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test 4 study guide - Lingual Papillae epithelial...

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Lingual Papillae- epithelial projections on the superior surface of the tongue. 3 different types Filiform papillae- provide friction that helps the tongue move objects around the in the mouth, but do not contain taste buds Fungiform Papillae- each contain about five taste buds Circumvallate papillae- each contain as many as 100 taste buds. Form a V near posterior margin of the tongue Taste buds- taste receptors and specialized epithelial cells. Are recessed into the surrounding epithelium, isolated from relatively unprocessed contents of the mouth. Each contain about 40 slender, spindle- shaped cells Basal cells appear to be stem cells. Divide to produce daughter cells that mature in stages Gustatory cells- basal cells in the last stage. Extend slender microvillus called taste hairs, into the surrounding fluids through the taste pore, a narrow opening 6 Taste Sensations Sweet, salty, sour, bitter, umami, and water Salt/sweet- detected anteriorly and sour/bitter detected posteriorly Umami- pleasant taste characteristic of beef broth, chicken broth, and parmesan cheese. Sensitive to the presence of amino acids (especially glutamate), peptides and nucleotides. Distribution not known put present in taste buds of the circumvallate papillae Water Receptors-present in the pharynx. The sensory output of these receptors is processed in the hypothalamus and affects several systems that affect water balance and regulation of blood volume. Gustation is dependent on the olfactory receptors because well airborne molecules reach the olfactory receptors it helps the brain relate a taste to the food. If airborne molecules cannot reach the olfactory tract then meals will be dull and unappealing. Physiology of Gustation Dissolved chemicals contact the hairs and bind to the receptor proteins of gustatory cells o Salty and sour receptors are chemically gated ion channels whose stimulation produces depolarization of the cell o Sweet, bitter, umami- Receptors are G proteins called gustducin which are protein complexes that use second messengers to produce their effects
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o Receptors adapt slowly but central adaption quickly reduces your sensitivity to the new taste o End result of the taste receptors stimulation is the release of neurotransmitters by the receptor cell. Dendrites of the sensory afferents are tightly wrapped by the folds of the receptor cell membrane, and neurotransmitters release leads to the generation of action potentials in the afferent fibers. Vision Light is refracted when it passes from one medium to another medium with a different density o In the human eye refraction occurs when light passes from the air to the corneal tissues which have a density close to water. How are the eyes protected by the skull?
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This note was uploaded on 11/18/2009 for the course BIO 121 taught by Professor Morris during the Spring '09 term at Widener.

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test 4 study guide - Lingual Papillae epithelial...

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