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Homeostasis and Feedback Systems - Anatomy & Physiology

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Terms in this set (20)

  • What is homeostasis?

    Homeostasis is the body's ability to maintain a relatively constant internal environment despite external changes.

  • Why is homeostasis considered dynamic and not absolute?

    Because regulated variables fluctuate slightly around the set point rather than staying fixed at one value.

  • Define negative feedback.

    A system where a change in a regulated variable causes a response that reverses the initial change to maintain balance.

  • What is a regulated variable?

    The specific factor or condition that a feedback system monitors and maintains within a set range.

  • List the five components of a negative feedback system.

    1. Sensor detects the variable
    2. Afferent pathway sends info to controller
    3. Integrating center compares to set point
    4. Efferent pathway sends response
    5. Effector makes corrective change

  • What is the set point in a feedback system?

    The desired or normal value of the regulated variable, calculated as (highest + lowest value) / 2.

  • How is the range of a negative feedback system calculated?

    By subtracting the lowest value from the highest value that activates or deactivates the system.

  • What does sensitivity of a feedback system indicate?

    Sensitivity is half the range and shows how much the variable can vary above or below the set point.

  • What happens when a physiological set point is reset? Give an example.

    The system adjusts to a new set point, such as a fever raising body temperature to fight infection.

  • Define positive feedback and give an example.

    Positive feedback amplifies a change, moving the variable further from the set point, e.g., oxytocin release during childbirth.

  • Why can positive feedback be dangerous if not stopped?

    Because it can cause uncontrolled changes that move the system away from homeostasis, potentially causing harm.

  • What is feedforward control? Provide an example.

    Feedforward anticipates changes and initiates responses before the change occurs, like increased heart rate before exercise.

  • In heart rate regulation, what is the actual regulated variable?

    The body regulates blood pressure, not heart rate directly.

  • What effect does the sympathetic nervous system have on heart rate?

    It increases heart rate to raise blood pressure when needed.

  • What effect does the parasympathetic nervous system have on heart rate?

    It decreases heart rate to lower blood pressure when it is too high.

  • Why are both sympathetic and parasympathetic systems needed for heart regulation?

    They provide balance, allowing heart rate to increase during activity and decrease during rest.

  • How does the negative feedback system respond when blood pressure rises above the set point?

    Pressure sensors signal the brain to increase parasympathetic and decrease sympathetic activity, lowering heart rate.

  • How does the negative feedback system respond when blood pressure falls below the set point?

    Pressure sensors signal the brain to decrease parasympathetic and increase sympathetic activity, raising heart rate.

  • What role do sensors play in negative feedback?

    Sensors detect changes in the regulated variable and send information to the integrating center.

  • What is the function of the effector in a negative feedback system?

    The effector makes the corrective change to return the variable toward the set point, such as sweat glands cooling the body.