S2 Block 1 Endo Phys

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  • 1/25 Questions

    Which of the following statements best describe the factor(s) regulating insulin secretion?

    • Calcium-dependent event.
    • Dependent on glucose uptake via GLUT-4.
    • Facilitated by changes in the level of glucagon.
    • Stimulated during exercise.
    • Triggered by glucose concentration above 4 mM.
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About This Quiz

This quiz, titled 'S2 Block 1 Endo Phys,' assesses knowledge in endocrinology, focusing on insulin secretion, glucose transport, hormone regulation, and clinical applications of somatostatin analogues. It is designed for medical students preparing for exams like USMLE.

S2 Block 1 Endo Phys - Quiz

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  • 2. 

    Glucose uptake is facilitated via the membrane-bound glucose transporters (GLUTs). Glucose uptake in hepatocytes is regulated primarily by which of the following GLUTs?

    • GLUT-1

    • GLUT-2

    • GLUT-3

    • GLUT-4

    • GLUT-5

    • GLUT-6

    Correct Answer
    A. GLUT-2
    Explanation
    Feedback: Glucose uptake in hepatocytes and pancreatic beta cells occurs via the GLUT-2
    transporter. The GLUT-2 transporter is regulated predominantly by the hepatocyte growth factor
    (HGF) cMET pathway, not by insulin. Note that the brain and nervous tissues express several
    members of the GLUT family, but do not express GLUT-2 and GLUT-4.
    Distracter explanations:
     GLUT-1 facilitates glucose transport across the blood brain barrier and is localized to most
    tissues throughout the body, but is not the primary GLUT in pancreatic beta cells, hepatocytes,
    adipocytes or skeletal muscle.
     GLUT-3 and GLUT-5 are predominantly localized to reproductive tract tissues and/or gametes.
    Some evidence also suggests GLUT-3 is the primary mechanism for glucose uptake in
    neurons.
     GLUT-4 is localized predominantly in skeletal muscle and adipose tissue.
     GLUT-6 was originally described as GLUT-9, functions to facilitate glucose uptake in the brain,
    spleen and leukocytes.

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  • 3. 

    Which of the following biomolecules exerts long-loop positive feedback on the hypothalamus?

    • Cortisol

    • Estradiol

    • GH

    • Insulin

    • Progesterone

    • Thyroxine

    Correct Answer
    A. Estradiol
    Explanation
    Feedback: Estradiol exerts long-loop positive feedback to stimulate the release of GnRH during the
    late-proliferative phase of the menstrual cycle before ovulation. Estradiol exerts long-loop negative
    feedback during the early- and mid-proliferative phase, and also throughout the secretory phase of
    the menstrual cycle (which is predominated by progesterone).
    Distracter explanations:
     Cortisol exerts long-loop negative feedback. During the “Flight or Fight” response cortisol does
    not stimulate more CRH – CRH stimulates the release of more CRH, which overrides the
    negative effects of increased negative cortisol feedback.
     Growth Hormone, from the anterior pituitary, exerts short-loop negative feedback on the
    hypothalamus.
     Insulin is stimulated by glucose concentration, and may exert some feedback on the
    hypothalamus (e.g. is can suppress the release of GHRH), but it does not exert long-loop
    positive feedback. Additionally, this would not be viewed as classic feedback, but rather as
    end-product feedback (similar to calcium levels regulating PTH).
     Progesterone, secreted primarily from the corpus luteum and the placenta, always exerts longloop
    negative feedback on the hypothalamus. Progesterone negative feedback is the basis for
    progesterone-only contraceptives.
     Thyroxine, from the thyroid gland, exerts long-loop negative feedback

    Rate this question:

  • 4. 

    Which of the following pituitary hormones is regulated by a statin and liberin?

    • FSH

    • GH

    • LH

    • Prolactin

    • TSH

    Correct Answer
    A. GH
    Explanation
    Feedback: Growth hormone (GH), released from the anterior pituitary, is under the dual regulation of
    the stimulatory Growth hormone releasing hormone (GHRH) and the inhibitory somatostatin (SRIF).
    Recall that liberins (e.g. GHRH) are released from the hypothalamus to stimulate the production
    and/or release of an anterior pituitary hormone, whereas statins (e.g. SRIF) are released from the
    hypothalamus to inhibit the production/release of an anterior pituitary hormone.
    Distracter explanations:
     Follicle stimulating hormone (FSH) and luteinizing hormone (LH) are stimulated by
    gonadotropin releasing hormone (GnRH), which is a liberin.
     Thyroid stimulating hormone (TSH) is regulated by thyroid releasing hormone (TRH), which is
    a liberin.
     Prolactin (PRL) is under the tonic inhibitory control of dopamine (DA), which is a statin.

