04.1B BIO Homeostasis & Feedback Loops (PART B)

Homeostasis

The body's ability to maintain relatively stable internal conditions

Variable

Any factor in the body that can change (temperature, concentrations of chemicals, etc.)

Set point

The normal range of a variable

Stimulus

Any change to a set point that is maintained in the body

Receptor

Detects changes in temperature, chemicals, water, touch, pressure, pain, etc.

Control Center

A region in the brain called the hypothalamus analyzes the information recieved from receptors and then determines the appropriate response or course of action

Effector

Organs, glands, tissues or cells that maintain the body's homeostatic set points

Response

The action taken by an effector to bring about homeostatic balance

Feedback

Always the opposite of the stimulus; receptors receive feedback when they sense desired changes have been made

Negative Feedback Loop (Description)

Produces a response that opposes the original stimulus and once the desired state is reached the feedback loop shuts off

Negative Feedback Loop (Examples)

Examples include maintaining body temperature and blood sugar levels

Positive Feedback Loop (Description)

Increases the initial stimulus during childbirth, lactation, blood clotting to amplify the response

Positive Feedback Loop (Examples)

Examples include labor contractions (birth), production of milk when nursing a baby, and blood clotting

Homeostatic Imbalance results in

Disease, illness and possibly death

Afferent pathway

The nerve pathway sending an electrochemical message from the receptors to the control center (hypothalamus of brain).

Efferent pathway

The nerve pathway sending an electrochemical message from the control center (hypothalamus of brain) to the effectors (muscles and glands).