1 / 43

Chapter 36: Endocrine Control

Chapter 36: Endocrine Control. Fig. 36-1b, p.618. Endocrine System. Main Sources Pituitary gland Adrenal glands Thyroid gland Parathyroid glands Pineal gland Thymus gland. Figure 36.2 Page 621. hypothalamus (part of the brain). pineal gland. pituitary gland, anterior lobe

divers
Download Presentation

Chapter 36: Endocrine Control

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 36: Endocrine Control

  2. Fig. 36-1b, p.618

  3. Endocrine System Main Sources • Pituitary gland • Adrenal glands • Thyroid gland • Parathyroid glands • Pineal gland • Thymus gland Figure 36.2 Page 621

  4. hypothalamus (part of the brain) pineal gland pituitary gland, anterior lobe pituitary gland, posterior lobe thyroid gland parathyroid glands (four) thymus gland adrenal gland (one pair) medulla pancreatic islets ovaries (one pair of female gonads) testes (one pair of male gonads) Fig. 36-2a, p.621

  5. Hormones • Secreted by endocrine glands, endocrine cells, and certain neurons • Travel through the bloodstream to nonadjacent target cells

  6. Hormone Action • Activation of receptor • Transduction of signal • Functional response

  7. Responses to Hormones Vary • Different hormones activate different responses in the same target cell • Not all types of cells respond to a particular hormone

  8. Two Main Hormone Types • Steroid hormones • Derived from cholesterol • Estrogens, progestins, androgens, cortisol, aldosterone • Peptide hormones • Peptides, proteins, or glycoproteins • Glucagon, ADH, oxytocin, TRH, insulin, somatotropin, prolactin, FSH, LH, TSH

  9. Steroid Hormones hormone • Most diffuse across the plasma membrane and bind to a receptor • Hormone-receptor complex acts in nucleus to inhibit or enhance transcription receptor hormone-receptor complex Figure 36.3 Page 623 gene product

  10. Protein Hormone glucagon • Hormone binds to a receptor at cell surface • Binding triggers a change in activity of enzymes inside the cell glucagon receptor cyclic AMP + Pi ATP cAMP activates protein kinase A Protein kinase A converts phosphorylase kinase to active form and inhibits an enzyme required for glucagon synthesis. Figure 36.3b Page 623

  11. The Hypothalamus • Region in the forebrain • Contains hormone-secreting cells • Interacts with pituitary hypothalamus pituitary gland

  12. Pituitary Gland • Pea-sized gland at base of hypothalamus • Two lobes • Posterior lobe stores and secretes hormones synthesized in the hypothalamus • Anterior lobe produces and secretes its own hormones

  13. Posterior Lobe cell body in hypothalamus • Antidiuretic hormone (ADH) • Oxytocin (OCT) axons to the general circulation Figure 36.4 Page 624

  14. Anterior Pituitary • ACTH • TSH • FSH • LH • PRL • STH Figure 36.5 Page 625

  15. Normal Hormone Production • Generally, the body produces only very small amounts of hormones • To isolate 1 milligram of TRH, researchers dissected 7 metric tons of hypothalamic tissue

  16. Abnormal Somatotropin Output • Gigantism • Pituitary dwarfism • Acromegaly

  17. Thyroid Gland epiglottis thyroid cartilage (Adam’s apple) pharynx thyroid gland trachea (windpipe) parathyroid gland anterior posterior Fig. 36-6, p.626

  18. Feedback Mechanisms • Negative feedback • Increase in hormone triggers activities that inhibit further secretion • Positive feedback • Increase in hormone triggers activities that stimulate further secretion

  19. Stimulus Response + Blood level of thyroid hormone falls below a set point. – Hypothalamus TRH – Anterior Pituitary Rise in the blood level of thyroid hormone inhibits secretion of TRH and TSH. TSH Thyroid Gland Thyroid hormone is secreted Fig. 36-7, p.626

  20. EXAMPLE: Cortisol • Cortisol secretion • Inhibits blood glucose uptake by muscle and other tissues • Causes breakdown of proteins to amino acids and conversion to glucose • Causes degradation of adipose tissue to fatty acids for use as energy source

  21. Feedback Control of Cortisol Secretion • Hypothalamus senses rise in glucose and secretes less releasing hormone (CRH) • Anterior pituitary responds by secreting less ACTH • Adrenal cortex slows its secretion of cortisol

  22. Localized Feedback in Adrenal Medulla • Norepinephrine secreted by neurons accumulates in the synaptic gap • Some molecules bind to receptors on the axon endings that secreted them • Prevents further secretion of norepinephrine by that axon

  23. Thyroid Gland Disorders • Goiter • Hyperthyroidism • Hypothyroidism Figure 36.6 Page 626

  24. Fig. 36-8a, p.627

  25. EXAMPLE: Calcium Regulation • Parathyroid hormone (PTH) is the main regulator of calcium in the blood • It is secreted when calcium levels drop • PTH causes bone cells to digest bone tissue and release calcium • PTH also stimulates calcium reabsorption by the kidneys and absorption by the gut

  26. EXAMPLE: Deformed Frogs • Something in water triggers deformities • Problem thyroid function? • Tadpoles from “hotspots” developed normally when given extra thyroid hormones • UV, parasites also play a role

  27. Fig. 36-9, p.627

  28. Control of Glucose Metabolism insulin Glucose uptake Glucose to glycogen Glucose falls Glucose is absorbed Cells use glucose Glucose rises Glycogen to glucose glucagon

  29. Diabetes Mellitus Excess glucose accumulates • Type 1 • Autoimmune disease • Usually appears in childhood • Insulin injections • Type 2 • Target cells don’t respond • Usually appears in adults • Diet, drugs

  30. Adrenal Cortex • Secretes cortisol • Negative feedback loops to hypothalamus and pituitary maintain proper cortisol levels • Corisol maintains glucose levels in the absence of food by inducing liver cells to break down stored glycogen

  31. Adrenal Medulla • Inner region of adrenal gland • Secretes epinephrine and norepinephrine, which are neurotransmitters or hormones, depending on context • Responsible for fight-flight response to stress and excitement

  32. Stress • Stress induces secretion of cortisol, epinephrine, and norepinephrine • Prolonged and repeated stress, as in baboons in lower levels of troop hierarchy, has greater physiological effect

  33. Fig. 36-13, p.631

  34. Stress • Chronic stress can interfere with: • growth • immune system • sexual function • cardiovascular function • In humans, Cushing’s syndrome is caused by long-term elevated cortisol levels

  35. The Pineal Gland • Photosensitive gland embedded in brain • Absence of light; secretes melatonin • Affects human biological clock • May also play role in human puberty and seasonal affective disorder

  36. Fig. 36-14, p.632

  37. Invertebrate Molting • Periodic discarding and replacement of a hardened cuticle • Under control of ecdysone • Steroid hormone • Secretion tied to environmental cues

  38. Hormone Coordination • Our bodies are attuned to hormones, which are coordinated and directed by hypothalamus and pituitary gland • Hormones bind to every tissue and are key players in development and maintenance of homeostasis

More Related