The Endocrine System Chapter 17 – Lecture Notes

1. The Endocrine SystemChapter 17 – Lecture Notes to accompany Anatomy and Physiology: From Science to Life textbook by Gail Jenkins, Christopher Kemnitz, Gerard Tortora

2. Chapter Overview 17.1 Endocrine System Overview 17.2 Hormone Secretion 17.3 Hypothalamus and Anterior Pituitary 17.4 Posterior Pituitary 17.5 Thyroid Gland 17.6 Parathyroid Glands 17.7 Adrenal Cortex 17.8 Pancreas 17.9 Gonads 17.10 Pineal Gland

3. Essential Terms hormone • chemical mediator that helps maintain homeostasis target cell • cell with a receptor that responds to the presence of a hormone

4. Introduction Endocrine secretion activity is less dramatic than activity of neurotransmitters Nervous system responses generally more immediate Endocrine system responses more prolonged and help maintain homeostasis Two systems are integrated

5. Concept 17.1Endocrine System Overview

6. Endocrine System • Nervous stimulation can trigger endocrine secretions • Endocrine system controls activities by releasing hormones • Most hormones enter interstitial fluid then are carried to target tissues by circulatory system • Endocrine system and nervous system function together as a “supersystem” • Endocrine system helps regulate virtually all types of body cells

7. Endocrine Glands • exocrine glands secrete products onto a surface • endocrine glands secrete products into the body fluids • hormones are carried to target tissues where activity is carried out • pituitary, thyroid, parathyroid, adrenal, pineal • Other hormone secreting structures • hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue, placenta

8. Table 17.1

9. Figure 17.1

10. Concept 17.2Hormone Secretion

11. Receptors • hormones only affect target cells • water soluble hormone receptors on outside surface and trigger response inside the cell • lipid soluble hormone receptors on inside of cell and trigger response inside cell • target cells generally have between 2,000 and 100,000 receptors for a given hormone

12. Chemical Classes of Hormones • water soluble • amino acid based • lipid soluble • steroids • thyroid hormones • nitric oxide • transported in blood by transport proteins • slow rate of loss in kidneys • ready reserve of hormone in blood stream

13. Table 17.2 pt 1

14. Table 17.2 pt 2

15. Hormone Action • variable depending on hormone and target cell • various targets respond differently to same hormone • some hormones activate synthetic or stimulatory processes • others activate degradation or inhibitory processes

16. Figure 17.2

17. Figure 17.3

18. Hormone Interactions • permissive effects • one hormone allows the other to function • synergistic effects • one hormone intensifies the effects of the other • antagonistic effects • one hormone inhibits or reduces the effects of the other

19. Control of Hormone Secretion • hormones secreted in bursts • as stimulation increases bursts increase in frequency • in absence of stimulation, bursts are minimal or inhibited • regulated by • neural signals • chemical changes in blood • other hormones

20. Concept 17.3Hypothalamus & Pituitary Gland

21. Hypothalamus • controls the activity of the pituitary gland • major integrating link between the nervous and endocrine systems • hormones that stimulate anterior pituitary are all either releasing hormones or inhibiting hormones

22. Figure 17.4

23. Pituitary Gland • two lobes • anterior lobe • stimulated by tropic hormones from hypothalamus • hypophyseal portal system • posterior lobe • neural tissue that releases hormones produced in the hypothalamus • neurosecretory cells

24. Table 17.3

25. Figure 17.5

26. Figure 17.6

27. Figure 17.11

28. FSH & LH • released by the anterior pituitary • triggered by GnRH • target tissue gonads • FSH • in females initiates development of ovarian follicles • in males stimulates sperm production • LH • in females triggers ovulation • in males triggers testosterone secretion

29. PRL • released by the anterior pituitary • trigger is PRH and PIH from hypothalamus • initiates and maintains milk secretion and production by mammary glands in females • in males can cause erectile dysfunction

30. ACTH • secreted by anterior pituitary • triggered by CRH • also triggered by stress • controls production and secretion of hormones called glucocorticoids • cortisol from adrenal cortex • cause negative feedback regulation of CRH and ACTH release

31. Figure 17.16

32. MSH • secreted by anterior pituitary • function unknown in humans • presence of MSH receptors in brain suggests it may influence brain activity • excessive CRH stimulates MSH release • PIH inhibits MSH release

33. Table 17.4 pt 1

34. Table 17.4 pt 2

35. Concept 17.4Posterior Pituitary

36. Posterior Pituitary • AKA neurohypophysis • store and release two hormones produced by hypothalamus • ADH • OT

37. Figure 17.4

38. OT • oxytocin • targets uterus and mammary glands during and after delivery • uterus contracts • milk ejection (“let down”) • function in non-reproducing women and in men is unknown • animal studies seem to indicate parental caretaking behavior toward offspring • sexual pleasure during and after intercourse

39. ADH • antidiuretic hormone • decreases urine production • kidneys return water to blood • decreases sweating • causes constriction of arterioles • increases blood pressure • AKA vasopressin

40. Figure 17.8

41. Table 17.5

42. Concept 17.5Thyroid Gland

43. TSH • follicular cells produce • thyroxine (T4) • triiodothyronine (T3) • parafollicular cells produce • calcitonin • involved in calcium homeostasis • brings calcium levels down when too high

44. Figure 17.10

45. Figure 17.11

46. Actions of Thyroid Hormones • thyroxine and triiodothyronine • regulate oxygen use and BMR

47. Concept 17.6Parathyroid

48. PTH • parathyroid hormone • major regulator of calcium, magnesium, and phosphate ions in blood • PTH brings blood levels of calcium up when too low

49. Figure 17.13

50. Table 17.7