Feedback SystemHow does the body sense, process

and respond to changes in body conditions?

Changes in internal and externalenvironments can lead tounbalancedconditions which leads to illness.

Receptors in different organs sense the change…

The endocrine and nervous systems process

the information…

and send out hormones and neurotransmitters…

… causing other organs to respond to the change…

… to restore homeostasis!

Feedback SystemSystem that monitors the output

and uses it to adjust the input.

Sense (Sensor)

Control Center

Respond

(Effector)

Three parts of a feedback system:1. SENSOR - detects the change 2. CONTROL CENTER- receives

info from sensor, processes info and sends a signal to the effector

3. EFFECTOR – responds by changing its activity

Feedback loops can be negative or positive.

Most body systems use

negative feedback.

Body responds to reverse the direction of change

(bring it back to the set point)

The Thermostat Analogy

The Body’s ThermostatBody

Temperature

Nerve Recept

ors

Brain

Muscles

Positive feedback is also possible.

(But does NOT result in balance)

response to a change pushes the variable even more in the

same direction

(amplifies the change)

Room Temperature

Thermometer

Thermostat

Furnace

Positive feedback used when rapid change is desirable.

Childbirth Pushes fetus into

birth canal >

stretches it Stretch

receptors

BrainOxytocin released

Stimulates

contractions