Biology Ch 36

The ligand/receptor complex likely acts by

Activating enzymes within the cell Initiating signaling cascades.

Aldosterone is a hormone secreted by the adrenal cortex, and insulin is a peptide secreted by the pancreas. Refer to the figures shown. When aldosterone contacts a target cell, it binds to an intracellular receptor and migrates to the nucleus. Insulin binds to extracellular receptors on the plasma membrane. What is the most likely reason for this difference?

Aldosterone is lipid-soluble and, therefore, easily crosses the phospholipid bilayer of the plasma membrane.

_____, which is released from _____, acts on the ovaries and testes.

Follicle-stimulating hormone; the anterior pituitary gland

A patient with a thyroid tumor has her thyroid gland removed. Without a thyroid gland and without Synthroid, a thyroid hormone replacement drug, which of these results is most likely to occur?

Her blood TSH levels will be abnormally high, and her metabolic rate will be low.

Which statement is true regarding histamine?

Histamine is classified as a paracrine signal and functions, indirectly, in wound repair.

Which statement is false?

Hormone receptors evolved later than many of the hormones with which they now interact.

Honeybee workers spend their first few weeks as young adults tending the colony's brood. Later, they shift jobs to forage for food outside the colony. When researchers fed the young bees candy spiked with the molecule ethyl oleate, the young bees continued to babysit and delayed the job shift to foraging. What would be required to demonstrate that ethyl oleate normally acts as a pheromone, not as an endocrine or paracrine signal.

It would require demonstrating that ethyl oleate is released into the air by another individual of the same species.

Which statement is true?

Peptide hormones can evolve through changes in their amino acid sequence.

_____ are chemical signals that, instead of being secreted into the bloodstream, are introduced by animals into their habitats. They can be used to attract mates and mark territories.

Pheromones

Many plants synthesize molecules that destroy the corpora allata, which are the structures responsible for synthesis of juvenile hormone. Insects exposed to these molecules do not molt. Which statement reflects how levels of juvenile hormone disrupt the insect life cycle?

Reduced juvenile hormone causes insects to molt prematurely into sterile adults.

Why are some body cells responsive to a particular hormone, whereas others are not?

Responsive cells express a receptor specific for the hormone.

How is synaptic signaling different from paracrine signaling?

Synaptic signaling specifically involves neurotransmitters that are released from neurons.

If ACTH secretion is inhibited, which of the following will result?

The adrenal glands will not release cortisol.

Which statement is false?

The effects of paracrine signals are more immediate, but longer-lasting than the effects of hormones.

What would likely be observed if a male silk moth lacked a receptor for bombykol?

The male would have difficulty locating a mate.

Which statement about nervous and endocrine signaling is accurate?

The nervous system transmits signals between adjacent cells using neurotransmitters, whereas the endocrine system signals with hormones.

The same hormone stimulates gene expression in one cell, but inhibits gene expression in another cell. What is the best explanation for this difference?

The two cells have different types of receptors for the hormone.

In Type I diabetes, the body fails to produce insulin and, thus, individuals must inject themselves with insulin before eating. Based on your knowledge of the control of glucose levels in the blood, what would happen if Type I diabetics injected themselves with too much insulin?

Their blood sugar levels would drop to potentially dangerous low levels.

(T/F) The production of pheromones is seen in many different types of organisms.

True

(T/F)Small amounts of hormones have large effects on an organism's physiology because the signals are amplified between glands and tissues in an endocrine axis and within the signal transduction systems of individual cells.

True

An endocrine axis describes:

a hormonal signaling pathway between endocrine glands and tissues.

A new hormone has been isolated from an organism. Although the structure of the hormone has not yet been determined, the hormone is known to exert its effects by forming a hormone-receptor complex that acts as a transcription factor within target cells. What type of hormone is this most likely to be?

a steroid hormone

Tropic hormones:

act on other endocrine organs.

The two main classes of hormones are:

amine/peptide hormones and steroid hormones.

Receptors for _____ hormones are located on the plasma membrane and affect target cells by _____.

amine; activating protein kinase enzymes

Which of these endocrine organs and hormones are paired incorrectly?

anterior pituitary gland: antidiuretic hormone

The _____ is stimulated by releasing factors from the _____ that are transported in the bloodstream.

anterior pituitary gland; hypothalamus

A scientist is searching for chemical compounds involved in embryonic limb development. He discovers a new compound that is transiently expressed in the limbs and only seems to affect cells in its immediate vicinity (up to a few cell lengths away). How should the scientist classify this chemical compound?

as a paracrine factor

Synthetic anabolic steroids:

build and strengthen muscle tissue. promote anabolic metabolism to store energy within cells. interfere with the normal production of anterior pituitary tropic hormones. promote protein synthesis.

In response to high circulating calcium levels, the release of _____ from the _____ shifts bone metabolism toward net bone formation.

calcitonin; thyroid gland

Steroid hormones are derived from:

cholesterol.

Which insect hormone acts on the body tissues to stimulate molting and metamorphosis?

ecdysone

A type 1 diabetic male gives his wife an injection pen and asks her to inject him with its contents if he ever passes out due to low blood sugar. What hormone does this pen likely contain?

glucagon

Kisspeptin is a protein that, in humans, has an important role in initiating secretion of the releasing factor gonadotropin-releasing hormone (GnRH). Endocrinologists are finding that the protein kisspeptin and its receptor are central to sexual maturation at puberty. If kisspeptin directs the release of GnRH, you can expect that the receptors for kisspeptin will be found in cells of the:

hypothalamus

Which of these structures serves as a connection between the nervous and endocrine systems?

hypothalamus

Which option is an example of a peptide hormone?

insulin

If you removed the prothoracic glands from the insect larva, the larva would:

never molt again.

Which of these structures would have the most wide-reaching effect on bodily functions of an adult human if removed?

pituitary gland

Their blood sugar levels would drop to potentially dangerous low levels.

prolactin

Type 1 and type 2 diabetes mellitus have different underlying causes. Type 1 diabetes is characterized by a loss of the insulin-producing cells of the pancreas, leading to insulin deficiency. Type 2 diabetes, at least in its early stages, is characterized by a loss of sensitivity to the hormone insulin by cells that normally respond to the hormone. Which step labeled in the diagram shown is inhibited in both type 1 and type 2 diabetes (either directly or indirectly)

step a: glycogen synthesis

A pediatrician sees a patient who is exhibiting symptoms of gigantism and rapid growth. Which of these endocrine glands is likely affected in this individual?

the anterior pituitary gland

In vertebrates, which structure frequently serves as the first intermediary between the areas of the brain that perceive sensory stimuli and the rest of the endocrine system?

the hypothalamus

Oxytocin and cholecystokinin are transported through the bloodstream and arrive at the uterus at the same time. Why does oxytocin cause the uterus to contract, whereas cholecystokinin has no effect?

the uterus has receptors for oxytocin but not cholecystokinin