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  • 5. 

    Synthetic somatostatin analogues, such as octreotide, exert inhibitory functions on several tissues throughout the body. Octreotide would exert the most beneficial physiological effects in a 25-yearold patient with which of the following problems?

    • Acromegaly

    • Hyposecretion of glucagon

    • Polycystic ovary syndrome

    • Type 1 Diabetes

    • Type 2 Diabetes

    Correct Answer
    A. Acromegaly
    Explanation
    Feedback: Recognize that acromegaly is disregulated release of growth hormone (GH) from the
    pituitary, resulting in increased growth during adulthood. Endogenous levels of GH are elevated, due
    to decreased levels of somatostatin (SRIF). Octreotide replacement therapy is used to increase the
    inhibitory actions of SRIF, to decrease GH and control growth rate.
    Distracter explanations:
     Large levels of SRIF inhibit the release of insulin, and therefore SRIF analogues would not be
    used in people with either Type 1 or Type 2 Diabetes.
     Women with polycystic ovary syndrome (PCOS) are at risk for developing insulin resistance
    and often have impaired metabolic function, but to date no studies have linked SRIF with
    PCOS.
     Large doses of SRIF have been shown to inhibit insulin and glucagon, and therefore SRIF
    analogues would not be used in patients exhibiting abnormally low glucagon secretion.

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  • 6. 

    Which of the following favorable characteristics promote the use of C-peptide as a marker for determining insulin resistance and/or glucose homeostasis? (Mark ALL that apply)

    • Metabolized by the kidney.

    • Released in a pulsatile manner.

    • Binds with albumin.

    • Directly indicates pancreatic α-cell function.

    • Long half-life compared with insulin.

    Correct Answer(s)
    A. Metabolized by the kidney.
    A. Long half-life compared with insulin.
    Explanation
    Feedback: C-peptide is also call the “C-chain”, and is stored in insulin-containing vesicles in the
    pancreatic beta cells. The half-life of C-peptide is ~20-30 minutes, compared with the relatively short
    half-life of insulin (~5 min). C-peptide is metabolized predominantly by the kidney, which contributes
    to the longer half-life. Approximately 75% of the insulin secreted from the beta cells is metabolized by
    the liver on the first-past effect – which contributes to insulin’s shorter half-life.
    Distracter explanations:
     C-peptide is released with insulin in response to elevated glucose, and therefore is not
    secreted in a pulsatile manner. The release of insulin and C-peptide granules is considered
    ‘episodic release’.
     The interactions of albumin with C-peptide and insulin are under investigation, to determine if
    albumin conjugates can be used for insulin replacement therapy.
     C-peptide is proteolytic product of proinsulin processing, is synthesized and stored in granules
    in the pancreatic beta cells, not alpha cells.

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  • 7. 

    Reductions in which of the following proteins will cause the greatest decrease in adrenal steroid production? (Mark ALL that apply)

    • 11-Hydroxylase

    • 17-Hydroxylase

    • 21-Hydroxylase

    • CYP11

    • CYP19

    • StAR Protein

    Correct Answer(s)
    A. CYP11
    A. StAR Protein
    Explanation
    Feedback: Steroidogenic acute regulatory (StAR) protein shuttles cholesterol across the outer
    mitochondrial membrane to the inner mitochondrial membrane, where the cytochrome enzymes
    reside. CYP11, also known as P450 side chain cleavage or 20-22 desmolase, resides on the inner
    mitochondrial membrane and converts cholesterol to pregnenolone. Reduced levels of either StAR or
    CYP11 will drastically reduce steroid production in the adrenal gland.
    Distracter explanations:
     CYP19 is also known as aromatase, and converts androgens to estrogens. This is one of the
    final stages of steroid production, and will not affect adrenal steroid production.
     11-Hydroxylase, 17-Hydroxylase, and 21-Hydroxylase are essential for production of the
    adrenal steroid hormones. However, CYP11A and StAR protein regulate the production of
    pregnenolone, which is the precursor for all steroids, and therefore reductions in CYP11A will
    result in reduced steroid production.
     Note: CYP11A and CYP11B (11-hydroxylase) both reside in the mitochondria in the adrenal gland

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  • 8. 

