2.19.10 - Animal control systems Hormones Hormones are...

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Animal control systems: Hormones Hormones are substances produced in one body region that have effects in some other region: chemical messengers Examples of animal hormones: Endocrine hormones: produced in specialized endocrine (‘ductless’) glands, distributed in blood Neurotransmitters, neurohormones: released from nerve cells directly onto other cells (neurotransmitters) or into blood (neurohormones) “local messengers:” not produced in specialized glands; tend to have local effects on nearby cells -- paracrine signaling (histamines, prostaglandins, nitrous oxide, cytokines, etc.) Some chemical messengers mediate interactions between individuals: Pheromones produced by one individual, change the behavior or physiology of other individuals Extremely common in all sorts of animals: species recognition group recognition territory marking navigation social interactions (aggression, cooperation, alarm, etc.) reproduction (sex recognition, attractants, receptivity indication, fertility control, etc.) parent-offspring interactions Animal control systems: Hormones Human pheromones probably unimportant -- only one or two conclusively demonstrated: small effects on the timing of female reproductive cycles NO proven sex attractants, social indicators, status enhancers, etc. Animal control systems: Hormones Animal control systems: Hormones Hormones are one control mechanism in animals. The other major control mechanism is the nervous system (a lot of overlap, such as neurohormones) Comparison between hormonal control and neuronal control: hormonal neuronal Speed: slow (seconds or more) fast (fractions of seconds) Duration: long-lasting very brief (milliseconds) Specificity of signal ‘broadcast’ widely; signal sent only to the target cells: only target cells have the intended target cells via correct receptors wire-like axons (like cell phone) (like desk telephone)
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General categories of hormone function Homeostatic regulation, especially blood-born substances ( aldosterone, vasopressin, insulin, glucagon, leptin ) Emergency responses ("fight or flight"), in concert with the nervous system to prepare for emergencies ( epinephrine ) Development, growth, maturation ( growth hormones in vertebrates; molting hormones in arthropods) Reproduction: maturation and functioning of gonads and other reproductive organs, secondary sexual characteristics, reproductive and parental behavior ( testosterone, estrogens, progesterone, prolactin, oxytocin… ) Biological rhythms , including circadian, monthly, or annual rhythms. These are often mediated by hormone activity ( melatonin, etc. ) Hormone chemistry Hormone chemical structure must be complex enough to be clearly unique. Three basic chemical classes: proteins or short polypeptides : 5-100 amino acids (e.g. insulin, growth hormone, vasopressin, endorphins, leptin ) or glycoproteins (
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This note was uploaded on 04/03/2010 for the course BIO Bio 5b taught by Professor Chappel/douhan during the Winter '10 term at UC Riverside.

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2.19.10 - Animal control systems Hormones Hormones are...

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