Deck 46: Chemical Signals in Animals

Question 1

The regulation of blood sugar levels and our stress responses are controlled in part by a negative feedback loop involving cortisol, ACTH, and CRH. What would likely be the result during times of stress if cortisol receptors in the hypothalamus were nonfunctional?

A) Blood sugar levels would be unaffected.
B) Cortisol production would cease.
C) CRH production would cease.
D) Blood sugar levels would rise to dangerous levels.
E) ACTH production would cease.

Answer 1

D

Question 2

All of the following are examples of amplification of a hormone signal EXCEPT

A) different cell types have different receptors capable of binding the same hormone.
B) 0.09 mg of growth hormone leads to a 10,000- mg weight gain in a cow.
C) epinephrine initiates an enzyme cascade.
D) steroids bind hormone- response elements in the cell and initiate gene transcription.

Answer 2

A

Question 3

Coffee drinkers urinate more frequently than those who do not drink coffee or other caffeinated beverages. Which of the following is a reasonable hypothesis for the effect of caffeine on your body?

A) Caffeine inhibits the release of erythropoietin.
B) Caffeine stimulates the release of erythropoietin.
C) Caffeine stimulates the release of antidiuretic hormone ADH).
D) Caffeine inhibits the release of antidiuretic hormone ADH).

Answer 3

D

Question 4

Which of the following is similar in structure to cholesterol?

A) testosterone
B) estradiol
C) cortisol
D) all of the above
E) only A and B

Question 5

After drinking alcoholic beverages, increased urine excretion is the result of which of the following?

A) increased aldosterone production
B) inhibited secretion of antidiuretic hormone ADH)
C) increased blood pressure
D) increased reabsorption of water in the proximal tubule
E) the osmoregulator cells of the brain increasing their activity

Question 6

You are dissecting a fish in your biology laboratory section. Your teaching assistant points out a long oval structure and tells you it is an endocrine gland. Which of the following is true about this structure?

A) It secretes a product that is carried in the bloodstream or other fluids to target cells.
B) The gland's product will interact with receptors on the cell membrane or inside target cells.
C) The gland's product is secreted into the cavity of some organ, outside of the circulatory system.
D) Only answers A and B apply.
E) Only answers B and C apply.

Question 7

Analysis of a blood sample from an individual who had fasted for 24 hours would be expected to reveal high levels of which of the following?

A) gastrin
B) insulin
C) secretin
D) glucagon
E) glucose

Question 8

You have three strains of mice: A, B, and C. You experimentally manipulate each strain and find that all three show increased secretion of molecule X. Now you perform a parabiosis experiment with the three combinations of these mice: AB, AC, and BC. You perform the same experimental manipulation as above on one mouse of each pair without directly affecting the other mouse and look for effects on the other mouse. You find no detectable effect on the unmanipulated partner in any of the combinations. What is the logical conclusion based on these results?

A) The effect on molecule X is not mediated by nerves.
B) The effect on molecule X is not mediated by hormones.
C) The effect on molecule X was just an artifact of the first experiment.
D) The effect on molecule X is controlled by higher integrative centers of the brain.

Question 9

In experiments where researchers suspect that a hormone may be responsible for a certain physiological effect, they may cut the neurons leading to the organ where the effect being studied occurs. What is the purpose of cutting these neurons?

A) To numb the organ so that it can be probed without inducing pain in the lab animal.
B) To impair the normal functions of the organ so that the hormonal effect can be more easily studied.
C) To make sure that the effect is not occurring through actions in the nervous system.
D) To make sure that the organ being effected cannot function unless the researchers stimulate it with an external electrical probe.

Question 10

People with type II diabetes mellitus have defective insulin receptors that cannot respond to insulin properly. Relative to normal individuals, what would be the effect on blood glucose levels of chronic stress that kept blood cortisol levels high?

A) There would be about the same effect on blood glucose levels in both types of individuals.
B) There would be less increase in blood glucose levels in individuals with type II diabetes mellitus than in normal individuals.
C) There would be less decrease in blood glucose levels in individuals with type II diabetes mellitus than in normal individuals.
D) There would be a greater increase in blood glucose levels in individuals with type II diabetes mellitus than in normal individuals.
E) There would be a greater decrease in blood glucose levels in individuals with type II diabetes mellitus than in normal individuals.

Question 11

Polypeptides can have which of the following types of effects?

A) autocrine
B) paracrine
C) endocrine
D) all of the above
E) only A and C

Question 12

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 signalling is occurring?

A) autocrine
B) endocrine
C) paracrine
D) neuroendocrine

Question 13

In human embryonic development, which of the following pairs of hormones are released by the developing testes and result in development of the male reproductive tract and inhibition of the female reproductive tract?