    Which of the following hormones has the longest half-life in serum?

    • Aldosterone

    • Angiotensin II

    • Cortisol

    • Epinephrine

    • Growth Hormone

    • Insulin

    • Prostaglandin F2

    Correct Answer
    A. Growth Hormone
    Explanation
    Feedback: The active half-life of native growth hormone (GH) is only 20-30 minutes in serum, but
    the circulating half-life of GH is 10-16 hrs. The circulating half-life of GH is drastically increased due
    to GH binding with growth hormone binding protein (GHBP), the soluble portion of the GH receptor.
    Distracter explanations:
     Angiotensin II and Epinephrine each have a half-life of ~2 min, and therefore these hormones
    have the shortest half-life of the biomolecules listed.
     The half-life of insulin is 3-10 min.
     The half-life of prostaglandin F2 is approximately 5-30 minutes, depending on the site of
    production.
     The half life of aldosterone and cortisol are approximately 30-60 minutes.

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  • 9. 

    Which of the following best describes the secretion pattern(s) of adrenocorticotropic hormone (ACTH) in adults?

    • Circadian

    • Pulsatile

    • Episodic

    • Circadian and Pulsatile

    • Circadian and Episodic

    • Pulsatile and Episodic

    • Circadian, Pulsatile and Episodic

    Correct Answer
    A. Circadian, Pulsatile and Episodic
    Explanation
    Feedback: Many of the hormones released from the anterior pituitary are release in pulsatile manner
    in response to the hypothalamic releasing factors. Most of the anterior pituitary hormones, including
    ACTH, also exhibit a circadian rhythm, exhibiting a peak and nadir each day. ACTH is unique, in that
    the ‘Fight or Flight’ response can cause an episodic release of CRH, leading to an episodic release of
    ACTH.
    Distracter explanations:
     Circadian refers to a daily rhythm or daily pattern, with the hormones exhibiting a peak and
    nadir each day. ACTH and GH both exhibit circadian patterns.
     Pulsatile refers to pulsatile release of a hormone throughout the day. All of the anterior
    pituitary hormones (LH, FSH, GH, ACTH, TSH and PRL) exhibit some pattern of pulsatile
    release throughout the day.
     Episodic release refers to release of a hormone in response to a specific stimuli. The classic
    example of episodic release is insulin release in response to elevated blood glucose.

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  • 10. 

    An 18-year old man displays gigantism. Functional MRI indicates the hypothalamus and pituitary gland are of normal size. Which of the following hormones was most likely reduced in this patient when he was a young boy?

    • Growth Hormone

    • Growth Hormone Releasing Hormone

    • Insulin

    • Insulin-like Growth Factor 1

    • Insulin-like Growth Factor 2

    • Somatostatin

    Correct Answer
    A. Somatostatin
    Explanation
    Feedback: Gigantism is very rare and has two primary causes: congenital which leads to
    physiological disruption of the hypothalamic-pituitary system. This condition results in decreased
    somatostatin (SRIF), increased growth hormone releasing hormone (GHRH) and elevated GH. The
    other half of the cases are due to a pituitary tumor which oversecretes GH and causes excessive
    growth. High levels of GH actually decrease GHRH and stimulate SRIF, in an attempt to turn off the
    pituitary – but because the tumor is hypersecreting GH, the pituitary cannot respond and continues to
    secrete high levels of GH. Regardless of the cause, gigantism is the result of increased and
    prolonged levels of GH throughout childhood, especially during puberty when growth rate is maximal.
    Distracter explanations:
     Growth hormone (GH), growth hormone releasing hormone (GHRH), insulin-like growth factor
    1 (IGF1) and insulin-like growth factor 2 (IGF2) would all be increased in this man when he
    was a young boy.
     Insulin would still be secreted in an episodic manner in response to blood glucose, and
    baseline levels of insulin would be normal unless there was an underlying (and additional)
    metabolic problem.

