Patho Endocrine ch 31
Which of the following physiologic processes best exemplifies a positive feedback mechanism? A. The increase in prolactin secretion that occurs with more frequent breast-feeding B. The regulation of blood glucose levels by insulin C. The release of parathyroid hormone in response to decreased serum calcium levels D. The release of antidiuretic hormone when sodium levels are higher than normal
A A positive feedback mechanism occurs when one hormonal or physiologic factor stimulates further hormonal release, creating a cascade that will increase until corrected. Correction of alterations in homeostasis is normally achieved using negative feedback mechanisms, such as those accomplished by insulin, parathyroid hormone, and ADH.
A hormone has been synthesized in the rough endoplasmic reticulum of an endocrine cell after which it has moved into the Golgi complex, been packaged in a vesicle, and been released into circulation. From the following list, which hormone is synthesized and released in this manner? A) Insulin B) Cortisol C) Testosterone D) Estrogen
A Insulin is a peptide hormone; as such, its synthesis and release are vesicle mediated. Glucocorticoids (such as cortisol), androgens (such as testosterone), and estrogens are synthesized by non-vesicle-mediated pathways.
When trying to explain hypothyroidism to a newly diagnosed client, the nurse stresses the fact that the thyroid hormone is transported in blood by specific: A. Proteins B. Target cells C. Cholesterol molecules D. Prohormones
A Some hormones, such as steroids and thyroid hormone, are bound to protein carriers for transportation to the target cell destination. The extent of carrier binding influences the rate at which hormones leave the blood and enter the cells. Cholesterol is a precursor for steroid hormone. Prohormones have an extra amino acid and are converted to hormones in the Golgi complex.
When hypofunction of an endocrine organ is suspected, which hormone test can be administered to measure and assess target gland response? A. Stimulation B. 24-hour urine C. Agglutination D. Antibody binding
A Stimulating hormone can be given to identify (determine hypofunction) if the target gland is able to increase hormone response to increased stimulation. Agglutination with enzymes is a way of measuring hormone antigen levels. The 24-hour urine sample measures hormone metabolite excretion. Radioactive hormone-antibody binding levels are a method of measuring plasma levels.
A diabetic client is controlled on Avandia (rosiglitazone), a thiazolidinedione medication that acts at the level of nuclear peroxisome proliferator-activated receptors (PPARs) to promote: A. Glucose uptake B. Stimulation of the beta cells in the pancreas C. Increase in basal metabolic rate D. Weight loss by shrinking fat cells
A The thiazolidinedione medications, which are used in the treatment of type 2 diabetes mellitus, act at the level of nuclear PPAR-γ receptors to promote glucose uptake and utilization by adipose tissue cells. These drugs do not increase release of insulin from the pancreas, increase BMR, or promote weight loss.
When explaining factors that influence the number of receptors present on target cells, the instructor will likely mention: Select all that apply. A. The role antibodies may have on receptor proteins. B. A decreased hormone level may produce increased receptor numbers. C. A sustained excess hormone level brings about a decrease in receptor numbers. D. How any given hormone can change its affinity to supply a need to all cells. E. It may take days to weeks before a hormone can react to target cells.
A, B, C, Target cell response varies with the number and affinity of the relevant receptors. The number of hormone receptors on a cell may be altered for any of several reasons. Antibodies may destroy or block the receptor proteins. Increased or decreased hormone levels often induce changes in the activity of the genes that regulate receptor synthesis. For example, decreased hormone levels often produce an increase in receptor numbers by means of a process called up-regulation; this increases the sensitivity of the body to existing hormone levels. Likewise, sustained levels of excess hormone often bring about a decrease in receptor numbers by down-regulation, producing a decrease in hormone sensitivity.
When sensors detect a change in a hormone level, the hormonal response is regulated by which of the following mechanisms that will return the level to within normal range. A. Metabolic B. Feedback C. Production D. Action potential
B Feedback (negative and sometimes positive) mechanisms respond to levels that are too high or too low. The level of many of the hormones in the body is regulated by negative feedback mechanisms. The function of this type of system is similar to that of the thermostat in a heating system. For example, when the sensors detect a decrease in blood levels, they initiate changes that cause an increase in hormone production. Metabolic responses and increased/decreased production occur as a consequence of hormone level fluctuations, not as a regulating mechanism. Action potential is not a regulating mechanism for this function.
The release of insulin from the pancreatic beta cells can inhibit its further release from the same cells. This is an example of which type of hormone action? A. Retinoid B. Autocrine C. Juxtaposed D. Arachidonic
B Hormones can exert autocrine action on the cells from which they were produced. Retinoids are compounds with hormone-like actions. Juxtacrine action involves a chemical messenger imbedded in a plasma membrane that interacts with a specific receptor on a juxtaposed cell. Arachidonic acid is a precursor for eicosanoid compounds (similar to retinoids).
Thyroid and steroid hormones, which exert their effect on target cells by way of nuclear receptors, have which of the following characteristics? A. The selective use of a second messenger B. The ability to cross the cell membrane of target cells C. The ability to regulate surface receptor affinity D. Both lipid solubility and water solubility
B Hormones that utilize nuclear receptors enter the target cell (i.e., cross the cell membrane) and bind to receptors in the cell nucleus that are gene regulatory proteins. These hormones do not selectively utilize second messengers, and they do not interact with surface receptors. They are not both lipid and water soluble.
