chapter 11 difficult quiz

Which of the following describes the synergistic effects of hormones? A) Two or more hormones working together to produce a particular result. B) One hormone is needed to enhance the responsiveness of an organ to a second hormone. C) The two hormones have no effect alone. D) The effects of the two hormones are always additive.

Two or more hormones working together to produce a particular result. Feedback: When two or more hormones work together to produce a particular result, their effects are said to be synergistic. These effects may be additive or complmentary. Permissive effects occur when one hormone is needed to enhance the responsiveness of an organ to a second hormone.

The production of cyclic AMP within target cell is regulated by the enzyme __________. A) protein kinase B) phosphodiestrase C) adenylate cyclase

adenylate cyclase Feedback: See Figure 11.8 The adenylate cyclase-cyclic AMP second messenger system.

Caffeine has which of the following effects? A) increased acetylcholine activity B) increased phosphodiesterase activity C) increased acetylcholinesterase activity D) decreased phosphodiesterase activity

decreased phosphodiesterase activity Feedback: Caffeine as well as the drug theophylline are phosphodiesterase inhibitors and thus exert effects by raising the cAMP concentrations within cells.

Prostaglandins are ___________. A) twenty-seven carbon-long fatty acids containing a 5-membered carbon ring B) derived from arachidonic acid released from phospholipids in the cell membrane C) produced by the enzyme lipoxygenase D) degraded by the action of cyclooxygenase

derived from arachidonic acid released from phospholipids in the cell membrane Feedback: Prostaglandins are 20-carbon long fatty acids containing a 5-membered carbon ring and the enzyme cyclooxygenase converts arachidonic acid into a prostaglandin. The enzyme lipoxygenase converts arachidonic acid into leukotrienes.

The regulatory molecule nitric oxide (NO) helps to relax the smooth muscle of blood vessels causing vasodilation by producing cyclic AMP as a second messenger. A) True B) False

false Feedback: NO helps to relax the smooth muscle of blood vessels causing vasodilation by stimulating the production of cGMP (cyclic guanosine monophosphate) as a second messenger.

Hormones bind to receptor proteins with high capacity and low affinity. A) True B) False

false Feedback: Hormones bind to receptors with high affinity (high bond strength) and low capacity (due to a limited number of receptors per target cell).

In most respects the actions of neurotransmitters and hormones on their target cells are distinctly different. A) True B) False

true Feedback: Regardless of whether a particular chemical is acting as a neurotransmitter or a hormone, the target needs to have a specific receptor protein and the combination of chemical molecule/receptor must cause a change in the target, therefore, hormones and neurotransmitters actions on their target cells are similar.

Between which of the following hormone pairs is the interaction between hormones not an example of the permissive effect of a first hormone for a second hormone? A) Estrogen for prolactin on the mammary glands during pregnancy. B) Parathyroid hormone for vitamin D3 on blood Ca2+ levels. C) Estrogen for progesterone on the uterus. D) Insulin for glucagon on adipose tissue.

Insulin for glucagon on adipose tissue. Feedback: The actions of insulin and glucagon on adipose tissue is an example of antagonistic effects

Whether a molecule acts as a neurotransmitter or a hormone, which statement about physiological regulation by these molecules is false? A) Target cells must have specific receptor proteins with which these molecules combine. B) When these molecules bind to target cells, specific sequences of changes must occur. C) There must be an "off-switch" that will stop the induced changes. D) Second messengers will always be involved in the response of the target cell.

Second messengers will always be involved in the response of the target cell. Feedback: Second messengers are involved with polar molecules in the response of the target cell whereas nonpolar molecules do not require a second messenger.

A person with a toxic goiter would have very high levels of which of the following hormones? A) Thyroxine B) TRH C) TSH D) PTH

Thyroxine Feedback: A toxic goiter is due to autoantibodies that have TSH like effects on the thyroid. Since these antibodies don't respond to negative feedback, there is a high secretion of thyroxine.

Steroid hormones ___________. A) are derived from cholesterol molecules B) are polar molecules C) include the prostaglandins and the sex hormones testosterone and progesterone D) bind mostly to receptors in the cell membrane

are derived from cholesterol molecules Feedback: See Figure 11.2 Simplified biosynthetic pathways for steroid hormones.

A person who is experiencing an endemic goiter can be treated with dietary supplements of ______________. A) calcium B) ADH C) corticosteroids D) iodine

iodine Feedback: See Figure 11.24 Endemic goiter is caused by insufficient iodine in the diet.

Which of the following specific regulators belong to the group of molecules called lymphokines that are produced by lymphocytes (WBC) are involved in specific immunity? A) bradykinins B) endothelins C) nitric oxide D) interleukins

interleukins Feedback: See Table 11.9 Examples of Autocrine and Paracrine Regulators.

The pulsatile secretion of hormones _______________. A) describes how all hormones are released B) is needed to prevent upregulation of target cells C) is needed to prevent the downregulation of target cells D) prolongs the half-life of a given hormone

is needed to prevent the downregulation of target cells Feedback: Prolonged exposure to high concentrations of polypeptide hormone has been found to desensitize the target cells. Subsequent exposure to the same concentration of the same hormone thus produces less of a target tissue response. This may be due to a decrease in the number of receptor proteins in the target cells, which is downregulation. To prevent this, polypeptide hormones as well as glycoproteins are released in a pulsatile secretion.

The enzyme that is activated by the production of cAMP as the second messenger of target proteins is ______________. A) protein kinase B) phosphodiesterase C) adenylate cyclase D) phospholipase C

protein kinase Feedback: See Figure 11.8 The adenylate cyclase-cyclic AMP second messenger system.

Thromboxanes ______________. A) are responsible for smooth muscle relaxation B) are synthesized from cholesterol C) stimulate aggregation of platelets D) induce vasodilation

stimulate aggregation of platelets Feedback: See Figure 11.34 The formation of leukotrienes and prostaglandins.

The hormones that are small, nonpolar and can be taken orally, yet are not steroids are __________________. A) prostaglandins B) estrogen and progesterone C) insulin and glucagon D) thyroid hormones (T3 and T4)

thyroid hormones (T3 and T4) Feedback: Prostaglandins are regulatory molecules but are not considered hormones. Estrogens and progesterones are nonpolar but are steroids. Insulin and glucagon are polar therefore cannot be taken orally.

The term often added as a suffix to the name of hormones such as those from the anterior pituitary is trophic which means "feed" often shortened to tropic which means "attracted to". A) True B) False

true Feedback: Although the anterior pituitary hormones are not food for their target organs, this term is used because high concentrations of anterior pituitary hormones cause the target organs to hypertrophy, while low levels cause atrophy.

The vascular link between the hypothalamus and the anterior pituitary is called the hypothalamo-hypophyseal portal system, transporting, releasing, and inhibiting hormones of the hypothalamus toward specific target cells in the anterior pituitary. A) True B) False

true Feedback: See Figure 11.15 Hypothalamic control of the anterior pituitary.

Anterior pituitary secretion of ACTH, TSH, and the gonadotropins (FSH and LH) is controlled by positive feedback loops from hormones produced by target cells. A) True B) False

true Feedback: These hormones are controlled by negative feedback loops from hormones produced by target cells. See Figure 11.16 The hypothalamus-pituitary-thyroid axis (control system), Figure 11.17 The hypothalamic-pituitary-gonad axis (control system), and Figure 11.20 Activation of the pituitary-adrenal axis by nonspecific stress.