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  • 11. 

    Which of the following biomolecules is the most sensitive and useful for clinically diagnosing thyroid function?

    • Thyroid Binding Globulin (TBG)

    • Thyroid Releasing Hormone (TRH)

    • Thyroid Stimulating Hormone (TSH)

    • Thyroxine (T4)

    • Triiodothyronine (T3)

    Correct Answer
    A. Thyroid Stimulating Hormone (TSH)
    Explanation
    Feedback: Thyroid stimulating hormone (TSH) is recognized as the most sensitive marker for thyroid
    function. TSH levels must be compared with the relative levels of both T4 and T3 to determine the
    primary source of the problem – but 90% of all thyroid problems are due to an abnormal thyroid
    gland, not the hypothalamic-pituitary axis. For example, primary hyperthyroidism is due to the thyroid
    gland, and Grave’s disease accounts for ~90% of all cases. Secondary hyperthyroidism – where T3,
    T4 and TSH are elevated, indicate a non-responsive hypo-pit axis – but only account for ~10% of all
    thyroid problems.
    Distracter explanations:
    Thyroid binding globulin may be measured to insure the amount of free thyroid hormone in the blood,
    but is not considered a sensitive assay.
    TRH is released into the portal blood and is not measured.
    T3 and T4 must also be measured to determine thyroid gland function. However, the levels of T4 and
    T3 only indicate the relative function of the thyroid gland – the levels of TSH indicate the source of the
    problem, therefore TSH is considered more sensitive and clinically useful (but recognize levels of T4
    and T3 are also clinically important and are the first indication of an abnormally functioning thyroid
    gland).

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  • 12. 

    Thyroid hormone stimulates thermogenesis primarily in which of the following tissues?

    • Adipose

    • Brain

    • Cardiac Muscle

    • Liver

    • Skeletal Muscle

    Correct Answer
    A. Adipose
    Explanation
    Feedback: Thyroid hormones regulate thermogenesis in adipose tissue, predominantly brown
    adipose tissue (BAT), by regulating the production of thermogenin, otherwise known as uncoupling
    protein 1 (UCP-1). Catecholamines trigger protein kinase activation, which leads to increased
    production of lipase and the release of free fatty acids. The free fatty acids cross into the
    mitochrondria. The hydrogen atoms, releases as part of the electron transport process, are then
    shuttled through the UCP-1 complex to generate heat. Approximately 20% of the hydrogen atoms
    are shuttled through the ATPase, to maintain adequate amounts of energy so the cells can maintain
    or increase thermogenesis. BAT thermogenesis occurs primarily in infants after birth.
    Distracter explanations:
     Minor amount of heat production may occur in liver and skeletal muscle when glycogen stores
    are mobilized – but not a major source of heat production.
     Brain and cardiac muscle do not exhibit thermogenesis, but benefit directly from the increased
    heat. The thermoregulatory center of the brain also is the primary site that regulates body
    temperature under normal physiological states, and predominates thermoregulation activities
    in adults.

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  • 13. 

    A pharmaceutical company develops a new glucocorticoid receptor antagonist. In vivo studies performed in wild-type mice (i.e. normal controls) suggest this compound also binds with additional steroid receptors. Based on the general principals of receptor homology, this compound most likely interacts with which of the following steroid receptors?

    • Androgen Receptor

    • Estrogen Receptor alpha

    • Estrogen Receptor beta

    • Mineralocorticoid Receptor

    • Progesterone Receptor

    Correct Answer
    A. Mineralocorticoid Receptor
    Explanation
    Feedback: The glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) exhibit a high
    homology in both the DNA binding domain and ligand binding domain regions. Thus, MR is the most
    likely receptor interaction with the GR antagonists.
    Distracter explanations:
     The antagonist may also interact with the progesterone receptor (PR), which also shares a
    high degree of homology with the corticoid receptors. This has been observed in real-life –
    Mifepristone (RU-486) was developed as a GR antagonist, but was found to exhibit a higher
    affinity for the PR. You could have also chosen this as a correct answer.
     The androgen receptor has an ~50% homology with corticoid receptors, and therefore some
    cross-reactive binding may occur. Although the AR and corticoid receptors exhibit lower
    homology than GR/MR with PR, you could also argue that this answer may be possible and
    therefore also correct.
     The estrogen receptors (ERs) exhibit a low homology with any of the other receptors, and
    therefore the antagonist would likely not interact with the ERs. These are the only true ‘wrong’
    answers to this question.

