feedback systems in the body

8/10/2019 Feedback Systems in the Body

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Feedback Systems In The Body

Anatomy & Physiology IBiology 1611 Lecture


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Feedback System A Feedback System is a cycle of events in

which information about the status of a

condition is continually monitored and fed

back or reported to a central control region.


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A feedback system consists of 3

basic components The Control Center: Determines the point at

which a controlled condition should be

maintained. The Receptor: Monitors changes in the

controlled condition and then sens the

information called the input to the control center.

The Effector: Receives information called output

from the control center and produces a response

called an effect.


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Negative Feedback This occurs if a response reverses the

original stimulus.

Negative Feedback systems tend tomaintain conditions that require frequentmonitoring and adjustment within

physiological limits. Negative Feedback is by far the most

common type of feedback in the body.


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An Example of Negative

Feedback Homeostasis of Blood Pressure is an example of

Negative Feedback.

If a stimulus (such as stress) causes bloodpressure (controlled condition) to rise, pressuresensitive nerve cells (receptors) in certain arteriessend impulses (input) to the brain (control

center). The brain sends impulses (output) to the heart

(effector) which causes the heart rate to decrease(response) and the return of normal blood

pressure and thus, restoration of homeostasis.


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Positive Feedback Positive Feedback occurs when a response

enhances the original stimulus.

Positive Feedback systems tend to regulateconditions that do not occur often and donot require continual fine tuning.

Positive Feedback systems only occur inlimited and very specific instances in thebody. An example is labor and delivery.


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An Example of Positive

Feedback Labor and delivery (contractions) is an example

of positive feedback.

When labor begins, the uterus is stretched(stimulus) and stretch-sensitive nerve cells in thecervix of the uterus (receptors) send nerveimpulses (input) to the hypothalamus (control

center.) The hypothalamus causes the release of the

hormone oxytocin (output) which stimulates theuterus (effector) to contract more forcefully

(response).


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Positive Feedback Continued Movement of the babys head down the

birth canal causes further stretching and the

release of more oxytocin. This in turn causes more contractions to

occur.

This upward cycle of stretching-release ofoxytocin-increased contractions is broken(stopped) by the delivery of the baby.


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Homeostatic Imbalance Disruptions of homeostasis can lead to

disease and death.

Disease: any change from a state of health

that is characterized by symptoms and

signs.


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Types of Diseases Local Disease: A disease that affects one

part of a limited area of the body.

Systemic Disease: A disease that affects

either the entire body or several parts.


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Symptoms versus Signs Symptoms: SUBJECTIVE changes in body

functions that are not apparent to an

observer. Examples: headache, nausea or

fatigue.

Signs: OBJECTIVE changes that a

clinician can observe and measure.Examples: fever, rash, edema or fracture


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Diagnosis The ART of distinguishing one disease

from another or determining the nature of a

disease; a diagnosis is generally arrived at

after the taking of a medical history and the

administration of a physical examination.

To diagnose a patient is as much an ARTas it is a SCIENCE


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Other Medical Terms Autopsy: A medical procedure done to establish

a cause of death and to verify previous diagnoses.

Autopsies can be done to uncover the existence ofdiseases not detected during life, to establish the

effects of drugs, to reveal congenital conditions

and to resolve investigations by law enforcement

officials.

Necropsy: An autopsy of an animal.

feedback systems in the body

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