Homeostasis: Feedback and Set Points - Anatomy and Physiology
- What is negative feedback?
- A response that opposes the original change, returning the variable toward its set point.
- After a meal, rising blood glucose triggers insulin release, which lowers blood glucose. Which type of feedback is this?
- Negative feedback, because the response reverses the original rise.
- Activated platelets release chemicals that activate more platelets until a plug forms. Which type of feedback is this?
- Positive feedback, because each step amplifies the original change until the plug is complete.
- During labor, stretch of the cervix triggers stronger uterine contractions, which stretch the cervix further. Which type of feedback is this?
- Positive feedback, which continues until the baby is delivered.
- What are the three basic components of a homeostatic feedback system?
- A receptor (sensor), a control center, and an effector.
- In the baroreceptor reflex, which component of the feedback system are the baroreceptors in the carotid sinus?
- The receptors (sensors), which detect changes in blood pressure and signal the control center.
- What is positive feedback?
- A response that amplifies the original change; it usually ends when a culminating event occurs.
- When body temperature rises, sweat glands increase their output. Which component of the feedback system are the sweat glands?
- The effectors, which carry out the response that returns temperature toward the set point.
- What is feedforward control?
- An anticipatory adjustment made before a regulated variable changes, such as heart rate rising just before exercise begins.
- What is a set point?
- The target value or narrow range around which a physiological variable is regulated.
- What is homeostasis?
- The maintenance of a relatively stable internal environment despite changing conditions, a dynamic equilibrium rather than a fixed state.
- What are the afferent and efferent pathways in a feedback system?
- The afferent pathway carries information from the receptor to the control center; the efferent pathway carries commands from the control center to the effector.