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  • 14. 

    Which of the following biomolecules binds to a nuclear receptor and directly regulates gene transcription?

    • Angiotensin II

    • Calcitriol

    • Growth Hormone

    • Insulin

    • Insulin-like Growth Factor 1

    Correct Answer
    A. Calcitriol
    Explanation
    Feedback: Calcitriol is the active metabolite of Vitamin D. Recall that steroid hormones, thyroid
    hormones, Vit D and Vit A all bind with nuclear (i.e. intracellular) receptors. Calcitriol has recently
    been shown to regulate approximately 800 genes in man.
    Distracter explanations:
     The other ligands bind to membrane-bound receptors, stimulate second-messenger signaling
    cascade, and therefore indirectly regulate gene transcription.
     Insulin and insulin-like growth factor bind to heterotetramer membrane-bound receptors (IGF
    Type 2 receptor is a monomer/dimer hybrid).
     Growth hormone binds to a membrane-bound monomer that quickly forms an active dimer
    receptor
     Angiotensin II binds to a G-protein coupled membrane-bound receptor.

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  • 15. 

    Which of the following hormones is synthesized in the hypothalamus and secreted from the pituitary?

    • Adrenocorticotropic Hormone

    • Antidiuretic Hormone

    • Follicle Stimulating Hormone

    • Growth Hormone

    • Prolactin

    Correct Answer
    A. Antidiuretic Hormone
    Explanation
    Feedback: Antidiuretic hormone (ADH, also known as vasopressin) and oxytocin are nonapeptides
    that are synthesized in hypothalamic neurons. These peptides then migrate along the nerve axis to
    the neuron terminals, which reside in the posterior pituitary. The peptides are then stored in secretory
    vesicles and released upon stimulation. Oxytocin is predominantly released due to neural reflex arcs,
    stimulated by nerve endings in the myometrium and breast.
    Distracter explanations:
     Adrenocorticotropic hormone (ACTH), follicle stimulating hormone (FSH), growth hormone
    (GH) and prolactin (PRL) are all synthesized and stored in their respective cells within the
    anterior pituitary.
     Production and secretion of these hormones are regulated by the liberins and statins produced
    in the hypothalamus and then subsequently released into the portal circulation. The liberins
    and statins then bind to specific receptors in the pituitary to regulate production of ACTH, FSH,
    GH and PRL, respectively.

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  • 16. 

    A 65-year-old woman, recovering from a bacterial infection after visiting the island of Guadeloupe, suddenly develops severe nausea and vomiting. The woman is rushed to the emergency room. The patient is confused and cannot answer basic questions – she does not remember her age. Blood pressure is 90/55 and the patient is severely dehydrated. This woman is diagnosed with which of the following disorders?

    • Adrenal crisis

    • Adrenal Disease

    • Adrenal Syndrome

    • Primary adrenal insufficiency

    • Secondary adrenal insufficiency

    • Tertiary adrenal insufficiency

    Correct Answer
    A. Adrenal crisis
    Explanation
    Feedback: This patient’s symptoms are consistent with sudden onset adrenal failure, also termed
    ‘Adrenal Crisis’ or ‘Addisonian Crisis’. This is the acute withdrawal of corticoid hormone production,
    which can quickly lead to shock and subsequent death if not treated immediately.
    Distracter explanations:
     Adrenal Disease refers to chronic onset, and Adrenal Syndrome refers to general adrenal
    insufficiency before the cause can be determined.
     Primary insufficiency occurs when levels of ACTH are normal but the adrenal gland does not
    respond accordingly.
     Secondary and tertiary adrenal insufficiency indicate inadequate amounts of ACTH.
     Tertiary is often attributed to decreased production of CRH. CRH is a unique hypothalamic
    releasing hormone, in that CRH binds to serum proteins and can be measured in serum.
    However, the measurements are often inprecise, the assay is expensive, and oftentimes it is
    irrelevant because the result is still reduced ACTH.
     Adrenal crisis is often due to primary adrenal insufficiency – but without levels of ACTH to
    determine the source of the problem, this is not the correct answer.

