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Introduction to Body Function
Physiology Clinical Applications and Diagrams, Chapter 1
Part I. Clinical Applications
1. The hormone thyroxine is released in response to a pituitary hormone called thyroid
stimulating hormone (TSH). As thyroxine levels increase in the blood, they exert negative
feedback on the release of TSH by the pituitary gland. What effect will this have on the release
of TSH?
The release of TSH is decrease. Negative feedback causes the initial stimulus, TSH in
this case, to decline.
2. During exercise, blood flow to skeletal muscles increases. The initial response that increases
blood flow is due to changes that happen within the muscle and is independent of the nervous
and endocrine systems. Which type of homeostatic regulation (intrinsic or extrinsic) is this and
why?
The initial increase in blood flow to active muscles is an example of autoregulation or
intrinsic control. The increased demands for oxygen and for waste removal cause a
local increase in blood flow even before responses from the nervous or endocrine
system take place. Autoregulation is an immediate and automatic response to
environmental change (in this case, low oxygen levels, CO2 buildup, decreased pH and
increased wastes) that does not require the nervous or endocrine system.
3. Blood Pressure drops when a person goes from a lying to standing position. In order to correct
the decreased drop in blood pressure the body uses mechanisms to increase blood pressure.
Do these mechanisms use positive or negative feedback processes? Describe how the body
responds to correct this situation.
Correction of blood pressure in this situation is an example of a negative feedback process
because the initial change (decreased blood pressure) is corrected by the response (increased
blood pressure) which reveres the direction of the initial change.
When you stand up, gravity causes blood to settle in the lower part of your body. Blood
pressure receptors known as baroreceptors (sensors) detect the change in blood pressure.
Baroreceptors are specialized sensory neurons in the walls of the aortic arch and the
carotid sinuses that measure the degree of stretch in the vessel wall. Information is sent from
the baroreceptors to the medulla oblongata via sensory nerves. The Medulla oblongata
(control center) analyzes the change in blood pressure and sends a nerve impulse to the
heart and blood vessels (mainly arterioles), both of which are effectors, to correct the decrease
in blood pressure.
– Heart rate and amount of blood pumped are increased causing an increase in blood
pressure
– Vasoconstriction of arterioles increases blood pressure.
Thus if BP is too high or too low, a reflex change in cardiac output is initiated in order to correct
it.
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4. Are the events of child birth a positive or negative feedback process? Describe the events
that support your answer.
Child birth is an example of a positive feedback process. When the baby is ready to be
delivered, it drops lower in the uterus causing stretching of the uterus and cervix. Stretch
receptors in the cervix and uterine wall are monitored by the hypothalamus of the brain. As the
uterus stretches the hypothalamus releases oxytocin via the posterior pituitary gland, which
causes the uterus to contract. This contraction further distorts and open the cervix resulting in
more oxytocin to be released which increase uterine contractions. The cycle continues until the
baby is delivered and the stretching stimulation is eliminated stopping the positive feedback
loop.
5. Using insulin as an example, explain how the secretion of this hormone is stimulated and the
mechanism by which its secretion is turned off. Hint: Think about feedback systems
A rise in plasma glucose concentration stimulates insulin secretion from structures in the
pancreas known as the pancreatic islets (islets of Langerhans). Insulin causes blood glucose
to be taken into the body cells which results in a lowered amount of blood glucose. The
lowering of blood glucose which due to insulin’s action inhibits further insulin secretion. A
fantastic example of a negative feedback mechanism.
6. Who are Claude Bernard and Walter Cannon? Why are the concepts they introduced so
important in physiology and medicine?
French physiologist Claude Bernard (1813 – 1878) is considered the father of modern
physiology because he observed that the milieu interieur (internal environment) remains
remarkable constant despite changing conditions in the external environment. American
physiologist Walter Cannon (1871 – 1945) coined the term homeostasis to describe this
internal constancy and suggested that many mechanisms of physiological regulation have but
one purpose – the maintenance of internal constancy. The body is healthy when homeostasis
is maintained and thus is very important in the study of physiology and medicine. Homeostatic
imbalance can result in a disorder, disease or death.
7. Monitoring fetal development may be dangerous for the fetus if improper diagnostic techniques
are used. Why is ultrasound an effective means of monitoring fetal development?
No adverse effects have been attributed to the sound waves, and fetal development can
be monitored without a significant risk of birth defects. Ultrasound machines are
relatively inexpensive and portable.
8. Gastroenterologists use X-rays to check for ulcers or other stomach and upper digestive tract
disorders. Before the X-rays are taken why is it necessary for the patient to drink large
quantities of a solution that contains barium ions?
Barium is very radiodense, and the contours of the gastric and intestinal lining can be
seen against the white of the barium solution.
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9. The following are advanced imaging techniques have been discussed in lecture: CT, DSA,
PET, ultrasound, and MRI. Which of these techniques uses X-rays? Which uses radio waves
and magnetic fields? Which uses radioisotopes? Which displays body regions in sections?
