Other Important Senses: Touch, Taste, and Smell Chapter 5 Other Important Senses: Touch, Taste, and Smell

Touch Essential for development Skin = the largest sense organ body — allows for touch; detects pressure Most sensitive – fingers, lips, cheek, foot, & forehead Least sensitive – belly, upper arm, shoulder, thigh, & calf Sense of touch has 4 basic sensations: 1. Pressure 2. Pain 3. Warmth 4. Cold

Pain Pain experiences can be: Tells you something is wrong – change behavior Pain experiences can be: Biological- Nerve fibers sending info to the brain Psychological- Situation and our past experiences Social-cultural- Cultural expectations/presence of others

Pain is in the brain Lamaze classes teach women the technique of distraction during childbirth 7-10 amputees feel pain in their non-existent limb (phantom limb) Occurs also with hearing, sight, taste & smell losses.

Gate Control Theory Gate-Control Theory- spinal cord contains a “gate” that either blocks pain signals or allows them to pass to brain Rub area around pain to stimulate “gateclosing” activity. Release of endorphins (neurotransmitters) natural painkiller

Body Position and Movement Kinesthetic Sense (Kinesthesis) monitors and coordinates movement among body parts through information sent from sensory neurons (proprioceptors) Allows to be aware of movement without actually seeing limb move.

Vestibular Sense - Sense of Balance Vestibular Sense monitors head position and balance. Fluids in the inner ear (vestibular sacs & semicircular canals) help to maintain your equilibrium. Semicircular Canal - Pretzel like canals holding fluid which are connected to the cochlea. Allows us to sense our body position and to maintain balance by moving when the head rotates or tilts. MAIN CAUSE OF MOTION SICKNESS

Taste - Gustation Taste Buds - sensory receptors located on tongue Taste is a chemical sense As you grow older taste buds decrease (Smoking & alcohol use accelerate the decline) Believed genetics predispose us to certain taste Taste receptors reproduce every week or so

Taste - Gustation Traditionally, taste sensations consisted of sweet, salty, sour, and bitter tastes. Recently, receptors for a fifth taste have been discovered called “Umami.” All other tastes are a mixture. Preview Question 11: How do we experience taste? Sweet Sour Salty Bitter Umami (Fresh Chicken)

Taste - Gustation All other tastes are mixtures Taste buds contain a pore that catches food chemicals. Molecules are then sensed by taste receptor cells. Taste receptor cells project antenna-like hairs into pores Taste receptors reproduce themselves every week or two

Sensory Interaction When one sense affects another sense, sensory interaction takes place. Smell plus texture plus taste equals flavor In interpreting the world, the brain blends the inputs of a senses.

Smell – Olfaction (Chemical Sense) We smell something when molecules of a substance carried in the air reach a tiny cluster of 10-20 million receptor cells at the top of each nasal cavity. Olfactory receptor cells in nasal cavity wave around and respond selectively to alert the brain Olfactory Bulb - smell is registered and converted into neural messages

Olfactory nerves Olfactory Tract- takes information to different parts of brain Limbic System emotional significance is associated Temporal Lobe - recognition of smells Smell does not go to the thalamus like the other senses.

A few last notes on smell Attractiveness of smells depends on learned associations Odors have the power to evoke memories and feelings