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?

Accepted Answer

If cortisol receptors in the hypothalamus were nonfunctional, there would be a lack of negative feedback on the hypothalamus, leading to continued production of CRH and ACTH. This would result in excessive cortisol production, which would lead to elevated blood sugar levels. Without functional cortisol receptors, this response would not be halted, causing blood sugar levels to rise to dangerous levels during times of stress.

Question 2

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

Accepted Answer

Different cell types having different receptors capable of binding the same hormone is an example of hormone versatility and specificity, not amplification of a hormone signal. Amplification refers to the process where a small amount of hormone triggers a large-scale cellular response, as seen in options B, C, and D.

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?

Accepted Answer

Antidiuretic hormone (ADH) is responsible for regulating the amount of water your kidneys excrete as urine. Caffeine inhibits the release of ADH, causing more water to be excreted as urine and resulting in more frequent urination.

Question 4

Which of the following is similar in structure to cholesterol?

Accepted Answer

All of the choices listed, testosterone, estradiol, and cortisol, are steroid hormones, which share a similar structural foundation to cholesterol. Cholesterol serves as a precursor for the synthesis of these steroid hormones, indicating their structural similarity.

Question 5

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

Accepted Answer

Drinking alcohol inhibits the secretion of antidiuretic hormone (ADH), also known as vasopressin, which normally acts on the kidneys to increase water reabsorption, leading to increased urine output. Therefore, option B is the correct answer. Increased aldosterone production would result in increased sodium reabsorption and potassium excretion, but it would not affect water reabsorption or urine output. Increased blood pressure would lead to increased filtration and decreased reabsorption, but it would not directly affect urine output. Increased reabsorption of water in the proximal tubule would actually decrease urine output. The osmoregulator cells of the brain regulate thirst and urine production, but their activity is not directly affected by alcohol.

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?

Accepted Answer

Endocrine glands secrete hormones directly into the bloodstream (A), and these hormones interact with specific receptors on or in target cells (B), making both statements correct.

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?

Accepted Answer

After fasting for 24 hours, the body's glucose stores become depleted, leading to an increase in the hormone glucagon. Glucagon stimulates the liver to break down glycogen into glucose and release it into the bloodstream to maintain blood sugar levels. The other hormones listed (gastrin, insulin, and secretin) are typically involved in digestive processes and would not be expected to be elevated in a fasting state. Glucose levels may actually be low in a fasting individual due to the lack of dietary intake.

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?

Accepted Answer

The lack of effect on the unmanipulated partner in the parabiosis experiments suggests that the increased secretion of molecule X is not mediated by circulating factors such as hormones, which would be expected to affect both mice in each pair if they were the mechanism of action.

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?

Accepted Answer

Cutting the neurons leading to the organ where the effect being studied occurs ensures that the effect is not occurring through actions in the nervous system, which could confound the results and make it difficult to isolate and study the hormonal effect specifically.

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?

Accepted Answer

The answer of People with type II diabetes mellitus have...

Question 11

Polypeptides can have which of the following types of effects?

Accepted Answer

Polypeptides can have autocrine effects, meaning they can act on the same cell that produced them. They can also have paracrine effects, meaning they act on nearby cells. Lastly, they can have endocrine effects, meaning they can act on distant cells after being secreted into the bloodstream. Therefore, the best choice is D, which indicates that polypeptides can have all three types of effects.

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?

Accepted Answer

Endocrine signaling involves the release of hormones into the bloodstream to affect distant target cells, which aligns with the scenario where cells in the pancreas secrete a chemical (hormone) that influences appetite, a systemic effect.

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?

Accepted Answer

The developing testes release both testosterone and Mullerian inhibitory substance, which results in the development of the male reproductive tract and inhibition of the female reproductive tract. Estrogen and progesterone are hormones associated with female reproductive development, while testosterone and estradiol, as well as estradiol and estrogen, are hormone pairs that do not specifically result in male reproductive tract development or inhibition of the female reproductive tract.

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?

Accepted Answer

Cholecystokinin (CCK) is the intestinal hormone responsible for causing the pancreas to release digestive enzymes and the gall bladder to release bile salts into the intestine. Secretin also plays a role in regulating digestion, but its main function is to stimulate the release of bicarbonate from the pancreas to neutralize stomach acid. Epinephrine and corticosterone are hormones that are not directly involved in regulating digestion. Insulin is a hormone involved in glucose regulation, but not digestion.

Question 15

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

Accepted Answer

ACTH stimulates the release of cortisol from the adrenal cortex.

Question 16

Which of the following statements is not true of hormones?

Accepted Answer

Hormones typically have systemic effects rather than just local effects on nearby cells. Some hormones do have localized effects, but this is not characteristic of hormones in general, which are known for their ability to act on distant target tissues.

Question 17

Which of these glands lies closest to the throat region?

Accepted Answer

The thyroid gland lies closest to the throat region, specifically below the laryngeal prominence (Adam's apple) in the neck. The hypothalamus is located in the brain, the pancreas is located in the abdomen, the pituitary gland is located in the brain, and the adrenal glands are located on top of the kidneys.

Question 18

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

Accepted Answer

The pituitary gland is often referred to as the "master gland" because it secretes hormones that regulate the function of other endocrine glands throughout the body. This means that removing the pituitary gland would have the most wide-reaching effect on bodily functions. Hormones secreted by the pituitary gland include growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, luteinizing hormone, and prolactin, which are all important for maintaining optimal physiological function.

Question 19

What do steroid and peptide hormones typically have in common?

Accepted Answer

Both steroid and peptide hormones need to travel through the bloodstream to reach their target cells and exert their effects.

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?

Accepted Answer

The cluster of tumor cells is secreting growth factors that are inducing surrounding cells to grow and divide. This indicates that the tumor cells are using paracrine signaling, which involves the secretion of signaling molecules that act on neighboring cells. Endocrine signaling involves the secretion of signaling molecules into the bloodstream to act on distant target cells, while neuroendocrine signaling involves the secretion of signaling molecules from nerve cells into the bloodstream to act on target cells. Autocrine signaling involves the secretion of signaling molecules that act on the same cell that produced them.

Quiz 46: Chemical Signals in Animals