Finals physiology

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• Take notes! Prepare for a short quiz after the lecture. Long Exams will cover book and lecture discussions.
• Disclaimer: Most information are lifted from Chapter 5 p. 154-207 of Christopher D. Moyes, Patricia M. Schulte - Principles of Animal Physiology, 3 ed. Pearson (2016)
• Sensory System


  Range from single cells to complex sense organs
• Types of receptors


  • Chemoreceptors
  • Mechanoreceptors
  • Photoreceptors
  • Electroreceptors
  • Magnetoreceptors
  • Thermoreceptors
• Receptor transduction


  1. Receptor protein detects stimulus

  2. Opening or closing of ion channel

  3. Change in membrane potential

  4. Signal sent to integrating center (central nervous system)
• All receptors transduce incoming stimuli into changes in membrane potential
• Taking of pictures
• Take notes!
• Prepare for a short quiz after the lecture
• Long Exams will cover book and lecture discussions
• Most information are lifted from Chapter 7 p. 257-309 of Christopher D. Moyes, Patricia M. Schulte - Principles of Animal Physiology, 3 ed. Pearson (2016) and Chapter 6 Christopher D. Moyes, Patricia M. Schulte - Principles of Animal Physiology, 2 ed. Pearson (2008)
• BIO4210 Animal Physiology
• Module 2: Sensory System and Sensation
• Cyd Vincent L. Zamora, MD, Florence Marie Maramba, MD, Armeo Eugenio Peñafiel, Jr., MD
• Sensory System – General Properties: Range from single cells to complex sense organs

  
• Types of receptors


  • Chemoreceptors
  • Mechanoreceptors
  • Photoreceptors
  • Electroreceptors
  • Magnetoreceptors
  • Thermoreceptors
• Receptor transduction process


  • Receptor protein detects stimulus
  • Opening or closing of ion channel
  • Change in membrane potential
  • Signal sent to integrating center (central nervous system)
• Classification of Sensory Receptors

  • Stimulus Location: Telereceptor, Exteroceptors, Interoceptors
  • Stimulus Modality: Chemoreceptors, Mechanoreceptors, Photoreceptors, Electroreceptors, Magnetoreceptors, Thermoreceptors

  
• Sensory Receptors: Generator potential and Receptor potential

  
• Generator potential


  Sensory receptor is also the primary afferent neuron, change in membrane potential spreads along membrane

  
• Receptor potential


  Sensory receptor is separate from the afferent neuron, change in membrane potential triggers release of neurotransmitter

  
• Receptive field


  Region of the sensory surface that causes a response when stimulated, smaller receptive field allows more precise location of the stimulus (i.e., greater acuity)
• Improved ability to localize stimuli by using more than one sensory receptor cell and lateral inhibition

  
• Two classes of receptors that encode stimulus duration

  • Phasic: Produce APs at the beginning or end of the stimulus, encode change in stimulus, but not stimulus duration
  • Tonic: Produce APs as long as the stimulus continues, encode duration of stimulus
• Receptor adaptation – AP frequency decreases if stimulus intensity is maintained at the same level
• Most cells can sense chemical stimuli, animals have many types of chemoreceptors
• Olfaction (smell)


  Detection of chemicals in air
• Gustation (taste)


  Detection of chemicals emitted from food
• Odorant receptors in the olfactory system

  
• Vomeronasal organ detects pheromones, chemical signals between animals, structurally and molecularly distinct from the olfactory epithelium

  
• Olfactory system in invertebrates: Located in many parts of the body, primarily on antennae, contain sensilla with odorant receptor neurons

  
• Five classes of tastants

  • Salty
  • Sweet
  • Bitter
  • Sour
  • Umami (savory or meaty)
• Sweet, umami, and salty indicate carbohydrates, proteins, and ions, bitter and sour indicate potentially toxic substances
• Taste receptors are epithelial cells that release neurotransmitter, taste receptor cells clustered in groups on tongue, soft palate, larynx, and esophagus, and on external surface of the body in some fish
• Taste receptor transduction pathways
• Taste in invertebrates: Located on sensilla inside and outside the mouth, along the wing margin, and at the ends of the legs, receptors are bipolar sensory neurons that express only a single receptor protein
• Mechanoreceptors


  Mechanical to Electrical signals, 3 classes: Baroreceptor, Tactile, Proprioceptor, two main types of mechanoreceptor proteins: ENaC and TRP channels
• Tactile receptors
• Equilibrium and hearing utilize mechanoreceptors, vertebrates have ears for both, invertebrates have separate organs