Unit3: Ch 40- Mechanisms of Endocrine Control (Porth's 5th Ed) Flashcards
Which of the following statements best captures an aspect of the role of hormones in the
body?
A) Some chemical substances can function as hormones or be integrated with the
central and peripheral nervous systems.
B) Hormones directly initiate many of the processes that contribute to homeostasis.
C) Control of body processes is ensured by the fact that a single hormone can only
exert one effect on one specific system or tissue.
D) Each hormone that exists in the body is produced by only one specific endocrine
gland
Ans: A
Feedback:
Some chemicals, such as epinephrine, can both function as a hormone and be closely
integrated with the central and peripheral nervous systems as well as the immune
systems, leading to current terminology such as “neuroendocrine.” Hormones modulate,
but do not initiate, changes in the body, and one hormone may exert multiple effects on
multiple body systems. Hormones are produced by a variety of body tissues, not solely
by endocrine glands.
An example of a single hormone that can exert effects in different tissues,
erythropoietin, made in the kidney stimulates the bone marrow to produce
A) platelets.
B) natural killer cells.
C) red blood cells.
D) mast cells.
Ans: C
Feedback:
A characteristic of hormones is that a single hormone can exert various effects in
different tissues. For example, erythropoietin, a traditional circulating hormone, is made
in the kidney and stimulates erythropoiesis in the bone marrow.
A nurse who works in the office of an endocrinologist is orienting a new staff member.
Which of the following teaching points is the nurse justified in including in the
orientation? Select all that apply.
A) “A bodily process can be the result of the combined effect of several different
hormones from different sources.”
B) “A single hormone can act not only on one process or organ but often on several
different locations or processes.”
C) “It’s common for production of hormones to be far removed from the tissue where
they ultimately exert their effect.”
D) “Sometimes hormones act locally on the area where they were produced, like in
the case of paracrine and autocrine actions.”
E) “The regulation in homeostasis requires that hormones be absent from the body
when their effect is not needed.”
Ans: A, B, C, D
Feedback:
A single hormone can exert various effects in different tissues or, conversely, a single
function can be regulated by several different hormones. Hormones act both distant
from their source and more locally, as in the case of autocrine and paracrine actions.
Hormones are normally present at all times.
When explaining about structural classifications to a group of students, the instructor
discusses the peptides and proteins. They talk about small hormones and hormones as
large and complex as growth hormone (GH) has approximately how many amino
acids involved?
A) 50 amino acids
B) 100 amino acids
C) 150 amino acids
D) 200 amino acids
Ans: D
Feedback:
Growth hormone is a very large and complex protein that has approximately 200 amino
acids.
Which of the following hormones are derivatives of cholesterol? A) Epinephrine and norepinephrine B) Insulin and glucagon C) Aldosterone and testosterone D) Eicosanoids and retinoids
Ans: C
Feedback:
Steroids such as aldosterone and testosterone are a classification of hormones that are
derived from cholesterol. Epinephrine and norepinephrine are both amino acids, while
insulin and glucagon are classified among peptides, polypeptides, proteins, and
glycoproteins. Eicosanoids and retinoids consist of fatty acid compounds.
A 51-year-old woman has been experiencing signs and symptoms of perimenopause and
has sought help from her family physician. A deficiency in estrogen levels has been
determined to be a contributing factor. Which of the following phenomena could
potentially underlie the woman’s health problem?
A) Sufficient synthesis of estrogen but inadequate vesicle-mediated release
B) Inadequate synthesis in the rough endoplasmic reticulum of her ovarian cells
C) Insufficient estrogen production within the smooth endoplasmic reticulum of the
relevant cells
D) A lack of prohormone precursors needed for estrogen synthesis and release
Ans: C
Feedback:
Steroids such as estrogen are produced in the smooth endoplasmic reticulum. Synthesis
and release are not separate processes as in the case of peptide hormones, and
prohormones are associated with peptide, polypeptide, and protein hormones.
Which of the following best describes the half-life of a highly protein-bound drug such
as thyroxine (99% protein bound)? The half-life would be
A) much longer to reduce the concentration of the hormone by one half.
B) shorter because only a little of the hormone has to be used up to reduce the
concentration.
C) dependent on which drugs were in the blood system holding on to the hormone.
D) dependent on the liver to carry the hormone to its designated target organ.
Ans: A
Feedback:
The half-life of a hormone—the time it takes for the body to reduce the concentration of
the hormone by one half—is positively correlated with its percentage of protein binding.
Thyroxine, which is more than 99% protein bound, has a half-life of 6 days, whereas
aldosterone, 15% bound, has a half-life of only 25 minutes.
Since steroid hormones are bound to protein carriers for transport, this means
A) they are water soluble and circulate freely in the blood.
B) they are degraded by enzymes in the blood.
C) they are inactive in the bound state.
D) they will be converted into a useable form by enzymes in the blood.
Ans: C
Feedback:
Steroid hormones are bound to protein carriers for transport and are inactive in the
bound state. Their activity depends on the availability of transport carriers.
