Endocrine Midterm study guide Flashcards
(19 cards)
What imbalance lessens the rate of secretion of parathyroid hormone (PTH)?
a. Increased serum calcium levels
b. Decreased serum magnesium levels
c. Decreased levels of thyroid-stimulating hormone
d. Increased levels of thyroid-stimulating hormone
ANS: A
The overall effect of parathyroid hormone (PTH)is to increase serum calcium and to decrease serum phosphate concentration.
Regulation of the release of catecholamines from the adrenal medulla is an example of which type of regulation?
a. Negative feedback c. Neural
b. Positive feedback d. Physiologic
ANS: C
The release of hormones occurs either in response to an alteration in the cellular environment or in the process of maintaining a regulated level of certain hormones or certain substances. Several different mechanisms, one of which is neural control (e.g., stress-induced release of catecholamines from the adrenal medulla), regulate the release of hormones.
How does a faulty negative-feedback mechanism result in a hormonal imbalance?
a. Hormones are not synthesized in response to cellular and tissue activities.
b. Decreased hormonal secretion is a response to rising hormone levels.
c. Too little hormone production is initiated.
d. Excessive hormone production results from a failure to turn off the system.
ANS: D
Negative-feedback systems are important in maintaining hormones within physiologic ranges. The lack of negative-feedback inhibition on hormonal release often results in pathologic conditions. Excessive hormone production, which is the result of the failure to turn off the system, can cause various hormonal imbalances and related conditions. The correct option is the only accurate description of this hormonal function.
Which of the following is a lipid-soluble hormone?
a. Cortisol c. Epinephrine
b. Oxytocin d. Growth hormone
ANS: A
Cortisol and adrenal androgens are lipid-soluble hormones and are primarily bound to a carrier or transport protein in circulation. The other options are water-soluble hormones.
Most protein hormones are transported in the bloodstream and are:
a. Bound to a lipid-soluble carrier
b. Free in an unbound, water-soluble form
c. Bound to a water soluble–binding protein
d. Free because of their lipid-soluble chemistry
ANS: B
Peptide or protein hormones, such as insulin, pituitary, hypothalamic, and parathyroid, are water soluble and circulate in free (unbound) forms. The other options are not true statements related to the transport of protein hormones.
Thyroid-stimulating hormone (TSH) is released to stimulate thyroid hormone (TH) and is inhibited when plasma levels of TH are adequate. This is an example of:
a. Positive feedback c. Neural regulation
b. Negative feedback d. Physiologic regulation
ANS: B
Feedback systems provide precise monitoring and control of the cellular environment. Negative feedback occurs because the changing chemical, neural, or endocrine response to a stimulus negates the initiating change that triggered the release of the hormone. Thyrotropin-releasing hormone (TRH) from the hypothalamus stimulates TSH secretion from the anterior pituitary. Secretion of TSH stimulates the synthesis and secretion of THs. Increasing levels of T4 and triiodothyronine (T3) then generate negative feedback on the pituitary and hypothalamus to inhibit TRH and TSH synthesis.
ANS: B
Feedback systems provide precise monitoring and control of the cellular environment. Negative feedback occurs because the changing chemical, neural, or endocrine response to a stimulus negates the initiating change that triggered the release of the hormone. Thyrotropin-releasing hormone (TRH) from the hypothalamus stimulates TSH secretion from the anterior pituitary. Secretion of TSH stimulates the synthesis and secretion of THs. Increasing levels of T4 and triiodothyronine (T3) then generate negative feedback on the pituitary and hypothalamus to inhibit TRH and TSH synthesis.
Lipid-soluble hormone receptors are located:
a. Inside the plasma membrane in the cytoplasm
b. On the outer surface of the plasma membrane
c. Inside the mitochondria
d. On the inner surface of the plasma membrane
ANS: A
Lipid-soluble hormone receptors are located inside the plasma membrane and easily diffuse across the plasma membrane to bind to either cytosolic or nuclear receptors. The other options are not true statements.