Your may have more than one answer for each question.
Techniques that use X-rays: CT and DSA
Radiowaves and magnetic field: MRI
Radioisotopes: PET
Techniques that display body regions in sections: CT, MRI, and PET
10. You are studying for your first physiology exam and want to know which areas of your brain
are working hardest as you study. Your classmate suggests that you could have a computed
tomography (CT) scan done to assess your brain activity. Would this be the best way to
determine brain activity?
No. Computed tomography is used to look at differences in tissue density. To assess
activity in an organ such as the brain, a positron emission tomography (PET) scan
would provide a colorized visual assessment of brain activity.
11. Certain bacterial infections can cause a fever to develop. Describe the bases for fever
formation and dissipation and how antipyretics such as aspirin work.
The hypothalamus regulates body temperature. A fever is an elevation of core temperature
caused by a resetting of the hypothalamic thermostat. Normal body temperature is at 98.6 F
(37 C)
Steps involved with fever formation caused by bacterial infection.
1. When macrophages and other phagocytes ingest certain bacteria, they are
stimulated to secrete a pyrogen (pyro=fire, -gen=produce), a fever-producing
substance. One pyrogen is interleukin -1 (IL-1).
2. IL-1 circulates to the hypothalamus and induces neurons to secrete prostaglandins
that reset the hypothalamic thermostat at a higher temperature, lets say the
hypothalamus thermostat is reset at 39 C (103 F).
• Prostaglandins are local chemical mediators which in this case, act directly on
the hypothalamus.
3. Temperature regulating reflex mechanisms then act to bring the core body temperature
up to this new setting. The heatpromoting mechanisms
(vasoconstriction, increased
metabolism, shivering) are
operating at full force. Thus, even
though core temperature is climbing
higher than normal – say, 38 C (101
F) – the skin remains cold, and
shivering occurs. This condition,
called a chill, is a definite sign that
core temperature is rising. After
several hours, core temperature
reaches the setting of the
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thermostat, and the chills disappear. But now the body will continue to regulate
temperature at 39 C (103 F).
4. When the pyrogens disappear, the thermostat is reset at normal – 37 C (98.6 F).
Because core temperature is high in the beginning, the heat-losing mechanisms
(vasodilation and sweating) go into operation to decrease core temperature. The skin
becomes warm, and the person begins to sweat. This phase of the fever indicates the
core temperature is falling.
•
Antipyretics and Fever Reduction
– Antipyretics such as aspirin are agents that relieve or reduce fever by inhibiting
synthesis of certain prostaglandins within the hypothalamus and thus inhibit the effects
of pyrogens to reset the hypothalamic thermostat.
Part II
1. receptor
2. control center
3. afferent
4. control center
5. effector
6. efferent
7. negative
8. positive
9. negative
10. cells
11. tissues
12. organs
13. organ systems
14. ventral
15. dorsal
16. dorsal
17. abdominopelvic
18. abdominopelvic
19. abdominopelvic
20. abdominopelvic
21. abdominopelvic
22. spinal
23. abdominopelvic
24. thoracic
25. thoracic
26. cranial
27. abdominopelvic
28. abdominopelvic
29. endocrine
30. urinary
31. reproductive
32. lymphatic/immune
33. skeletal
34. integumentary
35. digestive
36. same; stays
37. interstitial; internal
38. 1) gases (oxygen, carbon dioxide)
2) nutrients (proteins, glucose, etc.)
3) electrolytes (sodium, potassium, etc.)
4) fluids
5) temperature
6) pressure
39. lower; decreasing; stimulus; receptors;
input; control
40. output; effectors; response
41. negative; increase; positive
42. negative; labor contractions or blood
clotting
43. B
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Part III
1. physiology
2. anatomy
3. homeostasis
4. metabolism
5. urinary
6. endocrine
7. skeletal
8. cardiovascular
9. integumentary
10. lymphatic/immune
11. digestive
12. respiratory
13. cardiovascular
14. muscular
15. urinary
16. reproductive
17. endocrine
18. integumentary
19. ventral cavity
20. thoracic cavity
21. diaphragm
22. abdominal cavity
23. pelvic cavity
24. cranial cavity
25. spinal cavity
26. dorsal cavity
27. Lt Pleural cavity
28. pericardial cavity
29. Rt pleural cavity
30. diaphragm
31. abdominal cavity
32. subatomic particles
33. atoms
34. molecules
35. protoplasm
36. organelles
37. cells
38. tissues
39. organs
40. systems
41. organism
Part IV
1. At #1 on the graph there will be increased blood flow to the skin and increased sweating if the
body temperature rises above 99 F. Result will be a body surface that cools and the body
temperature declines. At #2 on the graph, if the temperature falls below 98 F there is a
decrease in blood flow to the skin and shivering occurs. These activities help to conserve body
hear and the body temperature rises.
2. Calcitonin is released when calcium
14. D
levels are elevated. This hormone
15. C
should bring about a decrease in blood
16. D
calcium levels, thus decreasing the
17. A
stimulus for its own release.
