Chapter 50 - Chapter 50 Homeostasis I. Homeostasis...

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Chapter 50 Homeostasis I. Homeostasis Maintaining constant internal environment, this environment fluctuates within a narrow range. Why is this important? How does this happen? A. Feedback loops 1. Negative feedback loops a. sensors (nerves) monitor internal environment b. messages are relayed to an integrating center (set point )
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c. deviation from set point causes integrating center to send message to effectors (muscles, glands) d. effectors change value back towards set point Ex. thermostat These systems are called negative because they reverse the effect of the perturbing factor Temperature regulation, blood sugar 2. Positive feedback loops Perturbing factor is pushed even farther from the set point Ex. Labor, blood clotting I I. Thermoregulation 1. Importance of temperature regulation
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a. physiological functions linked to temp b. enzyme activity increases as temp ↑ c. increased temp speeds up molecular movement 2. Heat exchange Body temp = metabolic heat + heat gained from environment - heat lost to environment a. conduction – heat transfer from environment by direct contact Higher temperature to lower Lizard sitting on a hot rock gains heat Lizard sitting on a cold rock loses heat b. convection – movement of air over a surface Heat loss if air is cooler than body temp Heat gain if air is warmer than body temp
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c. evaporation – cools, as water evaporates it takes heat with it d. radiation – solar energy warms up an object (basking) 3. Solutions to temperature fluctuations a. live in an environment where temp remains constant b. physiological processes adapt to a range of
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This note was uploaded on 05/10/2009 for the course BIOLOGY 21909 taught by Professor Jefffeaster during the Spring '09 term at Fullerton College.

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Chapter 50 - Chapter 50 Homeostasis I. Homeostasis...

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