D3.3.1 Homeostasis Notes

Homeostasis Ensures Stability for Survival

1. Life depends on stable internal conditions, even when the external environment changes.
2. This balance is called homeostasis which allows organisms to survive and function efficiently.

Why Is Homeostasis Important?

1. Cells require specific conditions to work properly:
   1. Temperature affects enzyme activity (too hot = enzymes denature, too cold = reactions slow down).
   2. pH determines protein structure (deviations can cause malfunction or denaturation).
   3. Glucose levels regulate energy supply for cellular functions.
   4. Osmotic balance controls water movement, preventing cells from shrinking or bursting.
2. By regulating these variables, homeostasis ensures stability, allowing cells to function despite external fluctuations.

How Homeostasis Works: Key Components

To maintain homeostasis, the body relies on a feedback system involving:

1. Receptors: Specialized sensors that monitor the internal environment and detect stimuli (changes in temperature, pH, glucose levels, etc.).
2. Control center: The control center (usually the brain or specific glands) receives input from receptors, compares it to a set point, and determines if a response is needed.
3. Effectors: If conditions deviate from the set point, effectors (muscles, glands, or organs) activate to restore equilibrium.

Negative Feedback: The Core Mechanism of Homeostasis

Most homeostatic processes rely on negative feedback loops, which reverse changes to bring the body back to its set point.

Key Homeostatic Variables in Humans

1. Body Temperature

1. Maintaining a stable body temperature is crucial for enzyme function.
   1. Set Point: Around 37°C.
   2. Receptors: Thermoreceptors in the skin and hypothalamus.
   3. Control Center: Hypothalamus.
   4. Effectors: Sweat glands, blood vessels, and muscles.

2. Blood pH