Chapter 23 concept questions Flashcards
Name the two parts of the adrenal gland and the major hormones secreted by each part.
The medulla secretes catecholamines (epinephrine, norepinephrine), and the cortex secretes aldosterone, glucocorticoids, and sex hormones.
For what hormones is androstenedione a prohormone? (See Fig. 23.1b.) Why might this prohormone give an athlete an advantage?
Androstenedione is a prohormone for testosterone. Testosterone is anabolic for skeletal muscle, which might give an athlete a strength advantage.
What do the abbreviations HPA and CBG stand for? If there is an alternate name for each term, what is it?
HPA = hypothalamic-pituitary-adrenal
CBG= corticosteroid-binding
You are mountain-biking in Canada and encounter a bear, which chases you up a tree. Is your stress response mediated by cortisol? Explain.
This immediate stress response is too rapid to be mediated by cortisol and must be a fight-or-flight response mediated by the sympathetic nervous system and catecholamines.
The illegal use of anabolic steroids by bodybuilders and athletes periodically receives much attention. Do these illegal steroids include cortisol? Explain.
No, because cortisol is catabolic on muscle proteins.
For primary, secondary, and iatrogenic hypercortisolism, indicate whether the ACTH level is normal, higher than normal, or lower than normal.
Primary and iatrogenic hypercortisolism: ACTH is lower than normal because of negative feedback. Secondary hypercortisolism: ACTH is higher because of the ACTH-secreting tumor.
Would someone with Addison’s disease have normal, low, or high levels of ACTH in the blood?
Addison’s disease: high ACTH due to reduced corticosteroid production and lack of negative feedback.
Can you think of a situation where it might be the advantage for the body to co-secrete ACTH and beta-endorphin?
ACTH is secreted during stress. If the stress is a physical one caused by an injury, the endogenous opioid beta-endorphin can decrease pain and help the person continue functioning.
A woman who had her thyroid gland removed because of cancer was given pills containing only T4. Why was this less active form of the hormone an effective treatment for her hypothyroidism?
In peripheral tissues, T4 is converted to
T3, which is the more active form of the hormone.
Why would excessive production of thyroid hormone, which uncouples mitochondrial ATP production and proton transport[p. 108], cause a person to become intolerant of heat?
When mitochondria are uncoupled, energy normally captured in ATP is released as heat. This raises the person’s body temperature and causes heat intolerance.
Which pituitary hormone in addition to GH has two hypothalamic factors that regulate its release?
prolactin
Which hormones are essential for normal growth and development?
Normal growth and development require growth hormone, thyroid hormone, insulin, and insulin-like growth factors.
Why don’t adults with growth hormone hypersecretion grow taller?
Their epiphyseal plates have closed.
What does hypercalcemia do to neuronal membrane potential, and why does that effect depress neuromuscular excitability?
Hypercalcemia hyperpolarizes the membrane potential, which makes it harder for the neuron to fire an action potential.
Describe the movement of
from lumen of the nephron or intestine to the ECF as active, passive, facilitated diffusion, and so on.
The Na+ -Ca2+ exchanger is a secondary active transporter, and the Ca2+ -ATPase is an active transporter.
