HOMEOSTASISkecture

📘 BIOLOGY LECTURE: HOMEOSTASIS

🔹 Introduction

Homeostasis is the process by which living organisms maintain a stable internal environment despite changes in the external environment. This stability is essential for proper functioning of cells, tissues, and organs.

Definition: Homeostasis is the maintenance of constant internal conditions such as temperature, pH, water balance, and glucose level.

🔹 Importance of Homeostasis

• Ensures optimal enzyme activity
• Maintains stable body temperature
• Regulates water and salt balance
• Keeps blood glucose level constant

🔹 Components of Homeostasis

Homeostasis involves three main components:

• Receptor: Detects changes (stimulus)
• Control Center: Processes information (brain/hypothalamus)
• Effector: Responds to restore balance

🔹 Feedback Mechanisms

1. Negative Feedback

This is the most common mechanism where a change in a variable triggers a response that reverses the change.

Diagram: Negative Feedback Loop

2. Positive Feedback

This amplifies a change rather than reversing it. It is less common and occurs in processes like childbirth.

🔹 Temperature Regulation in Humans

The human body maintains a constant temperature (~37°C) using the hypothalamus in the brain.

Diagram: Thermoregulation

🔹 Osmoregulation

Osmoregulation is the control of water and salt balance in the body. The kidneys play a major role in filtering blood and producing urine.

Diagram: Kidney Function

🔹 Blood Glucose Regulation

The pancreas regulates blood sugar using two hormones:

• Insulin: Lowers blood glucose
• Glucagon: Raises blood glucose

🔹 Summary

Homeostasis is essential for survival. It ensures that internal conditions remain stable through feedback mechanisms involving receptors, control centers, and effectors.

Exam Tip: Always mention stimulus, receptor, control, and response when explaining homeostasis in exams.