Homeostasis

📌 Physiology – Normal Body Function

- Studying normal function is essential to understand disease.

- Any deviation (increase or decrease) from normal = disease (Dis-ease).

🖇 Anatomy – Levels of Organization

- Systems → Organs → Tissues → Cells.

- Cell = Structural Unit of the human body.

🖇 Physiology – Internal Environment

- Intracellular Fluid (ICF): Inside the cell.

- Extracellular Fluid (ECF): Outside the cell = Internal Environment.

- ECF contains ions, gases, nutrients → supports cell function.

📌 Homeostasis

- Stability of ECF is vital for optimal cell and body function.

- Homeo = internal environment, Stasis = stability.

- Disruption → disease → requires correction.

- Failure to restore balance → serious complications or death.

🚨 Clinical Importance – Why Constancy Matters

- Enzymes work within narrow temperature and pH ranges.

- Small changes affect enzyme activity → disrupt body function.

🖇 Physiology – Set Point & Normal Range

- Set Point: Ideal value (e.g., Temp 37°C, BP 120/80).

- Normal Range: Acceptable fluctuation around set point.

- Deviation requires Correction or Compensation.

📌 Control Systems

- All systems help maintain stability.

- Two main leaders:

- Nervous System: Fast, short-term response.

- Endocrine System: Slow, long-term hormonal response.

🟠 Feedback Loop – Mechanism of Action

1. Stimulus (change/disturbance).

2. Receptor (detects change).

3. Afferent Pathway (signal to control center).

4. Control Center (analyzes, decides response).

5. Efferent Pathway (sends orders).

6. Effector Organ (executes correction).

🟣 Feedback Mechanisms

🔹 Negative Feedback:

- Response opposes the stimulus.

- Most common and essential for homeostasis.

- Examples:

- Temperature regulation.

- Blood glucose control (Insulin).

🔹 Positive Feedback:

- Response amplifies the stimulus.

- Rare, potentially dangerous if unchecked.

- Useful in specific cases:

- Blood clotting.

- Childbirth (Oxytocin → uterine contractions → more Oxytocin).

🚨 Forward Control

- Anticipatory mechanism: body predicts and prepares for changes.

- Mentioned briefly; main focus remains on feedback systems.