Topic 3 6 Chemical Senses Taste Gustation We

Topic 3. 6 - Chemical Senses

Taste (Gustation) • We have bumps on our tongue called papillae. • Taste buds are located on the papillae (they are actually all over the mouth). • Taste sensations: Sweet, salty, sour, bitter and umami (Japanese for savory)

Taste • Some taste sensations are genetically programmed, such as sweet, and finding bitter and sour foods unpleasant • A study of babies had sweet tastes eliciting smiles, lip smacking, and sour tastes eliciting protrusion of tongue- what could this mean?

Smell (Olfaction) Olfactory nerve Olfactory bulb Nasal passage Receptor cells in olfactory membrane

Smell (Olfaction) • We smell something when molecules of a substance carried in the air reach a tiny cluster of 5 million or more receptor cells at the top of each nasal cavity • The ability to identify scents peaks in early adulthood and gradually declines thereafter • The attractiveness of certain smells depends on learned associations- this will be the focus of Unit 4 • Why can smells elicit powerful memories? Could brain circuitry explain it?

So how are smell and taste related to each other? • Although smell and taste have their own separate receptors, there is little doubt that they are closely linked • When your sense of smell is impaired (a cold, for example), is the taste of your food impacted? • We can argue that “flavor” of the food is the intersection of smell and taste

Topic 3. 7 - Other Senses

Touch • Skin sensations include pressure, warmth, cold and pain. • Only pressure has identifiable receptors • Touch sensations involve more than tactile stimulation- for example, why can’t we tickle ourselves?

Gate-Control Theory • theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain • “gate” opened by the activity of pain signals traveling up small nerve fibers • “gate” closed by activity in larger fibers or by information coming from the brain

How do we feel pain? • Pain is an important signal to our bodies • The experience of pain can be influenced by information from the brain • Chronic pain—est. that over 100 million people suffer from this • One study had teen age burn patients undergo a few minutes of wound treatment while they played Nintendo or while they were in a VR environment—the patients felt less pain and spent less time thinking about their pain in virtual reality than Nintendo due to concept of “presences”—illusion of going inside another world. • The big takeaway: Pain requires attention

Vestibular Sense • Tells us where our body is oriented in space. • Controls our sense of balance. • Located in semicircular canals and vestibular sacs in our inner earcan be disrupted by sudden motion or rotation, causing temporary loss of balance. Think about a merry-go-round or a dizzy bat race

Kinesthetic Sense • Tells us where our body parts are in terms of position and movement. • Sensors located in our joints, tendons, bones and ears. • What would happen if this sense was permanently damaged? Look at Ian Waterman’s story This Photo by Unknown author is licensed under CC BY-NC.