Passage—General Endocrine

Cholesterol-derived hormones are carried by the circulatory system to their specific target organs. Hormones are always present in minute concentrations and are capable of both stimulatory and inhibitory effects. One of the main effects of hormones is the stimulation of other endocrine glands to secrete their product. These types of stimulators are known as trophic hormones. Such endocrine cascading allows for tight control of overall hormone production, which may be affecting several distinct organs. In some cases, chemicals are secreted into the extracellular space, affecting cells that are in close proximity to the secretory cell. The metabolic effects of such paracrine regulators are local, compared to the distal or global effects of hormones. Insulin and prostaglandins can also be released locally in order to perform their designated functions. Hormones travel through the blood either in free solution or in association with carrier proteins such as albumin. Target cells contain receptors for their specific hormones, which then trigger the metabolic changes necessary by complex mechanisms. The body houses a number of controlled hormone-releasing cascades. According to the passage, an example of a trophic hormone is: A. insulin B. glucagon C. epinephrine D. TSH (thyroid stimulating hormone) ACTH stimulates the release of cortisol from the adrenal cortex. It can be inferred from the passage that the average blood cortisol concentration at 4 pm on a given day would most likely be: A. 713 nmol/L B. 997 nmol/L C. 101 nmol/L D. 4.7 × 10⁻⁴ mol/L Digitalis is a Na⁺/K⁺ ATPase inhibitor. Which of the following cellular changes will result upon the administration of digitalis? A. There will be an increase in sodium reabsorption by unaffected cells. B. There will be a decrease in the intracellular sodium concentration. C. There will be a decrease in the intracellular potassium. D. There will be an increase in the amount of ATP consumed by the cell. In males, seminiferous tubules require high levels of testosterone, which is secreted by nearby interstitial cells of the testes. In this specific situation testosterone is exerting which effect? A. autocrine effect B. exocrine effect C. paracrine effect D. endocrine effect Which of the following is both an endocrine and exocrine gland? A. the pancreas B. the anterior pituitary C. the liver D. the testes Albumin is a critical factor in determining colloid osmotic pressure. Which other plasma protein can be utilized as a transporter of lipid hormones? A. fibrinogen B. myosin C. C peptide D. F-actin