Bios 1710 Chapter 38

When iodine intake is too low, production of _____ by the anterior pituitary gland ______.

TSH; increases

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

The two main classes of hormones are:

Amine/peptide hormones and steroid hormones.

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

Anterior pituitary gland; hypothalamus

Positive feedback loops:

Are activated by a stimulus. Continue until interrupted or broken by an external signal. Cause a response in the same direction as the initial stimulus. Move the system further and further away from the set point.

Which of the following would allow a cell to self-regulate its own secretion of chemical signals?

Autocrine signals

Which of the following organisms can produce pheromones? (Select all that apply.)

Birds Fish Dogs Ants Orchids

Which of the following is an accurate statement about hormones and their receptors?

Cells with different hormone receptors typically have different gene expression patterns.

The diurnal or nocturnal behavior of animals is regulated, in large part, by which of the following hormones?

Melatonin.

Release of _____ from the _____ in response to high circulating calcium levels shifts bone metabolism toward net bone formation.

Calcitonin; thyroid gland

Which of the following statements about nervous and endocrine signaling is false?

Correct: The nervous system and endocrine system are both regulatory systems, but the two systems do not communicate directly with one another. The nervous system and endocrine system are both regulatory systems, but the two systems do not communicate directly with one another. The nervous system transmits signals between adjacent cells using neurotransmitters, whereas the endocrine system signals with hormones. Endocrine signaling is generally more prolonged than nerve cell signaling. Nerve cell signaling is generally more rapid than endocrine signaling. Neurotransmitters function only over short distances, whereas hormones can affect cells throughout the body.

Which of the following insect hormones acts on the body tissues to stimulate molting and metamorphosis?

Ecosyne.

Which of the following statements about homeostasis is false?

False: It depends primarily on positive feedback. It is the maintenance of a steady physiological state within an organism or cell. The endocrine system plays a major role in maintaining homeostasis. It is necessary for proper functioning of the body.

Which of the following statements is true regarding histamine?

Histamine functions (indirectly) in wound repair. Histamine would be classified as an autocrine signal. Correct: Histamine would be classified as a paracrine signal and functions (indirectly) in wound repair. Histamine would be classified as a paracrine signal and functions (indirectly) in wound repair. Histamine, like hormones, is released into the bloodstream and can act over long distances. Histamine would be classified as an endocrine signal.

Hormones are typically involved in maintaining _____, which is a given steady state for a particular factor (such as sugar or calcium levels in the blood).

Homeostasis.

An amine hormone would possess which of the following traits? (Select all that apply.)

It would only contain amino acid chains. It would be hydrophobic. Its chemical structure would resemble that of cholesterol. True: It would be hydrophilic. True: It would made from a single aromatic amino acid.

An individual who is experiencing a prolonged period of stress would likely have _____ levels of circulating _____than an individual who was not experiencing stress.

Lower; cortisol Higher; ADH Correct: higher; cortisol Higher; cortisol Lower; ADH Lower; ACTH

Blood glucose levels are regulated by ___________________,in which an increase or decrease in glucose signals the pancreas to stop producing glucagon or insulin, respectively.

Negative feedback

What is the difference between negative feedback and positive feedback mechanisms?

Negative feedback mechanisms return a system to a set point; positive feedback mechanisms amplify a response.

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

Oxytocin blocks the activity of cholecystokinin. Correct: The uterus has receptors for oxytocin, but not for cholecystokinin. The uterus has receptors for oxytocin, but not for cholecystokinin. Oxytocin alters gene expression patterns, whereas cholecystokinin does not. Oxytocin is able to diffuse through the plasma membrane of uterine cells, whereas cholecystokinin cannot. Oxytocin is at a higher concentration in the bloodstream than cholecystokinin.

Which of the following statements about insect hormones is false?

PTTH stimulates the release of ecdysone to trigger molting and metamorphosis. In the absence of juvenile hormone, an insect will metamorphose into the adult form. Ecdysone is released from the prothoracic gland and stimulates molting. Correct: High levels of circulating juvenile hormone inhibit molting.

Growth factors are examples of which type of chemical signal?

Paracrine signals.

Which of the following statements is false?

Peptide hormones and amine hormones are both derived from amino acids. Steroid hormones are hydrophobic, whereas amine hormones are hydrophilic. Correct: Peptide hormones act on time scales of days to months. Peptide hormones act on time scales of days to months. Amine hormones are more abundant than steroid hormones. 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.

Synthetic anabolic steroids:

Promote protein synthesis. Promote anabolic metabolism to store energy within cells. Build and strengthen muscle tissue. Interfere with the normal production of anterior pituitary tropic hormones.

It has been discovered that many plants synthesize molecules that destroy the corpora allata, which are the structures in insects responsible for synthesis of juvenile hormone. Insects exposed to these molecules do not molt. Which of the following statements reflects how levels of juvenile hormone disrupt the insect life cycle?

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

Hormones play a role in which of the following processes in humans? (Select all that apply.)

Sense of smell Sense of taste True: Childbirth True: Metabolism True: Regulating blood glucose levels True: Sexual arousal True: Circadian rhythms

Which of the following statements is false?

The adrenal medulla releases epinephrine and norepinephrine. The adrenal medulla is innervated by the sympathetic nervous system. The cells of the adrenal medulla are modified nerve cells. Correct: Adrenaline released by the adrenal cortex acts as a hormone. Adrenaline released by the adrenal cortex acts as a hormone. Adrenaline and noradrenaline make the body more alert and ready for action.

In the human body, which of the following structures contains cells that are part of the endocrine system? (Select all that apply.)

The brain The intestines The pancreas The stomach The ovaries All of them.

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 hormone is degraded more quickly in one cell than the other. Correct: The two cells have different types of receptors for the hormone. The two cells have different types of receptors for the hormone. The two cells receive the hormone at different times. The hormone can diffuse through the plasma membrane of one cell, but not the other. The two cells receive different amounts of the hormone.

In vertebrates, which of the following 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.

Which of the following statements is correct?

The posterior pituitary gland develops from epithelial cells. Both the anterior and posterior pituitary glands release tropic hormones. Neurosecretory cells of the hypothalamus extend axons to the anterior pituitary gland. The posterior pituitary gland produces more types of hormones than the anterior pituitary gland. Correct: None of the answer options is correct. None of the answer options is correct.

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.

Which of the following statements is TRUE regarding hormones? (Select all that apply.)

They only act on one organ. They are only released into the bloodstream. True: They can act as transcription factors (in conjunction with proteins). True: They can act over long distances in the body. True: They can produce effects with very small concentrations. True: They can be transported through the bloodstream. True: They can act as neurotransmitters.