BBB - Skin, Chemical, and Body Senses and Senory Interaction Lesson

Learning Targets:

  • Describe the four primary touch sensations and how our bodies perceive touch.
  • Analyze the biological, psychological, and socio-cultural factors that influence our perception of pain, and discuss how placebos and distraction techniques can mitigate pain.
  • Describe the processes involved in our senses of taste and smell.
  • Explain the mechanisms by which we detect our body's position and movement.
  • Discuss how sensory interaction shapes our perceptions and define the concept of embodied cognition.

Courtesy of the AP psychology course and exam description, effective fall 2024. (n.d.). Links to an external site.

 

Understanding Touch Sensation: Exploring Our Skin's Perceptions

Our skin, our largest sense organ, plays a crucial role in our daily experiences. With approximately twenty square feet of skin weighing about six pounds, we can perceive four primary touch sensations: pressure, warmth, cold, and pain. Pressure, for instance, is uniquely identified by receptors known as Pacinian corpuscles, which are triggered by pressure and send neural messages to the brain. Notably, some areas of our body are more sensitive to specific sensations. Additionally, our tactile sense, seen in touch, contributes significantly to our holistic well-being and development. For example, touching various textures on the skin, from soft hair to warm and cool wires, helps identify spots sensitive to pressure, warmth, cold, or pain. This intricate interplay of touch sensations goes beyond mere physical stimulation to deeply impact our overall sensory experiences.

Understanding Pain and the Gate Control Theory

Pain is a crucial sensation that is a warning sign for our bodies. It is a physical feeling and an emotional experience linked to actual or potential tissue damage. Nociceptors, the body's pain receptors, detect pain signals. These nociceptors vary in distribution, with our skin housing the highest concentration and our muscles and internal organs having fewer. The body distinguishes between fast and slow pain systems, with A-delta fibers triggering sharp and intense pain sensations, like the initial sting of a paper cut. At the same time, C-fibers produce a lingering, throbbing discomfort.

Gate Control Theory

The Gate Control Theory of Pain delves into the complexity of pain perception, emphasizing the interplay between physical sensations and psychological factors. According to this theory, the spinal cord acts as a gate that amplifies or diminishes pain signals sent to the brain. The gate opens in response to intense stimulation, intensifying the experience of pain, but closes to reduce pain perception. Many factors, including our genetic makeup, physical attributes, attention, and cultural norms, influence our perception of pain. Placebos and distraction techniques can effectively alleviate pain by targeting the central nervous system’s response to painful stimuli, offering insights into the biopsychosocial nature of pain management.

Vestibular

The vestibular sense is the body's ability to sense and maintain balance and spatial orientation via signals from the inner ear. This sense detects changes in head position and movement, as well as changes in direction and speed. The vestibular system is also responsible for coordinating eye movements with head movements, which helps keep eyes clear while moving. Dizziness, vertigo, and balance and spatial orientation problems can be caused by dysfunctions in the vestibular system. We depend on the vestibular sense for activities such as walking, running, and driving and for athletes, dancers, and pilots who require precise balance and coordination. Consequently, understanding the vestibular sense is essential to understanding how we navigate and interact with our surroundings and developing treatments for vestibular-related conditions.

Kinesthesis

Kinesthesis is the ability of the body to sense the position and movement of muscles, joints, and limbs. It is essential for performing coordinated movements and maintaining balance as it provides information about the body's location and orientation in space. Kinesthetic receptors in muscles and joints control a person's movements, which send information to the brain. Proprioception, the ability to determine the location of body parts without seeing them, is also enhanced by kinesthetic feedback. Disorders of the kinesthetic sense can cause motor control, coordination, and balance issues.

Taste and Smell

Each taste bud contains 50-100 receptor cells that catch food chemicals and send neural messages along pathways to the thalamus of the brain.

Taste and smell are linked through sensory interaction (the principle that one sense may influence another). The interaction between the two is undeniable if you have ever had a cold. When your nose is stuffed up, it will also affect your sense of taste. Foods taste bland when we are sick. Smell both changes and adds to our perception of taste. The flavor of food is affected by how it smells, its texture, and its taste.

Unlike vision and hearing, taste and smell are perceived through various chemical substances. Each has specialized sensory receptors that respond to different chemicals.

Taste (Gustation)

The stimulation of special sensory receptors in the mouth causes us to taste. Chemical stimuli are produced by chemical substances in whatever you eat or drink. The substances are dissolved by saliva, activating our taste buds. Each taste bud contains 50-100 receptor cells that catch food chemicals and send neural messages along pathways to the brain's thalamus. Taste buds are located on your tongue, your cheeks, the roof of your mouth, and in your throat. They reproduce every week or two. Therefore, burning your tongue on a hot dish heals itself within a few days. As we age, the number of taste buds we have decreases, as does our sensitivity to taste.

Each taste bud has maximum sensitivity to one taste and less to others. For tastes that are complex, multiple receptors are activated. There are five basic taste sensations, each showing a maximum sensitivity to one taste and a lesser to others.

In the activity below, roll over each number to reveal the basic taste sensations.

Exploring the Sixth Primary Taste: Oleogustus

In the world of taste perception, the concept of Oleogustus, derived from the Latin term for "a taste for fat," has sparked intriguing discussions among researchers. A significant milestone in this exploration occurred in 2015 when a study was published in Chemical Senses. This study proposed that fat should be recognized as the sixth primary taste, joining the ranks of sweet, sour, bitter, salty, and umami. This groundbreaking idea challenges traditional notions of taste and opens up new avenues for understanding how our chemical senses interact with the foods we consume.

Smell (Olfaction)

Airborne molecules from various substances provide the sensory stimuli that create the sensation of odor or smell. Like taste, smell is also a chemical sense. It is an important sense as it alerts us to danger and changes our perception of taste. Smell is also the only sense that bypasses the thalamus on its way to the brain. It is important to know this is the only one that bypasses the thalamus.

The airborne molecules travel through an opening in the palate in the back of the throat. The molecules then enter some five million receptor cells at the top of each nasal cavity. Each odor is specialized in responding to molecules of different chemical substances. The brain is alerted through axon fibers and messages are sent to the olfactory bulb, then the temporal lobes, smell cortex, and parts of the limbic system involved in memory and emotion.

 

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