1. © 2013 Pearson Education, Inc. Endocrine System: Overview Acts with nervous system to coordinate and integrate activity of the body Influences metabolic activities via hormones transported in blood Controlling effect on another part of the body - specific target cells. Response slower but longer lasting than nervous system

2. © 2013 Pearson Education, Inc. Endocrine System: Overview Exocrine glands –Nonhormonal substances (sweat, saliva) –Have ducts to carry secretion to membrane surface Endocrine glands –Produce hormones –Lack ducts

3. © 2013 Pearson Education, Inc. Figure 16.1 Location of selected endocrine organs of the body. Pineal gland Hypothalamus Pituitary gland Thyroid gland Parathyroid glands (on dorsal aspect of thyroid gland) Thymus Adrenal glands Pancreas Gonads Testis (male) Ovary (female)

4. © 2013 Pearson Education, Inc. Chemistry of Hormones Two main classes 1. Steroids: lipids from cholesterol. Interact with DNA of their target tissue, stimulating the synthesis of new proteins. Sex organs and adrenal cortex produce these. 2. Amino acid- never enter target cells, but interact with surface proteins of the cell, inducing the production of an internal messenger that produces the desired effect. Most are this class.

5. © 2013 Pearson Education, Inc.

6. Figure 16.3 Direct gene activation mechanism of lipid-soluble hormones. Slide 1 The steroid hormone diffuses through the plasma membrane and binds an intracellular receptor. 1 5 The receptor- hormone complex enters the nucleus. The receptor- hormone complex binds a specific DNA region. Binding initiates transcription of the gene to mRNA. The mRNA directs protein synthesis. New protein Nucleus mRNA DNA Receptor Binding region Receptor- hormone complex Receptor protein Steroid hormone Plasma membrane Extracellular fluid Cytoplasm 2 3 4

7. © 2013 Pearson Education, Inc.

8. Hypothalamus controls pituitary by making it secrete or stop secreting hormones - EX. Secretion of TRH (thyroid-releasing hormone) by the hypothalamus, induces the pituitary to secrete TSH (thyroid stimulating hormone). TSH causes the thyroid to release thyroxin into the blood which increases most cells metabolic rate. Increasing thyroxin levels have a negative- feedback on the release of TSH.

9. © 2013 Pearson Education, Inc. Hypothalamus TRH Anterior pituitary TSH Thyroid gland Thyroid hormones Target cells Stimulates Figure 16.8 Regulation of thyroid hormone secretion. Inhibits

10. © 2013 Pearson Education, Inc. Neurosecretory cells extend from the hypothalamus into the pituitary and synthesize the hormone oxytocin. Oxytocin induces contractions of the uterine muscles during childbirth and causes the mammary gland to release milk during nursing.

11. © 2013 Pearson Education, Inc.

12. Thyroid regulates development and metabolism. a. In adults, thyroid hormone maintains blood pressure, heart rate, muscle tone, digestive and reproductive function. b. Hyperthyroidism causes overheating, profuse sweating, irritability, high blood pressure and weight lose. c. Hypothyroidism causes lethargy, intolerance to cold, and weight gain. If prolonged, this causes goiter, which may be from to little iodine consumed. The normal neg.-feedback control of TSH is interrupted.

13. © 2013 Pearson Education, Inc. Hypothalamus TRH Anterior pituitary TSH Thyroid gland Thyroid hormones Target cells Stimulates Figure 16.8 Regulation of thyroid hormone secretion. Inhibits

14. © 2013 Pearson Education, Inc.

15. Figure 16.9 The thyroid gland. Hyoid bone Thyroid cartilage Common carotid artery Inferior thyroid artery Trachea Aorta Gross anatomy of the thyroid gland, anterior view Epiglottis Superior thyroid artery Isthmus of thyroid gland Left subclavian artery Left lateral lobe of thyroid gland Colloid-filled follicles Follicular cells Parafollicular cells Photomicrograph of thyroid gland follicles (145x)

16. © 2013 Pearson Education, Inc. Figure 16.10 Synthesis of thyroid hormone. Slide 1 Thyroglobulin is synthesized and discharged into the follicle lumen. 1 2 3 4 5 6 7 Golgi apparatus Iodide (I−) Rough ER Capillary Iodide (I – ) is trapped (actively transported in). Lysosome Lysosomal enzymes cleave T 4 and T 3 from thyroglobulin and hormones diffuse into bloodstream. Thyroglobulin colloid is endocytosed and combined with a lysosome. Iodinated tyrosines are linked together to form T 3 and T 4. Iodide is oxidized to iodine. Iodine is attached to tyrosine in colloid, forming DIT and MIT. To peripheral tissues Colloid in lumen of follicle Thyroid follicular cells Tyrosines (part of thyroglobulin molecule) Thyro- globulin colloid T3T3 T4T4 T3T3 T4T4 T3T3 T4T4 Iodine DITMIT Colloid

17. © 2013 Pearson Education, Inc.

18. Figure 16.12 The parathyroid glands. Parathyroid glands Parathyroid cells (secrete parathyroid hormone) Capillary Oxyphil cells Pharynx (posterior aspect) Thyroid gland Esophagus Trachea

19. © 2013 Pearson Education, Inc. Figure 16.13 Effects of parathyroid hormone on bone, the kidneys, and the intestine. Osteoclast activity in bone causes Ca 2+ and PO 4 3- release into blood Hypocalcemia (low blood Ca 2+ ) PTH release from parathyroid gland Ca 2+ reabsorption in kidney tubule Activation of vitamin D by kidney Ca 2+ absorption from food in small intestine Ca 2+ in blood Initial stimulus Physiological response Result

20. © 2013 Pearson Education, Inc.

21. Figure 16.6 Growth-promoting and metabolic actions of growth hormone (GH). Hypothalamus secretes growth hormone–releasing hormone (GHRH), and GHIH (somatostatin) Anterior pituitary Inhibits GHRH release Stimulates GHIH release Inhibits GH synthesis and release Feedback Indirect actions (growth- promoting) Liver and other tissues Insulin-like growth factors (IGFs) Produce Effects Skeletal Extraskeletal Fat metabolism Carbohydrate metabolism Direct actions (metabolic, anti-insulin) Effects Growth hormone (GH) Increased cartilage formation and skeletal growth Increased protein synthesis, and cell growth and proliferation Increased fat breakdown and release Increased blood glucose and other anti-insulin effects Increases, stimulates Initial stimulus Reduces, inhibits Physiological response Result

22. © 2013 Pearson Education, Inc. Figure 16.7 Disorders of pituitary growth hormone.

23. © 2013 Pearson Education, Inc. Figure 16.17 Stress and the adrenal gland. Short-term stressProlonged stress Nerve impulses Spinal cord Preganglionic sympathetic fibers Adrenal medulla (secretes amino acid– based hormones) Catecholamines (epinephrine and norepinephrine) Short-term stress response Stress Hypothalamus Corticotropic cells of anterior pituitary To target in blood CRH (corticotropin- releasing hormone) Adrenal cortex (secretes steroid hormones) MineralocorticoidsGlucocorticoids ACTH Heart rate increases Long-term stress response Kidneys retain sodium and water Proteins and fats converted to glucose or broken down for energy Blood glucose increases Blood pressure increases Bronchioles dilate Liver converts glycogen to glucose and releases glucose to blood Blood flow changes, reducing digestive system activity and urine output Metabolic rate increases Blood volume and blood pressure rise Immune system supressed

24. 24