2007PSY Biopsyc Week 2 Mindmap

2007PSY Biopsyc Week 2 Mindmap

1. Generating Action Potentials

   • 1. Electrical signal developed in presynaptic neuron
     • 2. Duplicated down length of axon
       • 3. Arrives at axon terminal, switches from electric to chemical signalling
         • 4. Presynaptic neuron releases molecules of neurochemical from terminal
           • 5. Neurochemical molecules float across the synaptic gap to waiting postsynaptic or recieving neuron
   • Voltage flow
     • 1. Threshold of -65mV must be reached
       • 2. Voltage-gated sodium ion channels allow sodium to flow into neuron
         • 3. Voltage-gated potassium ion channel opens near peak of action potential to let potassium flow out of cell
           • 4. Conclusion of AP, the membrane hyperpolarises
             • 5. AP are "all or none"

2. Voltage

   • Atoms have positively charged nucleus
     • Surrounded by -ive electrons
       • In normal state, equal each other out
   • Atoms loose electron (-ive) become positive
     • Atoms gain electron (-ive) become negative
   • Maintaining resting potential
     • Extracellular +ive sodium ions (more outside than inside) will be strongly attracted to inside of cell
       • - electrostatic, + diffusion
     • Intracellular +ive potassium ions will be more attracted to extracellular fluid
       • - diffusion

3. Synapses

   • Gap Junction
     • - Instantaneous
     • - Excitatory messge only
     • - Large presynaptic neuron to influence small postsynaptic neurons
     • - 3.5mn synaptic gap
     • - Method of transmisson: Direct movement of ions from one cell to the other
   • Chemical Synapses
     • - 20mn synaptic gap
     • - Several milliseconds
     • - Method of transmission: release of neurochemicals
     • - Excitatory or inhibitory
     • - Small presynaptic neurons can influence large postsynaptic neurons
     • 1. Neurotransmitters are released from presynaptic cell
       • 2. Neurotransmitters bind to postsynaptic receptor sites
         • 3. Chemical signal is then terminated
     • NT Release
       • 1. AP goes down axon
         • 2. Terminal boutins (synaptic terminal)
           • 3. Voltage-gated calcium channels open
             • 4. Ca2 enters
               • 5. Exocytosis
                 • 6. Synaptic vesicles fuse with presynaptic membrane and spill contents into gap
                   • 7. NT diffuse across synaptic gap and bind to postsynaptic neuron
                     • Can't be left in gap or will continue to be blocker
           • Contain synaptic vesicles w NTs

4. Receptors

   • Ionotropic Receptor
     • 1. Neurochemical molecules bind to an ion channel
     • 2. Channel opens and ions pass through
   • Metabotropic Receptor
     • 1. Neurochemical binds to a receptor
     • 2. The receptor releases a G protein, which binds to an ion channel
     • 3. The G protein causes the ion channel to open, and ions pass through