Researchers measured prolactin and growth hormone in the blood plasma of six subjects at regular intervals over a 24-hour period. The investigators were interested in determining if the levels of these two hormones cycle over a 24-hour period. The Figure presents the results of their experiments, with the y axis values showing the amount of each hormone expressed as a percentage of the 24-hour mean value, and each point showing the average of the six subjects’ levels.
FIGURE Mean concentrations of prolactin and growth hormone in plasma, averaged for six subjects and expressed as a percentage of the average concentrations measured for the 24-hour period.
Do the results support the hypothesis that the changes in prolactin level over a 24-hour period are associated with the sleep–wake cycle?
Source: From J. F. Sassin et al. 1972. Human prolactin: 24-hour pattern with increased release during sleep. Science 177:1205–1207.
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Chapter 42 Solutions
Biology: The Dynamic Science (MindTap Course List)
- Levels of the Female Reproductive Hormones during the Menstrual Cycle Hormone Day 4 Day 14 Day 21 Estrogen (pg/mL) N/A >100 <60 Progesterone (ng/mL) N/A <1.5 >15 LH (mIU/mL) <7 >15 N/A FSH (mIU/mL) <13 >15 N/A Identify the hormones numbered in the graph above. Number: Answer Answer Answer Answer Hormone: Estrogen Progesterone LH FSHarrow_forwardOne of the main endocrine glands in the human body is the pituitary gland. This gland produces a variety of hormones with different effects. Among these are a heterogeneous group of hormones called tropic hormones, which directly stimulate the secretion of other hormones from downstream endocrine glands. Which of the following are tropic hormones? Select all that apply. LH Prolactin Oxytocin ACTH TSH testosteronearrow_forwardPlace the following steps (showing how a steroid hormone changes the activities of its target cells) in order of what happens first, second, third, fourth, and last. Refer to image. The hormone-receptor complex enters the nucleus of the cell and binds to the DNA. The steroid hormone passes through the cell membrane. The hormone attaches to a receptor in the cytoplasm, forming a hormone-receptor complex. A gene in the DNA is activated, and transcription and translation take place. Proteins that alter the cell′s activities, such as enzymes, are made. 2. Place the following steps (showing how a hydrophilic hormone changes the activities of its target cells) in order of what happens first, second, third, and last. Refer to image. The activity of the target cell is changed by the final enzyme in the cascade. The second messenger activates or deactivates certain enzymes in a cascade fashion. A second messenger is activated. Hormone binds to a receptor protein.arrow_forward
- Give answer to the question in the picturearrow_forwardConsider the communication between the hypothalamus, pituitary and various target organs when answering this question. For each condition discussed, state the change you would expect to find for each hormone/compound addressed - INCREASED, DECREASED, UNAFFECTED, CAN'T INTERPRET: A patient suffering from untreated Graves disease: A) TSH B) Calcitonin C) Thyroxine(T4/T3) D) TRH A patient suffering from untreated goiter: A) TSH B) Calcitonin C) Thyroxine(T4/T3) D) TRH A patient suffering from pituitary tumor secreting ACTH: A) CRH B) ACTH C) Cortisol D) Plasma potassium level Now, let's consider calcium metabolism and balance. For each condition discussed, state the change you would expect to find for hormone/calcium levels - INCREASED, DECREASED, UNAFFECTED, CAN'T INTERPRET: A patient with…arrow_forwardAll of themarrow_forward
- The interaction between the hormones and behavior is bidirectional. How do hormones affect the behavior of an individual and vice versa? Cite an example for each to support your answer. Explain in 4-6 sentences only.arrow_forwardWhat are the possible interferences or sources of variability in the assay? How do these interference affect the result in cortisol determination?arrow_forwardConsider the following: Hormone X is released by Secretory Cell A and binds to its receptor on Target Cell 1. In response to this binding, Target Cell 1 releases Hormone Y. Based on the information above, identify whether the following statement is true or false: Hormone X is considered a tropic hormone. a. True b. Falsearrow_forward
- Give only typing answer with explanation and conclusionarrow_forwardExplain how mutations in the following proteins might result in either loss of responsiveness to a given hormone or production of a continuous signal even in the absence of the hormone: a mutation in the regulatory (R) subunit of cAMP-dependent protein kinase, making R incapable of binding to the catalytic (C) subunitarrow_forwardDoes the following table properly summarize negative feedback loop of each tropic hormone? If not, place the correct answer beside each box.arrow_forward
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