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Transcript
I. Hormones • chemical messengers inside a body o relay a message from one part of body to another II. Endocrine System all cells, tissues, and organs involved in producing hormones • III. Categories of Hormones A. pheromones • B. act between two organisms, usually same species endocrine hormones 1. 2. act within an organism, some distance away from where produced endocrine glands vs. exocrine glands C. paracrine hormones • D. act within an org., in cells adjacent to where they are produced autocrine hormones • act within an org., in the same cells in which they are produced Three different categories of hormones IV. Basic Facts About Hormones A. B. C. hormonal activity/control is much slower than neural activity/control transported in circulatory or lymphatic system chemical nature of hormones 1. proteins • peptide hormones 2. lipids a. sterols (4-ring structure) b. prostaglandins (linear) D. hormones work in a very specific manner 1. attach to receptor sites on their target cells • attachment is in a lock-and-key fashion 2. only affect their target cells • most cause powerful and important effects Fig. 40.3 Target cell concept E. rate of secretion determines short-term vs. long-term effects 1. 2. F. quick bursts short-term effects slow, steady secretion long-term effects hormone release • prompted by physical, chemical, and environmental cues G. control of hormone secretion 1. 2. negative feedback releasing and inhibiting hormones • releasing hormones often cause release of stimulating hormones o stimulate a target gland to release one or more of its hormones 3. other hormones with opposite effects • antagonistic hormones Page 740 Some elements of hormone control V. Hormones and the Target Cell A. peptide hormones 1. most interact with membrane receptors on target cell • hormone on receptor (1st messenger) activates 2nd messenger o cAMP, cGMP 2. 2nd messenger relays message to nucleus by triggering an enzyme cascade • series of reactions, each using its own enzyme 3. enzyme cascade releases an end-product causes an effect or response Fig. 40.4 Peptide hormones B. lipid hormones 1. no 2nd messengers or enzymes 2. directly effect gene action 3. hormone diffuses through membrane moves into nucleus joins with receptor proteins activates a gene gene synthesizes a protein protein carries out response VI. Invertebrate Hormones A. B. source is often nervous system involved in many aspects of life 1. molting • periodic shedding of exoskeleton 2. metamorphosis • egg larva pupa adult Fig. 40.5 Lipid hormones Fig. 40.2 An overview of the human endocrine system VII. Human Endocrine System A. pituitary gland (hypophysis) 1. anterior pituitary • releases 7 different hormones o incl., gonadotropins hormones that affect the gonads 2. posterior pituitary a. releases two categories of hormones b. more directly controlled by nervous system than ant. 3. both halves controlled by hypothalamus a. “hormone control center” b. releasing and inhibiting hormones Fig. 40.6 Hypothalamus and the pituitary gland B. thyroid gland and parathyroid gland 1. 2. 3. parathyroid embedded within thyroid regulation of metabolism and Ca hyperthyroidism vs. hypothyroidism vs. goiter C. pancreas 1. insulin vs. glucagon a. great example of antagonistic hormones b. both affect blood glucose levels • insulin lowers; glucagon raises 2. diabetes mellitus Fig. 40.10 Regulation of blood calcium level Fig. 40.15 Regulation of blood glucose level D. adrenal glands 1. located on top of each kidney 2. usually release hormones in response to stress 3. adrenal cortex • releases corticosteroids o long-term responses to stress 4. adrenal medulla • epinephrine (adrenalin) and norepinephrine o short-term responses to stress Fig. 40.11 Adrenal glands E. ovaries • estrogen and progesterone F. testes • testosterone G. thymus gland • hormones involved in immune response H. pineal gland 1. located deep inside brain 2. melatonin • helps regulate daily rhythms of sleep and wakefulness o circadian rhythms 3. some influence over hypothalamus and pituitary glands I. prostaglandins 1. lipid hormones of nonspecific origin 2. aid in birth process, blood clotting, and inflammation Fig. 40.2 An overview of the human endocrine system