1. Chapter 47
Endocrine Regulation

2. The endocrine system
Endocrine glands, cells, and tissues that secrete hormones
Hormones are an important type of chemical signal by which cells communicate
Secreted into the interstitial fluid and typically transported by the blood
Bind with receptors or in specific target cells

3. Some types of endocrine signaling

4. Four main chemical groups
Fatty acid derivatives
Prostaglandins and the juvenile hormone of insects
Steroids
Secreted by the adrenal cortex, ovary, and testis, as well as the molting hormone of insects

5. Four main chemical groups, cont.
Amino acid derivatives
Thyroid hormones and epinephrine
Peptides or proteins
ADH and glucagon are peptide hormones
Insulin is a small protein

6. Major chemical groups of hormones

7. Hormone secretion Typically regulated by negative feedback mechanisms
Hormone is released in response to some change in a steady state
Triggers a response that counteracts the changed condition
This process restores homeostasis

8. Regulation by negative feedback

9. Steroid and thyroid hormones
Hydrophic molecules
Pass through the plasma membrane
Combine with receptors within the target cell
The hormone-receptor complex may activate or repress transcription of messenger RNA coding for specific proteins

10. Mechanism of action of steroid hormones

11. Peptide hormones are hydrophillic and do not enter target cells
Combine with receptors on the plasma membrane of target cells
Many hormones bind to G protein-linked receptors
Act via signal transduction

12. Overview of peptide hormone action

13. Mechanism of action of hormones that use G protein-linked receptors and second messengers

14. Most peptide hormones are first messengers
Carry out their actions by way of second messengers
Cyclic AMP (cAMP)
Calcium ions

15. Phospholipid products as second messengers

16. Inositol trisphosphat (IP3) and diacylglycerol (DAG)
Second messengers that
Increase calcium concentration
Activate enzymes

17. Receptor tyrosine kinases
Enzyme-lined receptors
Bind growth factors, including insulin and nerve growth factors

18. Signal amplification
Occurs as each hormone-receptor complex stimulates the production of second messenger molecules
Second messengers activate protein kinase molecules that activate protein molecules

19. Four functions of hormones in invertebrates
Neurohormones secreted by neurons rather than endocrine glands

20. Four functions of hormones in invertebrates, cont.
Help regulate
Metabolism
Growth and development
Regeneration
Molting
Metamorphosis
Reproduction and behavior

21. Regulation of growth and molting in insects

22. Human endocrine glands

23. Some endocrine glands and their hormones

24. Consequences of endocrine malfunction

25. Nervous and endocrine regulation
Integrated in the hypothalamus, which regulates the pituitary gland

26. Oxytocin and ADH Produced by the hypothalamus
Released by the posterior lobe of the pituitary

27. Hypothalamus Secretes
Releasing hormones
Inhibiting hormones
These regulate the hormone output of the anterior lobe of the pituitary

28. Anterior lobe of the pituitary
Secretes the growth hormone, prolactin
Several tropic hormones that stimulate other endocrine glands

29. The hypothalamus regulates the anterior lobe of the pituitary gland

30. Growth hormone (GH) Anabolic hormone that stimulates body growth
Stimulates the liver to produce insulin-like growth factors (IGFs), which promote skeletal and tissue growth

31. Thyroid gland Secretes Stimulate the rate of metabolism Thyroxine
Triiodothyronine
Stimulate the rate of metabolism

32. Regulation of thyroid secretion
Depends mainly on a negative feedback system
Anterior pituitary gland
Thyroid gland

33. Thyroid hyposecretion
Childhood cretinism
Adult myxedema
Thyroid hypersecretion
Most common cause is Grave’s disease
Goiter associated with both hyposecretion and hypersecretion

34. Regulation of thyroid secretion by negative feedback

35. Calcitonin, secreted by the thyroid, acts antagonistically to PTH
Parathyroid glands
Secrete PTH
Regulates calcium level in the blood
Stimulates calcium release from bones
Calcitonin, secreted by the thyroid, acts antagonistically to PTH

36. Regulation of calcium homeostasis by PTH and calcitonin

37. Islets of Langerhans Secrete insulin Secrete glucagon
Stimulates cells to take up glucose and so lowers blood glucose
Secrete glucagon
Raises blood glucose concentration
Diabetes mellitus
Results in decreased use of glucose

38. Islets of Langerhans

39. Adrenal glands Secrete hormones that help the body cope with stress
Adrenal medulla secretes
Epinephrine
Norepinephrine
Adrenal cortex secretes
Sex hormones

40. Adrenal gland

41. Response to stress