While teaching a science class, the instructor mentions that both autocrine and paracrine hormonal actions occur without entering the blood stream. The instructor then asks the students, "What cells do paracrine actions affect?" The student with the correct answer is: A.Self B. Local C. Stored D. Target
B Paracrine actions are hormonal interactions with local cells other than those that produce the hormone; autocrine actions are with self-cells (cells from which they were produced). Both autocrine and paracrine hormonal actions affect target cells. Neither paracrine nor autocrine actions affect cell storage.
A client with many nonspecific complaints has been ordered a positron emission tomography (PET) scanning for evaluation of: A. The pancreas response to an insulin injection B. Tumors located on the endocrine glands C. Bone density D. Radioactivity of the thyroid gland
B Positron emission tomography (PET) scanning is being used more widely for evaluation of endocrine tumors. PET scans do not calculate the pancreas response to insulin. A DEXA is used for diagnosis and monitoring of osteoporosis (bone density). Isotopic imaging includes radioactive scanning of the thyroid (using radioiodine) and parathyroids.
When describing to a newly diagnosed diabetic client how insulin is regulated, the nurse will draw upon her knowledge of which hormonal regulation mechanism? A. Basal metabolic rate B. The hypothalamic-pituitary-target cell system C. The cytokine-interleukin regulatory mechanism D. The angiotensin I to angiotensin II to aldosterone system
B The hypophysis (pituitary plus hypothalamus) and hypothalamus stimulatory hormones regulate the release and synthesis of anterior pituitary hormones. The levels of hormones such as insulin and antidiuretic hormone (ADH) are regulated by feedback mechanisms that monitor substances such as glucose (insulin) and water (ADH) in the body. The levels of many of the hormones are regulated by feedback mechanisms that involve the hypothalamic-pituitary-target cell system.
When discussing luteinizing hormone and follicle-stimulating hormone with students, the instructor will emphasize that these hormones are under the control of: A. Thyroid gland B. Anterior pituitary gland C. Posterior adrenal cortex D. Pancreas
B The pituitary gland has been called the master gland because its hormones control the functions of many target glands and cells. The anterior pituitary gland or adenohypophysis contains five cell types: (1) thyrotrophs, which produce thyrotropin, also called TSH; (2) corticotrophs, which produce corticotropin, also called ACTH; (3) gonadotrophs, which produce the gonadotropins, LH, and FSH; (4) somatotrophs, which produce GH; and (5) lactotrophs, which produce prolactin.
Paracrine action involves which of the following characteristics? A. Action on a distant target cell B. Autoregulation C. Act locally on cells other than those that produce the hormone D. Action on nearby target cells
C When hormones act locally on cells other than those that produced the hormone, the action is called paracrine. Paracrine action is not synonymous with autoregulation, and action on the same cells that produced the hormone is autocrine action.
While discussing the elimination of hormones from the body to prevent overaccumulation, which of the following hormones are eliminated in bile? Select all that apply. A. Catecholamines B. Unbound adrenal hormones C. Gonadal steroid hormones D. Thyroid hormones E. Peptide hormones
B, C, D Steroid hormones are bound to protein carriers for transport and are inactive in the bound state. Unbound adrenal and gonadal steroid hormones are conjugated in the liver, which renders them inactive, and then excreted in the bile or urine. Thyroid hormones also are transported by carrier molecules. The free hormone is rendered inactive by the removal of amino acids in the tissues, and the hormone is conjugated in the liver and eliminated in the bile. The catecholamine production is measured by some of their metabolites. In general, peptide hormones also have a short life span in the circulation. Their major mechanism of degradation is through binding to cell surface receptors, with subsequent uptake and degradation by peptide-splitting enzymes in the cell membrane or inside the cell.
Which of the following hormones are synthesized by non-vesicle-mediated pathways? Select all that apply. A. Epinephrine B. Estrogen C. Insulin D. Aldosterone
B, D Glucocorticoids, androgens, estrogens, and mineralocorticoids (aldosterone is an example of a mineralocorticoid) are all hormones synthesized by non-vesicle-mediated pathways. Epinephrine and insulin are synthesized by vesicle-mediated pathways.
As part of maintaining homeostasis, hormones secreted by endocrine cells are inactivated continuously to: A. Free receptor sites B. Stimulate production C. Prevent accumulation D. Absorb metabolic waste
C Continuous inactivation of secreted hormones is necessary to prevent accumulation that could disrupt the feedback mechanism. Increased secretion stimulates production of more receptor sites. Metabolic waste absorption is not a function of the endocrine system.
