OAP B - Class Test 3

• Perception


  The way we interpret differences in the external or internal environment is defined as
• In the somatosensory and autonomic nervous system, what are the 3 main types of sensory receptors?

  Exteroceptor, Interoceptor and Proprioceptor
• Exteroceptor


  Near surface body, sense external stimuli (Merkel's disc, Meissners corpuscles, hair root plexus, Ruffini corpuscles)
• External stimuli


  Taste, touch, pressure, pain, vibration and temperature
• Interoceptor


  Senses internal environment (viscera)(chemoreceptor), not conscious except for pain + pressure
• Proprioceptor


  Senses body position, movement and equilibrium (muscle spindles and joint receptors)
• Which neuron would most likely pick up an itch sensation?

  Free nerve ending
• Nociceptors


  Responsible for perceiving pain
• What receptors perceive temperature?

  Free nerve endings with 1mm diameter receptive fields on the skin surface
• What temperature changes induce pain?

  Below 10 degrees Celsius and over 40.5 degrees Celsius
• Cold receptors temperatures


  Between 10-40.5 degrees Celsius
• Cold receptors location


  Stratum basale
• Warm receptors temperatures


  Between 32.2-47.8 degrees Celsius
• Warm receptors location


  Dermis
• Cold and warm pain receptors

  Both adapt rapidly at first but continue to generate impulses at a low frequency
• Direct motor pathways


  Pyramidal pathways
• Indirect motor pathways


  Consist of 2 major tracts
• Lateral corticospinal tracts


  Component of the direct motor pathways
• Rubrospinal tracts


  Part of indirect motor pathways
• Primary information carried by the spinocerebellar tracts

  Unconscious proprioceptive information
• Lateral spinothalamic tract


  Carries information about pain and temperature
• Odourant molecules


  Bind to olfactory receptor protein activating a G protein coupled receptor
• Step 2 for odourant molecules binding

  Cascade opens Na+ channels which may trigger an action potential
• Step 3 for odourant molecules binding

  Action potential travels down the olfactory receptor cell axon which becomes part of the olfactory nerve
• Step 4 for odourant molecules binding

  Axons synapse onto neurons in the olfactory bulb
• Step 5 for odourant molecules binding

  Axons of olfactory bulb form the olfactory tract and extend to synapse on neurons in the primary olfactory area in the temporal lobe
• Step 6 for odourant molecules binding


  Signals travel from the primary olfactory area to orbit frontal area in the frontal lobe
• Cell types in the olfactory cells

  Bipolar first order neurons
• Gustatory receptors


  One of three epithelial cell types found within a taste bud
• How many tastants are there?

  5
• Name the tastants?


  Salty, sweet, sour, bitter and umami
• What are tastants?


  Chemicals that stimulate gustatory receptor cells
• What are tastants dissolved in?

  Saliva
• What processes tastants?


  Taste buds
• What happens after gustatory receptors are processed?

  Gustatory receptors are stimulated triggering neurotransmitter release
• How do salty + sour tastants achieve processing?

  Entering receptor cells directly
• How do sweet, bitter + umami tastants achieve processing?

  G protein coupled receptor activation
• Auricle


  Funnels sound waves towards tympanic membrane causing it to vibrate
• Process of sound waves transmitted down into inner ear - Step 1

  Vibration of tympanic membrane triggers vibration in the auditory ossicles which vibrates oval window
• Process of sound waves transmitted down into inner ear - Step 2

  Pressure waves arise in the perilymph