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Unformatted text preview: Chapter 26 Lecture Outline Introduction Testosterone and Male Aggression: Is There a Link? A. The male sex hormone testosterone has been associated with male aggression in a variety of species. The difficulty for researchers in the field of endocrinology is to definitively prove the association between aggression and testosterone levels. B. The cichlid fish (Oreochromis mossambicus) has been extensively studied. Its testosterone levels rise when in battle over territory. Even spectator cichlid fish demonstrate elevated levels of testosterone when viewing other male cichlid fish in a battle over territory. C. Testosterone in males develops and maintains the reproductive organs and secondary sex characteristics. But how does one define aggression in humans? Is it a desire to fight, or can it be determined through psychological testing? At best, researchers agree that testosterone has little, if any, direct measurable effect on humans and aggressive behavior. D. Testosterone is classified with a group of chemical signals (hormones) that coordinate body functions at the basic level, including such activities as metabolism, energy usage, and growth. This chapter will cover the subject of hormones and other chemical signals with an emphasis on homeostasis. I. The Nature of Chemical Regulation Module 26.1 Chemical signals coordinate body functions. A. Hormones are chemical signals secreted into body fluids, usually blood, and have a regulatory effect on the body via specific target cells. Hormones are produced mainly by endocrine glands (Figure 26.1A). B. Collectively, all hormone-secreting tissues constitute the endocrine system. This system is particularly important in controlling whole-body activities such as metabolic rate, growth, maturation, and reproduction. Hormones also control the response to stimuli such as stress, dehydration, and low body glucose. C. Local regulators are secreted into the interstitial fluid and cause changes in cells near the point of secretion. Pheromones transmit messages between individuals, particularly during mating season. Preview: The nervous system is the subject of Chapters 28 and 29. D. The two systems, endocrine and nervous, coordinate most of their activities. The nervous system provides split-second control, and the endocrine system provides control over longer duration, from minutes to days. E. Neurosecretory cells secrete neurotransmitters that play a role in nerve impulse conduction (Modules 28.628.8) and are also transported in the blood to target cells. For example, epinephrine is the fight-or-flight hormone and is also a neurotransmitter (Figures 26.1B and C). Module 26.2 Hormones affect target cells by two main signaling mechanisms. A. Three types of molecules make up hormones: 1. Protein and polypeptides; made from amino acids, are water soluble....
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This note was uploaded on 03/10/2011 for the course BIOL 10 taught by Professor Kite during the Spring '11 term at Laney College.
- Spring '11
- Blood-Glucose Levels