The Endocrine System!

1. The Endocrine System! • Our hormones! • Chemical messengers of the BODY! • Help you to maintain Homeostasis! (constant internal environment) http://www.youtube.com/watch?v=-S_vQZDH9hY

2. Types of Glands: • Exocrine Gland – produces secretions that are released into tubular ducts • i.e., digestive system • Endocrine Gland – releases contents into blood stream and generally produces hormones

3. Purpose of the Endocrine System • Control and regulation of body functions • through the use of glands and hormones • Effects are slower than the nervous system, but tend to last longer

4. NS vs ES! • NS ES____________ • fast acting slower • short term long term (lingers) • neuron involved hitches a ride on • the circulatory system • Electrochemical Chemical comm. • Very Specific Less specific

6. Glands of the Endocrine System

7. How Homeostasis Works! • Homeostasis is the term used to denote the constancy of the body’s internal environment! • Human cells grow best under the following conditions: • glucose concentration is 80mg/dL • O2 & CO2 concentration are 100ml/L & 40 ml/L • pH is 7.4 • Na and K concentrations are 142 and 4mg/Lrespectively • Body temperature is 37 oC

9. Natural factors that disrupt Homeostasis include: • Increases or decreases in temperature • Excess intake or loss of fluids • Influx of nutrients or medications after swallowing (or fasting) • Stress • Fatigue

10. Homeostasis Sample! • Start on far left: It’s cold in here! • Turn up the thermostat • Furnace lights ‘er up • Room heats up and thermostat is satisfied • Furnace turns itself downuntil the next imbalance requires the above sequence to start over again! RU Ready?

11. Hormones • Two types: Protein (polypeptide) and steroid hormones • Target: Organs or cells. Cells with specific receptors to hormones (receptors combine with hormones in a lock-and-key fit) • Origin (Gland)  Blood Stream  Target  Message/Function

13. Steroid Hormones • Made from cholesterol (lipid) • Ex. Sex hormones • Not soluble in water, but are soluble in fat • Hormone diffuses through the cell membrane and attaches to a specific receptor molecule in the cytoplasm or nucleus • Hormone-receptor complex moves into the nucleus (bonds to DNA) and activates a specific gene • Gene sends a message to the ribosome and begins to produce a specific protein

15. Protein (Polypeptide) Hormone • Made from proteins (aa) • Activates existing enzymes in cells therefore rapid acting • Soluble in water but not fat • Ex, Insulin, hGH • Combines with specific receptors on the cell membrane • Results in production of cyclic AMP • Peptide hormone is the 1st messenger since it never enters the cell; c AMP is the 2nd messenger in the cytoplasm to carry out the function

17. How Hormones Communicate! • Hormones are chemicals & their regulation is unique. • If you increase production we call it  POSITIVE FEED BACK (rare) • Symbol +ve = Positive feedback • If your decrease production we call it  NEGATIVE FEEDBACK (common) • Symbol –ve = Negative feedback

18. Hormone A released (targets Gland B) Gland A Gland B Hormone B tells Gland A to keep releasing Hormone A Hormone B released (targets Gland A) Feedback Loops • Positive Feedback = reinforcing loop Is this good for homeostasis? +ve feedback is typical of disorders or periods of growth in the body.

19. Hormone A released (targets Gland B) Gland A Gland B Hormone B tells Gland A to stop releasing Hormone A Hormone B released (targets Gland A) Feedback Loops X • Negative Feedback = terminating loop Is this good for homeostasis? -ve feedback is typical for normal homeostatic regulation in the body. http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter46/positive_and_negative_feedback.html

20. To Do: • Textbook Q’s pg. 477 # 1-5

21. The Pituitary Gland: • Referred to as the master gland because it has control over most other endocrine glands • Connected directly to the hypothalamus (like a pendant on a necklace) • Together they are called the PITUITARY-HYPOTHALAMUS COMPLEX

23. The Pituitary is divided into two different lobes: A) POSTERIOR PITUITARY LOBE PPG): (1/3 of gland) • Stores & releases hormones produced in the HYPOTHALAMUS • The hypothalamus stores the hormones in the PPG until needed

24. B) ANTERIOR PITUITARY LOBE (APG): (2/3 of gland) • It produces its own hormones (unlike the PPG) • Nerves from the hypothalamus extend into the APG to trigger hormone release • Hypothalamus contains the CHEMORECEPTORS necessary to identify a need to release APG hormones

25. Role of the Hypothalamus • Does the “sensing” for the pituitary • Contains chemoreceptors

28. https://sites.google.com/a/grccs.ca/mr-bado/science-8b/Biology-30-Instructional-Videohttps://sites.google.com/a/grccs.ca/mr-bado/science-8b/Biology-30-Instructional-Video

29. AND Pg. 477 #6-8 Questions: • Define what a hormone is • Distinguish between a target & non-target hormone • Distinguish between endocrine & exocrine glands • Why is the pituitary gland called the master gland? • What is negative feedback and how does it work? • Describe the signaling action of a steroid hormone & and protein hormone.