We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Simple Reflex?

Deanna Baranyi
Updated Mar 03, 2024
Our promise to you
The Health Board is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At The Health Board, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A simple reflex is an automatic response to a stimulus. It does not involve any thought, but simply is an involuntary action. Humans and animals use simple reflexes to escape from danger as well as in some basic survival situations. Medical doctors often use reflexes to check for neurological disorders, paralysis, and other health issues as well.

One of the most common examples of a simple reflex is the patellar test, or the knee jerk response. When someone hits a particular spot on the knee, the sensory cells in the knee work as receptors. Those receptors send a signal to the person’s spinal cord via the sensory nerve cell. Inside the spinal cord, a reflex arc sends the signal directly back to the effectors in the leg muscles through intermediate and motor nerve cells. At that time the muscles of the leg contracts and the lower leg jerks or kicks upward.

The interesting thing about a simple reflex is that there are only three kinds of nerve cells that are involved: the sensory nerve cell, intermediate nerve cell, and motor nerve cell. The brain only becomes aware of the response after it occurs. In the case of the patellar test, the brain is only aware that the lower leg kicked upward, after the action was complete.

There are plenty of other examples of simple reflexes that occur in the human body as well. For example, if an insect, piece of dust, or other foreign object flies into a person’s eye, she will blink within milliseconds. Also, if a person has light shone into her eyes, the pupils will dilate or get smaller. Generally, a person cannot control whether her pupils will dilate in bright light. These things happen involuntarily and each one exemplifies a simple reflex.

Usually, an infant will have more simple reflexes than older humans. The simple reflexes in a newborn are designed to help the newborn survive. For example, an infant will involuntarily hold her breath when placed underwater. Also, most newborns innately know how to suckle and root for milk. It is not something that they are taught, but is a simple reflex.

Sometimes a simple reflex can help a medical doctor diagnose issues in a person’s neurological pathways. For example, if the doctor uses the plantar simple reflex test, it will show him whether a person over the age of six months has an abnormality of the spinal cord or brain. With the plantar reflex test, the outside of the sole of the person’s foot is stroked with a hard object, like a key. If the person’s big toe turns upward and the rest of the toes spread out, there may be damage. If the person’s toes have a downward curl, it is a sign that there may not be damage.

The Health Board is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Deanna Baranyi
By Deanna Baranyi
Deanna Baranyi, a freelance writer and editor with a passion for the written word, brings a diverse skill set to her work. With degrees in relevant fields and a keen ability to understand and connect with target audiences, she crafts compelling copy, articles, and content that inform and engage readers.
Discussion Comments
By AnswerMan — On Feb 18, 2014

I remember the patellar reflex test became the basis for a lot of visual jokes in cartoons and comedy shows. The doctor would tap on a patient's knee with a rubber mallet and the resulting kick would send things flying through the air. When I was a kid, I didn't realize it was an involuntary reaction, and it wasn't nearly as dramatic when a real doctor performed the test.

Deanna Baranyi
Deanna Baranyi
Deanna Baranyi, a freelance writer and editor with a passion for the written word, brings a diverse skill set to her...
Learn more
The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.

The Health Board, in your inbox

Our latest articles, guides, and more, delivered daily.