Answers to Test & Quantitative and Thought Questions
709
directly stimulate acid secretion by the parietal cells
and also cause the release of gastrin, which in turn
stimulates acid secretion. Impulses in the vagus
nerves are increased during both the cephalic and
gastric phases of digestion. Vagotomy, by decreasing
the amount of acid secreted, decreases irritation
of existing ulcers, which promotes healing and
decreases the probability of acid contributing to the
production of new ulcers.
Chapter 16
Test Questions
16-1 a
Glucose can be converted to fat, but fatty acids
cannot be converted to glucose.
16-2 b
HSL is an intracellular enzyme that acts on
triglycerides.
16-3 a
Glucagon acts to prevent hypoglycemia from
occurring.
16-4 c
If untreated, Type 1 DM causes an osmotic diuresis
when the transport maximum for glucose is
exceeded in the kidney.
16-5 d
Insulin stimulates lipogenesis, not lipolysis.
16-6 e
Recall that vitamin defi ciencies occur even with
normal dietary intake of vitamins, because the
metabolic rate is increased in hyperthyroidism.
16-7 b
16-8 T
16-9 F
Core temperature is generally kept fairly constant,
but skin temperature can vary.
16-10 T
16-11 F
As muscles begin contracting during exercise, they
become partially insulin-independent.
16-12 F
BMI equals body mass in kg divided by (height in
meters)
2
.
16-13 T
16-14 F
Skin vessels dilate in such conditions in order to
help dissipate heat by bringing warm blood close to
the skin surface.
16-15 T
Quantitative and Thought Questions
16-1
The concentration in plasma would increase, and
the amount stored in adipose tissue would decrease.
Lipoprotein lipase cleaves plasma triglycerides, so
its blockade would decrease the rate at which these
molecules were cleared from plasma and would
decrease the availability of the fatty acids in them for
the synthesis of intracellular triglycerides. However,
this would only reduce but not eliminate such
synthesis, because the adipose tissue cells could still
synthesize their own fatty acids from glucose.
16-2
The person might be an insulin-dependent diabetic
or might be a healthy fasting person; plasma glucose
would be increased in the fi rst case but decreased in
the second. Plasma insulin concentration would be
useful because it would be decreased in both cases.
The fact that the person was resting and unstressed
was specifi ed because severe stress or strenuous
exercise could also produce the plasma changes
mentioned. Plasma glucose would increase during
stress and decrease during strenuous exercise.
16-3
Glucagon, epinephrine, cortisol, and growth
hormone. The insulin will produce hypoglycemia,
which then induces refl ex increases in the secretion
of all these hormones.
16-4
It might reduce it but not eliminate it. The
sympathetic effects on organic metabolism during
exercise are mediated not only by circulating
epinephrine but also by sympathetic nerves to
the liver (glycogenolysis and gluconeogenesis), to
adipose tissue (lipolysis), and to the pancreatic islets
(inhibition of insulin secretion and stimulation of
glucagon secretion).
16-5
Increase. The stress of the accident will initially
elicit increased activity of all the glucose
counterregulatory controls and will therefore
necessitate more insulin to oppose these infl uences.
16-6
It will lower plasma cholesterol concentration. Bile
salts are formed from cholesterol, and losses of these
bile salts in the feces will be replaced by the synthesis
of new ones from cholesterol. Chapter 15 describes
how bile salts are normally absorbed from the small
intestine so that very few of those secreted into the
bile are normally lost from the body.
16-7
Plasma concentrations of HDL and LDL. It is
the ratio of LDL cholesterol to HDL cholesterol
that best correlates with the development of
atherosclerosis (HDL cholesterol is “good”
cholesterol). The answer to this question would have
been the same regardless of whether the person was
an athlete, but the question was phrased this way to
emphasize that people who exercise generally have
increased HDL cholesterol.
16-8
Heat loss from the head, mainly via convection and
sweating, is the major route for loss under these
conditions. The rest of the body is
gaining
heat by
conduction, and sweating is of no value in the rest
of the body because the water cannot evaporate.
Heat is also lost via the expired air (insensible loss),
and some people actually begin to pant under such
conditions. The rapid, shallow breathing increases air
fl ow and heat loss without causing hyperventilation.
16-9
They seek out warmer places, if available, so that
their body temperature increases. That is, they use
behavior to develop a fever. This is excellent evidence
that the hyperthermia of infection is a fever (i.e., a
set-point change).
Chapter 17
Test Questions
17-1 e
Without the presence of the Y chromosome in the
testes and the local production of SRY protein,
the undifferentiated gonads are programmed to
differentiate into ovaries.
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