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Biology: The Dynamic Science (Mind...

4th Edition
Peter J. Russell + 2 others
ISBN: 9781305389892

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BuyFindarrow_forward

Biology: The Dynamic Science (Mind...

4th Edition
Peter J. Russell + 2 others
ISBN: 9781305389892
Textbook Problem

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.

Chapter 42, Problem 1ITD, Researchers measured prolactin and growth hormone in the blood plasma of six subjects at regular

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.

How did the level of growth hormone change over the 24-hour period and, in particular, how did it relate to the sleep period?

Source: From J. F. Sassin et al. 1972. Human prolactin: 24-hour pattern with increased release during sleep. Science 177:1205–1207.

Summary Introduction

To review:

The mechanism through which the level of growth hormone changes over the 24-h period and the process through which it is related to sleep period.

Introduction:

Growth hormone is also known as somatotropin. It is a peptide hormone that enhances growth, cell regeneration, and cell reproduction. Therefore, it plays a significant role during the development of humans and other animals. This hormone is synthesized, stored, and secreted by the somatotropic cells. The somatotropic cells are present within the lateral wings of the anterior pituitary.

Explanation

The growth hormone levels fluctuate during the 24-hour period. The maximum amount of growth hormone is secreted between the time period of 1 a.m. to 5 a.m. The level of hormone remains minimal after the 2’O clock in the day till 11’O clock in the night. After 12’O clock, the secretion of growth hormone increases and decreases subsequently after each hour.

The secretion of growth hormone is directly related to the sleep period...

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