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Hormones and the Endocrine System

Hormones and the Endocrine System. Chapter 40. Hormones chemical messengers inside a body relay a message from one part of body to another Endocrine System all cells, tissues, and organs involved in producing hormones Categories of Hormones pheromones

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Hormones and the Endocrine System

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  1. Hormones and the Endocrine System Chapter 40

  2. Hormones • chemical messengers inside a body • relay a message from one part of body to another • Endocrine System • all cells, tissues, and organs involved in producing hormones • Categories of Hormones • pheromones • act between two organisms, usually same species • endocrine hormones • act within an organism, some distance away from where produced • endocrine glands vs. exocrine glands • paracrine hormones • 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

  3. Three different categories of hormones

  4. Basic Facts About Hormones • hormonal activity/control is much slower than neural activity/control • transported in circulatory or lymphatic system • chemical nature of hormones • proteins • peptide hormones • lipids • sterols (4-ring structure) • prostaglandins (linear) • hormones work in a very specific manner • attach to receptor sites on their target cells • attachment is in a lock-and-key fashion • only affect their target cells • most cause powerful and important effects

  5. Fig. 40.3 Target cell concept

  6. rate of secretion determines short-term vs. long-term effects • quick bursts  short-term effects • slow, steady secretion  long-term effects • hormone release • prompted by physical, chemical, and environmental cues • control of hormone secretion • negative feedback • releasing and inhibiting hormones • releasing hormones often cause release of stimulating hormones • stimulate a target gland to release one or more of its hormones • other hormones with opposite effects • antagonistic hormones

  7. Page 740 Some elements of hormone control

  8. Hormones and the Target Cell • peptide hormones • most interact with membrane receptors on target cell • hormone on receptor (1st messenger)  activates 2nd messenger • cAMP, cGMP • 2nd messenger relays message to nucleus by triggering an enzyme cascade • series of reactions, each using its own enzyme • enzyme cascade releases an end-product  causes an effect or response Fig. 40.4 Peptide hormones

  9. lipid hormones • no 2nd messengers or enzymes • directly effect gene action • hormone diffuses through membrane  moves into nucleus  joins with receptor proteins  activates a gene  gene synthesizes a protein  protein carries out response • Invertebrate Hormones • source is often nervous system • involved in many aspects of life • molting • periodic shedding of exoskeleton • metamorphosis • egg  larva  pupa  adult Fig. 40.5 Lipid hormones

  10. Fig. 40.2 An overview of the human endocrine system

  11. Human Endocrine System • pituitary gland (hypophysis) • anterior pituitary • releases 7 different hormones • incl., gonadotropins • hormones that affect the gonads • posterior pituitary • releases two categories of hormones • more directly controlled by nervous system than ant. • both halves controlled by hypothalamus • “hormone control center” • releasing and inhibiting hormones

  12. Fig. 40.6 Hypothalamus and the pituitary gland

  13. thyroid gland and parathyroid gland • parathyroid embedded within thyroid • regulation of metabolism and Ca • hyperthyroidism vs. hypothyroidism vs. goiter • pancreas • insulin vs. glucagon • great example of antagonistic hormones • both affect blood glucose levels • insulin lowers; glucagon raises • diabetes mellitus Fig. 40.10 Regulation of blood calcium level

  14. Fig. 40.15 Regulation of blood glucose level

  15. adrenal glands • located on top of each kidney • usually release hormones in response to stress • adrenal cortex • releases corticosteroids • long-term responses to stress • adrenal medulla • epinephrine (adrenalin) and norepinephrine • short-term responses to stress

  16. Fig. 40.11 Adrenal glands

  17. ovaries • estrogen and progesterone • testes • testosterone • thymus gland • hormones involved in immune response • pineal gland • located deep inside brain • melatonin • helps regulate daily rhythms of sleep and wakefulness • circadian rhythms • some influence over hypothalamus and pituitary glands • prostaglandins • lipid hormones of nonspecific origin • aid in birth process, blood clotting, and inflammation

  18. Fig. 40.2 An overview of the human endocrine system

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