1. Chapter 13 Endocrine System
Endocrine glands are ductless
Exocrine glands have ducts

2. Endocrine Glands Paracrine secretions Endocrine glands act locally
release hormones
hormones travel through blood to target cells
Paracrine secretions
act locally
affect only neighboring cells
Autocrine secretions
affect only the secreting cell

3. Comparison of Nervous System and Endocrine System
Neurons release neurotransmitters into a synapse, affecting postsynaptic cells
Glands release hormones into the bloodstream
Only target cells of hormone responds

4. Comparison of Nervous System and Endocrine System

5. Major Endocrine Glands

6. Chemistry of Hormones Nonsteroid Hormones
amines
proteins
peptides
glycoproteins
most hormones
Steroid or Steroid-Like Hormones
sex hormones
adrenal cortex hormones

7. Types of Hormones

8. Structural Formulas of Hormones

9. Actions of Steroid Hormones
hormone crosses membranes
hormone combines with receptor in nucleus
synthesis of mRNA activated
mRNA enters cytoplasm to direct synthesis of protein

10. Actions of Steroid Hormones

11. Actions of Nonsteroid Hormones
hormone binds to receptor on cell membrane
adenylate cyclase activated
ATP converted to cAMP
cAMP promotes a series of reactions leading to cellular changes

12. Actions of Nonsteroid Hormones

13. Prostaglandins paracrine substances act locally
very potent in small amounts
regulate cellular responses to hormones
can activate or inhibit adenylate cyclase
controls cAMP production
alters cell’s response to hormones
wide variety of functions

14. Control of Hormonal Secretions
primarily controlled by negative feedback mechanism

15. Negative Feedback

16. Major Endocrine Glands

17. Pituitary Gland Two distinct portions
anterior pituitary (adenohypophysis)
posterior pituitary (neurohypophysis)

18. Pituitary Gland Control
Hypothalamic releasing hormones stimulate cells of anterior pituitary to release hormones
Nerve impulses from hypothalamus stimulate nerve endings in the posterior pituitary gland to release hormones

19. Hypothalamic Hormones

20. Hormones of the Pituitary Gland

21. Thyroid Gland

22. Thyroid Gland Hormones

23. Disorders of the Thyroid Gland

24. Disorders of the Thyroid Gland
Graves Disease
Hyperthyroidism
Cretinism
Infantile hypothyroidism

25. Parathyroid Glands

26. Parathyroid Hormone

27. Parathyroid Hormone
Mechanism by which PTH promotes calcium absorption in the intestine

28. Disorders of the Parathyroid Glands

29. Adrenal Glands

30. Hormones of the Adrenal Medulla

31. Hormones of the Adrenal Cortex

32. Hormones of the Adrenal Cortex

33. Hormones of the Adrenal Cortex

34. Pancreas

35. Hormones of the Pancreatic Islets

36. Insulin and Glucagon
Insulin and glucagon function together to stabilize blood glucose concentrations

37. Other Endocrine Glands
Pineal Gland
secretes melatonin
regulates circadian rhythms
Thymus Gland
secretes thymosins
promotes development of certain lymphocytes
important in role of immunity

38. Other Endocrine Glands
Reproductive
ovaries produce estrogens and progesterone
testes produce testosterone
placenta produces estrogens, progesterone, and gonadotropins

39. Stress
Types of Stress
physical stress
psychological stress

40. Responses to Stress

41. Life-Span Changes endocrine glands decrease in size
muscular strength decreases as GH levels decrease
ADH levels increase due to slower break down in liver and kidneys
calcitonin levels decrease; increase risk of osteoporosis
PTH level changes contribute to risk of osteoporosis
insulin resistance may develop
changes in melatonin secretion affect the body clock
thymosin production declines increasing risk of infections

42. Clinical Application Growth Hormone Ups and Downs
Gigantism - hypersecretion of GH in children
Acromegaly – hypersecretion of GH in adults
Dwarfism – hyposecretion of GH in children
Figure shows oversecretion of GH in adulthood as changes occur in the same person at ages (a) nine, (b) sixteen, (c) thirty-three, and (4) fifty-two