Chp.45: Hormones & the Endocrine System (review: Chp.11 Cell Communication)

1. Chp.45: Hormones & the Endocrine System(review: Chp.11 Cell Communication) AP Bio 3/14/13

2. Remember: • Why cells need to communicate: • Coordinate activities in multicellular organisms • Hormone actions • Cell recognition • To find mates (yeast cells) • Turn pathways on/off • apoptosis

3. 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. Signal Transduction Animation • Click on this link to access the animation: http://www.wiley.com/college/boyer/0470003790/animations/signal_transduction/signal_transduction.htm

5. Chemical Communication

6. Pheromones • 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.

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

8. Chemical Communication

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

10. Short Distance Communication • Paracrine signals diffuse to and affect nearby cells • Ex. Neurotransmitters • Ex. Prostaglandins

11. Neurotransmitters and Neurohormones Neuron Synapse Response Synaptic signaling Neurosecretorycell Bloodvessel Response Neuroendocrine signaling

12. 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.

13. Long Distance Communication • Endocrine hormones via signal transduction pathway:

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

15. Summary:

16. 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

17. 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?

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, maintain homeostasis, respond to environmental stimuli, and growth & development.

19. Endocrine System • The endocrine system produces more than 30 different chemicals used by your body to 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.

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 communicate regulatory info throughout body. • The nervous system uses neurons to transmit signals; these signals can regulate the release of hormones.

22. Table 45.1a

23. Table 45.1b

24. Example Figure 45.17 Pathway Stimulus Cold Sensory neuron  Hypothalamus Hypothalamus secretesthyrotropin-releasinghormone (TRH). Neurosecretory cell Releasing hormone Blood vessel  Anterior pituitary secretesthyroid-stimulatinghormone (TSH, also knownas thyrotropin). Anterior pituitary Tropic hormone Negative feedback Thyroid gland secretesthyroid hormone(T3 and T4). Endocrine cell Hormone Targetcells Body tissues Increased cellularmetabolism Response

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

26. Typical Signal Transduction Pathway

27. 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

28. 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

29. Type of Receptor: Ex- G-protein linked(Water soluble = polypeptides & amines, can’t pass cell membrane)

30. Type of Receptor: Intracellular Receptor (Lipid Soluble = Steroid Hormones, can pass cell membrane)

31. SECRETORYCELL Lipid-solublehormone Water-solublehormone VIABLOOD Transportprotein Signal receptor TARGETCELL OR Signalreceptor Cytoplasmicresponse Generegulation Cytoplasmicresponse Generegulation NUCLEUS (a) (b)

32. 3 2 1 Recap EXTRACELLULARFLUID CYTOPLASM Plasma membrane Response Reception Transduction Receptor Activationof cellularresponse Relay molecules in a signal transductionpathway Signalingmolecule

33. 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

34. Multiple Effects of Hormones • 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

36. (b) Skeletal muscleblood vessel (c) Intestinal bloodvessel Same receptors but differentintracellular proteins (not shown) Different receptors Different cellularresponses Different cellularresponses Epinephrine Epinephrine Epinephrine  receptor  receptor  receptor Glycogendeposits Vesseldilates. Vesselconstricts. Glycogenbreaks downand glucoseis releasedfrom cell. (a) Liver cell

37. 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.

38. Insulin Figure 45.13 Body cellstake up moreglucose. Beta cells ofpancreasrelease insulininto the blood. Liver takesup glucose and stores itas glycogen. STIMULUS:Blood glucose level rises (for instance, after eating acarbohydrate-rich meal). Blood glucoselevel declines. Homeostasis:Blood glucose level(70–110 mg/100mL) STIMULUS:Blood glucose level falls (for instance, afterskipping a meal). Blood glucoselevel rises. Liver breaksdown glycogenand releasesglucose intothe blood. Alpha cells of pancreasrelease glucagon intothe blood. Glucagon

39. 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.

40. Out of Balance: Diabetes Mellitus • Type 1 diabetes mellitus (insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells. • Type 2 diabetes mellitus (non-insulin-dependent) involves insulin deficiency or reduced response of target cells due to change in insulin receptors.

41. Insulin & Glucose Regulation

42. Endocrine System Summary Assignment • Copy the general Endocrine System Negative Feedback Summary (Fig.13.10) pg.479 • Then, create your own feedback summary for any other Hormone of the Endocrine System ***Bring Books MONDAY***