1. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 45 Hormones and the Endocrine System

2. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Learning Target: 1.Distinguish between the following pairs of terms: hormones and local regulators, paracrine and autocrine signals 2.Describe the evidence that steroid hormones have intracellular receptors, while water-soluble hormones have cell-surface receptors 3.Explain how the antagonistic hormones insulin and glucagon regulate carbohydrate metabolism 4.Distinguish between type 1 and type 2 diabetes

3. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 5.Explain how the hypothalamus and the pituitary glands interact and how they coordinate the endocrine system Learning Target:

4. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 1.The endocrine system secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy metabolism, growth, and behavior 2.The nervous system conveys high-speed electrical signals along specialized cells called neurons; these signals regulate other cells 2 systems coordinate communication throughout the body

5. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Hormones and other signaling molecules bind to target receptors, triggering specific response pathways Chemical signals bind to receptor proteins on target cells Only target cells respond to the signal

6. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Types of Secreted Signaling Molecules 1.Hormones 2.Local regulators 3.Neurotransmitters 4.Neurohormones 5.Pheromones

7. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 1. Hormones are secreted into extracellular fluids and travel via the bloodstream mediate responses to environmental stimuli and regulate growth, development, and reproduction Endocrine glands are ductless and secrete hormones directly into surrounding fluid Exocrine glands have ducts and secrete substances onto body surfaces or into body cavities (for example, tear ducts)

8. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 2. Local Regulators are chemical signals that travel over short distances by diffusion help regulate blood pressure, nervous system function, and reproduction divided into two types – Paracrine signals act on cells near the secreting cell – Autocrine signals act on the secreting cell itself

9. Blood vessel Response Endocrine signaling Paracrine signaling Autocrine signaling

10. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 3. Neurotransmitters and 4. Neurohormones Neurons contact target cells at synapses – secrete chemical signals called neurotransmitters that diffuse a short distance to bind to receptors and play a role in sensation, memory, cognition, and movement Neurohormones are a class of hormones that originate from neurons in the brain and diffuse through the bloodstream

11. Response Synaptic signaling Neuron Neurosecretory cell Neuroendocrine signaling Blood vessel Synapse Response

12. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 5. Pheromones are chemical signals that are released from the body and used to communicate with other individuals in the species mark trails to food sources, warn of predators, and attract potential mates

13. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Chemical Classes of Hormones Three major classes of molecules function as hormones in vertebrates: 1.Polypeptides (proteins and peptides) 2.Amines derived from amino acids 3.Steroid hormones

14. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Lipid-soluble hormones (steroid hormones) pass easily through cell membranes, while water-soluble hormones (polypeptides and amines) do not The solubility of a hormone correlates with the location of receptors inside or on the surface of target cells

15. Water-soluble Lipid-soluble Steroid: Cortisol Polypeptide: Insulin Amine: Epinephrine Amine: Thyroxine 0.8 nm

16. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cellular Response Pathways Water and lipid soluble hormones differ in their paths through a body Water-soluble hormones are secreted by exocytosis, travel freely in the bloodstream, and bind to cell-surface receptors Lipid-soluble hormones diffuse across cell membranes, travel in the bloodstream bound to transport proteins, and diffuse through the membrane of target cells

17. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings – Reception – Signal transduction – Response Signaling by any of these hormones involves three key events:

18. Signal receptor TARGET CELL Signal receptor Transport protein Water- soluble hormone Fat-soluble hormone Gene regulation Cytoplasmic response Gene regulation Cytoplasmic response OR (a) NUCLEUS (b)

19. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Pathway for Water-Soluble Hormones Binding of a hormone to its receptor initiates a signal transduction pathway leading to responses in the cytoplasm, enzyme activation, or a change in gene expression Animation: Water-Soluble Hormone Animation: Water-Soluble Hormone

20. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings has multiple effects in mediating the body’s response to short-term stress binds to receptors on the plasma membrane of liver cells – This triggers the release of messenger molecules that activate enzymes and result in the release of glucose into the bloodstream The hormone epinephrine

21. cAMP Second messenger Adenylyl cyclase G protein-coupled receptor ATP GTP G protein Epinephrine Inhibition of glycogen synthesis Promotion of glycogen breakdown Protein kinase A

22. Hormone (estradiol) Hormone-receptor complex Plasma membrane Estradiol (estrogen) receptor DNA Vitellogenin mRNA for vitellogenin

23. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Multiple Effects of Hormones The same hormone may have different effects on target cells that have – Different receptors for the hormone – Different signal transduction pathways – Different proteins for carrying out the response A hormone can also have different effects in different species

24. Glycogen deposits  receptor Vessel dilates. Epinephrine (a) Liver cell Epinephrine  receptor Glycogen breaks down and glucose is released. (b) Skeletal muscle blood vessel Same receptors but different intracellular proteins (not shown) Epinephrine  receptor Different receptors Epinephrine  receptor Vessel constricts. (c) Intestinal blood vessel

26. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Signaling by Local Regulators In paracrine signaling, nonhormonal chemical signals called local regulators elicit responses in nearby target cells Types of local regulators: – Cytokines and growth factors – Nitric oxide (NO) – Prostaglandins

27. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Prostaglandins help regulate aggregation of platelets, an early step in formation of blood clots

28. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Negative feedback and antagonistic hormone pairs are common features of the endocrine system Hormones are assembled into regulatory pathways

29. Major endocrine glands: Adrenal glands Hypothalamus Pineal gland Pituitary gland Thyroid gland Parathyroid glands Pancreas Kidney Ovaries Testes Organs containing endocrine cells: Thymus Heart Liver Stomach Kidney Small intestine

30. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Simple Hormone Pathways Hormones are released from an endocrine cell, travel through the bloodstream, and interact with the receptor or a target cell to cause a physiological response

31. PathwayExample StimulusLow pH in duodenum S cells of duodenum secrete secretin ( ) Endocrine cell Blood vessel Pancreas Target cells Response Bicarbonate release Negative feedback –

32. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings inhibits a response by reducing the initial stimulus Negative feedback regulates many hormonal pathways involved in homeostasis A negative feedback loop

33. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Insulin and Glucagon: Control of Blood Glucose Insulin and glucagon are antagonistic hormones that help maintain glucose homeostasis The pancreas has clusters of endocrine cells called islets of Langerhans with alpha cells that produce glucagon and beta cells that produce insulin

34. Homeostasis: Blood glucose level (about 90 mg/100 mL) Insulin Beta cells of pancreas release insulin into the blood. STIMULUS: Blood glucose level rises.

35. Homeostasis: Blood glucose level (about 90 mg/100 mL) Insulin Beta cells of pancreas release insulin into the blood. STIMULUS: Blood glucose level rises. Liver takes up glucose and stores it as glycogen. Blood glucose level declines. Body cells take up more glucose.

36. Homeostasis: Blood glucose level (about 90 mg/100 mL) Glucagon STIMULUS: Blood glucose level falls. Alpha cells of pancreas release glucagon.

37. Homeostasis: Blood glucose level (about 90 mg/100 mL) Glucagon STIMULUS: Blood glucose level falls. Alpha cells of pancreas release glucagon. Liver breaks down glycogen and releases glucose. Blood glucose level rises.

38. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Target Tissues for Insulin and Glucagon Insulin reduces blood glucose levels by – Promoting the cellular uptake of glucose – Slowing glycogen breakdown in the liver – Promoting fat storage

39. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Glucagon increases blood glucose levels by – Stimulating conversion of glycogen to glucose in the liver – Stimulating breakdown of fat and protein into glucose Target Tissues for Insulin and Glucagon

40. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Diabetes Mellitus is perhaps the best-known endocrine disorder is caused by a deficiency of insulin or a decreased response to insulin in target tissues is marked by elevated blood glucose levels

41. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Type I (insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells Type II (non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors Diabetes Mellitus

42. The secretion of hormone A causes a change in the amount of protein X in an organism. If this mechanism works by positive feedback, which of the following statements represents that fact? A) An increase in A produces an increase in X. B) An increase in X produces a decrease in A. C) A decrease in A produces an increase in X. D) A and B are correct. E) B and C are correct.

43. The secretion of hormone A causes a change in the amount of protein X in an organism. If this mechanism works by positive feedback, which of the following statements represents that fact? A)An increase in A produces an increase in X. B) An increase in X produces a decrease in A. C) A decrease in A produces an increase in X. D) A and B are correct. E) B and C are correct.

44. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Which of the following statements about hormones is incorrect? A) Glands that produce them are ductless glands. B) They are produced only by organs called endocrine organs. C) Some are water soluble and some are not. D) They often maintain steady-state conditions. E) They may turn genes off or on.

45. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Which of the following statements about hormones is incorrect? A) Glands that produce them are ductless glands. B) They are produced only by organs called endocrine organs. C) Some are water soluble and some are not. D) They often maintain steady-state conditions. E) They may turn genes off or on.

46. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Which of the following statements about hormones that promote homeostasis is incorrect? A) A stimulus causes an endocrine cell to secrete a particular hormone. B) The hormone travels in the bloodstream to target cells. C) Specific receptors bind with the hormone. D) Signal transduction brings about a response in the target cell. E) This response feeds back to promote the release of more hormone. Answer: E

47. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Which of the following statements about hormones that promote homeostasis is incorrect? A) A stimulus causes an endocrine cell to secrete a particular hormone. B) The hormone travels in the bloodstream to target cells. C) Specific receptors bind with the hormone. D) Signal transduction brings about a response in the target cell. E) This response feeds back to promote the release of more hormone.

48. Blood samples taken from an individual who had been fasting for 24 hours would have which of the following? A) high levels of insulin B) high levels of glucagon C) low levels of insulin D) low levels of glucagon E) both B and C

49. Blood samples taken from an individual who had been fasting for 24 hours would have which of the following? A) high levels of insulin B) high levels of glucagon C) low levels of insulin D) low levels of glucagon E) both B and C