1. 1 Endocrine Control Chapter 32

2. 2 Sex and Society Jane Goodall’s observations of chimps in Tanzania showed that sex is a major binding force in their social life Females use their sexual attractiveness to build alliances with high-ranking males

3. 3 Advertising Availability When a female chimp nears the fertile part of her cycle, her external sexual organs become swollen and vivid pink The change is induced by hormones

4. 4 An Orchestra of Hormones Hormones influence the growth, development, and reproductive cycles of nearly all animals They influence behavior, physical appearance, and well-being

5. 5 Hormones Secreted by endocrine glands, endocrine cells, and certain neurons Animal hormones travel through the bloodstream to nonadjacent target cells

6. 6 Other Signaling Molecules Neurotransmitters Local signaling molecules Pheromones

7. 7 Discovery of Hormones (1) Bayliss and Starling wanted to know what triggers secretion of pancreatic juices into canine gut Was it nerves or something else? Severed nerves to dog’s upper intestine; left blood vessels intact

8. 8 Discovery of Hormones (2) Results - Even with nerves severed, pancreas still secreted alkaline solution into intestine Conclusion - The nervous system was not stimulating the pancreatic response, some other substance was the trigger

9. 9 Endocrine System Main Sources Pituitary gland Adrenal glands Thyroid gland Parathyroid glands Pineal gland Thymus gland

10. 10 Responses to Hormones Vary Different hormones activate different responses in the same target cell Not all types of cells respond to a particular hormone

11. 11 Two Main Hormone Types Steroid hormones –Derived from cholesterol –Estrogens, progestins, androgens (such as testosterone), cortisol, aldosterone Peptide hormones –Peptides, proteins, or glycoproteins –Glucagon, ADH, oxytocin, TRH, insulin, somatotropin, prolactin, FSH, LH, TSH

12. 12 Steroid Hormone Action Most diffuse across the plasma membrane and bind to a receptor Hormone-receptor complex acts in nucleus to inhibit or enhance transcription

13. 13 Steroid Hormones receptor hormone-receptor complex gene product hormone Most diffuse across the plasma membrane and bind to a receptor Hormone-receptor complex acts in nucleus to inhibit or enhance transcription

14. 14 Protein Hormone Hormone binds to a receptor at cell surface Binding triggers a change in activity of enzymes inside the cell glucagon receptor cyclic AMP+ P i ATP cAMP activates protein kinase A glucagon Protein kinase A converts phosphorylase kinase to active form and inhibits an enzyme required for glucagon synthesis.

15. 15 The Hypothalamus Region in the forebrain Contains hormone-secreting cells Interacts with pituitary hypothalamus pituitary gland

16. 16 Pituitary Gland Pea-size gland at base of hypothalamus Two lobes –Posterior lobe stores and secretes hormones that were synthesized in the hypothalamus –Anterior lobe produces and secretes its own hormones

17. 17 Posterior Lobe Antidiuretic hormone (ADH ) Oxytocin (OCT) cell body in hypothalmus axons to the general circulation

18. 18 Anterior Pituitary ACTH TSH FSH LH PRL STH

19. 19 Normal Hormone Production Generally, the body produces only very small amounts of hormones To isolate 1 milligram of TRH, researchers dissected 7 metric tons of hypothalamic tissue

20. 20 Abnormal Somatotropin Output Gigantism results from overproduction of STH during childhood Pituitary dwarfism results from underproduction of STH during childhood Acromegaly results from overproduction of STH during adulthood

21. 21 Effects and Control of Hormone Secretion Hormones often interact Negative feedback mechanisms often control secretion Environmental cues may mediate secretion

22. 22 Feedback Mechanisms Negative feedback –An increase in concentration of a hormone triggers activities that inhibit further secretion Positive feedback –An increase in concentration of a hormone triggers activities that stimulate further secretion

23. 23 Control of Cortisol Secretion (1) Hypothalamus senses decline in glucose and secretes a releasing hormone (CRH) CRH stimulates anterior pituitary to secrete ACTH ACTH acts on the adrenal cortex to stimulate cortisol secretion

24. 24 Control of Cortisol Secretion (2) Cortisol secretion –Inhibits blood glucose uptake by muscle and other tissues –Causes breakdown of proteins to amino acids and conversion to glucose –Causes degradation of adipose tissue to fatty acids for use as energy source

25. 25 Control of Cortisol Secretion (3) Decrease in glucose uptake and release of glucose from protein breakdown causes blood glucose level to rise Hypothalamus and anterior pituitary detect the increase and decrease secretion of CRH and ACTH Adrenal cortex decreases cortisol secretion

26. 26 Localized Feedback in Adrenal Medulla Norepinephrine secreted by neurons in the medulla accumulates in the synaptic gap Some molecules bind to receptors on the axon endings that secreted them This prevents further secretion of norepinephrine by that axon

27. 27 Thyroid Gland Disorders Goiter Hyperthyroidism Hypothyroidism

28. 28 Feedback Control of Ovaries Pituitary produces hormones (LH, FSH) that stimulate egg maturation and ovulation in the ovary They also stimulate ovary to produce progesterone and estrogen After ovulation, rising levels of these hormones inhibit further secretion of LH and FSH

29. 29 Calcium Regulation Parathyroid hormone (PTH) is the main regulator of calcium in the blood It is secreted when calcium levels drop PTH causes bone cells to digest bone tissue and release calcium PTH also stimulates calcium reabsorption by the kidneys and absorption by the gut

30. 30 Local Signaling Molecules Prostaglandins –Produced and secreted in response to local changes –Sixteen types with a variety of effects Growth factors –Affect cell division rates in tissues

31. 31 Control of Glucose Metabolism insulin Glucose rises Glucose falls Glucose is absorbed Cells use glucose glucagon Glycogen to glucose Glucose uptake Glucose to glycogen

32. 32 Diabetes Mellitis Disease in which excess glucose accumulates in blood, then urine Effects include –Excessive urination –Constant thirst –Weight loss –Ketone formation and acid-base imbalances

33. 33 Two Types of Diabetes Type 1 Autoimmune disease Usually appears in childhood Treated with insulin injections Type 2 Target cells don’t respond Usually appears in adults Treated with diet, drugs

34. 34 The Pineal Gland Photosensitive gland embedded in brain In the absence of light, secretes melatonin Controls seasonal sexual behavior in many animals Affects the human biological clock May also play a role in human puberty and in seasonal affective disorder

35. 35 Deformed Frogs The number of deformed frogs is increasing worldwide One factor may be water pollutants that interfere with thyroid function In one study, frogs from polluted water developed normally when they were given extra thyroid hormones

36. 36 Control of Molting In arthropods, molting is controlled by the steroid hormone ecdysone In crustaceans, molting glands produce and store this hormone Hormone-secreting neurons control its release The neurons respond to environmental cues

37. 37 Control of Molting absence of suitable stimulus hormone-secreting neurons of X organ produce, release molt-inhibiting hormone (MIH) MIH stored in sinus gland, then released into blood MIH stops cells in Y organ, an endocrine gland located near mouthparts or at base of antennae, from producing ecdysone Y organ is free to produce ecdysone Signals inhibit MIH production in C organ; MIH level in blood drops brain regions suitable internal signals suitable environmental cues MOLTING STIMULATEDMOLTING INHIBITED