Homeostasis

A state of A state of balance balance

in the bodyin the body WhoaWhoa

Homeostasis

Maintenance of a stable internal environment = a dynamic state of equilibrium

Homeostasis must be maintained for normal body functioning and to sustain life

Homeostatic imbalance – a disturbance in homeostasis resulting in disease

Overview of Homeostasis

Maintaining Homeostasis The body communicates through neural

and hormonal control systems The primary systems responsible for

maintaining homeostasis are the nervous and endocrine systems.

Components of Feedback Mechanisms

Variable-factor or event being regulated.

Set point-ideal normal value Receptor

Responds to changes in the environment (stimuli)

Sends information to control center

Maintaining Homeostasis

Control center Determines set point Analyzes information Determines appropriate response

Effector Provides a means for response to the

stimulus

Feedback Mechanisms

Negative feedback Includes most homeostatic control

mechanisms Shuts off the original stimulus, or

reduces its intensity Works like a household thermostat

Human Example of Negative Feedback Human example: shivering in response

to cooling of body during cold weather or sweating when their core temperature gets too hot.

Homeostasis allows an organism to remain in balance with its environment.

If homeostasis is not maintained, it can harm or kill the organism.

Feedback Mechanisms

Positive feedback Increases the original stimulus to

push the variable farther In the body this only occurs in blood

clotting and birth of a baby

High-Wire Artist Model

With your elbow partner,With your elbow partner,identify the following:identify the following:

VariableVariable SetpointSetpoint ReceptorsReceptors Control CenterControl Center EffectorsEffectors

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High-wire Artist Model

Variable: position of bodySetpoint: directly over the wireReceptors (Sensors): nerve

receptors (eyes, inner ears, muscle stretch receptors, etc.)

Control Center: brainEffectors: skeletal muscles

High-wire artist uses negative feedback to maintain relatively constant position on wire.