1. Endocrine & Cell Communication Part I: Introduction to Communication

2. How does a cell communicate? He uses a cell phone. HA HA HA

3. Why do cells need to communicate? Here are a few reasons: – Coordinate activities in multicellular organisms – Hormone actions – Cell recognition – To find mates (yeast cells) – Turn pathways on/off – apoptosis 3

4. Evolutionary ties of cell communication Cell-to-cell communication is everywhere in biological systems from Archaea and bacteria to multicellular organisms. The basic chemical processes of communication are shared across evolutionary lines of descent. Signal transduction is an excellent example 4

5. Chemical Communication Outside the body Ex. Pheromones Ex. Quorum sensing Inside the body Short Distance Long Distance 5

6. Pheromones 6 Members of the same animal species sometimes communicate with pheromones, chemicals that are released into the environment. Pheromones serve many functions, including marking trails leading to food, defining territories, warning of predators, and attracting potential mates. Here’s an example of a termite following a “manmade” trail: http://edutube.org/en/video/termites- and-pheromones-ink-trails http://edutube.org/en/video/termites- and-pheromones-ink-trails

7. Quorum sensing Quorum sensing in bacteria – single celled bacteria monitor their environment by producing, releasing and detecting hormone- like molecules called autoinducers. 7

8. Direct Contact Communication Ex. Plant cells communicate directly through openings called plasmodesmata. 8

9. Short Distance Communication Paracrine signals diffuse to and affect nearby cells – Ex. Neurotransmitters – Ex. Prostaglandins 9

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

11. Autocrine signals These chemicals affect the same cells that release them. – Ex. Interleukin-1 produced by monocytes and can bind to receptors on the same monocyte. – Tumor cells reproduce uncontrollably because they self-stimulate cell division by making their own division signals. 11

12. Long Distance Communication Endocrine hormones via signal transduction pathway: 12

13. Hormones Endocrine glands produce hormones which are – Chemical signals – Transported in tissue fluids – Detected only by target cells 13

14. Review of Body Signaling 14

15. Communication Features Secreting cell - releases the signal Signal = chemical = ligand Receptor - accepts and temporarily joins with the ligand forming receptor/ligand complex Target cell – contains the receptor 15

16. Apply the features Insulin is secreted by beta cells of the pancreas. Once secreted, insulin travels around the body. When insulin docks with an integral protein on the membrane of a muscle cell, glucose can enter the cell. What is the secreting cell, the target cell, ligand, and the receptor? 16

17. To trust or not to trust? Ask Oxytocin Some people trust others easily while others require additional time to decide if a person is trustworthy. A recent article in Scientific American indicates that the hormone oxytocin known for its role in social attachment and interaction may also play an important role in our ability to trust. 17

18. Endocrine System The human endocrine system is composed of a collection of glands that secrete a variety of hormones. These chemicals use long distance communication to control the daily functioning of the cells of the body. 18

19. Endocrine System The endocrine system produces more than 30 different chemicals used by your body to maintain homeostasis and promote normal body function. This system contains 9 primary glands as well as endocrine cells found within major organs. The endocrine system is a ductless system that employs the circulatory system when delivering chemical signals over long distances. 19

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21. The Endocrine System works with the Nervous System Two systems coordinate communication throughout the body: the endocrine system and the nervous system. The endocrine system secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy, metabolism, growth, and behavior. The nervous system conveys high-speed electrical signals along specialized cells called neurons; these signals regulate other cells.

22. Coordination of Endocrine and Nervous Systems in Vertebrates The hypothalamus receives information from the nervous system and initiates responses through the endocrine system. Attached to the hypothalamus is the pituitary gland, composed of the anterior pituitary and the posterior pituitary. The anterior pituitary makes and releases hormones under regulation of the hypothalamus. The posterior pituitary stores and secretes hormones that are made in the hypothalamus. © 2011 Pearson Education, Inc.

23. Anterior and Posterior Pituitary © 2011 Pearson Education, Inc.

24. Posterior Pituitary Hormones The two hormones released from the posterior pituitary act directly on nonendocrine tissues. – Oxytocin regulates milk secretion by the mammary glands and stimulates contraction of the uterus. – Antidiuretic hormone (ADH) promotes retention of water by the kidneys.

25. Neurosecretory cells of the hypothalamus Neurohormone Posterior pituitary Hypothalamus Axons Anterior pituitary HORMONE TARGET ADHOxytocin Kidney tubules Mammary glands, uterine muscles Production and Release of Posterior Pituitary Hormones

26. Anterior Pituitary Hormones Hormone production in the anterior pituitary is controlled by releasing and inhibiting hormones from the hypothalamus. For example, prolactin-releasing hormone from the hypothalamus stimulates the anterior pituitary to secrete prolactin (PRL), which has a role in milk production and secretion. Another example is Thyroid Stimulating Hormone (TSH), which stimulates the thyroid gland to produce thyroxine which stimulates and maintains metabolic processes.

27. Tropic effects only: FSH LH TSH ACTH Nontropic effects only: Prolactin MSH Nontropic and tropic effects: GH Hypothalamic releasing and inhibiting hormones Posterior pituitary Neurosecretory cells of the hypothalamus Portal vessels Endocrine cells of the anterior pituitary Pituitary hormones HORMONEFSH and LHTSH ACTH ProlactinMSHGH TARGETThyroidMelanocytesTestes or ovaries Adrenal cortex Mammary glands Liver, bones, other tissues Figure 45.16

28. Table 45.1a

29. Table 45.1b

30. Thyroid Regulation: A Hormone Cascade Pathway A hormone can stimulate the release of a series of other hormones, the last of which activates a nonendocrine target cell; this is called a hormone cascade pathway. The release of thyroid hormone results from a hormone cascade pathway involving the hypothalamus, anterior pituitary, and thyroid gland. Hormone cascade pathways typically involve negative feedback.

