Chapter 14.1Chapter 14.1Pages 446-448Pages 446-448

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TASTE AND SMELL Taste receptors

Found in diff. locations in diff. species Octopuses – tentacles Crayfish – antennae Insects - legs

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in humans, receptor cells for taste are

modified epithelial cells organized into taste buds

there are five taste perceptions: sweet sour salty bitter umami (savory)(elicited by glutamate)

Once dissolved, specific chemicals stimulate receptors

Taste

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1) Taste4 types of taste that are stimulated by dissolved chemicals in specific taste buds:•Sweet•Salty•Sour•Bitter

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Figure 16.4

(a) Specialized hair- like receptor ends in the tongue detect specific chemicals, Axons from the sensory neurons are shown in yellow, (b) Taste buds of a rabbit tongue, The taste bud appears as a bulblike structure,

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Taste receptors

http://www.mhhe.com/biosci/genbio/espv2/data/animals/003/index.html Click on taste sensation

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•Taste receptors and olfactory create the perception of taste

Smell (olfaction)

Detection of a specific airborne chemicals that stimulates an olfactory cell to produce action potential that is perceived in the olfactory bulb.

Olfactory receptor cells are neurons that line the upper portion of the nasal cavity

Binding of odorant molecules to receptors triggers a signal transduction pathway, sending action potentials to the brain

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DETECTING SMELLDETECTING SMELL

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• Olfactory cells demonstrate sensory adaptationsensory adaptation• People who live in cities

with pulp mills adjust to odor• Odor seems to fade after a

short period of time Taste http://www.bbc.co.uk/science/

humanbody/body/factfiles/taste/taste_ani_f5.swf

Smell http://www.bbc.co.uk/science/

humanbody/body/factfiles/smell/smell_ani_f5.swf

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•Each mechanoreceptor is a modified dendrite of a sensory neuron

3) Sensory receptors in human skin•Despite an incredible collection of specialized sensory receptors, much of environment remains undetected

Skin receptors http://www.sumanasinc.com/webcontent/animations/content/skinreceptors.html

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Senses game http://www.bbc.co.uk/science/humanbody/

body/interactives/senseschallenge/