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  • 17. 

    A 65-year-old woman, recovering from a bacterial infection after visiting the island of Guadeloupe, suddenly develops severe nausea and vomiting. The woman is rushed to the emergency room. The patient is confused and cannot answer basic questions – she does not remember her age. Blood pressure is 90/55 and the patient is severely dehydrated. Which of the following hormones is most likely decreased in this patient and the cause of her symptoms and signs?

    • Angiotensin

    • Aldosterone

    • Cortisol

    • Corticosterone

    • Renin

    Correct Answer
    A. Cortisol
    Explanation
    Feedback: Low levels of cortisol are the primary problem. Recall that cortisol acts throughout the
    body. Cortisol binds with the corticoid receptor to directly regulate gene transcription, and cortisol is a
    permissive hormone that augments the actions of many hormones throughout the body. Both cortisol
    and thyroid hormones are permissive hormones that are required to maintain homeostasis.
    Distracter explanations:
     Angiotensin II is produced in the lungs and is not dependent on the adrenal. Levels will likely
    rise in an attempt to increase aldosterone production, which in itself can cause severe
    problems, because ANG II is a powerful vasoconstrictor.
     Renin is released by the kidney, not the adrenal gland.
     Corticosterone is primarily converted, and is not the active metabolite.
     Aldosterone levels will also fall, but the primary cause for this patient’s problems are due to the
    rapid withdrawal of cortisol. Mineralocorticoid therapy will begin once the patient is stabilized.

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  • 18. 

    A 22-year-old man presents with acute onset of severe aldosterone deficiency. The patient’s cortisol levels are normal. Which of the following biomolecules is most likely reduced in this patient?

    • Adrenocorticotropic hormone

    • Angiotensinogen

    • Angiotensin I

    • Angiotensin II

    • Renin

    Correct Answer
    A. Angiotensin II
    Explanation
    Feedback: Recognize that aldosterone production is regulated by angiotensin II and blood pressure.
    The patient’s cortisol levels are normal – which indicates that the majority of the adrenal steroidogenic
    enzymes are produced and active, which indicates that levels of adrenocorticotropic hormone levels
    are likely adequate. Recall that ACTH regulates the expression of the rate-limiting enzymes, CYP11
    and StAR, whereas ANG II regulates aldosterone synthase.
    Distracter explanations:
     Cortisol levels are normal which indicates ACTH levels are most likely not reduced.
     Angiotensinogen and ANG I are precursors for ANG II – but these biomolecules are not
    biologically inactive. You cannot determine from the information provided that levels of
    angiotensinogen or ANG II are abnormal.
     Renin is produced by the kidney and convert angiotensinogen to ANG 1, and may be
    abnormal, but you cannot determine if levels of ANG I are reduced, because ANG I is (for the
    most part) biologically inactive.

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  • 19. 

    A 46-year-old woman complains of weight gain. History reveals sudden onset of hot flashes and amenorrhea for 11 months. Physical exam reveals engorged and tender breasts; otherwise unremarkable. Which of the following biomolecules is most likely elevated in this patient?

    • Cortisol

    • Follicle Stimulating Hormone

    • Growth Hormone

    • Prolactin

    • Thyroid Stimulating Hormone

    Correct Answer
    A. Prolactin
    Explanation
    Feedback: Physical exam reveals engorged and tender breasts, which is attributed to high levels of
    prolactin. The woman has not had a menstrual period for 11 months, and therefore she is not
    pregnant or breastfeeding. The woman is exhibiting symptoms associated with hyperprolactinemia,
    most likely caused by hypothyroidism.
    Distracter explanations:
     Levels of cortisol may be elevated and this woman may be stressed, but the primary hormone
    stimulating breast development is prolactin, not cortisol.
     FSH acts on the ovary and therefore would not cause these effects. This woman could be
    exhibiting menopause symptoms, which will result in elevated FSH – but FSH has no known
    affects on the mammary glands.
     GH may stimulate breast development, but would not cause hot flashes.
     This woman most likely also has hyperthyroidism – however, the increased prolactin is due to
    an interaction with TRH on the pituitary lactotrophs. TSH would has no known effects on the
    mammary glands.

