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Sensory Systems - Coggle Diagram

- - - - Cation channels open up (i.e. mechanosensitive Na+ channels) to depolarize nerve endings
        
        Receptor potential is generated in the transducer region. As stimulus intensity increases >>> Magnitude of receptor potential increases >>> Recruitment of voltage-gated Na+ channels in the spike generator region
        
        Action potential is generated in the spike generator region, then travels along the axonal membrane
        
        If axon is myelinated: Action potential travels by saltatory conductions
        If axon is unmyelinated: Action potential travels by way of continuous propagation
  - - - Production:
        
        In the nerve endings
        
        In specialized NEURAL cells
        
        In specialized NON-NEURAL cells
        
        A GRADED response (i.e. as stimulus increases, it increases also)
        
        A LOCAL potential (DOES NOT travel along the whole length of the sensory nerve)
        
        Can undergo SPATIAL and TEMPORAL summation
        
        Function of a Receptor Potential
        
        To TRIGGER action potentials
- - - - Receptor Potential produced in the transducer region >>> Recruits voltage-gated Na+ channels in the spike generator region >>> Action Potential
        
        Ex. Pacinian Corpuscle
        
        Its cell is a vibration sensor
  - - - Endogenous CM that are DIRECT Activators:
        
        Bradykinin, Serotonin, Histamine, K+, H+, Acetylcholine, Proteolytic Enzymes, Nerve endings, Naked nerve endings
      - Endogenous CM that are INDIRECT Activators: (Sensitizers)
        
        Prostaglandin, Substance P
      - In cutaneous unmyelinated nerve fibers
        
        Molecular Receptors on the endings of nociceptive sensory nerves that respond = TRP Family (Transient Receptor Potential Channels)
  - - - Warm Receptor Free Nerve Endings (C-Fiber)
        
        Molecular Receptor: TRPV4 (Up to 34C) + TRPV3 (Up to 35-39C)
      - Cold Receptor Free Nerve Endings (alpha-delta in myelinated, C-fibers in unmyelinated)
        
        Molecular Receptor: CRM1 or TRPM8 (Sensitive to moderate cold)
      - Increase in STIMULUS INTENSITY
        
        Increase in Receptor Potential MAGNITUDE
        
        Increased spike discharge >>> Increased FREQUENCY of action potential until it reaches the somatosensory cortex