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Today’s Objectives

Today’s Objectives. Review Vocabulary with Keyword Game Review Homeostasis WS #4 Intro to Hormonal Control and ADH Work through Homeostasis WS # 5 ( homework if we run out of time) 2 nd Period, Kidney Dissection Lab. ADH and Osmoregulation. Homeostatic Control of Kidneys.

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Today’s Objectives

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  1. Today’s Objectives • Review Vocabulary with Keyword Game • Review Homeostasis WS #4 • Intro to Hormonal Control and ADH • Work through Homeostasis WS #5 (homework if we run out of time) • 2nd Period, Kidney Dissection Lab

  2. ADH and Osmoregulation

  3. Homeostatic Control of Kidneys • What percent water is absorbed back into blood? • About 99%; 1% leaves as urine • Vary with external factors • What kind of system works best for regulating around a set point? • Negative feedback loop • How does this loop work? • Receptor gets input, it is compared to a set point, Effector causes a response that drives towards the set point • Loop shuts itself off

  4. Osmoregulation • Negative feedback loop the regulates water absorptionby kidneys • Receptor? • Hypothalamus; center of Endocrine system • Input? • Amount of H2O in blood • Effector? • Pituitary gland and Collecting Ducts • Response? • Antidiuretic Hormone (ADH) • 9 Amino acids long; highly soluble and breaks down quickly

  5. ADH and Dehydration • Running outside all day and you don’t drink enough water. What does your brain do? • Hypothalamus triggers release of ADH • ADH travels through blood and diffuses into the epithelial cells of the collecting ducts • How can we absorb more water into the blood? • Increase osmotic rate; make ducts more permeable • add more aquaporins (proteins channels for water)

  6. ADH and Dehydration • ADH diffuses into duct cells • Chain reactions causes release of pre-made vesiclesfull of aquaporins • Vesicles fuse with plasma membrane on the inside of the duct • Osmotic rates increase and blood absorbs more water • Urine becomes more concentrated

  7. Where is the Negative Feedback? • ADH raised are water absorption rates, but we are still losing water: • Exhaling H2O • Sweating • Some still lost in urine • How does ADH get us back to normal? • If absorption rate is enough, ADH production stopsand degrades over time (half-life of 20 minutes) • If it is not enough, build of ADH causes “thirst”

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