1. Endocrine & Cell Communication Part III: Hormonal Communication

2. Enduring Understanding 3.D Cells communicate by generating, transmitting and receiving chemical signals. EK 3D2: Cells communicate with each other through direct contact with other cells or from a distance via chemical signaling c. Signals released by one cell type can travel long distances to target cells of another cell types. 1. Endocrine signals are produced by endocrine cells that release signaling molecules, which are specific and can travel long distances through the blood to reach all parts of the body. 2

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

4. Typical Signal Transduction Pathway

5. 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 5

6. Ligands LIGAND: a molecule that binds to a larger molecule

7. Typical Signal Transduction Pathway

8. 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

9. Type of Receptor : G-protein linked

10. Type of Receptor: Ion Channel

12. Type of Receptor: Intracellular Receptor

14. Action of G-Protein Linked Receptor

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

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

18. Plasma membrane EXTRACELLULAR FLUID CYTOPLASM Reception Receptor Signaling molecule 1 Recap

19. Plasma membrane EXTRACELLULAR FLUID CYTOPLASM ReceptionTransduction Receptor Signaling molecule Relay molecules in a signal transduction pathway 2 1 Recap

20. Plasma membrane EXTRACELLULAR FLUID CYTOPLASM ReceptionTransduction Response Receptor Signaling molecule Activation of cellular response Relay molecules in a signal transduction pathway 3 2 1 Recap

22. Types of Receptors 22 +

23. Which is the receptor? G-Protein? Ligand?

24. Which Is A Receptor Through Which Ions Would Pass?

25. Which Of These Acts As A Second Messenger?

26. Lipid-soluble (hydrophobic)Water-soluble (hydrophilic) PolypeptidesSteroids 0.8 nm InsulinCortisol Amines EpinephrineThyroxine

27. 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

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

29. 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

30. 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

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

32. Pathway for Lipid-Soluble Hormones The response to a lipid-soluble hormone is usually a change in gene expression Steroids and thyroid hormones 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

33. Steroid Hormone Example: Testosterone

35. 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 35

36. 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 36

37. 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

38. 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

39. 39

40. 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)

41. 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.

42. Created by: Debra Richards Coordinator of Secondary Science Programs Bryan ISD Bryan, TX