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Ch 10, Part 3 PNS (Sight & Taste) Learning Objectives continued The eyes have it! http://video.google.com/videoplay?docid=52862717743253 7232 Bionic Eye? • http://video.google.com/videoplay?docid=2 713236639365268873&q=how+eye+work s&total=3516&start=0&num=10&so=0&typ e=search&plindex=1 How Do We See? Pg. 209 • The retina is a delicate two-layered membrane. It has a: a) ___________ layer – the outer layer that absorbs light and prevents its scattering. b) __________ layer, which contains: – – Photoreceptors that transduce light energy Bipolar cells and ganglion cells Retina continued • Ganglion cell axons: – Run along the inner surface of the retina – Leave the eye as the _____________ • The optic disc: – Is the site where the optic nerve leaves the eye – Lacks photoreceptors (is known as the ___________) Photoreceptors of the Retina • Rods: – Respond to ___ light – Are used for ________ vision • Cones: – Respond to ______ light – Have high-acuity ______ vision Vision When light passes from one transparent medium to another its speed changes and it refracts or ______. Light passing through a convex lens (as in the eye) is bent so that the rays converge to a focal point. When a convex lens forms an image, the image is _______ down and ________ right to left. Putting It All Together: Physiology of the Eye • http://video.google.com/videoplay?docid=5390890065360196056&q=rods+and+con es+of+eye&total=10&start=0&num=10&so =0&type=search&plindex=6 How Do We Taste? Pg. 212 • Taste is ____ smell • Chemical senses – gustation (____) and olfaction (_____) • Chemoreceptors respond to chemicals in aqueous solution – Taste – substances must be dissolved in saliva – Smell – substances must be dissolved in fluids of the nasal membranes Organ of Smell • A yellow-tinged patch of pseudostratified epithelium called the _________ epithelium. • Located in the _______ of the nasal cavity Most of the 10,000 or so taste buds are found on the tongue1 pg 212 Taste buds are found in the fungiform and circumvallate papillae of the tongue mucosa 1 A few taste buds are scattered on the soft palette, inner checks, & pharynx Taste Sensations pg 212 • There are ______ basic taste sensations – Sweet – sugars, saccharin, alcohol, and some amino acids – Salt – metal ions – Sour – hydrogen ions – Bitter – alkaloids such as quinine and nicotine – Umami – elicited by the amino acid glutamate In order to be tasted, a chemical: - Must be dissolved in saliva - Must contact gustatory hairs What are gustatory hairs? Gustatory cells? Look it up - try pg 212 or “google”