31. Simple Hormone Pathways and Homeostasis Hormones are released from an endocrine cell, travel through the bloodstream, and interact with specific receptors within a target cell to cause a physiological response

32. For example, the release of acidic contents of the stomach into the duodenum stimulates endocrine cells there to secrete secretin. This causes target cells in the pancreas, a gland behind the stomach, to raise the pH in the duodenum. The increased pH results in a decrease of secretin secretion. Simple Hormone Pathways

33. Pathway Example Stimulus Low pH in duodenum Endocrine cell S cells of duodenum secrete the hormone secretin ( ). Hormone Blood vessel Target cells Pancreas Response Bicarbonate release Negative feedback Simple Hormone Pathways

34. A negative feedback loop inhibits a response by reducing the initial stimulus, thus preventing excessive pathway activity. Positive feedback reinforces a stimulus to produce an even greater response. For example, in mammals oxytocin causes the release of milk, causing greater suckling by offspring, which stimulates the release of more oxytocin. Feedback Regulation

35. An example of positive feedback 35

36. Insulin and Glucagon: Control of Blood Glucose Hormones work in pairs to maintain homeostasis. Insulin (decreases blood glucose) and glucagon (increases blood glucose) are antagonistic hormones that help maintain glucose homeostasis. The pancreas has clusters of endocrine cells called pancreatic islets with alpha cells that produce glucagon and beta cells that produce insulin.

37. Body cells take up more glucose. Insulin Beta cells of pancreas release insulin into the blood. Liver takes up glucose and stores it as glycogen. Blood glucose level declines. Blood glucose level rises. Homeostasis: Blood glucose level (70–110 mg/100mL) STIMULUS: Blood glucose level rises (for instance, after eating a carbohydrate-rich meal). Liver breaks down glycogen and releases glucose into the blood. Alpha cells of pancreas release glucagon into the blood. Glucagon STIMULUS: Blood glucose level falls (for instance, after skipping a meal). Figure 45.13

38. Out of Balance: Diabetes Mellitus Diabetes mellitus is perhaps the best-known endocrine disorder. It is caused by a deficiency of insulin or a decreased response to insulin in target tissues. It is marked by elevated blood glucose levels.

39. Homeostasis in blood calcium levels PTH increases the level of blood Ca 2+ – It releases Ca 2+ from bone and stimulates reabsorption of Ca 2+ in the kidneys. – It also has an indirect effect, stimulating the kidneys to activate vitamin D, which promotes intestinal uptake of Ca 2+ from food. Calcitonin decreases the level of blood Ca 2+ – It stimulates Ca 2+ deposition in bones and secretion by kidneys.

40. The Process of Communication: Signal-Transduction Pathway Three stages of the Signal- Transduction Pathway 1. reception 2. transduction 3. response

41. Typical Signal Transduction Pathway

42. Ligand = Chemical Messenger Three major classes of molecules function as hormones in vertebrates (ligands) – Polypeptides (proteins and peptides) – Amines derived from amino acids – Steroid hormones 42

43. Phase 1: Reception The target cell detects the ligand Membrane proteins – G-protein linked receptors – Ion channel receptors – Tyrosine Kinase Intracellular receptor – Steroid hormone receptors

44. Types of Receptors 44 +

45. Type of Receptor : G-protein linked

46. Type of Receptor: Ion Channel

48. Type of Receptor: Intracellular Receptor

49. Transduction Binding changes the receptor protein. Can set off a cascade reaction

50. Response Set any of a variety of cell activities in motion. – Activation of an enzyme – Rearrangement of cytoskeleton features – Activation of a specific gene

51. 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

52. Lipid- soluble hormone SECRETORY CELL Water- soluble hormone VIA BLOOD Signal receptor TARGET CELL (a) (b) Signal receptor Transport protein NUCLEUS

53. Lipid- soluble hormone SECRETORY CELL Water- soluble hormone VIA BLOOD Signal receptor TARGET CELL OR Cytoplasmic response Gene regulation (a) (b) Cytoplasmic response Gene regulation Signal receptor Transport protein NUCLEUS

54. 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

55. Specific Example Notice the presence of the second messenger Click here to view the animation

56. Pathway for Lipid-Soluble Hormones The response to a lipid-soluble hormone is usually a change in gene expression Steroids, thyroid hormones, and the hormonal form of vitamin D enter target cells and bind to protein receptors in the cytoplasm or nucleus Protein-receptor complexes then act as transcription factors in the nucleus, regulating transcription of specific genes

57. Steroid Hormone Example: Testosterone

59. Compare protein and steroid hormones by completing this T chart CharacteristicProtein HormoneSteroid Hormone Speed of response Primary biomolecule composition Method of leaving secretory cell Location of receptor Example 59

60. Compare protein and steroid hormones by completing this T chart CharacteristicProtein HormoneSteroid Hormone Speed of responseRapid response, cascadeResponse is slower, gene expression Primary biomolecule composition Amino acidcholesterol Method of leaving secretory cell Exocytosisdiffusion Location of receptorMembrane boundIntracellular ExampleEpinephrineTestosterone 60

61. 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

62. The hormone epinephrine has multiple effects in mediating the body’s response to short-term stress Epinephrine 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 Multiple Effects of Hormones

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

64. Did you know… One reason that kittens sleep so much is because a growth hormone is released only during sleep. The levels of two stress hormones, cortisol and epinephrine which suppress the body's immune system, will actually drop after a dose of laughter. Chocolate is associated with the release of serotonin, the hormone that makes you feel relaxed, calm, and happy. So are hugs.