The Endocrine System

1. Dexamethasone is a drug used to suppress the secretion of ACTH from the anterior pituitary gland. Two patients with hypersecretion of cortisol are given dexamethasone. Anika's cortisol secretion level falls to normal after the medication, but Bonnie's cortisol secretion remains elevated. Which patient has primary hypercortisolism, also known as Cushing's syndrome? Explain your reasoning.

1. Bonnie has primary hypercortisolism, or Cushing's Syndrome, because the drug Dexamethasone that acted on the trophic-producing anterior pituitary gland did not affect her symptoms. This indicates that the problem lies further down in the reflex pathway, which must be the adrenal cortex where cortisol is produced. It seems that Bonnie's adrenal cortex is hypersecreting cortisol, despite normal secretion of trophic hormones. In fact this could be confirmed if the trophic hormones were found to have lower than normal levels, while cortisol was high, because that is a trademark sign of a primary disorder. When the pathology lies in the last endocrine gland of the pathway, such as in this case, it is said to be a primary pathology, or specific to this case primary hypercortisolism.

What normally stops hormone action, and why is this important?

2. Normally, the production of hormones further down the reflex serves as a negative feedback loop for previous hormones. For example, cortisol, the final product, feeds back to surpress secretion of hypothalmic corticotropin-releasing hormone (CRH) and adrenocorticotropin (ACTH) from the anterior pituitary pathway. This is important because if this didn't happen, (or if some pathology caused cortisol to fail to be produced), then the trophic hormones would build up creationg a state of hypersecretion. Without cortisol being produced, those cells of the adrenal cortex would atrophy. This could diminish future production capacity of the adrenal cortex, or if the pathology is sustained long enough, the cortex could lose all capacity to produce cortisol.

The posterior pituitary gland secretes A) ADH (Vasopressin). B) MSH C) TSH D) FSH. E) ACTH

A) ADH (Vasopressin).

The link between a first messenger and a second messenger in a cell that responds to peptide hormones is usually A) a G protein. B) cAMP. C) calcium. D) adenylyl cyclase. E) cAMP.

A) a G protein.

Synergism occurs when A) hormones working together produce a larger effect than predicted. B) hormones working together produce a smaller effect than predicted. C) one hormone triggers the secretion of a second hormone. D) one hormone inhibits the release of a second hormone. E) a hormone can exert its full effects only in the presence of another hormone.

A) hormones working together produce a larger effect than predicted.

The majority of hormones in the body are A) peptide hormones. B) amino acid-derived hormones. C) steroid hormones. D) All of the hormones are present in equal amounts in the body. E) neurohormones.

A) peptide hormones.

The pituitary hormone that controls the release of glucocorticoids from the adrenal cortex is A) FSH B) STH C) ACTH D) TSH E) LH

C) ACTH

Which of the following is NOT a method of hormone action? A) control of gene expression and protein synthesis B) control of enzymatic reaction rates C) All are methods of hormone action. D) control of electrical signaling pathways E) control of ion or molecule transport across cell membranes

C) All are methods of hormone action.

When stimulated by a particular hormone, there is a marked increase in the activity of G proteins in the membrane. The hormone is probably A) aldosterone. B) a steroid. C) testosterone. D) estrogen. E) a peptide.

E) a peptide.

aldosterone is made in the

adrenal cortex

The inner portion of the adrenal gland is called the

adrenal medulla

epinephrine is made in the

adrenal medulla

The adrenal cortex produces a steroid hormone called _______________ that controls Na+ and K+ homeostasis and and another steroid hormone called ______ that controls blood glucose levels.

aldosterone, and cortisol

derivatives of tyrosine

amino-acid derived hormones

prolactin is made in the

anterior pituitary

true endocrine gland of epithelial origin

anterior pituitary

When an organ or gland shrinks due to lack of use, that condition is referred to as

atrophy

The trophic hormones reach the pituitary through the

hypothalamic-hypophyseal portal system

site of vasopressin synthesis

hypothalamus

Chemical signals released into the blood by neurons are called

neurohormones

insulin is made in the

pancreas

lipophobic molecule that interacts with receptors on cell surface

peptide hormone

melatonin is made in the

pineal gland

A circulatory route with two capillary beds in series is known as a

portal system

storage and release site for oxytocin

posterior pituitary

cannot be stored in secretory vesicles

steroid hormones

calcitonin is made in the

thyroid

The term for any hormone that controls the secretion of another hormone is a

trophic hormone