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The Nervous system - Coggle Diagram

- - - - Vesicles of neurotransmitters
      - Mitochondria
      - Ca2+ channels (Membrane)
    - - The gap is called the synaptic cleft
      - Has receptors for neurotransmitters
      - Has Na+ channels
  - - - Caused by Ca2+ channels opening
        
        On the synaptic knob membrane
    - - Causes vesicles to fuse into presynaptic membrane
    - - Binding to receptors
        
        Located on post-synaptic membrane
    - - By exocytosis (Requires ATP)
    - - Located on post-synaptic membrane
      - Na+ diffuses into cell
        
        Causing depolarisation
    - - Using enzymes in synaptic cleft
      - Transporters take products back
        
        Into synaptic knob
    - - Which is repackaged into vesicles
      - Ensures impulses are not continually stimulated by receptors
  - - - Vesicles only found in synaptic knob
      - Receptors only found in post-synaptic membrane
    - - Ensures vesicles are not released continuously
        
        Also prevented by reabsorbing neurotransmitters
        
        using transport proteins
  - - - Prevents post-synaptic depolarisations
      - Ways they might work
        
        Prevents Ca2+ channels opening
        
        Prevents exocytosis
        
        Blocks receptors
        
        Causes hyperpolarisation of post synaptic membrane
        
        Harder to reach threshold
    - - Ways they might work
        
        More exocytosis
        
        Or preventing uptake of neurotransmitters from cleft
        
        Inhibits enzymes that break down neurotransmitters
        
        Mimics the effect of neurotransmitters
        
        links / binds to the receptors
- - - - Muscle
      - Gland
        
        Endocrine gland
        
        Endocrine responses
        
        Slow, but more present
        
        Hormones released into bloodstream
        
        Moves around the body, affecting target organs
  - - - Roots
      - Branches
  - - - Surrounded by three membranes (meninges)
    - - Entering (Sensory neurones)
        
        Enters by the dorsal root (back)
        
        Cell body located by swelling
        
        In the dorsal root ganglion
      - Exiting (Motor neurons)
    - - Myelinated neurons
    - - Relay neurons
        
        Connects sensory + motor neurons
        
        Synapses to both neurons
      - Non-myelinated neurons
      - Nuclei
      - Cell bodies
        
        Motor neurons
- - - - Measured using micro-electrodes inside the axoplasm and fluid
      - Potential difference is displayed on an oscilloscope
    - - Maintains -70mV
        
        Resting potential of the neurone
        
        Maintained by Na / K pump
        
        Three Na+ out neurone, Two K+ into neurone
      - Polarised
    - - K+ passes out of the axoplasm
        
        By facilitated diffusion
    - - Ma+ remains out of neurone
  - - - Permeability to Na+ increases
        
        Na+ channels open
    - - -55mV
        
        Dependant on strength of stimulus
        
        Full action potential is generated
        
        If not reached, Na+ channels close
        
        Resting potential restored
    - - Rapid influx of Na+ into axon
        
        Inside is +, outside is -
        
        Depolarisation
        
        Action potential is caused
    - - Potential difference falls
        
        Repolarisation
      - K+ leaves axoplasm
        
        By facilitated diffusion
        
        Travels quickly
        
        Through K+ channels
        
        Down concentration gradient
    - - From the potential difference falling too quickly
        
        Potential difference falls below resting potential
      - Hyperpolarisation of membrane
      - Prevents transmission from back tracking
        
        Keeping if only moving in one direction
        
        The area in front of the action potential is in resting potential
        
        Therefore, can be simulated to produce an action potential
  - - - Circuits set between nodes of Ranvier
      - Acts as an electrical insulater
      - Action potentials only generated at nodes
        
        So, action potential "jumps" to the next
        
        Called saltatory propagation / conduction
        
        Increasing speed of transmission of action potentials
        
        Na / K pumps only operate at nodes
        
        Less ATP used
        
        Voltage gated channels only operate at nodes
        
        Only these regions are depolarised
    - - Increases transmission speed
      - Diffusion is quicker
    - - Wider the diameter / diameter increase
        
        Less resistance
  - - - No matter the stimuli strength
    - - Number of action potentials per sec
- - - - Usually heat / pressure
    - - By a sensory neurone into spinal cord
    - - Occurs in "Gray matter"
    - - By a synapse
    - - Effector makes the response
        
        e.g. biceps muscle contraction, moving hand away from stimulus
- - - - Responds to limited range of stimuli
  - - - How many receptors are stimulated
    - - Creates a net-like structure
        
        Branching to other locations
    - - Slower