SFH - Homeostasis and Biofeedback Lesson

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Homeostasis and Biofeedback

 

Homeostasis definition

 

Homeostasis is the process of maintaining a good working environment for all of the parts inside of the human body. How, exactly, does the body temperature remain 98.6° F, when the temperature outside is 60°F?

Think about the thermostat located in a building. The thermostat is the control unit for the heating or cooling system. The temperature is manually entered for the desired comfort level of the area it services. The thermostat uses electronic sensors to constantly monitor temperature and signals the system to turn on or shut off to maintain the temperature entered.

In later modules, you will learn more about how the endocrine system and nervous system work together to deliver signals that trigger electrical or chemical responses to maintain "a good working environment" for the human body as a whole. In the same manner that a broken thermostat cannot regulate temperature, events may occur that impair how the body regulates the internal environment.  

 

 

Take a look at how the body works to maintain homeostasis by watching the video below:

We will explore each body system's role in the maintenance of homeostasis in the modules that follow.

What happens if stability is disrupted?

 

An arch made of stones sits on a beach to illustrate the concept of homeostasis, in which all systems work together to maintain stability.

 

All of the organs and organ systems of the human body work together like well-oiled machines. This is because they are closely regulated by the nervous and endocrine systems, which will be presented in later modules. Functioning together, the organ systems supply body cells with all the substances they need and eliminate their wastes. They also keep temperature, pH, and other conditions at just the right levels to support life processes.

Maintaining Homeostasis

Keeping a stable internal environment requires constant adjustments. Here are just three of the many ways that human organ systems help the body maintain homeostasis:

  • Respiratory system: A high concentration of carbon dioxide in the blood triggers faster breathing. The lungs exhale more frequently, which removes carbon dioxide from the body more quickly.
  • Excretory system: A low level of water in the blood triggers retention of water by the kidneys. The kidneys produce more concentrated urine, so less water is lost from the body.
  • Endocrine system: A high concentration of sugar in the blood triggers secretion of insulin by an endocrine gland called the pancreas. Insulin is a hormone that helps cells absorb sugar from the blood.

Negative Feedback

How does your body maintain homeostasis? The regulation of your internal environment is done primarily through negative feedback. Negative feedback is a response to a stimulus that keeps a variable close to a set value. Essentially, it shuts off or turns on a system when it varies from a set value.

 

An illustration of the process of negative feedback loops in theory, and the negative feedback loop of body temperature regulation

 

Your body has an internal thermostat that acts much like the thermostat in your home. On a cold winter day, the thermostat in your home senses the temperature in a room and responds by turning the heater on or off, depending on pre-set levels. 

When your body temperature rises, receptors in the skin and the brain sense the temperature change. The temperature change triggers a command from the brain. This command can cause several responses. If you are too hot, the skin makes sweat and blood vessels near the skin surface dilate. This response helps decrease body temperature.

Positive Feedback

Some processes in the body are regulated by positive feedback.  Positive feedback is when a response to an event increases the likelihood of the event to continue.

An example of positive feedback is milk production in nursing mothers. As the baby drinks her mother's milk, the hormone prolactin, a chemical signal, is released. The more the baby suckles, the more prolactin is released, which causes more milk to be produced.

Another example of positive feedback is contractions during childbirth. When constrictions in the uterus push a baby into the birth canal, additional contractions occur.

The positive feedback loop of contractions during childbirth.

 

 

Failure of Homeostasis

Many homeostatic mechanisms work continuously to maintain stable conditions in the human body. Sometimes, however, the mechanisms fail. When they do, cells may not get everything they need, or toxic wastes may accumulate in the body. If homeostasis is not restored, the imbalance may lead to disease or even death.

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