Questions from the book- Ch.18: The Endocrine System
List the three zones of the adrenal cortex.
Answer: The three zones of the adrenal cortex from superficial to deep are the zona glomerulosa, zona fasciculata, and zona reticularis.
Identify the two lobes of the pituitary gland.
Answer: The two lobes of the pituitary gland are the anterior lobe and the posterior lobe.
What primary factor determines each cell's hormonal sensitivities?
Answer: A cell's hormonal sensitivities are determined by the presence or absence of extracellular and intracellular receptors that bind a given hormone.
How would the presence of a substance that inhibits the enzyme adenylate cyclase affect the activity of a hormone that produces its cellular effects by way of the second messenger cAMP?
Answer: A substance that inhibits adenylate cyclase, the enzyme that converts ATP to cAMP, would block the action of any hormone that requires cAMP as a second messenger.
Which pancreatic cells secrete glucagon? List the effects of glucagon.
Answer: Alpha cells secrete glucagon. Glucagon increases blood glucose level by (1) increasing the breakdown of glycogen to glucose in liver and skeletal muscle, (2) increasing the breakdown of fat to fatty acids in adipose tissue, and (3) increasing the synthesis and release of glucose by the liver.
What effect would an elevated circulating level of cortisol, a steroid hormone from the adrenal cortex, have on the pituitary secretion of ACTH?
Answer: An elevated circulating level of cortisol would inhibit the endocrine cells that control the release of ACTH from the pituitary gland, so the ACTH level would decrease. This is an example of a negative feedback mechanism.
What effect would an increased blood glucagon level have on the amount of glycogen stored in the liver?
Answer: An increased blood level of glucagon stimulates the conversion of glycogen to glucose in the liver, which would in turn decrease the amount of glycogen in the liver.
What hormones are released from the posterior lobe of the pituitary gland and how does their release differ from hormones released by the anterior lobe of the pituitary gland?
Answer: Antidiuretic hormone (ADH) and oxytocin (OXT) are released from the posterior lobe of the pituitary gland. Posterior pituitary hormones are released directly from the hypothalamus, and regulatory hormones from the hypothalamus control the release of anterior pituitary hormones.
Describe negative feedback as it relates to humoral stimuli.
Answer: Humoral stimuli are those involving changes in the composition of the extracellular fluid. Such a stimulus triggers the secretion of a hormone, and the direct or indirect effects of the hormone reduce the intensity of the stimulus.
In a typical regulation pattern of endocrine secretion, which hormone is responsible for negative feedback?
Answer: In a typical regulation pattern of endocrine secretion, hormone 2 (which is released from the target organ) is responsible for negative feedback.
If a person were dehydrated, how would the amount of ADH released by the posterior pituitary lobe change?
Answer: In dehydration, blood osmotic concentration is increased, which would stimulate the posterior lobe of the pituitary gland to release more ADH.
The release of which pituitary hormone would lead to an increased level of somatomedins in the blood?
Answer: Somatomedins mediate the action of growth hormone. Elevated levels of growth hormone typically accompany elevated levels of somatomedins.
Identify the types of cells in the pancreatic islets and the hormones produced by each.
Answer: The cells of the pancreatic islets (and their hormones) are alpha cells (glucagon), beta cells (insulin), delta cells (GH-IH), and pancreatic polypeptide cells (pancreatic polypeptide).
The regulatory hormones from the hypothalamus control secretion from endocrine cells, which are located where?
Answer: The endocrine cells whose secretion is controlled by regulatory hormones from the hypothalamus are located in the anterior lobe of the pituitary gland.
Identify the hormone secreted by the parathyroid glands.
Answer: The hormone secreted by the parathyroid glands is parathyroid hormone (PTH).
Describe the location of the parathyroid glands.
Answer: The parathyroid glands are embedded in the posterior surfaces of the lateral lobes of the thyroid gland.
The removal of the parathyroid glands would result in a decrease in the blood concentration of which important mineral?
Answer: The removal of the parathyroid glands would result in a decrease in the blood concentration of calcium ions.
Identify the two regions of the adrenal gland, and cite the hormones secreted by each.
Answer: The two regions of the adrenal gland are the cortex and medulla. The cortex secretes mineralocorticoids (mainly aldosterone), glucocorticoids (mainly cortisol, corticosterone, and cortisone), and androgens; the medulla secretes epinephrine and norepinephrine.
Which zone of the adrenal cortex produces mineralocorticoids and what is the primary mineralocorticoid?
Answer: The zona glomerulosa produces mineralocorticoids. The primary mineralocorticoid is aldosterone.
Identify the hormones of the thyroid gland
Answer: Thyroxine (T4) and triiodothyronine (T3)
