Diseases, Toxins & Pathogens That Disrupt Homeostasis

Instructor: Bridgett Payseur

Bridgett has a PhD in microbiology and immunology and teaches college biology.

The body has many ways to control the internal environment so that cells can function properly. When that environment is no longer maintained, you get sick. Homeostasis can be disrupted by diseases, toxins, and pathogens as described in this lesson.


Homeostasis describes staying at the same, consistent level. It basically means keeping your body in its happy place. This includes maintaining temperature, pH, fluid levels, heart rate, blood sugar, blood pressure, etc.

Homeostasis is like a balancing act. When body temperature increases, different mechanisms will kick in to lower it until it gets back to where it should be. Blood vessels will dilate, allowing more heat to escape. Sweating also helps cool off the body. Once the body temperature is back to normal, the blood vessels will constrict again and sweating will stop. These are negative feedback mechanisms, or opposite outputs that tell the body that compensation can stop. Once the set point is reached, they turn off.

Maintaining homeostasis is important for the body to continuously function. Of course, there are different things that can disrupt homeostasis. When this happens, you get sick.

Diseases That Disrupt Homeostasis

Disease, by definition, is disruption of homeostasis. Anytime the body's balance is impaired, the result is illness. Some diseases have external causes - like a toxin or pathogen invading the body. Other diseases have internal causes.

Insulin dependent diabetes mellitus (IDDM) is a disease that severely affects homeostasis. It is an autoimmune disease, meaning the body is attacking itself. Insulin-producing cells in the pancreas are killed, so there is no insulin available in the blood. Insulin is an important protein that helps cells to bring in sugar.

In a diabetic patient, sugar stays in the blood stream. Untreated, high blood sugar levels can lead to diabetic coma, a life threatening condition. High blood sugar levels also put stress on the kidneys and liver, and lead to neuropathy - painful nerve problems in the foot.

Normal insulin fluctuations after glucose ingestion
pancreas levels

Toxins That Disrupt Homeostasis

Tobacco products contain many toxins that disrupt homeostasis, like nicotine and carbon monoxide. Toxins are products of plants, animals, fungi, or bacteria that hurt cells in some way. Toxins found in tobacco can cause damage to blood vessels, resulting in higher risks for heart attack and stroke. The heart works harder than it would otherwise, because of the damaged vessels.

Cells in the human trachea, a tube that leads to the lungs, are covered with microscopic hair-like fibers called cilia. Smoking tobacco paralyzes these cilia so that they can no longer sweep dirt and microbes out of the lungs. This makes infections more likely, breathing more difficult, and increases the likelihood of emphysema, chronic obstructive pulmonary disease, and other lung disorders.

Electron micrograph showing cilia found in respiratory tract

There are very few body systems that are not affected by tobacco use. Fortunately, after someone quits smoking, these damages can be reversed, letting the body go back to its normal, homeostatic state.

Pathogens That Disrupt Homeostasis

A pathogen is any small microbe that can infect your body and make you sick. Since we've already said that being sick means your body is out of balance, it follows that pathogens disrupt homeostasis.

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