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  • 20. 

    A 46-year-old woman complains of weight gain. History reveals sudden onset of hot flashes and amenorrhea for 11 months. Physical exam reveals engorged and tender breasts; otherwise unremarkable. Reduced levels of which of the following hormones is the most likely cause of this patient’s symptoms and signs?

    • Cortisol

    • Dopamine

    • Oxytocin

    • Somatostatin

    • Thyroid Releasing Hormone

    Correct Answer
    A. Dopamine
    Explanation
    Feedback: Prolactin is under the tonic inhibitory control of dopamine (DA). Reduced dopamine will
    result in increased prolactin levels. Reductions in the other hormones have no established effects on
    the production and/or secretion of prolactin.
    Distracter explanations:
    Cortisol is a red herring and should be omitted.
    Oxytocin is released during suckling to contract the muscle cells lining the mammary ducts, thereby
    stimulating milk ejection. Oxytocin is released in episodic spurts, and may be elevated in this patient,
    not reduced.
    Somatostatin levels are likely normal or may be slightly elevated in this patient, due to the decreased
    metabolic rate – again, this patient is most likely also hypothyroid.
    TRH is most likely increased, not decreased.

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  • 21. 

    A 46-year-old woman complains of weight gain. History reveals sudden onset of hot flashes and amenorrhea for 11 months. Physical exam reveals engorged and tender breasts; otherwise unremarkable. This patient is most likely diagnosed with which of the following disorder(s)?

    • Acromegaly

    • Addison’s Disease

    • Cushing’s Disease

    • Hyperprolactinemia

    • Hyperthyroidism

    • Hypothyroidism

    Correct Answer
    A. Hypothyroidism
    Explanation
    Feedback: This patient is exhibiting classic signs of hypothyroidism, which affects a greater number
    of women than men. Women with hypothyroidism often exhibit weight gain, irregular menstrual
    cycles, and thermoregulatory problems. It is now recognized that women starting the menopausal
    transition and afflicted with hypothyroidism often exhibit hot flashes. You should be able to clearly
    identify/describe why the other distracters are not correct.

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  • 22. 

    A 41-year-old man is on safari in African plains when he gets separated from his safari guides and becomes lost. The man has a 2 L bottle of clean water and no available food sources. After 8 hrs without food the man feels hungry. Which of the following hormones is most likely elevated and stimulates this man’s appetite and urge to eat?

    • Cortisol

    • Ghrelin

    • Growth Hormone

    • Leptin

    • Neuropeptide Y

    Correct Answer
    A. Neuropeptide Y
    Explanation
    Feeback: Neuropeptide Y is a potent orixegen, i.e. a biomolecule that stimulate’s appetite and food
    intake. Ghrelin is released by the stomach in response to hunger, binds to the Ghrelin receptor in the
    arcuate nucleus and stimulates the release of NPY.
    Distracter explanations:
     Cortisol does not play a role in short-term hunger. Cortisol may augment the actions of NPY
    and Ghrelin in fasting or acute starvation states.
     Ghrelin is released in response to hunger to stimulate eating – but does so by releasing NPY.
    NPY directly stimulates appetite and food intake. You could argue that Ghrelin could also be
    considered a correct answer – but recognize that NPY is the best answer.
     GH is released in response to Ghrelin and NPY, but does not directly stimulate appetite or food
    intake.
     Leptin will be released by adipocytes after feeding to suppress the release of NPY. Leptin may
    stimulate appetite and food intake during starvation states, as an adipocyte pro-survival
    mechanism – but there is not enough date to clearly demonstrate this proposition.

    Rate this question:

  • 23. 

    A 41-year-old man is on safari in African plains when he gets separated from his safari guides and becomes lost. The man has a 2 L bottle of clean water and no available food sources. The man does not find food and goes 5 days without eating. Which of the following hormones is most likely elevated and stimulating glycogenolysis of this man’s liver glycogen stores?

