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Chapter 7b

Chapter 7b. Introduction to the Endocrine System. Simple Endocrine Reflex: Parathyroid Hormone. Low plasma [ Ca 2+ ]. Negative feedback. Parathyroid cell. Parathyroid hormone. Bone and kidney. Kidney reabsorption of calcium. Production of calcitriol leads to intestinal

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Chapter 7b

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  1. Chapter 7b Introduction to the Endocrine System

  2. Simple Endocrine Reflex: Parathyroid Hormone Low plasma [Ca2+] Negative feedback Parathyroid cell Parathyroid hormone Bone and kidney Kidney reabsorption of calcium Production of calcitriol leads to intestinal absorption of Ca2+ Bone resorption Plasma [Ca2+] Figure 7-10

  3. Neurohormones: Major Groups • Adrenal medulla • Catecholamines • Hypothalamus • Anterior pituitary • Posterior pituitary

  4. Endocrine Control • Three levels • Hypothalamic stimulation—from CNS • Pituitary stimulation—from hypothalamic trophichormones • Releasing factors or Neurohormones • Endocrine gland stimulation—from pituitary trophichormones • Stimulate other hormones

  5. Negative Feedback Controls Figure 7-14

  6. Control Pathway for Cortisol Secretion Figure 7-15

  7. A Complex Endocrine Pathway HYPOTHALAMUS • Growth hormone is an example of a complex endocrine pathway Hypothalamus GHRH ANTERIOR PITUITARY GH cells in anterior pituitary GH Liver IGFs Bone and soft tissue Growth Figure 7-17

  8. The Pituitary Gland Anatomy Figure 7-11

  9. The Pituitary Gland: Anterior HYPOTHALAMIC HORMONES Neurons in hypothalamus secreting trophic hormones Dopamine* TRH CRH GHRH* GnRH PRFs Somatostatin Portal system Anterior pituitary ANTERIOR PITUITARY HORMONES TSH ACTH Prolactin GH FSH LH Endocrine cells (Gonadotropins) GTFLAP To target tissues ENDOCRINE TARGETS AND THE HORMONES THEY SECRETE Endocrine cells of the gonads Thyroid gland Adrenal cortex Liver Thyroid hormones Estrogens, progesterone Cortisol IGFs Androgens NONENDOCRINE TARGETS Germ cells of the gonads Many tissues Breast Figure 7-13

  10. The Hypothalamic-Hypophyseal Portal System HYPOTHALAMUS 1 Neurons synthesizing trophic hormones release them into capillaries of the portal system. Capillary bed Artery 2 Portal vessels carry the trophic hormones directly to the anterior pituitary. POSTERIOR PITUITARY 3 Endocrine cells release their hormones into the second set of capillaries for distribution to the rest of the body. Capillary bed ANTERIOR PITUITARY Veins TO TARGET ORGANS Prolactin Gonadotropins (LH & FSH) GH ACTH TSH Ovary Testis Mammary glands Musculoskeletal system Thyroid gland Adrenal cortex Gonads Figure 7-16

  11. The Pituitary Gland: Posterior • Posterior pituitary • Vasopressin (ADH) • Oxytocin HYPOTHALAMUS 1 Hormone is made and packaged in cell body of neuron. 2 Vesicles are transported down the cell. 3 Vesicles containing hormone are stored in posterior pituitary. POSTERIOR PITUITARY Vein 4 Hormones are released into blood. Figure 7-12

  12. The Pituitary Gland: Posterior HYPOTHALAMUS 1 Hormone is made and packaged in cell body of neuron. POSTERIOR PITUITARY Figure 7-12, step 1

  13. The Pituitary Gland: Posterior HYPOTHALAMUS 1 Hormone is made and packaged in cell body of neuron. 2 Vesicles are transported down the cell. POSTERIOR PITUITARY Figure 7-12, steps 1–2

  14. The Pituitary Gland: Posterior HYPOTHALAMUS 1 Hormone is made and packaged in cell body of neuron. 2 Vesicles are transported down the cell. 3 Vesicles containing hormone are stored in posterior pituitary. POSTERIOR PITUITARY Figure 7-12, steps 1–3

  15. The Pituitary Gland: Posterior HYPOTHALAMUS 1 Hormone is made and packaged in cell body of neuron. 2 Vesicles are transported down the cell. 3 Vesicles containing hormone are stored in posterior pituitary. POSTERIOR PITUITARY Vein 4 Hormones are released into blood. Figure 7-12, steps 1–4

  16. The Pituitary Gland: Posterior HYPOTHALAMUS 1 Hormone is made and packaged in cell body of neuron. 2 Vesicles are transported down the cell. 3 Vesicles containing hormone are stored in posterior pituitary. POSTERIOR PITUITARY Vein 4 Hormones are released into blood. Figure 7-12

  17. Hormone Interactions • Synergism • Multiple stimuli—more than additive • 1 + 1 = 3 • Permissiveness • Need second hormone to get full expression • Antagonism • Glucagons oppose insulin

  18. Example of Synergism Glucagon + Epinephrine + Cortisol Glucagon + Epinephrine Epinephrine Glucagon Cortisol Figure 7-18

  19. Endocrine Pathologies Figure 7-19

  20. Endocrine Pathologies • Hypersecretion: excess hormone • Tumors or cancer • Autoimmune • Grave’s disease—thyroxin • Hyposecretion: deficient hormone • Goiter—thyroxin • Low Iodine • Diabetes melitus type I—insulin

  21. Goiter

  22. Pathologies: Abnormal Receptors • Downregulation • Hyperinsulinemia • Transduction abnormalities • Testicular feminization syndrome • Pseudohypothyroidism • Abnormalities of control mechanisms

  23. Primary and Secondary Pathologies Figure 7-20

  24. Stress Pathologies: Hypocortisolism (a) (b) Hyposecretion from damage to the pituitary Hyposecretion from atrophy of the adrenal cortex Hypothalamus Hypothalamus CRH CRH Anterior pituitary Anterior pituitary ACTH ACTH Adrenal cortex Adrenal cortex Cortisol Cortisol Symptoms of deficiency Symptoms of deficiency Figure 7-21

  25. Pineal Gland and Melatonin • Influences body clock and antioxidant activity • Other roles need research • SAAD and sexual behavior

  26. Pineal Gland and Melatonin Corpus callosum Thalamus The pineal gland Figure 7-22 (1 of 3)

  27. Pineal Gland and Melatonin Figure 7-22 (2 of 3)

  28. Pineal Gland and Melatonin Figure 7-22 (3 of 3)

  29. Summary • Introduction to hormones • Classifications and features of hormones • Regulation controlled by the endocrine and nervous systems • Interactions of hormones with other hormones • Endocrine pathologies

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