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UNIT B: Human Body Systems

Chapter 8: Human Organization: Section 8.3 Chapter 9: Digestive System Chapter 10: Circulatory System and Lymphatic System Chapter 11: Respiratory System Chapter 12: Nervous System Chapter 13: Urinary System Chapter 14: Reproductive System. UNIT B: Human Body Systems. UNIT B.

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UNIT B: Human Body Systems

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  1. Chapter 8: Human Organization: Section 8.3 Chapter 9: Digestive System Chapter 10: Circulatory System and Lymphatic System Chapter 11: Respiratory System Chapter 12: Nervous System Chapter 13: Urinary System Chapter 14: Reproductive System UNIT B: Human Body Systems

  2. UNIT B Chapter 8: Human Organization In this chapter, you will learn about how the systems in our bodies are connected and work together to maintain a relatively constant internal environment. Chapter 8: Human Organization • What situations might disrupt the internal state of the body? • How can alleviating stress improve your health and quality of life? TO PREVIOUS SLIDE

  3. UNIT B Chapter 8: Human Organization Section 8.3 Homeostasis is the maintenance of a relatively constant internal environment by an organism or single cell. Internal conditions in the body stay within a narrow range (e.g., body temperature stays at 37ºC) The internal state of the body is a dynamic equilibrium, since internal conditions are not absolutely constant Illness can result if the internal conditions change to a great degree 8.3 Homeostasis TO PREVIOUS SLIDE

  4. UNIT B Chapter 8: Human Organization Section 8.3 Negative feedback is the main homeostatic mechanism that keeps a variable close to a set point. A homeostatic system has at least two components: Sensor: detects a change in internal conditions Control centre: directs a response that brings conditions back to normal Negative Feedback TO PREVIOUS SLIDE

  5. UNIT B Chapter 8: Human Organization Section 8.3 Figure 8.5 Negative feedback mechanism. The sensor and control centre of a feedback mechanism work together to keep a variable close to a particular value. TO PREVIOUS SLIDE

  6. UNIT B Chapter 8: Human Organization Section 8.3 Examples of negative feedback Regulation of room temperature Thermostat is set at 20ºC (set point) Temperature above set point: The sensor (thermometer in thermostat) detects the increase in temperature The control centre (also in the thermostat) turns the furnace off, and the room cools Temperature below set point: The sensor detects the decrease in temperature The control centre turns the furnace on, and the room warms TO PREVIOUS SLIDE

  7. UNIT B Chapter 8: Human Organization Section 8.3 Figure 8.6 Complex negative feedback mechanism. When a room becomes too warm, negative feedback allows the temperature to return to normal. A contrary cycle, in which the furnace turns on and gives off heat, returns the room temperature to normal when the room becomes too cool. TO PREVIOUS SLIDE

  8. UNIT B Chapter 8: Human Organization Section 8.3 Regulation of body temperature The body temperature set point is 37ºC Temperature above set point: The sensor (hypothalamus in the brain) detects the increase in temperature The control centre (also in the hypothalamus) directs the blood vessels in the skin to dilate and activates sweat glands Temperature below set point: The sensor detects the decrease in temperature The control centre directs the blood vessels in the skin to constrict and inactivates sweat glands TO PREVIOUS SLIDE

  9. UNIT B Chapter 8: Human Organization Section 8.3 Figure 8.7 Regulation of body temperature. Normal body temperature is maintained by a negative feedback system. TO PREVIOUS SLIDE

  10. UNIT B Chapter 8: Human Organization Section 8.3 Positive feedback is a mechanism that brings about an even greater change in the same direction. Example: blood clotting Injured tissues release chemical factors that activate platelets Platelets initiate the clotting process and release factors that stimulate further clotting Positive Feedback TO PREVIOUS SLIDE

  11. UNIT B Chapter 8: Human Organization Section 8.3 All body systems contribute toward maintaining homeostasis. The Transport Systems Circulatory system: conducts blood to and away from capillaries where exchange of gases, nutrients, and wastes occurs; regulates tissue fluid composition Lymphatic system: collects excess tissue fluid, which is returned via lymphatic vessels to the circulatory system Homeostasis and Body Systems TO PREVIOUS SLIDE

  12. UNIT B Chapter 8: Human Organization Section 8.3 Figure 8.8 Regulation of tissue fluid composition. Cells are surrounded by tissue fluid, which is continually refreshed because oxygen and nutrient molecules constantly exit, and carbon dioxide and waste molecules continually enter the bloodstream. TO PREVIOUS SLIDE

  13. UNIT B Chapter 8: Human Organization Section 8.3 The Maintenance Systems Respiratory system: adds oxygen and removes carbon dioxide from the blood; regulates blood pH Digestive system: ingests and digests food, providing nutrients to the blood to replace nutrients that are used in body cells Liver: regulates blood glucose and removes toxic chemicals Urinary system: kidneys regulate blood volume, salt balance, and pH TO PREVIOUS SLIDE

  14. UNIT B Chapter 8: Human Organization Section 8.3 TO PREVIOUS SLIDE

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