Special Senses_02.pdf - SPECIAL SENSES Special senses have receptors located in specific structures and their sensory impulses are sent to specific

Special Senses_02.pdf - SPECIAL SENSES Special senses have...

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SPECIAL SENSES Special senses have receptors located in specific structures and their sensory impulses are sent to specific areas of the brain unlike the general senses which had receptors scattered throughout the body. Hearing, Vision, Taste and Smell Smell When air is drawn in through the nose, the nasal conchae produce turbulent airflow that brings airborne compounds into contact with the olfactory organs; the molecules become trapped in the mucus Anatomy o 10-100 million chemical receptors; o Olfactory epithelium located on the inferior surface of the cribriform plate, superior portion of the perpendicular plate, and the superior nasal conchae o Olfactory receptor cells – modified neurons; exposed tip is a knob-shaped dendrite; one month lifespan Do not adapt but central adaptation in the brain will block constant awareness o Olfactory hairs – cilia that project from the dendrite knob; respond to chemical stimulation; only takes 4 molecules to activate a receptor o Supporting cells – columnar epithelium; physical support, nourishment, electrical insulation, and chemical detoxification o Basal cells – lie between the supporting cells; produce new olfactory receptor cells o Olfactory (Bowman’s) glands – produce mucus; stimulated by the facial nerve in response to strong chemicals such as perfumes, ammonia, pepper Olfactory pathway – only sensory pathway that does not go through the thalamus o Axons leaving the olfactory epithelium synapse with neurons in the olfactory bulbs. These neurons travel in the olfactory tract to the olfactory cortex, hypothalamus, and the limbic system (emotional brain). Taste Chemical sense; must be dissolved to be tasted; sweet (tip of tongue), sour (sides), salty (all over but mostly sides), bitter (back), umami (chicken broth or parmesan cheese – amino acids), and water (thought to help homeostatic mechanisms that regulate fluid levels in the body). Bitter location though to be for protection; most poisons are bitter; causes gag reflex Anatomy o Taste buds found on the tongue, soft palate, pharynx, and larynx; grouping of cells § Gustatory receptor cells have a single long microvillus, gustatory hair , that projects through the taste pore to the surface of the bud; receptor cells have a lifespan of 10 days § Basal cells – stem cells that produce cells which later become gustatory receptor cells o Papillae – bumps on the surface of the tongue where the taste buds are located § Circumvallate papillae – the largest, form a V-shape at the back of the tongue; 100 taste buds per papillae § Fungiform papillae –
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