your chemical senses
Post on 24-Feb-2016
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Your Chemical Senses
Taste and Smell
When you look at your
tongue in the mirror you can
see raised areas or
“bumps” you are seeing papillae.
Papillae Structure
Nutrition
1. Cue logs due tomorrow2. Article on taste perception
– read and summarize, due Thursday
Taste Bud Structure• Taste buds are made of taste receptor
cells• Taste receptor cells have microvilli
–Sensitive, microscopic hairs on taste buds
–Send chemical signals to brain• The brain interprets the signals and
identifies the taste
Chemoreception• Sensory receptors: the presence of
certain molecules creates an action potential which is understood by the brain
• Action potential: spikes of electrical charge which carry information rapidly to the brain
• Neurons are specialized to use changes in membrane potential for fast communication
Action Potentials• There is a difference in value
or charges (voltage) across a membrane: it is said that the membrane is polarized
• When the membrane potential of a cell becomes less negative than usual, we say that the cell is depolarized.
Chemoreception:Salty and Sour
• Salty: Na+ ions–Presence in ion channels depolarizes membrane
• Sour: H+ ions–Presence in proton channel closes K+ channels, K+ can’t leave cell, depolarizes membrane
Chemoreception: Bitter, Sweet, Umami
• Sweet/Umami: –Substance binds with receptor, activates gustducin
which activates the production of cyclic AMP • Cyclic AMP regulates Ca2+ ion channels; calcium
causes neurotransmitter release; depolarizes membrane
• Bitter: –Substance binds with receptor, activates gustducin
which activates phosphodiesterase; which in turn destroys cyclic AMP. • This closes K+ channels, depolarizing membrane
Chemoreception
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