In a positive-feedback system where hormone A alters the amount of protein X
an increase in A always produces an increase in X.
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
an autocrine signal, a paracrine signal, and an endocrine signal.
Which category of signal exerts its effects on target cells by binding to membrane-bound receptor proteins?
A paracrine signal that relaxes smooth muscle cells is
Prostaglandins are local regulators whose chemical structure is derived from
Ecdysone is a(n)
Aspirin and ibuprofen both
inhibit the synthesis of prostaglandins.
A cell with membrane-bound proteins that selectively bind a specific hormone is called that hormone's
The reason that the steroid hormone aldosterone affects only a small number of cells in the body is that
only its target cells contain aldosterone receptors.
Different body cells can respond differently to the same peptide hormones because
) a target cell's response is determined by the components of its signal transduction pathways.
Insect hormones and their receptors
are a focus in pest-control research.
Endocrine glands that are sources of steroid hormones
have a very short latency between steroid synthesis and steroid release.
A chemical signal operating in a paracrine manner is one that
is active at a neuronal synapse.
Hormone X activates the cAMP second messenger system in its target cells. The greatest response by a cell would come from
) applying a molecule of hormone X to the extracellular fluid surrounding the cell.
When a steroid hormone and a peptide hormone exert similar effects on a population of target cells, then
the steroid hormones affect the synthesis of effector proteins, whereas peptide hormones activate effector proteins already present in the cell.
For hormones that homeostatically regulate cellular functions,
negative feedback typically regulates hormone secretion.
Nitric oxide and epinephrine
both function as neurotransmitters.
Suppose that substance X is secreted by one cell, travels via interstitial fluid to a neighboring cell, and produces an effect on that cell. All of the following terms could describe this substance except
Hormones that promote homeostasis
usually operate as part of a negative feedback system
) During mammalian labor and delivery, the contraction of uterine muscles is enhanced by oxytocin. This is an example of
a hormone that is involved in a positive feedback loop.
During short-term starvation, most available fuel molecules are catabolized to provide energy for metabolism rather than being used as building blocks for growth and repair, a trade-off that is hormonally regulated by
Based on their effects, which pair below would not be expected to be active at the same time and place?
prostaglandin F and nitric oxide
The interrelationships between the endocrine and the nervous systems are especially apparent in
a neurosecretory cell in the hypothalamus.
The hypothalamus modulates hormone secretion by the anterior pituitary by means of
Portal blood vessels connect two capillary beds found in the
hypothalamus and anterior pituitary.
If a person loses a large amount of water in a short period of time, he or she may die from dehydration. ADH can help reduce water loss through its interaction with its target cells in the
includes neurosecretory cells that terminate in the posterior pituitary.
Prolactin stimulates mammary gland growth and development in mammals and regulates salt and water balance in freshwater fish. Many scientists think that this wide range of functions indicates that prolactin
is an evolutionarily conserved hormone.
A product of the anterior pituitary gland that causes color changes in its target cells is
To prevent insect pests from maturing into reproducing adults, pest controllers use synthetic agonists of
In a lactating mammal, the two hormones that promote milk synthesis and milk release, respectively, are
prolactin and oxytocin.
Oxytocin and antidiuretic hormone are synthesized in the
Endocrine structures derived from nervous tissue include the
posterior pituitary gland and the adrenal medulla.
Iodine is added to table salt to help prevent deficiencies of an essential mineral needed for the proper function of the
A tropic hormone from the anterior pituitary gland regulates the secretion of
Which endocrine disorder is correctly matched with the malfunctioning gland?
diabetes insipidus and the posterior pituitary gland
One reason a person might be severely overweight is due to
an undersecretion of thyroxine.
Fight-or-flight reactions include activation of
the adrenal medulla, leading to increased secretion of epinephrine
The endocrine glands include the
The body's reaction to PTH (parathyroid hormone), a reduction in plasma levels of calcium, can be opposed by
Which of the following has both endocrine and exocrine activity?
Linkage to membrane-bound receptor proteins on target cells activates the typical actions of the
Analysis of a blood sample from a fasting individual who had not eaten for 24 hours would be expected to reveal high levels of
When the beta cells of the pancreas release insulin into the blood,
the skeletal muscles and the adipose cells take up glucose at a faster rate.
A chemical signal that has both endocrine and neural roles is
The amino acid tyrosine is a starting substrate for the synthesis of
The autonomic nervous system includes an endocrine gland known as the
A disease that destroys the adrenal cortex should lead to an increase in the plasma levels of
adrenocorticotropic hormone (ACTH).
During a stressful interval
ACTH stimulates the adrenal cortex, and neurons of the sympathetic nervous system stimulate the adrenal medulla.
In response to stress, the adrenal gland promotes the synthesis of glucose from noncarbohydrate substrates via the action of the steroid hormone
Melatonin is secreted by
the pineal gland during the night.
Winter hibernation and spring reproduction in bears are cued by seasonal changes in the secretion of
melatonin from the pineal gland.
The steroid hormone that coordinates molting in arthropods is
After eating a carbohydrate-rich meal, the mammalian pancreas increases its secretion of
The higher level of metabolic activity typical of nonhibernating temperate mammals during the winter months is due to increased secretion of
The increased contraction of the human uterus during labor and delivery is at least partially due to the actions of
Abnormally reduced somatic growth (dwarfism) can be a consequence of decreased hormone secretion from the
anterior pituitary gland.
DES is called an "endocrine disrupting chemical" because it structurally resembles, and interferes with, the endocrine secretions of the A) pancreatic islet cells.
Testosterone is an example of
Estradiol is an example of
Epinephrine is an example of
In an experiment, rats' ovaries were removed immediately after impregnation and then the rats were divided into two groups. Treatments and results are summarized in the table. The results most likely occurred because progesterone exerts an effect on the
metabolism of the uterus.
A fantasy movie features a caterpillar that never matures into an adult, but simply gets larger and larger with each molt. It might be possible that the caterpillar did not mature into an adult because of
an increased level of juvenile hormone.
Which of the following is not an accurate statement?
Hormones of the same chemical class usually have the same function.
An example of antagonistic hormones controlling homeostasis is
insulin and glucagon in glucose metabolism.
Growth factors are local regulators that
bind to cell-surface receptors and stimulate growth and development of target cells.
Which hormone is incorrectly paired with its action?
insulin stimulates glycogen breakdown in the liver
Steroid and peptide hormones typically have in common
their requirement for travel through the bloodstream.
Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal?
hyposecretion of TSH
Shortly after ingesting a big plate of carbohydrate-rich pasta, you measure your blood's hormone levels. What results would you expect, compared to before the meal?
high insulin, low glucagon
The relationship between the insect hormones ecdysteroid and PTTH is an example of
an interaction of the endocrine and nervous systems.