BIOL 2312 Chapter 44.4-44.5: Chapter 44.4- 44.5 Sensory Systems
7 Feb 2017
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6:04 pm: 44. 4- chemoreceptors: taste, smell, and ph. Tate buds- collections of chemo sensitive epithelial cells associated with afferent neurons. Fish have taste buds scattered throughout their surface body. Microvilli poke through top of taste bud forming a taste pore. Chemicals from food dissolve in saliva---> contact taste cells through pore. Salty- due to na ions diffusing through na into receptor cells in the taste bud---> depolarizes membrane---> receptor cells releases neurotransmitter---> activates sensory neuron. Sour works same way but with h+ Sour tastes associated with increases concentration of protons. Different tastes are encoded based off of what receptor cells are activated. Smell can identify a vast number of complex molecules. Olfaction involves chemoreceptors in the upper passages on the nasal cavity. Have receptors which have dendrites with tassel cilia that go into the nasal mucosa with axon directly into the cerebral cortex. Particles in air must dissolve in extracellular fluid before they can activate olfactory receptors.
