What is Homeostasis?
- Homeostasis means “same state” or “steady state.”
- It is the ability of the body to maintain a stable internal environment despite changes in the external environment.
Definition:
Homeostasis is the dynamic process by which the body maintains internal stability (like temperature, BP, pH, glucose level, etc.) through regulatory mechanisms.
Examples of Homeostasis:
|
Parameter |
Normal Value |
|
Body temperature |
98.6°F / 37°C |
|
Blood pressure |
120/80 mm Hg |
|
Blood glucose |
70–110 mg/dL |
|
Blood pH |
7.35–7.45 |
|
Na⁺ level |
~135–145 mEq/L |
Mnemonic to remember examples:
"T BAGS"
T – Temperature
B – Blood pressure
A – Acid-base (pH)
G – Glucose
S – Salt (Na⁺)
Components of Homeostatic Mechanism
There are 3 main parts of a control system:
- Receptor (Sensor) – detects the change (stimulus)
- Control Center (Integrator) – processes info (like brain)
- Effector – corrects the change (like muscles or glands)
Mnemonic: "RCE = Real Control Engine"
Types of Feedback Mechanisms
1. Negative Feedback (Most common)
- Reverses the change to bring the body back to normal.
- Maintains homeostasis.
Examples:
- Regulation of blood sugar by insulin
- Thermoregulation
- BP control via baroreceptors
Mnemonic: "Negative = Neutralize"
2. Positive Feedback
- Enhances or amplifies the change.
- Usually for short-term, special events.
Examples:
- Uterine contractions during labor (oxytocin)
- Blood clotting
- Lactation (milk ejection)
Mnemonic: "Positive = Push further"
Mechanism Example: Regulation of Body Temperature
- Receptor – Thermoreceptors in skin detect heat
- Control center – Hypothalamus compares temp to set point
- Effector – Sweat glands activated → body cools
Negative feedback brings temp back to normal
Comparison Table: Negative vs Positive Feedback
|
Feature |
Negative Feedback |
Positive Feedback |
|
Action |
Reverses the change |
Amplifies the change |
|
Frequency |
Common |
Rare |
|
Stability |
Maintains stability |
May cause instability |
|
Example |
BP, Glucose, Temp control |
Labor, Clotting, Lactation |
Importance of Homeostasis
- Keeps internal environment stable.
- Maintains health and survival.
- Prevents diseases caused by imbalance (e.g., diabetes, hypertension, acidosis).
FAQs – Frequently Asked Questions
Q1. What is the meaning of homeostasis?
Ans:
Homeostasis is the ability of the body to maintain stable internal
conditions, like temperature, pH, BP, etc.
Q2. What are the components of homeostatic control?
Ans:
- Receptor (detects change)
- Control Center (processes info)
- Effector (brings change)
Q3. What is the difference between negative and positive feedback?
Ans:
- Negative feedback reverses the change to restore normal (e.g., BP regulation)
- Positive feedback enhances the change (e.g., uterine contraction)
Q4. Is homeostasis always constant?
Ans:
No, homeostasis maintains a dynamic equilibrium, not a fixed
value—it keeps values within a normal range.
Q5. What happens if homeostasis fails?
Ans:
Disruption of homeostasis can lead to disease or even death,
e.g., uncontrolled sugar = diabetes.
