HUMAN BIOLOGY

264 Chapter 13

CritiCaL thinKing

1. Meningitis is an inflamma tion of the membranes that cover
   the brain and spinal cord. Diagnosis involves making a
   “spinal tap” (lumbar puncture) and analyzing a sample of
   cerebrospinal fluid for signs of infection. Why analyze this
   fluid and not blood?


2. In newborns and premature babies, the blood–brain barrier
   is not fully developed. Explain why this might be reason
   enough to pay careful attention to their diet.


3. In PET scans, red areas are brain regions that are most active,
   while blue, yellow, and green areas are least active. Figure
   13.28 shows PET scans of normal brain activity (left) and of
   the brain of a person while using cocaine (right). The frontal
   lobes of the brain hemispheres are toward the top of the
   scans. Their neurons play major roles in reasoning and other
   intellectual functions. Looking at these scan images, how do
   you suppose cocaine may affect mental functioning?

For the most part, the adult brain can’t

replenish neurons damaged by injury

or disease. The only known exceptions

have been glial cells that act like stem

cells in the hippocampus (Section

13.10), which is a center for aspects

of learning and memory. Recently,

however, scientists discovered that

glial cells called ependymal cells, which normally help produce

cerebrospinal fluid, may have a dormant capacity to revert

to stem cells and give rise to new neurons. The search is on

for chemical triggers that can stimulate this stem cell activity.

The goal is to unlock mechanisms for self-repair in the brain—

and potentially develop powerful new therapies for restoring

damaged brain functions.

seLF-Quiz Answers in Appendix VI your Future

1. The nervous system senses, interprets, and issues
   commands for responses to.


2. A neuron responds to adequate stimulation with ,
   a type of self-propagating signal.


3. When action potentials arrive at a synapse between a
   neuron and another cell, they stimulate the release of
   molecules of a that diffuse over to that cell.


4. In the simplest kind of reflex, directly signal ,
   which act on muscle cells.
   a. sensory neurons; interneurons
   b. interneurons; motor neurons
   c. sensory neurons; motor neurons
   d. motor neurons; sensory neurons


5. The accelerating flow of ions through gated
   channels across the membrane triggers an action potential.
   a. potassium
   b. sodium
   c. hydrogen
   d. a and b


6. nerves slow down the body overall and divert
   energy to housekeeping tasks; nerves slow down
   housekeeping tasks and increase overall activity during
   times of heightened awareness, excitement, or danger.
   a. Autonomic; somatic
   b. Sympathetic; parasympathetic
   c. Parasympathetic; sympathetic


7. The three meninges are membranes of tissue that
   .
   a. muscle; physically support the brain hemispheres
   b. connective; help protect the brain and spinal cord
   c. adipose; directly cushion the brain and spinal cord


8. Cerebrospinal fluid _____.
   a. fills cavities and canals in the brain and spinal cord
   b. is chemically similar to blood plasma
   c. cushions both the brain and spinal cord
   d. both a and c, but not b
   e. a, b, and c


9. Match each region of the central nervous system with some
   of its functions.
   spinal cord a. receives sensory input,
   medulla integrates it with stored
   oblongata information, coordinates
   hypothalamus motor responses
   limbic system b. monitors internal organs and
   cerebral cortex related behavior (e.g., hunger)
   c. governs emotions
   d. coordinates reflexes
   e. makes reflex connections
   for limb movements,
   internal organ activity Figure 13.28^ crack cocaine has major effects on the brain. PET
   scans of normal and cocaine-addicted brains (left and center).
   (Left: Science Source; Right: Ogden Gigli/Science Source)

© From Neuro Via Clinical Research Program, Minneapolis Medical Center

Copyright 2016 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).