Overview
The lecture introduces the receptor-control center-effector circuit diagram, illustrating how negative feedback mechanisms maintain homeostasis, particularly body temperature, with both physiological and real-world (HVAC) examples.
The Receptor-Control Center-Effector Circuit
- The circuit consists of a receptor (sensor), control center (decision-maker), and effector (responder).
- The receptor gathers information about internal or external conditions and sends it to the control center.
- The control center processes input, decides on a response, and signals the effector.
- The effector takes action to adjust the condition back toward the desired range.
Homeostasis and Body Temperature
- Homeostasis refers to maintaining ideal internal conditions for body function, such as temperature.
- Normal body temperature averages around 98.6°F but varies by individual and throughout the day.
- Each person has a temperature setpoint, with normal fluctuations around that point.
Negative Feedback Mechanism: HVAC Analogy
- In an HVAC system, room temperature is regulated within a set window (e.g., 68–69°F) by negative feedback.
- The thermometer (receptor) senses temperature and informs the thermostat (control center).
- If the temperature rises, the air conditioner (effector) cools the room; if it falls, the furnace (effector) heats the room.
- The system works to counteract deviations from the setpoint, maintaining homeostasis.
Body Temperature Regulation Example
- Body thermo receptors (receptors) detect temperature changes and send signals to the hypothalamus (control center).
- If body temperature rises, sweat glands and vasodilation (effectors) cool the body.
- If body temperature falls, shivering and blood vessel constriction (effectors) warm the body.
- These are examples of negative feedback correcting deviations from the temperature setpoint.
Key Terms & Definitions
- Receptor — A sensor detecting changes in the environment or body.
- Control Center — Receives receptor input, processes it, and decides on a response.
- Effector — Carries out the action to restore homeostasis.
- Homeostasis — Maintenance of stable internal conditions within a physiological range.
- Negative Feedback — A process that counteracts changes, returning conditions to a setpoint.
Action Items / Next Steps
- Review the circuit diagram for receptor-control center-effector.
- Be prepared to see this model applied to other physiological systems in future lectures.