3.50 Sense of Touch

Your skin can transmit an amazing amount of information to your brain through the sense of touch. In this lesson, learn about the receptors and pathways that let your body process many types of touch.

Touch: A Complicated Sense

When you are a baby, everything is new: the carpet you crawl on, the bird you see and hear through the window, the strawberry yogurt you sniff and lick. And your five senses (touch, sight, hearing, smell, and taste) are the means through which your brain processes new things, which helps you discover the world. But it's not just when you are a baby that your senses are being used, but rather, almost every minute of every day!

In this lesson, we will explore the sense of touch. Your sense of touch is one of the most complicated senses. How so? Well, there are many types of touch. For example, place your hand on any flat surface around you. Did you do it? How do you know? Because your brain tells you that your hand has made contact with the surface through the sense of touch.

But, your sense of touch can tell you so much more than just if you made contact. For example, is the surface you are touching rough or smooth? Is it hot or cold? Is it dry or wet? Is it still or vibrating? Your body is able to sense pressure, vibration, temperature, and pain. You probably didn't realize how much information is passed to your brain through the sense of touch!

1. Main points:

The sense of touch is a complex sense that provides the brain with information about contact, texture, temperature, moisture, movement, pressure, and pain, helping us interact with and understand our environment.

2. Questions:

• Content Analysis: What types of sensations can the sense of touch detect?
• Contextual Analysis: How does the sense of touch contribute to our understanding and interaction with the world?
• Linguistic Analysis: What words in the text describe the various aspects and capabilities of the sense of touch?

3. Further Discussion:

Why is the sense of touch considered one of the most complicated senses?

4. Answers:

• Content Analysis: "Your body is able to sense pressure, vibration, temperature, and pain."
• Contextual Analysis: The sense of touch helps us "discover the world" by providing detailed information about our surroundings.
• Linguistic Analysis: Words like "rough," "smooth," "hot," "cold," "dry," "wet," "still," "vibrating," "pressure," and "pain" describe the various aspects and capabilities of the sense of touch.

How does the Sense of Touch Work?

In order to process so many different bits of information, the skin comes equipped with millions of sensory nerve receptors. There are several types of sensory nerve receptors. Some receptors tell the difference between hot and cold; others sense an itch or a pain. For this reason, touch is one of the most complicated senses for researchers to study.

Your skin contains many important structures, like blood vessels, glands, and sensory nerve receptors. These receptors transmit what is felt on the skin up to the brain!

Once the sensory nerve receptors have picked up on a specific type of touch, this message is passed to a neuron, or nerve cell. The neuron passes the message to more neurons along a specific pathway. Different types of touch travel along different pathways. Pain has its own pathway. Temperature has its own pathway. Basic touch has its own pathway. But eventually, all pathways lead to the brain where the message is sent.

1. Main points:

The skin is equipped with millions of sensory nerve receptors that detect various sensations like heat, cold, itch, and pain. These receptors send signals to neurons, which then transmit the information along specific pathways to the brain for interpretation.

2. Questions:

• Content Analysis: What role do sensory nerve receptors and neurons play in the sense of touch?
• Contextual Analysis: How do different types of touch sensations travel to the brain?
• Linguistic Analysis: What words in the text describe the complexity and functionality of the sensory nerve receptors and neurons?

3. Further Discussion:

Why is the differentiation of pathways for different touch sensations (like pain and temperature) important for our sensory experience?

4. Answers:

• Content Analysis: "Sensory nerve receptors... pick up on a specific type of touch... message is passed to a neuron."
• Contextual Analysis: "Different types of touch travel along different pathways... Pain has its own pathway. Temperature has its own pathway."
• Linguistic Analysis: Words like "millions," "sensory nerve receptors," "neuron," "pathway," and "brain" describe the complexity and functionality of the system.

Not All Parts are Equal

The sensory nerve receptors are nestled in your skin alongside various glands and blood vessels. In one square centimeter of skin on your fingertip, there are approximately 2,500 sensory nerve receptors! So, a key on a computer keyboard is about one square centimeter. Imagine in that small space, over two thousand nerve receptors are at work!

Your fingertips are one of the most sensitive parts of the body to touch. This is because they contain so many sensory nerve receptors.

However, not all skin is created equally sensitive to touch. For example, lightly run your finger over your cheek. Now, run your finger over your knee cap. Although you most likely made almost the exact same motion, it feels different in the two different places. This difference in sensitivity to touch is due to a different amount of sensory nerve receptors in different areas.

For example, your knee cap has less receptors than your cheek. And your cheek has less than the inside of your mouth! Ever notice how a tiny piece of food stuck in your teeth feels HUGE to your tongue, but once you get it out and look at it, it's usually quite small?

1. Main points:

Sensory nerve receptors vary in density across different parts of the body, leading to varying levels of touch sensitivity. Fingertips are highly sensitive due to a high concentration of receptors, while other areas like the knee cap have fewer receptors and are less sensitive.

2. Questions:

• Content Analysis: Why do different parts of the body have varying sensitivities to touch?
• Contextual Analysis: How does the density of sensory nerve receptors affect the perception of touch?
• Linguistic Analysis: What words in the text describe the distribution and impact of sensory nerve receptors in the skin?

3. Further Discussion:

How does the variation in touch sensitivity across different body parts benefit us in daily life?

4. Answers:

• Content Analysis: "Different amount of sensory nerve receptors in different areas."
• Contextual Analysis: "Your fingertips... contain so many sensory nerve receptors... your knee cap has less receptors than your cheek."
• Linguistic Analysis: Words like "sensitive," "density," "varying," "receptors," and "perception" describe the distribution and impact of sensory nerve receptors.

Lesson Summary

In summary, your sense of touch is one of the five senses and is amazingly complex. It is able to tell the difference between temperature, pressure, vibration, and more! Thousands of sensory nerve receptors pick up on these various messages, which are relayed by neurons, or nerve cells, along specific pathways to the brain.