Neurotransmitters like catecholamines (e.g., dopamine and epinephrine) have a reaction time of A) milliseconds. B) less than 10 minutes. C) 24 to 36 hours. D) 4 to 7 days.
Ans: A
Feedback:
The neurotransmitters, which control the opening of ion channels, have a reaction time
of milliseconds.
A client with a history of an endocrine disorder exhibit signs and symptoms of
hormone deficiency. Which of the following processes would the client’s care team most
likely rule out first as a contributing factor?
A) The client’s target cells lack sufficient receptors for the hormone in question.
B) Hormone production is sufficient, but affinity on the part of the target cells is
lacking.
C) The process of down-regulation has resulted in decreased hormone sensitivity.
D) Up-regulation has increased the sensitivity of the body to particular hormone
levels.
Ans: D
Feedback:
Up-regulation is a response to low hormone levels in which the number of receptors
increases. As such, it would not likely result in signs and symptoms of deficiency but is
rather a compensatory mechanism that counters a deficiency. Insufficient numbers of
receptors, low affinity, and down-regulation could all contribute to signs and symptoms
of a hormone deficiency.
Which of the following statements best captures the essence of a second messenger in
the mechanisms of the endocrine system?
A) Second messengers act as the intracellular signal that responds to the presence of
a hormone.
B) Endocrine-producing cells must release both a hormone and a second messenger
in order to exert a distant effect.
C) Second messengers act to supplement hormone effects on cell receptors when the
desired hormonal effect must be either increased.
D) Second messengers provide an alternative pathway for endocrine effects on a cell
that bypass the normal receptor pathways.
Ans: A
Feedback:
Second messengers interact with hormones that cannot cross the cell membrane, and
they mediate the ultimate effect on the cell. They are not produced by the
hormone-producing cell, and they are necessary to bring about hormonal effects, not
simply for increasing the intensity of the effect. They are not an alternative mechanism
of effect but rather a prerequisite for certain hormonal effects on body cells.
A client with a new diagnosis of an endocrine disorder is unclear how the body can
control the levels of different hormones over time. Which of the following statements
most accurately underlies the dominant regulation process of hormone levels in the
body?
A) A positive feedback cycle ensures that stable levels of hormones exist in the body
over time.
B) With input from various sensors, hormone production and release are adjusted
based on existing hormone levels.
C) The hypothalamus ensures that hormone levels correspond accurately to the
diurnal cycle.
D) The pituitary gland is genetically programmed to stimulate and inhibit hormone
production and/or release based on the needs at different points in the life cycle.
Ans: B
Feedback:
Most hormone levels are controlled by way of a negative feedback cycle, in which low
levels stimulate production and/or release. A positive feedback cycle would not achieve
this effect. While some hormones are released on a diurnal schedule, the dominant form
of hormone regulation in the body is that of negative feedback. Hormone release is not
predetermined by the pituitary gland.
A 21-year-old female is suspected of having inadequate function of her hypothalamic–
pituitary–thyroid system. Her care provider is planning to inject thyrotropin-releasing
hormone (TRH) and then measure her levels of TSH. Which of the following diagnostic
tests is being performed?
A) Suppression test
B) Radioimmunoassay (RIA) test
C) Stimulation test
D) Metabolite excretion test
Ans: C
Feedback:
A stimulation test involves the introduction of an element that stimulates the production
of another factor or hormone followed by measurement of that hormone. This is not the
case in a suppression test, RIA test, or metabolite excretion test.
Following a meal, a woman’s blood glucose level has increased. In addition, her
pancreas has increased the amount of insulin produced and released. Which of the
following phenomena has occurred?
A) Increased hormone level according to a negative feedback mechanism
B) Adjustment according to the level of the substance a hormone regulates
C) Hormone production and release via the positive feedback cycle
D) Hypothalamic–pituitary control of hormone levels
Ans: B
Feedback:
The level of some hormones is adjusted according to the amount of the substance that
they control. In this case, insulin controls glucose levels and would increase in response
to the increase in serum glucose that follows a meal. This differs from a negative
feedback cycle in which a simple decrease in a hormone level stimulates production
and/or release of that hormone. Positive feedback and hypothalamic–pituitary control
are not evident in this situation.
Which of the following statements best captures the relationship between the
hypothalamus and the pituitary gland as it relates to endocrine function?
A) The hypothalamus directly measures the levels of most hormones throughout the
body and inhibits or stimulates the pituitary accordingly.
B) The pituitary gland coordinates and dictates the release of hormones from the
hypothalamus that act on their intended target cells.
C) The pituitary gland and hypothalamus have two-way communication that
mediates the signals from neuronal inputs.
D) The hypothalamus receives input from numerous sources throughout the body and
directs the pituitary to then control many target glands and cells.
Ans: D
Feedback:
The hypothalamus can be viewed as a bridge by which signals from multiple systems
are relayed to the pituitary gland. The hypothalamus collects data from sources
throughout the body rather than directly measuring levels, and communication normally
flows from the hypothalamus to the pituitary.
