What is homeostasis?

Homeostasis is the ability or tendency of an organism or cell to maintain internal equilibrium by adjusting its physiological processes. All living organisms strive to maintain homeostasis, using a variety of techniques which range from the release of hormones to physical reactions.

In most homeostatic mechanisms the control center is the brain. The control center then sends signals to an effector, which can be muscles, organs or other structures that receive signals from the control center. After receiving the signal, a change occurs to correct the deviation by either enhancing it with positive feedback or depressing it with negative feedback.

Homeostasis works by way of a feedback mechanism.

When a change of variable occurs, there are two main types of feedback to which the system reacts -- Positive Feedback and Negative Feedback.

Examples of Homeostasis

EXAMPLE 1: Your normal body temperature, for example, is around 98.6 deg F. If you start to get cold you shiver. Shivering is a bodily function in response to early hypothermia in warm-blooded animals. When the core body temperature drops, the shivering reflex is triggered to maintain homeostasis. Muscle groups around the vital organs begin to shake in small movements in an attempt to create warmth by expending energy.

EXAMPLE 2: --When blood pressure rises, the heart slows down

EXAMPLE 3: When glucose levels in the blood are too high, the pancreas secretes insulin to stimulate the absorption of glucose and the conversion of glucose into glycogen.

EXAMPLE 4: Acid- Base Balance --Acid-base balance refers to the balance between alkalinity and acidity in the blood, as measured on the pH scale. The pH of blood is 7.4. When the body consumes or produces more acidic compounds or when the body fails to eliminate acids, the kidneys and lungs along with buffer system will be signaled. The lungs can help control pH by excreting carbon dioxide. The kidneys can also excrete excess acids and bases.

 

Resources:

HOMEOSTASIS: A Multimedia Resource

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