Where is antidiuretic hormone (ADH) synthesized, and where does it act?
a. Hypothalamus; renal tubular cells c. Anterior pituitary; posterior pituitary
b. Renal tubules; renal collecting ducts d. Posterior pituitary; loop of Henle
ANS: A
Once synthesized in the hypothalamus, ADH acts on the vasopressin 2 (V2) receptors of the renal duct cells to increase their permeability.
Where is oxytocin synthesized?
a. Hypothalamus c. Anterior pituitary
b. Paraventricular nuclei d. Posterior pituitary
ANS: D
ADH and oxytocin are synthesized in hypothalamic neurons but are stored and secreted by the posterior pituitary.
Which mineral is needed for thyroid-stimulating hormone (TSH) to stimulate the secretion of thyroid hormone (TH)?
a. Iron c. Iodide
b. Zinc d. Copper
ANS: C
TSH, which is synthesized and stored in the anterior pituitary, stimulates secretion of TH by activating intracellular processes, including the uptake of iodine necessary for the synthesis of TH.
What effect does hyperphosphatemia have on other electrolytes?
a. Increases serum calcium. c. Decreases serum magnesium.
b. Decreases serum calcium. d. Increases serum magnesium.
ANS: B
Hyperphosphatemia leads to hypocalcemia; the other options are incorrect.
What is the action of calcitonin?
a. Increases metabolism. c. Increases serum calcium.
b. Decreases metabolism. d. Decreases serum calcium.
ANS: D
Calcitonin, also called thyrocalcitonin, acts to lower serum calcium levels by inhibiting bone-resorbing osteoclasts, making the other options incorrect.
Which hormone is involved in the regulation of serum calcium levels?
a. Parathyroid hormone (PTH)
b. Thyroxine (T4)
c. Adrenocorticotropic hormone (ACTH)
d. Triiodothyronine (T3)
ANS: A
The parathyroid glands produce PTH, a regulator of serum calcium; therefore the other options are incorrect.
Which hormone inhibits the secretion of growth hormone (GH)?
a. Somatostatin c. Thyroid-stimulating hormone
b. Thyroxine d. Calcitonin
ANS: C
Two hormones from the hypothalamus control GH secretion: (1) GH-releasing hormone (GHRH), which increases GH secretion; and (2) somatostatin, which inhibits it.
Target cells for parathyroid hormone are located in the:
a. Tubules of nephrons c. Glomeruli of nephrons
b. Thyroid gland d. Smooth and skeletal muscles
ANS: A
Parathyroid hormone acts on its plasma membrane receptor only in the distal and proximal tubules of the kidney’s nephron.
Which compound or hormone is secreted by the adrenal medulla?
a. Cortisol c. Androgens
b. Epinephrine d. Aldosterone
ANS: B
Of the available options, the catecholamine epinephrine (adrenaline) is the only major product secreted.
Which hormone inhibits the secretion of growth hormone (GH)?
a. Somatostatin c. Thyroid-stimulating hormone
b. Thyroxine d. Calcitonin
ANS: A
Two hormones from the hypothalamus control GH secretion: (1) GH-releasing hormone (GHRH), which increases GH secretion; and (2) somatostatin, which inhibits it.
Target cells for parathyroid hormone are located in the:
a. Tubules of nephrons c. Glomeruli of nephrons
b. Thyroid gland d. Smooth and skeletal muscles
ANS: A
Parathyroid hormone acts on its plasma membrane receptor only in the distal and proximal tubules of the kidney’s nephron.
The secretion of adrenocorticotropic-stimulating hormone (ACTH) will result in the increased level of which hormone?
a. Thyroxine c. Cortisol.
b. Insulin d. Antidiuretic hormone
ANS: C
Psychologic and physiologic stress (e.g., hypoxia, hypoglycemia, hyperthermia, exercise) increases ACTH secretion, leading to increased cortisol levels.
