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, behavior, 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?

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

Which of the following are properties of steroid hormones? I.Steroid hormones are lipid soluble and easily cross the phospholipid bilayer. II.Steroid hormones usually exert their effects on target cells through membrane receptor proteins. III.Steroid hormones act on cells close to where they were produced. IV.Steroid hormones regulate gene transcription by binding to intracellular receptor proteins.

The body's reaction to parathyroid hormone (PTH), raising plasma levels of calcium, can be opposed by ________.

If a biochemist discovers a new molecule, which of the following pieces of data would allow her to draw the conclusion that the molecule is a steroid hormone? I.The molecule is lipid soluble. II.The molecule is derived from a series of steps beginning with cholesterol. III.The molecule acts at a target tissue some distance from where it is produced. IV.The molecule uses a transport protein when in an aqueous solution such as blood.

Predict the effects of a drug that increases adrenocorticotropic hormone (ACTH) synthesis.

Polypeptides can have which of the following types of effects? I.autocrine II.paracrine III.endocrine

The relationship between the insect hormones ecdysteroid and PTTH is an example of

Following a stressful stimulus, the fight-or-flight response will cause ________.

Which of the following statements are correct? I.Hormones often regulate homeostasis through antagonistic functions. II.Hormones of the same chemical class usually have the same function. III.Hormones are secreted by specialized cells usually located in exocrine glands. IV.Hormones are often regulated through feedback loops.

Testosterone is an example of a chemical signal that affects the very cells that synthesize it, the neighboring cells in the testis, along with distant cells outside the gonads. Thus, testosterone is an example of ________. I.an autocrine signal II.a paracrine signal III.an endocrine signal

If a person loses a large amount of water in a short period of time, he or she may die from dehydration. Antidiuretic hormone (ADH) can help reduce water loss through its interaction with its target cells in the ________.

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

A product of the anterior pituitary gland that causes color changes in its target cells is ________.

Growth factors are local regulators that ________.

Analysis of a blood sample from a fasting individual who had not eaten for 24 hours would be expected to reveal high levels of ________.

Melatonin is secreted by the ________.

Which of the following is an example of a simple endocrine pathway?

Hormone X activates the cAMP second messenger system in its target cells. The greatest response by a target cell would come from ________.

If a portion of the pancreas is surgically removed from a rat and the rat subsequently loses its appetite, one explanation is that the removed portion contains cells that secrete a chemical signal that somehow stimulates appetite. Given this scenario, what type of chemical signaling is occurring?