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23.9A: Homeostatic Process

  • Page ID
    8121
  • LEARNING OBJECTIVES

    • Give an example and describe a homeostatic process.

    The human organism consists of trillions of cells working together for the maintenance of the entire organism. While cells may perform very different functions, the cells are quite similar in their metabolic requirements. Maintaining a constant internal environment with everything that the cells need to survive (oxygen, glucose, mineral ions, waste removal, etc.) is necessary for the well-being of individual cells and the well-being of the entire body. The varied processes by which the body regulates its internal environment are collectively referred to as homeostasis.

    Homeostasis

    Homeostasis, in a general sense, refers to stability, balance, or equilibrium. Physiologically, it is the body’s attempt to maintain a constant and balanced internal environment, which requires persistent monitoring and adjustments as conditions change. Adjustment of physiological systems within the body is called homeostatic regulation, which involves three parts or mechanisms: (1) the receptor, (2) the control center, and (3) the effector.

    The receptor receives information that something in the environment is changing. The control center or integration center receives and processes information from the receptor. The effector responds to the commands of the control center by either opposing or enhancing the stimulus. This ongoing process continually works to restore and maintain homeostasis. For example, during body temperature regulation, temperature receptors in the skin communicate information to the brain (the control center) which signals the effectors: blood vessels and sweat glands in the skin. As the internal and external environment of the body are constantly changing, adjustments must be made continuously to stay at or near a specific value: the set point.

    Purpose of Homeostasis

    The ultimate goal of homeostasis is the maintenance of equilibrium around the set point. While there are normal fluctuations from the set point, the body’s systems will usually attempt to revert to it. A change in the internal or external environment (a stimulus) is detected by a receptor; the response of the system is to adjust the deviation parameter toward the set point. For instance, if the body becomes too warm, adjustments are made to cool the animal. If the blood’s glucose rises after a meal, adjustments are made to lower the blood glucose level by moving the nutrient into tissues in the command center that require it, or to store it for later use.

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    Blood glucose homeostasis: An example of how homeostasis is achieved by controlling blood sugar levels after a meal.

    Key Points

    • Homeostasis is the body’s attempt to maintain a constant and balanced internal environment, which requires persistent monitoring and adjustments as conditions change.
    • Homeostatic regulation is monitored and adjusted by the receptor, the command center, and the effector.
    • The receptor receives information based on the internal environment; the command center, receives and processes the information; and the effector responds to the command center, opposing or enhancing the stimulus.

    Key Terms

    • homeostasis: the ability of a system or living organism to adjust its internal environment to maintain a stable equilibrium
    • effector: any muscle, organ etc. that can respond to a stimulus from a nerve