1. The Endocrine System
Human Physiology

2. Endocrine Functions: Hormones
Come from endocrine glands
Circulate in the blood stream
Act on specific cells in the body

3. Endocrine System Characteristics
Access to every cell
Each hormone acts only on specific cells (target cells)
Only specific cells have receptors for specific hormones
Endocrine control slower than nervous system
Endocrine and nervous systems interact

4. Steroid Hormone Action on a Target Cell
Figure 13.2

5. Classification of Hormones: Steroid
Steroid Hormones:
Lipid soluble, chemically derived from cholesterol
Enter target cells
Activate specific genes to produce specific proteins
Slower acting than nonsteroid hormones, minutes to hours

6. Nonsteroid Hormone Action on a Target Cell
Figure 13.3

7. Classification of Hormones: Nonsteroid
Nonsteroid hormones:
Water soluble
Bind to receptors on target cell membranes
Work through intermediate mechanisms to activate existing enzymes
Faster action than steroid hormones, seconds to minutes

8. Example of a Negative Feedback Loop:
Homeostasis

9. Location of Major Endrocrine Organs
Figure 9.3
Slide 9.14
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

10. Hormones of the Pituitary Gland
Table 13.1

11. Hypothalamus and the Anterior Pituitary Gland
Figure 13.7

12. Hypothalamus and the Anterior Pituitary Gland
Connection to hypothalamus: releasing and inhibiting hormones from hypothalamus travel to pituitary through pituitary portal system
Hormones
ACTH: stimulates adrenal cortex
TSH: acts on thyroid gland
FSH, LH, Prolactin: related to control of reproductive cycles and lactation
Growth Hormone: widespread effects on body

13. Hypothalamus and the Posterior Pituitary Gland
Connection to hypothalamus: hormones made in hypothalamus, stored in posterior pituitary
Hormones: nonsteroidal
Antidiuretic hormone (ADH): conserves water in kidneys, regulates water balance in body
Oxytocin: causes uterine contractions during labor and milk ejection through neuroendocrine reflex

14. Pituitary Disorders Gigantism: hypersecretion of growth hormone
Pituitary Dwarfism: hyposecretion of growth hormone

15. Pituitary Gigantism

16. Pancreas: Endocrine Functions
Structures: islets of Langerhans
Hormones: nonsteroidal
Glucagon: made by alpha cells, raises blood sugar
Insulin: made by beta cells, lowers blood sugar

17. Location of Major Endrocrine Organs
Figure 9.3
Slide 9.14
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

18. Roles of Insulin and Glucagon in Regulating Blood Glucose
Figure 13.9

19. Location of Major Endrocrine Organs
Figure 9.3
Slide 9.14
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

20. Adrenal Glands: Cortex
Adrenal cortex
Secretion: mediated through hypothalamus-pituitary secretions
Hormones: steroidal
Glucocorticoids: cortisol – blood glucose regulation
Mineralocorticoids: aldosterone – sodium/fluid/urine

21. Secretion of Cortisol
Figure 13.10

22. Adrenal Glands: Medulla
Adrenal medulla: neuroendocrine organ
Secretion: sympathetic nervous system
Hormones: nonsteroidal
Epinephrine and Norepinephrine: enhance function of sympathetic nervous system (Fight or flight)

23. Roles of the Hypothalamus and Adrenal Glands in the Stress Response
Figure 9.12
Slide 9.31
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

24. Thyroid Gland
Secretion: mediated through hypothalamus-pituitary secretions
Steroidal hormones:
Thyroxine (T4) and Triiodothyronine (T3): both regulate production of ATP from glucose, affects metabolic rate
Calcitonin: lowers blood calcium levels

25. Negative Feedback Control of Thyroxine Secretion
Figure 13.13

26. Homeostatic Regulation of Blood Calcium Concentration
Figure 13.15A

27. Homeostatic Regulation of Blood Calcium Concentration (cont.)
Figure 13.15B

28. Parathyroid Glands Secretion: response to lowered blood calcium levels
Hormone: Parathyroid hormone (PTH), nonsteroidal
Removes calcium and phosphate from bone
Increases absorption of calcium by the digestive tract
Increases renal retention of calcium and excretion of phosphate

29. Location of Major Endrocrine Organs
Figure 9.3
Slide 9.14
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

30. Testes Hormone: testosterone (steroidal) Functions:
Regulates development and normal functioning of sperm, male reproductive organs, male sex drive
Development of male secondary sex characteristics

31. Ovaries Hormones (steroidal) and functions:
Estrogen: initiates development of secondary sex characteristics, regulates menstrual cycle
Progesterone: regulates menstrual cycle

32. Ovarian Cycle
Figure 16.6

34. Disorders of the Endocrine System
Thyroid
Hypothyroidism:
Children: cretinism
Adults: myxedema
Hyperthyroidism: Graves Disease
Adrenal glands
Addison’s Disease: failure of adrenal cortex, cortisol deficiency
Cushing’s Syndrome: excessive cortisol

36. Grave’s Disease – overactive thyroid