after A.P occurs, there is an imbalance of Na+ and K+

• more Na+ inside when there should be more outside (to return to rest)
• more K+ outside when there should be more inside

balance restored through PUMP → restores to ion level found at rest

• 3 Na+ out
• 1 K+

A.P can only occur when ion levels are how they need to be when at rest

• Failed: EPSBs (small changes in positive direction)
• PUMP happening where hyperpolarization is happening

DRAW:

• neuron
• action potential
• axon

summary: the action potential ion movement

• Na+ in HIGH concentration OUTSIDE
• K+ in HIGH concentration INSIDE
• Na+ rushes in because:
  • opposite chages attract
  • Na+ channels open
  • ions move from HIGH → LOW concentration
• K+ rushes out because:
  • like charges repel
  • K+ channels open
  • ions move from HIGH → LOW concentration
• there was a house with a porch in the middle of winter. even though it was winter, it was a beautiful sunny day. but inside the house, it was super super cold. the porch was covered in snow. inside, there were tons of bananas that took up the space of basically the entire house. the snow had a mine of its own and knew that it would melt if it stayed on the porch in the sun, so it wanted to get inside. inside the house, the bananas were beginning to overlow. finally, one more banana joined the banana party inside to the point where the windows and doors burst open and the bananas came sprawling outside. this was perfect, because the snow got to go inside where it was nice and chilly.

relavent to pysch

chemical signaling: transmission between neurons

• neurotransmitters: ****info passed between neurons through chemicals
  • terminal buttons: knoblike structures that branch out from axon
  • neurotransmitters: chemicals that transmit information across the synpase to a receiving neuron's dendrite
  • receptors: parts of cell membrane that receive neurotransmitter + initiate/prvent a new electric signal

terminal button

• pre and post synaptic neuron

  

  1. A.P travels down axon skipping node to node
  2. This leads to release of neurotransmitters from vesciles
  3. They bind to post-synaptic dendrites of neuron → could start a whole new A.P
  4. Once neurotransmitters are cleared out by synapse they can
     1. reuptake into the sending neuron
     2. be broken down by enzymes in the synpase
     3. bind to autoceptors on sending neuron
     4. diffusion/osmosis
  • we process the world through biology, our reactions to that biology is psychology

  types of neurotransmitters

  • acetylocholine (ACh): involved in number of functions including motot control
  • dopamine (DA): regulates motor behavior, pleasure, emotional arousal
  • glutamate: major exitatory neurotransmitter involved information transmission throughout the brain
  • GABA: major inhibitory neurotransmitter in the brain
  • norepinephrine: particuarly involved in states of vigilance or heightened awareness of dangers in enviornment
  • serotonin: involved in the regulation of sleep and wakefulness, eating, and aggressive behavior
  • endorphins: chemicals that act within the pain pathways and emotion centers of the brain

  summary: the neuron and action potential

  • at rest: negative voltage (-70mv)

    • voltage due to distribution of ions inside + outside neuron

  • neurotransmitters attach to receptors in cell body → ligand-gated channel

  • ions flow into neuron (- or +)

  • small changes in voltage EPSP or ISPs summate

  • if summation reaches threshold (-55mv), volatge gated channels in the axon hillock open

    • Na+ flows in and iniatiates the action potential

  • the A.P propagates, skipping from node to node

    • also known as saltatory conduction
      • Na+ IN, K+ OUT at each node

  • ultimately, this leads to the fusion of a vesicle in the terminal button with the neuronal membrane and through the process of exocytosis the release of the neurotransmitter

    

  • drugs to treat schizophrenia are dopamine blocking drugs

  • parkinson's: too little dopamine

    • how do we help patients with schizophrenia without causing them parkinson's

  • tolerance up → receptors desensitized

    • normal level of dopamine but receptors desensitized

  • depression: too little serotonin

  • how do you treat depression caused by chronic use of cocaine?

    • anti-depressants raise levels back
    • depression is both biology + in reaction to biology + environment