18. D
3. cardiovascular
19. C
4. endocrine
20. D
5. urinary
21. B
6. reproductive
22. A
7. digestive
23. C
8. skeletal
24. C, E
9. nervous
25. D
10. B
26. B
11. A
27. B
12. D
28. A, B, C, D
13. D
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Part V
1. DSA
2. PET
3. CR
4. US
5. CT
Part VI
Exercise A
1. Cranial cavity
2. Spinal cavity
3. Mediastinum
4. Pleural cavity
5. Pericardial cavity
6. Diaphragm
7. Abdominal cavity
8. Pelvic cavity
9. Abdominopelvic cavity
10. Ventral cavity
6. MRI
7. 2
8. 3
9. 1
10. 4
11. A
12. D
13. A
14. C
Exercise B
1. Cranial cavity
2. Dorsal cavity
3. Spinal cavity
4. Thoracic cavity
5. Diaphragm
6. Abdominal cavity
7. Pelvic cavity
Part VII Experimental Design
For the following statements / hypothesis identify the variables, control group, and experimental group.
1. Cigarette smoking increases the risk of lung cancer. Hypothesis: If you smoke cigarettes, then your
chances of getting cancer increases.
Independent Variable: Smoking cigarettes; Dependent Variable: Whether you get cancer
Control Group: People who do not smoke; Experimental Group: Smokers
2. Eating breakfast increases performance in school. Hypothesis: If you eat breakfast, then you will get
better grades.
Independent Variable: breakfast;
Dependent Variable: Grades
Control Group: students who do not eat breakfast; Experimental Group: students who eat breakfast
3. Hummingbirds are attracted to the color red. Hypothesis: If a bird feeder is red, then it will attract
hummingbirds
Independent Variable: color of feeder;
Dependent Variable: number of hummingbirds present
Control Group: feeder that is not red;
Experimental Group: feeder that is red
4. iBook batteries last for 5 hours. Hypothesis: If you use iBook batteries, then your iBook will run for 5
hours.
Independent Variable: battery type;
Dependent Variable: time plays
Control Group: different type of battery;
Experimental Group: iBook battery
5. You conduct an experiment on twenty 18-year-old male subjects to see how various intensities of
exercise influence heart rate. Which of the following is/are considered an independent variable?
A) age of subjects
B) sex of subjects
C) intensity of exercise
D) heart rate
6. You conduct an experiment on twenty 18-year-old male subjects to see how various intensities of
exercise influence heart rate. Which of the following is/are considered a dependent variable?
A) age of subjects
B) sex of subjects
C) intensity of exercise
D) heart rate
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7. Suzie wants to know the effect of different colors of light on the growth of plants. She believes that
plants can survive best in white light. She buys 5 ferns of the same species, which are all approximately
the same age and height. She places one in white light, one in blue light, one in green light, one in red
light and one in the closet. All of the ferns are planted in Miracle-Grow and given 20 mL of water once a
day for 2 weeks. After the two weeks, Suzie observes the plants and makes measurements. Hypothesis:
If plants are grown in white light, then they will grow taller
Independent Variable: type of light
Dependent Variable: height of plant
Control Group: plants in different colors of light; Experimental Group: plants in white light
8. Place these terms in the typical sequence in which they appear in the process of scientific inquiry:
collect and analyze data, theory, model, question, hypothesis, replication, experiment, observation.
Observation, question, hypothesis, experiment, collect and analyze data, model, theory
Possible terms to use for the following questions:
Blind
Double-blind
Crossover
Retrospective
Control
hypothesis
Model
Theory
Independent variable
Dependent variable
Placebo
Nocebo
Double-blind crossover
9. A study in which a participant acts as an experimental subject in part of the experiment and a control in
another part of the experiment is called a _Crossover____ study.
10. An inactive drug or treatment that is expected to have no pharmacological or medical effect is called a
_Placebo_____.
11. Term of an educated (logical) guess as to how that event happens: __hypothesis______
12. If a scientific model is supported or verified repeatedly by multiple investigators, it may become a
___Theory________
13. It is an ill effect caused by the suggestion or belief that something is harmful. It is the phenomenon
whereby a patient who has been informed of the side effects of a drug he is taking is more likely to
experience some of the side effects than an otherwise similar patient receiving the same drug who has
not been so informed. This is known as the __Nocebo____ effect.
14. The __independent variable__ is the variable that is controlled by the experimenter, it is the variable that
is altered or removed.
15. _Double-blind _____ study is when a third party, not involved in the experiment, is the only one who
knows which group is receiving the experimental treatment and which group is receiving the control
treatment.
16. __ Double-blind crossover __ study is when the control group is the first half of the experiment becomes
the experimental group in the second half, and vice versa, but no one involved (except the third party)
knows who is taking the active treatment.
17. The _placebo________ effect is where a patient taking an inactive substance thinks they are taking the
actual medication and due to the power of their mind, there is a positive change in health not
attributable to medication or treatment