EXAM 1: CHAPTER 48
A nurse examines the laboratory values of a patient in heart failure. Which of the following values indicates a compensatory hormone mechanism?
Elevated atrial natriuretic hormone In heart failure, the patient experiences fluid backlog in the heart as venous blood continues to return, but cardiac output is reduced. This stretches the atria, which secrete atrial natriuretic hormone (or peptide) to stimulate vasodilation and increased renal excretion of sodium and water. This reduces the volume and the strain in the heart.
Which of the following is an example of a positive feedback system?
Estradiol and follicle-stimulating hormone (FSH) In positive feedback control, rising levels of a hormone cause another gland to release a hormone that stimulates the first. Release of the female hormone estradiol during the follicular stage of the menstrual cycle causes increased release of gonadotropin (FSH) which further increases release of estradiol until the follicle dies and ceases production. The other options are examples of negative feedback.
Which gland acts as a signal relaying bridge between multiple body systems and the pituitary gland?
Hypothalamus The activity of the hypothalamus is regulated by both hormonally mediated signals (e.g., negative feedback signals) and by neuronal input from a number of sources3. Neuronal signals are mediated by neurotransmitters such as acetylcholine, dopamine, norepinephrine, serotonin, ?-aminobutyric acid (GABA), and opioids. Cytokines that are involved in immune and inflammatory responses, such as the interleukins, also are involved in the regulation of hypothalamic function. This is particularly true of the hormones involved in the hypothalamic-pituitary-adrenal axis. Thus, the hypothalamus can be viewed as a bridge by which signals from multiple systems are relayed to the pituitary gland. This cannot be said of the other options.
Select the process that allows hormones to exert influence upon some cells and not others.
Receptor binding Receptor binding is a process that allows target cells to respond to one hormone and not to others. For example, receptors in the thyroid are specific for thyroid-stimulating hormone, and receptors on the gonads respond to the gonadotropic hormones. Positive feedback control occurs when rising levels of a hormone cause another gland to release a hormone that is stimulating to the first. Protein binding describes the ability of proteins to form bonds with other substances. Pituitary-hypothalamic feedback describes negative feedback.
In major athletic competition, athletes are required to submit to liquid chromatography testing looking for:
Use of performance-enhancing agents to increase the chances of winning For some steroid or peptide hormones, mass spectrometry is becoming increasingly useful and can be combined with other analytical techniques, such as liquid chromatography. These approaches provide definitive identification of the relevant hormone or compound according to its chemical or physical characteristics (e.g., unequivocal detection of performance-enhancing agents in sports).
