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Somatic Sense

Somatic Sense

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This lesson will describe how your body detects and interprets somatic sensations.

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Tutorial

What's Covered

Welcome to this lesson today on somatic senses. Today you’ll be learning how the body detects somatic sensations. Specifically, you will be learning about:

  1. Somatic Sensation Detection
  2. Pain Overview
  3. Types of Pain
  4. How Pain Works
  5. Types of Sensory Detectors

1. Somatic Sensation Detection

Somatic sensations are detected by sensory input from sensory receptors and sensory receptors can be found scattered throughout your body. They can be found in the skin and skeletal muscles and in the walls of some internal organs. Somatic sensations can include things like pain, touch, pressure, temperature, motion, et cetera.

Term to Know

Somatic Sensations

Sensations such as touch, pressure and pain that are detected by sensory receptors in the body.

Signals from sensory receptors will be sent to the somatosensory cortex, which is located in the cerebrum of the brain, more specifically the parietal lobe. Interneurons within the somatosensory cortex are associated with various parts of the body. These interneurons are organized and laid out like a map, and larger parts of the map are associated with more sensitive areas of the body because more sensitive areas of the body have more receptors.

Term to Know

Somatosensory Cortex

A location in the cerebrum that interprets somatic sensations.

IN CONTEXT
Your fingertips and your lips, which are very sensitive parts of your body are associated with more receptors and therefore take up a larger part of this map basically that's organized in the somatosensory cortex.

2. Pain Overview

Pain is an example of a somatic sensation.

Pain is a perceived injury and although pain is not a pleasant thing to experience, it is actually an important protective feature of our body. Pain warns us that we've experienced some sort of injury to our body and that we need to withdraw from the situation that's causing that injury before further injury occurs.

Term to Know

Pain

Perceived pain to the body.

IN CONTEXT

If you've ever been cooking before, near a stove, and you've accidentally touched your hand on the burner, you will feel pain in your hand.  As a reaction, you'll pull your hand away because of that pain.

As you pull your hand away, it's not allowing for any more damage to occur.

3. Types of Pain

Visceral and somatic pain are pain related to the body, where visceral pain relates to internal organs and somatic pain relates to pain on the skin, skeletal muscles, joints, and tendons. A person's perception of pain that can be wrongly projected from an internal organ to the body's surface because the brain cannot pinpoint the source of the pain, and this is called referred pain.

ExampleAn example of this is when a person has a heart attack, oftentimes they'll feel pain down their left arm. The body or the brain is not able to properly identify where that source of pain is coming from, so it will project it to another part of the body.

Phantom pain is when a person experiences pain in a missing limb and is common among amputees. If a person has had their leg amputated, oftentimes they will say they can still experience pain in that missing limb even though it's not there anymore. This is something that's not really fully understood yet and requires more research.

Terms to Know

Somatic Pain

Pain felt in the skin, skeletal muscles, joints or tendons.

Visceral Pain

Pain felt in the internal organs.

Referred Pain

Referred pain is when pain from internal organs is wrongly projected to another part of the body.


4. How Pain Works

When signals of pain reach the brain the hypothalamus will send signals to release endorphins and enkephalins. Endorphins and enkephalins are natural opiates that reduce our ability to perceive pain. Some scientists think that this might be some sort of evolutionary trait that's developed. So we know pain is important, because it warns us of some sort of perceived injury.

Think About It

QUESTION:  If it's important for us to feel pain to warn us of perceived injury, why would our body also release substances that reduce our ability to perceive pain? It seems like they kind of contradict one another, right?

ANSWER: Scientists sometimes believe that these will be released in a really stressful situation when a person has become injured as a way to not be incapacitated by that pain and continue to function.


IN CONTEXT

If you're a fan of Shark Week on the Discovery Channel, you've probably seen this before. If a person is swimming and they get attacked by a shark oftentimes they'll say they didn't really feel anything.

They were scared, but they didn't feel any pain because endorphins and enkephalins were released that inhibited their ability to perceive that pain so that they could continue to swim and try and survive.

They could continue to function, because if they were able to feel that pain, they would become incapacitated and would probably end up drowning.

Pain is not felt until after the stressful situation has ended.  That's why some scientists think it's an evolutionary trait that has developed in order to allow a person to escape a stressful situation.

5. Types of Sensory Receptors

There are actually thousands of sensory receptors that are found in the skin that detect touch, pressure, cold, warmth, and pain. Different types of receptors can be found at different layers of skin and within different depths, depending on which type of sensation they are there to detect.

One type of receptor that can be found in the skin are thermoreceptors which are used to detect temperature changes. There are a couple different types of thermoreceptors, depending on which type of temperature they are detecting.

Free nerve endings are also found within the skin, but they're also found in other internal tissues. There are actually several different types of free nerve endings that can detect touch, pressure, heat, cold, or pain. Free nerve endings are very simple in structure and they are the dendrites of sensory neurons. Nociceptors are actually examples of free nerve endings that specifically detect pain.

Term to Know

Free Nerve Ending

Receptors that detect touch, pressure, heat, cold and pain.

Encapsulated receptors are enclosed in a capsule of connective tissue or epithelial tissue and there are a variety of different encapsulated receptors.

ExamplePanacinian corpuscles detect deep pressure or vibrations. Merkel's discs are also encapsulated receptors that detect steady touch.

Then we also have other types of encapsulator receptors that detect light touch. So depending on the type of touch, we have different types of receptors that will interpret that information.  There is also the case of becoming less aware of a stimulus with repeated exposure, which is called sensory adaptation.

Term to Know

Encapsulated Receptor

A type of sensory receptor encapsulated or enclosed in epithelial or connective tissue.

Term to Know

    • Sensory Adaptation
    • An adaptation to a stimulus or becoming less aware of a stimulus over time.

Summary

This lesson has been an overview on somatic sensations. Specifically, you learned about somatic sensation detection. You also looked at an overview of pain, the types of pain and how pain works. Finally, you learned about the different types of sensory detectors.

Keep up the learning and have a great day!

Source: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND

TERMS TO KNOW
  • Sensory Adaptation

    An adaptation to a stimulus or becoming less aware of a stimulus over time.

  • Referred Pain

    A person's perception of pain that can be wrongly projected from an internal organ to the body's surface because the brain cannot pinpoint the source of the pain.

  • Visceral Pain

    Pain felt in the internal organs.

  • Somatic Pain

    Pain felt in the skin, skeletal muscles, joints or tendons.

  • Pain

    Perceived pain to the body.

  • Encapsulated Receptor

    A type of sensory receptor encapsulated or enclosed in epithelial or connective tissue.

  • Free Nerve Ending

    Receptors that detect touch, pressure, heat, cold and pain.

  • Somatosensory Cortex

    A location in the cerebrum that interprets somatic sensations.

  • Somatic Sensations

    Sensations such as touch, pressure and pain that are detected by sensory receptors in the body.