A) estrogen and progesterone
B) testosterone and Mullerian inhibitory substance
C) testosterone and estradiol
D) testosterone and estrogen
E) estradiol and estrogen

Question 14

When partially digested food enters the small intestine from the stomach, several events must occur to protect the intestine and allow for the continued digestion of the food. One hormone in particular performs two of these functions. What intestinal hormone is responsible for causing the pancreas to release digestive enzymes and the gall bladder to release bile salts into the intestine?

A) secretin
B) cholecystokinin
C) epinephrine
D) corticosterone
E) insulin

Question 15

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

A) decrease in cortisol release
B) decrease in release of corticotropin- releasing hormone CRH)
C) increase in glucocorticoid production
D) increase in release of corticotropin- releasing hormone CRH)
E) all of the above

Question 16

Which of the following statements is not true of hormones?

A) Some have only local effects on nearby cells.
B) Some are derived from amino acids.
C) All are organic molecules.
D) All are secreted from the cells where they are synthesized.
E) They have large effects on target tissues relative to their concentrations.

Question 17

Which of these glands lies closest to the throat region?

A) hypothalamus
B) thyroid
C) pancreas
D) pituitary
E) adrenal

Question 18

Removing which of the following glands would have the most wide- reaching effect on bodily functions of an adult human?

A) thyroid gland
B) ovaries in female) or testes in male)
C) pituitary gland
D) adrenal glands

Question 19

What do steroid and peptide hormones typically have in common?

A) their requirement for travel through the bloodstream
B) the building blocks from which they are synthesized
C) their solubility in cell membranes
D) the location of their receptors
E) their reliance on signal transduction in the cell

Question 20

A cluster of tumor cells that produces and secretes growth factors to induce surrounding cells to grow and divide are showing which type of cell- to- cell signalling?

A) endocrine
B) neuroendocrine
C) paracrine
D) autocrine

Question 21

The posterior pituitary is anatomically and developmentally an extension of the hypothalamus. Which of the following is a true statement about the posterior pituitary?

A) The posterior pituitary's many hormone products and their diverse functions have led to it being called by the term master gland.
B) The posterior pituitary's hormones are actually produced in neurosecretory cells that originate in the hypothalamus.
C) None of the above answers apply.
D) Both answers A and B apply.

Question 22

Oxytocin helps initiate labour in mammals. During labour and delivery, the contraction of uterine muscles increases the release of oxytocin. This is an example of

A) a hormone that is involved in a positive feedback loop.
B) signal transduction immediately changing gene expression in its target cells.
C) a negative feedback system.
D) the key role of the anterior pituitary gland in regulating uterine contraction.
E) a hormone that acts in an antagonistic way with another hormone.

Question 23

Which of the following is not considered a second messenger?

A) norepinephrine
B) IP3
C) cAMP
D) DAG

Question 24

Signal transduction occurs when a chemical message at the cell surface elicits a response inside the cell. Which one of the following events is not associated with signal transduction?

A) second messenger activation
B) protein phosphorylation
C) internal receptor binding
D) cell- surface receptor binding

Question 25

The release of hormones by the posterior pituitary is the result of what process?

A) Releasing hormones from the hypothalamus directs the production and release of oxytocin from the posterior pituitary.
B) Neurosecretory cells of the hypothalamus directly release hormones into blood vessels within the posterior pituitary.
C) The anterior pituitary regulates the activity of the posterior pituitary gland.
D) Hypothalamic neurons form synapses on the adrenal gland, which in turn regulates the pituitary.
E) The release of regulatory hormones increases activity in the adrenal medulla, altering the activity of the posterior pituitary.

Question 26

Which of the following statements correctly describes the relationship between the hypothalamus H) and the anterior AP) and posterior PP) lobes of the pituitary?

A) The AP regulates the H through negative feedback mechanisms while the PP regulates the H through positive feedback.
B) The H is the neural system that releases hormones directly into the AP and communicates with the PP only through the circulation.
C) The H communicates directly with the PP and indirectly with the AP through the circulatory system.
D) The H regulates secretions from the PP, which then regulates all secretions from the AP.

Question 27

What changes might you predict/expect if a mutation caused a change in the timing of juvenile hormone, such that it remained high throughout the lifetime of the organism?

A) The organism would form structures that allowed it to respond to stress.
B) The organism would mature reproductively.
C) The organism would undergo metamorphosis at an earlier time.
D) The organism would maintain its juvenile state for the remainder of its life.

Question 28

Which of the following best describes the neuroendocrine- to- endocrine pathway of hormone action?

