Special Senses

Special Senses - SPECIAL SENSES I. II. III. IV. Sensory...

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SPECIAL SENSES I. Sensory Receptors a. Characteristics i. ii. Convert physical or chemical stimulus into an action potential b. Named by location i. Exteroreceptors 1. external surface ii. Visceroreceptors 1. viscera iii. proprioreceptors 1. c. Types of Receptors: i. Tactile, pain, chemical, temperature, photo, proprioception ii. Smell iii. Taste iv. Hearing v. Vision II. Chemoreceptors a. Activated by chemical stimulus b. c. Nutrients in GI or blood d. Regulation of breathing e. Located in lg. Blood vessels (eg. aorta) III. Mechanoreceptors a. Activated by pressure or stretch b. Stretch receptors=arteries, stomach lungs, muscles, ligaments, tendons c. d. 4 types: i. Meissner’s corpuscles (skin) 1. hairless area, respond to constant contact (touch) ii. Pacinian corpuscles (skin) 1. respond to deep, heavy pressure (dermis) iii. proprioceptors 1. stretch receptors found in ligaments, tendon, muscles 2. communicate info. About position limbs are in 3. Eg. Hold arm out/know arm is held out w/o looking iv. Baroreceptors- sensitive to pressure 1. stretch receptors located in walls of blood vessels 2. detect blood pressure IV. Thermoreceptors a. Sensitive to temp (via free nerve endings) b. Located in skin (dermis), hypothalamus, internal organs c. Two major types:
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i. Bulbs of Krause=feel cold <20C (pain at < 10C 1. cold receptors ii. Organs of Ruffini=feel hot >25C (pain at > 45C). 1. heat receptors iii. sometimes when you are so cold, your pain receptors may start going off in addition to your cold receptors. d. Exhibit adaptation—getting into hot bath or cold pool e. ADAPTATION =(getting used to it) if stimulus remains the same get decrease in action potentials (requires change in stimulus strength—eg. Elastic on socks, smell of perfume) i. Fast adaptors: smell, sitting in a chair ii. Slow adaptors: pain (fx=protection) V. Pain Receptors (Nociceptors) a. Pain is basically a FREE DENDRITE… b. Little sensory adaptation!!!! c. Free nerve endings; no other structures associated d. Detect extremes in heat/cold, pressure, sense chemicals (acid & damaged tissues). e.
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This note was uploaded on 04/20/2008 for the course BIO 130 taught by Professor Rapps during the Spring '06 term at Carroll WI.

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Special Senses - SPECIAL SENSES I. II. III. IV. Sensory...

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