Hormones are usually divided into categories according to their structure. The release of epinephrine would be classified as: A. Proteins B. Steroids C. Amines and amino acids D. Peptides and polypeptides
C Hormones are divided into three categories according to their structures: amines and amino acids; polypeptides, proteins, and glycoproteins; and steroids. The amine and amino acid hormones include norepinephrine and epinephrine, which are derived from a single amino acid (i.e., tyrosine). The peptide, polypeptide, protein, and glycoprotein hormones can be as small as thyrotropin-releasing hormone (TRH), which contains three amino acids, and as large, and as large and complex as growth hormone (GH) and follicle-stimulating hormone (FSH). Steroid hormones, such as the glucocorticoids, are derivatives of cholesterol.
Which of the following statements best describes the relationship between the hypothalamus and the posterior pituitary in the normal functioning of the endocrine system? A. Posterior pituitary hormones are constituted from components of both the hypothalamus and the pituitary gland itself. B. The posterior pituitary gland regulates the release of hypothalamic hormones. C. Posterior pituitary hormones are produced in the hypothalamus but released from the pituitary gland. D. The hypothalamus regulates the production and release of posterior pituitary hormones by the pituitary gland.
C The posterior pituitary hormones, ADH and oxytocin, are synthesized in the cell bodies of neurons in the hypothalamus that have axons that travel to the posterior pituitary, where they are released when needed. The two glands do not contribute components that are subsequently combined.
When comparing the endocrine and nervous system functions, the nurse knows that the endocrine system: Select all that apply. A. Sends signals to neurons over a short distance to muscles B. Responds to neurotransmitter molecules within milliseconds C. Releases hormones into the blood that is transported throughout the body D. Glands are widely scattered throughout the body E. Takes longer to respond to innervations but has prolonged actions when they arrive
C, D, E The endocrine system uses chemical messengers called hormones as a means of controlling the flow of information between the different tissues and organs of the body. It does not act alone, however, but interacts with the nervous system to coordinate and integrate the activity of body cells. Hormones regulate and integrate body functions. Hormones act on specific target cells, but they cause a variety of effects on tissues. Hormones do not transport other substances; hormones are transported and present in body fluids at all times. The endocrine system uses hormones released into the blood and transported throughout the body to influence the activity of body tissues. Tissue and organ responses to endocrine hormones tend to take much longer than the response to neurotransmitters, but once initiated, they tend to be much more prolonged than those induced by the nervous system. The glands of the endocrine system are widely scattered throughout the body.
In major athletic competition, athletes are required to submit to liquid chromatography testing looking for: A. Blood doping to increase RBC levels B. Low serum sodium levels indicating dehydration C. Use of opioids to minimize pain during competition D. Use of performance-enhancing agents to increase the chances of winning
D 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).
Which of the following statements about immunoradiometric assay (IRMA) testing for measuring plasma hormone levels is most accurate? A. This bioassay test uses an intact animal or a portion of tissue from an animal to calculate specificity and sensitivity. B. This testing procedure uses antibody-coated plates to produce colored reaction. C. A 24-hour urine test will be required along with blood tests to calculate specific results. D. These tests are very specific since they utilize two antibodies instead of one.
D Immunoradiometric assay (IRMA) testing is very specific since they utilize two antibodies instead of one. These two antibodies are directed against two different parts of the molecule, and therefore IRMA assays are more specific. Hormones circulating in the plasma were first detected by bioassay test, which used an intact animal or a portion of tissue from an animal to calculate specificity and sensitivity. ELISA testing procedure utilizes antibody-coated plates to produce colored reaction. The IRMA is a blood test, not a urine test.
A client has received an injection containing thyrotropin-releasing hormone (TRH) and is now being assessed for levels of thyroid-stimulating hormone (TSH). This client has undergone which of the following diagnostic tests? A. Suppression testing B. Radioimmunoassay (RIA) C. Autoantibody testing D. Stimulation testing
D Introduction of TRH tests the pituitary gland's ability to produce TSH, and is an example of a stimulation test. Suppression testing examines a gland's response to a stimulus that would normally result in decreased hormone production. RIA and autoantibody testing are examples of direct and indirect measurement of serum levels of a hormone.
A nursing student who has a history of brain tumors that resulted in partial removal of her pituitary gland years ago is asking her OB/GYN doctor about her ability to breast-feed her infant. This is based on which physiological function of the pituitary gland that facilitates breast milk production? A. Growth hormone (GH) B. Oxytocin C. Corticotropin-releasing hormone (CRH) D. Lactotrophs
D The anterior pituitary gland or adenohypophysis contains five cell types: (1) thyrotrophs, which produce thyrotropin, also called TSH; (2) corticotrophs, which produce corticotropin, also called ACTH; (3) gonadotrophs, which produce the gonadotropins, LH, and FSH; (4) somatotrophs, which produce GH; and (5) lactotrophs, which produce prolactin that is involved with breast growth and milk production.
Cyclic adenosine monophosphate (cAMP) performs which of the following roles in the functioning of the endocrine system? A. Mediating hormone synthesis by non-vesicle-mediated pathways B. Acting as a high-affinity receptor on the surface of target cells C. Inactivating hormones to prevent excess accumulation D. Acting as a second messenger to mediate hormone action on target cells
D cAMP is one of the most common second messengers, whose role is to generate an intracellular signal in response to cell surface receptor activation by a hormone. cAMP does not mediate hormone synthesis, act as a receptor itself, or inactivate hormones.
