Lab Exercise 2 - Homeostasis and Feedback Loops

Lab Exercise Two - Overview

Homeostasis

Definition

  • Homeostasis is one of the essential characteristics of life.

  • It means maintaining a more or less stable internal environment in living organisms.

Key Concepts

  • Meaning of Homeostasis

    • Related to the terms 'homeo' (same) and 'stasis' (standing still).

    • Implies keeping internal conditions even or stable.

  • Examples of Parameters

    • Blood sugar levels.

    • Body temperature.

    • Blood pH.

    • Importance of maintaining balance around the set point.

  • Set Point

    • The target value for a physiological variable (e.g., average human oral temperature is 98.6°F).

    • Variations are normal, and slight deviations from the set point are not alarming.

  • Consequences of Imbalance

    • If homeostasis is disturbed (out of balance), it can lead to illness or danger.

Homeostatic Mechanisms

  • These are physiological systems that maintain homeostasis by utilizing feedback loops.

Feedback Loops

  • Components of Feedback Loops

    • Sensor (Receptor)

    • Monitors a particular variable (e.g., temperature).

    • Control Center

    • Processes information received from the sensor.

    • Makes decisions regarding necessary responses.

    • Effector

    • Implements the response directed by the control center.

  • Feedback loops operate in a cycle where:

    • The sensor detects changes and communicates to the control center.

    • The control center analyzes this information and commands the effector.

    • The effector responds, which changes the variable, satisfying the sensor's monitoring role.

  • Real-World Example: Temperature control in buildings.

Homeostasis in Humans

Components and Functions

  • Sensors in the Body

    • Various sensory receptors, including:

    • Pain receptors.

    • Temperature receptors.

    • Touch receptors.

    • Mechanoreceptors.

    • Receptors for internal monitoring (e.g., blood solute concentration).

  • Control Centers

    • Central Nervous System (Brain and Spinal Cord).

    • Endocrine system components, varying as per the parameter being regulated.

  • Effectors

    • Muscular tissues (carry out movement).

    • Glands (secrete hormones).

Feedback Loop Types

Negative Feedback Loops

  • Definition: Response of the effector counteracts the change detected by the sensor.

  • Example Scenarios:

    • Body temperature regulation: Body responds to overheating by sweating.

    • Blood glucose regulation: Insulin released when levels rise, glucagon when they drop.

  • Most physiological parameters are maintained this way (e.g., pH, body temperature).

Positive Feedback Loops

  • Definition: Response amplifies the changes detected by the sensor.

  • Examples:

    • Childbirth: Uterine contractions release oxytocin, which increases contractions.

    • Blood clotting: Sticky platelets attract more platelets, amplifying clot formation.

  • Very few physiological processes use positive feedback.

Practical Application in Class

  • Monitoring heart rate as an introduction to the concepts of feedback loops.

Conclusion

  • The lab session does not cover advanced parameters; it focuses on basic observations to understand homeostasis and feedback loops.