Transcutaneous electric nerve stimulator (TENS)
units produce electrical pulses via the skin to stim-
ulate the release of endorphins and enkephalins
within the CNS. These neurotransmitters help to
block pain signals from reaching the brain.
Migraine headaches are thought to involve areas of the
brain where the primary neurotransmitter is serotonin. Which pain medica-
tion might work best for this condition?
Jenny is 10 years old and has a cold. She fel from a step and twisted her
ankle, and her ankle is beginning to swel . Pediatricians do not recommend
giving children aspirin as it has been implicated in a deadly condition cal ed
Reye's syndrome. What medication might be best to give Jenny for the pain?
Pain Management
ealth providers vary their treatment of pain, depending on
the type of pain being experienced. Most pain can be man-
aged with medications (analgesics), which act at different places
in the somatosensory pathway:
• When an injury causes pain, damaged cells or immune cells
release certain products (such as bradykinin, prostaglan-
dins, and histamines) that activate nearby nociceptors.
Anti-inflammatory analgesics,
such as aspirin, ibuprofen,
acetaminophen, or naproxen, interfere with the enzymes
that make these products.
• A class of neurotransmitters called opioids (such as endor-
phin, dynorphin, and enkephalin) is responsible for synaptic
transmission in CNS pain pathways. At
the synapse,
opioid analgesics
as morphine, meperidine, oxycodone,
and codeine) bind to the opioid recep-
tors but do not activate them. Health
providers use opioid analgesics to treat
high levels of pain. Opioid analgesics
can become addictive and are easily
overdosed; therefore, health providers
must closely monitor their use.
• Pain relievers called
adjuvant analgesics
are used to treat other
conditions and also help relieve pain.
For example,
anti-epileptic drugs
as phenytoin) reduce the ability of CNS
neurons to conduct action potentials.
cyclic antidepressants
(such as amitripty-
line) block synaptic transmission involving the neurotransmit-
ter serotonin.
(such as lidocaine and benzocaine)
block sodium and potassium channels, thereby preventing
propagation of action potentials; most are applied topical y or
injected locally to relieve pain.
Other therapies can also be used to manage chronic pain without
the use of medications or in conjunction with smaller doses of
pain medications:
• Physical therapy involves a series of exercises, massage, ther-
mal stimulation, and electrotherapy to release muscle tension
and build muscle strength that can help to relieve pain caused
by pressure on peripheral nerves.
• Acupuncture and acupressure techniques involve the inser-
tion of needles or application of pressure to strategic parts
of the body, which helps to relieve pain in other parts of the
body The areas stimulated by the techniques share the spi-
nal segments with the area that will ultimately be “treated”
by the procedure.
• Biofeedback can sometimes be used to help patients man-
age chronic pain by helping individuals learn to control the
impact of the pain on their daily lives.
V id e o
What a Health Provider Sees
highlights a concept
or phenomenon and examines it from a clinical point
of view. Photos and figures are used to compare how a
nonscientist and a scientist see the issues, and students
apply their observational and critical thinking skills to
answer questions.
Numerous additional clinical applications
are presented as examples in
content modules for each chapter. These engaging
discussions of a wide variety of clinical scenarios from
disease coverage to tests and procedures fully engage
students in the material and help them comprehend
the relevance of understanding normal anatomy and
Think Critically
questions encourage
students to analyze the
material and develop
insights into essential
Coordinated with the
, at the end of
each section
Concept Check
questions allow students to
test their comprehension of
the learning objectives.
At the end of each learning objective module,
students can assess their progress with independent
practice opportunities and quizzes. This feature gives them the
ability to gauge their comprehension and grasp of the material.
Practice tests and quizzes help students self-monitor and prepare
for graded course assessments.
Preface ix
previous page 10 Craig Freudenrich, Gerard J  Tortora   Visualizing Anatomy and Physiology   2011 read online next page 12 Craig Freudenrich, Gerard J  Tortora   Visualizing Anatomy and Physiology   2011 read online Home Toggle text on/off