Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Senses  Somatic senses throughout body, including internal organs  Touch, vibrations  Temperature  Pressure  Pain  Body position, movements  Special senses - located in certain areas only  Smell  Taste  Sight  Hearing  Balance

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sensory Receptors: Receive and Convert Stimuli  Mechanoreceptors: mechanical energy  Thermoreceptors: hot or cold  Pain Receptors: tissue injury, excessive pressure  Chemoreceptors: chemicals; taste and smell  Photoreceptors: light

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Receptor Adaptation to Continuing Stimuli  Purpose: CNS concentrates on important stimuli and ignores others  Receptors that adapt: light touch, pressure, smell  Receptors that do not adapt: pain, joint, and muscle monitoring receptors

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sensory Receptors in Skin Figure 12.1

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings CNS Interpretation  Location: nerves hard wired to specific portions of brain, specific nerve stimulus results in assigning specific location  Referred pain  Strength of feeling: frequency of nerve stimulus

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Ear  Houses two senses in different organs  Hearing  Balance  Receptors are mechanoreceptors

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Anatomy of the Ear  The ear is divided into three areas  Outer ear  Pinna, auditory canal Figure 8.12

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Middle Ear  Air-filled cavity within the temporal bone  tympanic membrane  Three bones span the cavity  Malleus (hammer)  Incus (anvil)  Stapes (stirrup) auditory tube

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Inner Ear or Bony Labyrinth  converts sound vibrations to nerve impulses  balance  Filled with perilymph  Chambers:  Cochlea  Vestibule  Semicircular canals Figure 8.12

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Hearing Figure 8.16a–b Cochlea has 2 compartments: 1. Vestibular and tympanic canals (joined at far end) 2. Cochlear duct

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organs of Hearing Figure 8.15 Cochlea in transverse sectionOrgan of Corti

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Hearing Figure 8.16a–b 1. Sound waves 2. Tectorial membrane 3. Hair cells bend 4. Triggers action potential 5. Adaptation to stimulus

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organs of Equilibrium  Receptor cells are in two structures  Vestibule - static equilibrium  Semicircular canals - dynamic equilibrium Figure 8.14a–b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sensing rotational movement Ampulla with mechanoreceptors in cupula Tuft of hair cells  Cupula (gelatinous cap) covers the hair cells Figure 8.14c

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sensing head position and acceleration: Figure 8.13a–b vestibule with otoliths - reports on the position of the head

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Balance: Inner Ear  Specialized structures:  Vestibular apparatus: three semicircular canals and vestibule  Sensing rotational movement: ampulla with mechanoreceptors in cupula  Sensing head rotation and acceleration: in vestibule with otoliths

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemical Senses – Taste and Smell  Both senses use chemoreceptors  Stimulated by chemicals in solution  Taste has four types of receptors  Smell can differentiate a large range of chemicals  Both senses complement each other and respond to many of the same stimuli

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Olfaction – The Sense of Smell  Olfactory receptor cells: chemoreceptors that bind with odorants  Correlation between taste and smell: chewed food releases chemicals that come in contact with olfactory receptors