VIEWS: 4 PAGES: 24 POSTED ON: 6/23/2012
Smell, Taste, and Touch Smell and Taste Why do we study smell and taste together? • SENSORY INTERACTION: the principle that one sense may influence another. How do we taste? •Taste (and smell) are chemical senses. What is the central muscle involved in taste? Taste • Chemical sense composed of 4 basic senses: sweet, salty, sour, bitter • Taste receptors (taste buds) regenerate every 1-2 weeks • Each “bump” on tongue contains 200 taste buds Papillae • Those bumps on our tongue are called Papillae. • Papillae help grip food while your teeth are chewing. They also have another special job - they contain your taste buds Taste Buds Map out the tongue Taste cont. • Each bud contains a pore that catches food chemicals • Molecules sensed by taste receptors • Age, smoking, alcohol will lower taste bud number and sensitivity Smell (Olfaction) • Inhale and exhale 20,000 times per day • Nostrils fill with scent laden molecules • Smell is a chemical sense – molecules of a substance reach the 5 million receptor cells in nasal cavity • Olfactory receptor cells respond selectively and alert the brain Smell cont. • Information directly transmitted to our temporal lobe – only sense that doesn’t first go through thalamus • “hotline” between olfactory cortex and limbic system (memory & emotion) – Smell is a primitive sense Smell cont. • How olfactory receptors work is a mystery – no distinct receptors for each odor – Triggers combination of receptors that our olfactory cortex interprets – We can recognize 10,000 different odors Smell cont. • Ability to identify scents peaks in early adulthood • Very good at discriminating scents but not good at describing them • Odors have the power to evoke memories and feelings Gender related odors • Can you smell the difference between? Hands, Breath, Shirts So can we smell the difference? • Well….yes and no. Pheromones •Chemical messengers that are picked up through our sense of smell. •Founded in the early 1930’s by studying silkworms. •Jury is still out on whether they exist in humans. Best evidence we have comes out of the university of Chicago. Touch • Composed of 4 senses: warmth, pain, cold, pressure (the only sense with identifiable receptors) • Combinations of these create amazing feelings: – warmth and cold = hot – cold and pressure = wet – pressure and pain = tickling itch Touch - Pain • Gate-Control Theory – spinal cord has “gates” that open/close to transmit pain impulses • Spinal cord has small fibers (transmit pain messages) & large fibers (transmit most other sensory signals) – Small fibers OPEN gates = PAIN – Large fibers CLOSE gates = NO PAIN Touch - Pain • Pain memories – people overlook pains duration – “snapshot” of peak pain and then pain at the end Touch - Pain • Pain is merely a physical and psychological interpretation • Distraction methods – attention is focused elsewhere – can ease the pain felt - Lamaze Childbirth Method • Acupuncture(gate-control), electrical stimulation, and exercise can relieve pain Kinesthetic Sense • System for sensing the position and movement of individual body parts • Relies on sensors in muscles, tendons and joints • Ex. – body parts “falling asleep” – nerve temporarily stops transmitting kinesthetic information Vestibular Sense • System for sensing body orientation and balance, located in the fluid filled semicircular canals of the inner ear • Ex. – spin in circles until dizzy – after you stop spinning the fluid continues to spin – you are dizzy until the fluid stops spinning
"Smell and Taste"