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The Senses Ch 36.2. The 5 Major Senses. Smell Taste Sight Touch Hearing How our brain/body takes in stimulus from the environment How we learn about the world. Smell. Breathing air through your nose pulls in particulate matter (chemicals floating in the air) Olfactory :
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The 5 Major Senses • Smell • Taste • Sight • Touch • Hearing • How our brain/body takes in stimulus from the environment • How we learn about the world
Smell • Breathing air through your nose pulls in particulate matter (chemicals floating in the air) • Olfactory: • collection of receptors in top of the nose • Chemicals bind to receptors, and signals are sent to the brain along a cranial nerve • Brain interprets good and bad smells based on what chemicals are detected • Why have a sense of smell?
Good Smells vs. Bad Smells • Things smell good because they are good for the body or the mind: Meat- smell of fats and proteins Flowers- smell triggers release of hormones that relax us Fruits- smell of sugars and vitamins • Things smell bad because they might kill us: Waste material- contain bacteria; no useful material Rotten Food- contain bacteria; bad for digestion
Taste • Smell and taste are strongly linked • Taste buds: - receptors for each of the 5 tastes: salty, sweet, sour, bitter, umami - Chemical reacts with receptor and signals are sent to the brain Why do things taste good? Why do they taste bad?
Sight • Sight is detecting the photons of light bouncing of objects • Pupil: opening into the eye • Lens: focuses the light to clear the image; made of clear cells • Retina: special part of the eye that reacts to photons Images passing through the lens are flipped and our brain learns to flip them back
Rods and Cones • Rod cells: detect low levels of light (black and white) • Cone cells: detect high levels of light (color) S- detect blue light M- detect green light L- detect red light Overlapping signals from cones create the other colors
Hearing • Sound travels as waves through media (air, water, etc…) • Eardrum: • Vibrates to changing pressure from sound waves • Vibrations travel through the body’s smallest bones (Malleus, Incus, and Stapes) • Cochlea: • Vibrations from travel into fluid • Fluid activates hire-like receptors which send impulses to the brain • Ear as a hair for different frequencies
Hearing (Balance) • Cochlea as 3 semicircular canals filled with fluid and motion receptors (hair-like) • Movement in the fluid triggers impulses that tell the brain direction and orientation • Small Ca+ stones inside also push down on the hairs Why? -Feel which way is up/down
Touch • A collection of different receptors: • Temperature • Pressure • Pain • Different parts of the body have higher concentration of touch sensors • Eyelids, fingers, feet, tongue, etc… • Some receptors fire faster than others: • You can feel the texture of an object before its temperature
Extra Senses • Echolocation: use sound waves to find objects • Infrared vision: can see heat of an object • UV vision: see UV signals • Electroreception: can sense electric fields • Magnetoreception: can sense magnetic fields