Ch17NotesSum11

Ch17NotesSum11 - Ch. 17 The Special Senses Olfaction...

Info iconThis preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Ch. 17 – The Special Senses • Olfaction (smell) • Gustation (taste) • Vision (sight) • Equilibrium (balance) • Hearing • Seeing dead people Fig. 17-1a, p. 562 Olfaction (smell) Olfactory organs are made up of: Olfactory epithelium (see the next slide) – An underlying lamina propria (= areolar CT, BVs, and nerves)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Fig. 17-1b, p. 562 Olfactory epithelium Olfactory receptor cells = first-order sensory neurons (bipolar) – The dendrites have olfactory cilia with membrane receptor proteins that bind to specific inhaled water- or lipid-soluble chemicals (= odorants ) • The surface area of the olfactory cilia approximates the surface area of the entire body! – When stimulated, the receptors depolarize and send APs toward the olfactory bulbs and CNS Also present : supporting cells , basal (stem) cells (neuron regeneration!), and olfactory (Bowman) glands (which produce wet mucus to help dissolve odorants) Some ol’ facts • Olfaction is poorly understood overall • There is a low sensory threshold for olfaction – E.g. beta-mercaptan is added to natural gas, which is odorless • 1 mg of beta-mercaptan per 25 billion mL of natural gas can be sensed • There may be hundreds of “primary smells” that contribute to 2000-4000 distinguishable scents • Olfaction rapidly adapts (centrally); it’s also capable of being facilitated by other parts of the brain • Olfactory pathway : – 1. Olfactory receptor cells (= first-order neurons) – 2. Through the olfactory foramina of the ethmoid to the… – 3. Olfactory bulb (= second-order neuron cell bodies) – 4. Olfactory tract (= axons of second-order neurons), which… – 5. Synapse in the temporal lobe (in the olfactory cortex) • This sensory area provides conscious awareness (perception) of smell • Olfactory sensations don’t have to go to the thalamus first – 6. Olfactory information is also sent to the hypothalamus/limbic system
Background image of page 2
3 Fig. 17-2, p. 565 Gustation (taste) An anatomical overview Fig. 17-2c, p. 565 Taste buds • Contain 3 cell types : –1 . Gustatory cells = specialized receptor cells , NOT neurons (in contrast to olfactory receptors); they… • Have “taste hairs” (= microvilli) • Synapse with first-order sensory neurons • Are innervated by CNs VII (anterior 2/3 of the tongue), IX (posterior 1/3 of the tongue), and X (epiglottis) • Live about 10 days –2 . Basal cells = probably stem cells, which develop into… –3 .
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Fig. 17-2b, p. 565 Lingual papillae • = epithelial projections on the superior surface of the tongue • There are 3 types : –1 . Filiform papillae have no taste buds • They are for friction only –2 . Fungiform papillae have ~ 5 taste buds each –3 . Circumvallate papillae – have up to 100 taste buds each • These are located near the back of the tongue only The physiology of taste
Background image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/29/2011 for the course BIOLOGY 24011 taught by Professor Pan during the Fall '11 term at HCCS.

Page1 / 26

Ch17NotesSum11 - Ch. 17 The Special Senses Olfaction...

This preview shows document pages 1 - 5. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online