threatening. Why?
23. Infants have little to no control of the movements of their head. One of the consequences of this is that they are susceptible to shaken baby syndrome, caused by vigorous shaking of an infant or young child by the arms, legs, chest, or shoulders. Forceful shaking can cause brain damage leading to mental retardation, speech and learning disabilities, paralysis, seizures, hearing loss, and even death. Damage to which areas of the brain would account for the clinical signs observed in this syndrome?
24. Kayla is having difficulty controlling her eye movements and has lost some control of her facial muscles. After an examination and testing, Kayla’s physician tells her that her cranial nerves are perfectly normal but that a small tumor is putting pressure on certain fiber tracts in her brain. This pressure is the cause of Kayla’s symptoms. Where is the tumor most likely located?
25. Harry, a construction worker, suffers a fractured skull when a beam falls on his head. Diagnostic tests indicate severe damage to the motor cortex. His wife is anxious to know if he will ever be able to move or walk again. What would you tell her?
26. Denzel had to have his arm amputated at the elbow after an accident. He tells you that he can sometimes still feel pain in his fingers even though the hand is gone. He says this is especially true when he bumps the stub. How can this be?
27. Describe all the sensations and perceptions involved when a woman picks up an apple and bites into it. Explain which of these sensations are special and which are general. What types of receptors are involved?
28. Some student nurses are at a party. Because they love anatomy and physiology so much, they are discussing adaptation of the special senses. They make the following observations: a. When entering a room, people easily notice an odor, such as brewing coffee. A few minutes later, the odor might be barely detectable, if at all, no matter how hard they try to smell it. b. When entering a room, people can detect the sound of a ticking clock. Later the sound is not noticed until people make a conscious effort to hear it. Then the ticking is easy to hear. Explain the basis for each of these observations.
29. A patient suffered a loss of two-point discrimination and proprioception on the right side of the body. Voluntary movement of muscles was not affected, and pain and temperature sensations were normal. Is it possible to conclude that the right side of the spinal cord was damaged?
30. A patient has a lesion in the central core of the spinal cord. Physicians suspect that the fibers that decussate and are associated with the lateral spinothalamic tracts are affected in the area of the lesion. What observations are consistent with that diagnosis?
31. A person who was injured in a car accident exhibits the following symptoms: extreme paresis on the right side, including the arm and leg; reduction of pain sensation on the left side; and normal tactile sensation on both sides. Which tracts are damaged? Where in the spinal cord did the patient suffer tract damage?
32. A patient with a cerebral lesion exhibits loss of fine motor control of the left hand, arm, forearm, and shoulder. All other motor and sensory functions appear to be intact. Describe the location of the lesion as precisely as possible.
33. A patient suffers brain damage in an automobile accident. Physicians suspect that the cerebellum is the part of the brain affected. On the basis of what you know about cerebellar function, how can they confirm that the cerebellum is involved?
34. Woody Knothead was accidentally struck in the head with a baseball bat. He fell to the ground, unconscious. Later, when he regained consciousness, he could not remember any of the events that happened 10 minutes before the accident. Explain. What complications might develop at a later time?
35. Perry is a 93-year-old man who uses his computer to communicate with family and friends and to write poems and essays. One day last week, his daughter noticed that Perry was unable to use the computer keyboard normally with his right hand, and this ability deteriorated further over the next few hours. Perry was also experiencing muscle weakness on the right side, and soon he could not support himself with his right lower limb without using a cane; later in the day, he could hardly move his right lower limb at all. Concerned about a stroke, Perry’s daughter took him to the emergency room, where radiographs and an MRI revealed a subdural hematoma. Explain how a subdural hematoma could be responsible for Perry’s condition.