Exam 45: Hormones and the Endocrine System

Correct and appropriate signal transduction processes are generally under strong selective pressure and are determined by the properties of the molecules involved, the concentrations of signal and receptor molecules, and the binding affinities between signal and receptor. Therefore, a hormone action is very specific in a species at any one point in time. However, there are examples of very diverse functions of a specific hormone between groups of organisms. For example, thyroxin, which is produced in all vertebrates and many invertebrates, can trigger growth, differentiation, metamorphosis, maturation, reproduction, behaviour, temperature tolerance, osmoregulation, or seasonal adaptation depending on the organism in which it is produced. What is the most logical explanation for such different responses triggered by thyroxin in organisms?

In response to stress, the adrenal gland promotes the synthesis of glucose from noncarbohydrate substrates via the action of the steroid hormone ________.

Steroid and polypeptide hormones typically have in common ________.

What would be a likely outcome of a person not consuming enough iodine in their diet?

Growth factors are local regulators that

Which hormone is incorrectly paired with its action?

If the adrenal cortex were surgically removed, an increase in the plasma levels of ________ would likely be observed.

Nitric oxide and adrenaline ________.

The hypothalamus

Rapid changes to skin colour in many vertebrates is under the control of ________.

When a person drinks alcohol, the rate of urination increases. Which of the following best accounts for the increase in urination above normal rates?

The steroid hormone "aldosterone" affects only a small number of cells in the body because ________.

Osteoporosis is a condition in which the density of bones is decreased so much that the individual is at a higher risk of fractures. The more calcium in the bones, the better the bone density. Which of the following would produce the greatest increase in bone calcium levels?

A cell with membrane-bound proteins that selectively bind a specific hormone is called that hormone's ________.

DES is called an "endocrine disrupting chemical" because it interferes with the endocrine secretions of the ________.

An example of antagonistic hormones controlling homeostasis is ________.

Tadpoles must undergo a major metamorphosis to become frogs. This change includes reabsorption of the tail, growth of limbs, calcification of the skeleton, increase in rhodopsin in the eye, development of lungs, change in haemoglobin structure, and reformation of the gut from the long gut of an herbivore to the short gut of a carnivore. Amazingly, all of these changes are induced by thyroxine. What is the most likely explanation for such a wide array of effects of thyroxine?

Insect hormones and their receptors ________.

The amino acid "tyrosine" is a starting substrate for the synthesis of ________.

Which of the following are similar in structure to cholesterol? I. estradiol II. insulin III. glucocorticoids IV. testosterone V. antidiuretic hormone