A) a gland that releases hormones directly into a neural structure, thus regulating neural functions
B) a gland that exhibits negative feedback on the nervous system by releasing hormones into neural tissue both directly and indirectly through the circulation
C) a neural organ that produces hormones regulates another gland through the release of hormones into the circulation that travel to the effected gland
D) a neural organ that produces hormones releases its hormones directly into another gland that it regulates

Question 29

How can the body prevent a hormone with different effects on different tissues from acting on inappropriate cells at inappropriate times?

A) Internalize receptors on nontargeted cells.
B) Shunt blood supply to the desired tissues.
C) Change the conformation of receptors on nontargeted cells.
D) All of the above answers apply.

Question 30

Tadpoles must undergo a major metamorphosis to become frogs. This change includes reabsorption of the tail, growth of limbs, calcification of the skeleton, increase in rhodopsin in the eye, development of lungs, change in hemoglobin structure, and reformation of the gut from the long gut of an herbivore to the short gut of a carnivore. Amazingly, all of these changes are induced by thyroxine. What is the most likely explanation for such a wide array of effects of thyroxine?

A) There are many different forms of thyroxine, each specific to a different tissue.
B) Different tissues have different types of receptors.
C) Some tissues have membrane receptors for thyroxine, while other tissues have thyroxine receptors within the nucleus.
D) Different releasing hormones release thyroxine to different tissues.
E) Answers B and C both apply.

Question 31

Which of the following is an example of negative feedback?

A) A stressful stimulus leads to the release of epinephrine, which increases fatty acid and glucose in the blood and cardiovascular activity.
B) When the level of glucose in the blood increases, the pancreas produces and releases the hormone insulin. Insulin acts to decrease blood glucose. As blood glucose decreases, the rate of production and release of insulin decreases.
C) During birthing contractions, oxytocin is released and acts to stimulate further contractions.
D) When a baby is nursing, suckling leads to the production of more milk and a subsequent increase in the secretion of prolactin.

Question 32

What property of steroid hormones allows them to cross the phospholipid bilayer?

A) Steroid hormone transporters exist in most cell types.
B) Steroid hormones act on cells close to where they were produced, and very few molecules are required to travel such a short distance to cross the lipid bilayer.
C) Steroid hormones act on the same cells in which they are produced and, therefore, are within the cell they are acting upon.
D) Steroid hormones can act in very small concentrations, and very few molecules of steroids need to cross the lipid bilayer.
E) Steroid hormones are lipid soluble and easily cross the phospholipid bilayer.

Question 33

How can a single hormone can have multiple effects?

A) There could be different types of receptors in different target tissues.
B) There could be different second messengers in different target tissues.
C) There could be different signaling cascades in different target tissues.
D) All of the above answers apply.
E) Only answers A and B apply.

Question 34

Which of the following are examples of amplification of a hormone signal?
I. Epinephrine initiates an enzyme cascade.
II. Steroids bind hormone- response elements in the cell and initiate the transcription of many genes.
III. A quantity of 0.09 mg of growth hormone leads to a 10 000- mg weight gain in a cow.
IV. Different cell types have different receptors capable of binding the same hormone.

A) only I, II, and III
B) I, II, III, and IV
C) only II and IV
D) only I and III
E) only II and III

Question 35

Which of the following is true during a typical cAMP- type signal transduction event?

A) The hormone activates the second messenger by directly binding to it.
B) The second messenger is the last part of the system to be activated.
C) Adenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation occurs.
D) The second messenger amplifies the hormonal response by attracting more hormones to the cell being affected.

Question 36

You spend two months in the mountains of Peru at ~ 3500 m altitude. After returning to Toronto, you notice that you can run your regular 10 km route significantly more easily than before you left. What is the reason for this burst of fitness?

A) The time you spent at a high altitude resulted in an increased lung capacity and therefore extra oxygen intake. This extra oxygen stimulated the release of EP and in turn the production of red blood cells.
B) Due to lower oxygen concentrations at high altitudes, low blood oxygen levels stimulated release of EPO, which stimulated the production of red blood cells. This increased the oxygen binding capacity of your blood.
C) You were in the mountains, so you must have been hiking every day and got in better shape.
D) The time spent at a high altitude resulted in an increased active metabolic rate and therefore increased ATP production.

Question 37

A weightlifter decides to try taking steroids to improve his performance level. Following a month of use, he notes that the steroids have had no effect on his performance. Which of the following is the most likely reason for this?

A) The steroid hormone did not enter the nucleus and could not bind to the hormone response element.
B) The steroid hormone did not bind to the receptors at the cell surface and no signal transduction cascade was initiated.
C) The steroid hormone did no bind to the hormone receptor and the hormone response element was not activated.
D) The protein needed to transport the steroid hormone into the cell was not present at the cell membrane.

Question 38

Of the following types of molecules, which can function as both neurotransmitters and hormones?

A) second messengers
B) catecholamines
C) adipocytes
D) glucocorticoids