    • Cortisol

    • Epinephrine

    • Glucagon

    • Glucagon-like peptide 1

    • Insulin

    Correct Answer
    A. Glucagon
    Explanation
    Feedback: Glucagon will be released to stimulate glycogenolysis of glycogen stores, and to
    stimulate hepatic gluceoneogensis. Glucagon secretion will be enhanced by continued
    hypoglycemia.
    Distracter explanations:
     Cortisol levels will likely rise in response to continued stress. Cortisol will exert permissive
    effects and stimulate protein catabolism. Cortisol will also stimulate production of glucagon
    receptors, to stimulate glucagon’s glycogenolytic effects.
     GLP-1 and GIP may stimulate glucagon release, but the incretins do not directly regulate
    glycogenolysis.
     Insulin will be released to facilitate glucose uptake in cells and tissues, but will not be elevated
    to stimulate glycogenolysis.

    Rate this question:

  • 24. 

    A 41-year-old man is on safari in African plains when he gets separated from his safari guides and becomes lost. The man has a 2 L bottle of clean water and no available food sources. The man remains lost and begins to feel fatigued and very weak. He is able to find water but has found no food – he has been starving for 14 days. Which of the following biomolecules is most likely reduced in this man?

    • Cortisol

    • Ghrelin

    • Growth Hormone Releasing Hormone

    • Leptin

    • Neuropeptide Y

    Correct Answer
    A. Growth Hormone Releasing Hormone
    Explanation
    Feedback: Growth hormone will be released for the first 5-7 days of acute starvation, to stimulate
    glycogenolysis and inhibit glucose uptake by skeletal muscles. However, this man is now suffering
    with chronic starvation, and the prolonged high levels of GHRH will result in an ultra-short negative
    feedback loop – resulting in GHRH inhibiting its own release from the hypothalamus.
    Distracter explanations:
     Cortisol levels will remain elevated, in an attempt to return the man to metabolic homeostasis.
     Ghrelin levels will remain elevated (as demonstrated in animal studies), but the constant
    exposure to high Ghrelin levels causes desensitization and down-regulation of the Ghrelin
    receptor.
     As note in a previous answer, as lipolysis continues leptin will continue to be released in high
    levels. Leptin may actually stimulate appetite during chronic starvation.
     NPY levels will also remain high – but the NPY receptor will down-regulate. Note that high
    levels of NPY may reach the systemic circulation, which may result in adverse affects on
    cardiovascular health.

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  • 25. 

    Glucagon secretion is inhibited by which of the following biomolecules? (Mark ALL that apply)

    • Low concentrations of Insulin.

    • Low concentrations of Glucagon-like peptide 1 (GLP-1).

    • Low concentrations of Glucose.

    • High concentrations of Insulin.

    • High concentrations of Glucagon-like peptide 1 (GLP-1).

    • High concentrations of Glucose.

    Correct Answer(s)
    A. High concentrations of Insulin.
    A. High concentrations of Glucagon-like peptide 1 (GLP-1).
    A. High concentrations of Glucose.
    Explanation
    Feedback: Glucagon secretion is regulated predominantly by glucose concentration, and high levels
    of glucose are known to inhibit the secretion of glucagon from the pancreatic alpha cells. However,
    the question did not ask for the primary regulator.
    High levels of insulin are released in response to hyperglycemia, and insulin also can inhibit
    glucagon. GLP-1, an incretin released from L-cells, can also inhibit the release of glucagon. The
    effects of GLP-1 and insulin are – for the most part – likely indirect. The functionality of the insulin
    receptor on the pancreatic alpha cells is not clear, and GLP-1 receptors are largely not expressed on
    the alpha cells. Some recent reports have detected very low levels of GLP receptors mRNA in alpha
    cells (~ 0.2% of the mRNA level found in beta cells), and localization studies using
    immunocytochemistry have largely been unable to clearly demonstrate the presence of the GLP
    receptors on the beta cells.
    Distracter explanations:
     Low concentration of glucose (below 4 mM) is the primary stimulus to stimulate glucagon
    release.
     There is no evidence to suggest that low concentrations of insulin or GLP-1 will inhibit
    glucagon secretion.
     High levels of insulin and GLP-1 are released in response to a meal and increased glucose
    concentration; both proteins in high levels have been shown to inhibit glucagon release, largely
    by indirect mechanisms.

    Rate this question:

Quiz Review Timeline (Updated): Apr 27, 2023 +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Apr 27, 2023
    Quiz Edited by
    ProProfs Editorial Team
  • Feb 18, 2013
    Quiz Created by
    Macac013

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