Biologicalš§ ā¢ Neurotransmission + Studies Flashcards
Roughly what percentage of neurons are located in the brain?
80%
Label this diagram of a neuron
In what two ways do neurons transmit information?
electrically and chemically
What is another word for the cell body of a neuron?
the soma
What does the cell body/ soma of a neuron contain?
The nucleus containing the genetic mateiral of the cell
What are dendrites?
(the receving part of the neuron) Branch-like structures that stick out from the cell body of the neuron; the purpose of dendrites is to carry impulses from neighbouring neurons to the cell body to then be passed through the rest of the neuron
What is the axon?
A tube-like structure that carries impulses away from the cell body down the entire length of the neuron
What is the meylin sheath?
the fatty layer that covers the axon in many neurons
What is the purpose of the meylin sheath?
- to protect the axon
- speed up electrical transmission impulse for neuron to work at optimum speeds
What are the nodes of ranvier?
gaps on the axon inbetween the meylin sheath
What is the purpose of the nodes of ranvier?
They allow for the increase of speed from the meylin sheath by forcing the electrical impulse to jump across teh gaps along the length of the axon consequently increasing speed by making the journey shorter
What is the axon terminal?
The extension of the main axon into branch-like structures similar to that of dendrites (in appearance), they contain axon terminal buttons.
What are axon terminal buttons?
The small knobs on the end of the axon terminal that contain synapic vessicles used for neurotransmission
What is the tiny gap between neurons called?
synapse/ synaptic gap/ synaptic cleft
What is synaptic transmission?
A chemical process where by biochemical substances called neurotransmitters are used to transmit electrical signals from a neuron, chemically across a synapse
What are synaptic vessicles?
Tiny sacs full of neurotransmitters located in the axon terminal button
What is a post/presynaptic neuron?
- presynaptic neuron = neuron impulse is coming from
- postsynaptic neuron = neuron impulse is traveling too
From what part of the neuron on the presynaptic neruon do the neurotransmitters travel to on the postsynaptic neuron?
Neurotransmitters travel from the axon terminal buttons of the presynaptic neuron and to the dendrites of the postsynaptic neuron
What is an Action Potential?
The electrical impulse that is sent down a neuron
What triggers the synaptic vessicles to release the neurotransmitters into the synapse?
The presence of an Action Potential; when an action potential reaches the end of a neuron/ the axon terminal/terminal buttons
Label this diagram of Neurotransmission
Describe the process of neurotransmission
- AP arrives at axon terminal button, consequently triggering the synaptic vessicles to release neurotransmitters into the synapse
- The released neurotransmitters diffuse across the synapse until they arrive at the dendrite of the postsynaptic neuron
- The dentrite contains specialised receptor sites complementary in shape to the neurotransmitters
- Neurotransmitters are uptaken and bind to complementary receptors though **lock and key **; postsynaptic neuron then converts the chemical signal back into an electrical one to then fire another AP along the neuron
What is reuptake?
When neurotransmitters that have remained in the synapse are reabsorbed by the presynaptic neuron to then be used again
What is uptake?
Just what happens normally when neurotransmitters travel from pre-to-post-synaptic neuron
What type of cells carry out the reuptake of neurotransmitters?
Glial cells
When a neuron is in its resting state what is its charge?
negative
What happens when a neuron is sufficiently activated by a stimulus?
It becomes positively charged for a spilt second
What is depolarisation?
The rapid switch when a neuron is sufficiently activated by a stimulus from negatively charged to positive. It creates an electrical impulse, or Action Potential (AP) that then will travel all along the neruon to the axon/ terminal buttons. This can sometimes be reffered to as firing an action potential
What is the condition for an AP to be generated in depolarisation?
Depolarisation must reach a certain threshold, it always has to be the same intensity regardless the magnitude of the stimulus that originally triggered it.
What happens if the specific threshold isnt reaached in depolarisation?
The AP will not be produced
Do all neurotransmitters have the same molecular structure /shape?
All different types of neurotransmitters have a different shape and therefore also a differently shaped complementary receptor
What are the two main categories of neurotransmitters?
- excitatory
- inhibitory
What is an example of a inhibitory neurotransmitter?
Serotonin
What is an example of a excitory neurotransmitter?
Dopamine
What to inhibitory neurotransmitters e.g. serotonin do?
Causes inhibition in postsynaptic neuron by making it more negatively charged consequently making it less likely to fire
What to excitory neurotransmitters e.g. dopamine do?
Causes excitation in postsynaptic neuron by making it more positively charged consequently making it more likely to fire
What is serotonin?
A neurotransmitter linked to mood and sadness
What can serotonin be used for?
Treatment for depression - medicine that boosts serotonin levels in brain help with depression
Serotonin seems to ________ aggression
Serotonin seems to inhibit aggression
What is dopamine?
A neurotransmitter linked to attention and pleasure
What are anti-psychotic drugs?
Drugs that reduce dopamine levels in people suffering from schizophrenia which tend to reduce aggressive moods/ behaviours
Increased dopamine levels seems to equal ________ aggression
Increased dopamine levels seems to equal increased aggression
What is the supposed relationship between serotionin and dopamine?
Theorized that an imbalance in these neurotransmitters can lead to more aggressive behaviour e.g. LOW SEROTONIN + HIGH DOPAMINE = AGGRESSION
Explain the study conducted by Ferrari et al. (2003)
- He studied link between the neurotransmitters serotonin and dopamine and how they can lead to aggressive behaviour - in this study he used rats
- recorded blood sample to get intial recording of serotonin & dopamin before any catalysed aggression
- Allowed an āintruderā rat into the observed ratās own cage for a fight everyday for 10 days at aproximately the same time - taking blood sample each day
- On the 11th day at the aproximate time, no intruder rat was introduced
- Researchers measured levels of serotonin and dopamine in rats blood sample/ brain to find that the test ratās serotonin levels had decreased and dopamine levels increased because it was anticipating a fight
- This study acts as evidence for the supposed correlation between aggression and these 2 neurotransmitters with it being theorized low serotonin and high dopamine = aggressive behaviour
- however, study not carried out on humans so is anthropomorphic making it less generasliable/ representative of aggression in humans
What are SSRI drugs?
They stand for Selective Serotonin Re-uptake Inhibitors and prevent the pre-synaptic neuron from re-uptaking hence the neurotransmitters arent re-uptaken and left in synapse - therefore causing receptors to fill/ trigger at faster rates
