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MOLECULAR AND CELLULAR NEUROBIOLOGY, Example: ACh and muscle ACh opens…

- - - - Given the high concentration of potassium in the cell, it diffuses outwards and causes the cell to be depolarised. The diffusion of potassium drives membrane potential to -90mV
        
        However, this is countered by sodium that is diffusing into the cell. The diffusion of sodium into the cell drives the membrane potential to +60mV
        
        As a result, the resting membrane potential is at -70mV
- - - - Chemical
      - Thermal
      - Voltage
      - Mechanical
  - - - Membrane potential reaches threshold as a result of graded potential
        
        Sodium gates open when threshold potential is reached. This allows sodium to rush into the cell, depolarising to +30mV
        
        At the peak, the sodium gates close (and incapable of opening) and the potassium gates open.
        Even though the opening of potassium gates are triggered at threshold potential, there is a delay. The opening of the gates allows potassium to rush out, repolarising the membrane.
        
        After reaching resting potential, the sodium gates are closed but are capable of opening, ready to respond to another depolarising event.
        
        The potassium gate, with its delayed closure, continues to allow potassium to move out, leading to hyperpolarisation for a short while.
        
        When potassium gates finally close, the membrane goes back to its resting potential
    - - Dendrites receive information from other neurons
        
        Signals sent to cell body, or soma
        
        From the axon hillock, an action potential is triggered and propagated in succession across the length of the axon, or the nerve fibre
        
        Neurotransmitters are then sent out via the axon terminals to other cells
        
        Refractory period ensures one-way propagation of action potentials and limits their frequency
        
        Action potential cannot be initiated in a region that has just undergone an action potential.
        
        This is because sodium gates are closed (and incapable of opening)
        
        Because of hyperpolarisation due to delayed closure of potassium gate, no action potential can be initiated except for higher than normal stimulus
- - - - Synaptic cleft
        
        Neurotransmitters go across the synaptic cleft
        
        Postsynaptic terminal
        
        Neurotransmitters reaches here
        
        Received by receptors