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Sensory and Motor Mechanisms Chapter 49 PowerPoint Presentation
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Sensory and Motor Mechanisms Chapter 49
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  1. Sensory and Motor Mechanisms Chapter 49

  2. Sensory and motor mechanisms • Sensory receptors in general - transduction • Sound receptors - the cochlea and pitch • Chemoreceptors - insect pheromones • Electromagnetic receptors - migration

  3. Functions Performed by Sensory Receptors • All stimuli represent forms of energy • Sensation involves converting energy into change in the membrane potential of sensory receptors • Functions of sensory receptors: sensory transduction, amplification, transmission, and integration

  4. LE 49-2a Sensory reception: crayfish stretch receptors - Fig. 99.2a Weak muscle stretch Strong muscle stretch Muscle Dendrites Receptor potential –50 –50 –70 –70 Stretch receptor Membrane potential (mV) Action potentials 0 0 Axon –70 –70 0 2 0 2 1 3 4 5 6 7 1 3 4 5 6 7 Time (sec) Time (sec) in the axon of the stretch receptor. A stronger stretch produces a larger receptor potential and higher frequency of action potentials. muscles and dendrites stretch, producing a receptor potential in the stretch receptor. The receptor potential triggers action potentials Crayfish stretch receptors have dendrites embedded in abdominal muscles. When the abdomen bends,

  5. Sensory reception: vertebrate hair cells - Fig. 99.2b No fluid movement Fluid moving in one direction Fluid moving in other direction “Hairs” of hair cell More neuro- trans- mitter Neuro- trans- mitter at synapse Less neuro- trans- mitter Axon –50 –50 –50 Receptor potential –70 –70 –70 Membrane potential (mV) Membrane potential (mV) Membrane potential (mV) Action potentials 0 0 0 –70 –70 –70 0 2 0 2 1 3 4 5 6 7 0 2 1 3 4 5 6 7 1 3 4 5 6 7 Time (sec) Time (sec) Time (sec) at a synapse with a sensory neuron, which conducts action potentials to the CNS. Bending in one direction depolarizes the hair cell, causing it to release more Vertebrate hair cells have specialized cilia or microvilli (“hairs”) that bend when surrounding fluid moves. Each hair cell releases an excitatory neurotransmitter neurotransmitter and increasing frequency of action potentials in the sensory neuron. Bending in the other direction has the opposite effects. Thus, hair cells respond to the direction of motion as well as to its strength and speed.

  6. Sensory and motor mechanisms • Sensory receptors in general - transduction • Sound receptors - the cochlea and pitch • Chemoreceptors - insect pheromones • Electromagnetic receptors - migration

  7. Transduct-ion in the cochlea -- Fig. 49.8

  8. Transduct-ion in the cochlea -- Fig. 49.8

  9. Transduct-ion in the cochlea -- Fig. 49.8

  10. Transduct-ion in the cochlea -- Fig. 49.8

  11. Transduct-ion in the cochlea -- Fig. 49.8

  12. Transduction in the cochlea -- Fig. 49.9 Cochlea Stapes Axons of sensory neurons Vestibular canal Perilymph Oval window Apex Base Basilar membrane Tympanic canal Round window

  13. Sensing pitch in the cochlea -- Fig. 49.10 Cochlea (uncoiled) Basilar membrane Apex (wide and flexible) 500 Hz (low pitch) 1 kHz 2 kHz 4 kHz 8 kHz 16 kHz (high pitch) Frequency producing maximum vibration Base (narrow and stiff)

  14. Sensory and motor mechanisms • Sensory receptors in general - transduction • Sound receptors - the cochlea and pitch • Chemoreceptors - insect pheromones • Electromagnetic receptors - migration

  15. text

  16. Chemoreceptors in a silkworm moth - Fig. 49.4

  17. The pheromones and the protein that binds them are known

  18. text

  19. Sensory and motor mechanisms • Sensory receptors in general - transduction • Chemoreceptors - insect pheromones • Sound receptors - the cochlea and pitch • Electromagnetic receptors - migration

  20. Electromagnetic receptors - beluga whales migrating

  21. a molecular profile for the baluga whale…

  22. Trout have magnets in their noses. magnet response of individual particles

  23. Magnetotactic bacteria synthesize magentite in membrane-bound vesicles – the vesicles align to make a compass. One cell One string of vesicles

  24. Sensory and motor mechanisms • Sensory receptors in general - transduction • Chemoreceptors - insect pheromones • Sound receptors - the cochlea and pitch • Electromagnetic receptors - migration