transmission between neurons Flashcards
What is transmission?
-Neurons send messages via synaptic transmission
-Neurotransmitter released from one neuron and attach to another
-Initiates reaction that results in postsynaptic potentials
What is the difference between presynaptic and postsynaptic?
-Presynaptic - Passes neuron
-Postsynaptic - Receives neuron
What are synaptic vesicles?
-Contains neurotransmitters
-Made in soma
-Get transported down
What is the synaptic cleft?
-Gap between two membranes
Describe the process of synaptic transmission
1: AP arrives at terminal button
2: Opens calcium channel and calcium enters 3: Calcium makes the diffusion pore open -4: 4:Widens
5:Releases NT’s into cleft (exocytosis)
6:NT diffuses through cleft and binds to postsynaptic membrane
7:Postsynaptic channels open
8:Ions flow through and this creates either excitatory or inhibitory PSP’s
Describe what happens during binding
-NT’s binds to binding site on postsynaptic membrane (lock and key)
-Postsynaptic potential depends on which ion channel is opened
-EPSP - excitatory postsynaptic potential (depolarisation)
-IPSP - inhibitory postsynaptic potential (hyperpolarisation)
What are the 2 types of receptors?
-Ionotropic receptors
-Metabotropic receptors
Describe ionotropic receptors
-Contains binding site and an ion channel
-Opens when molecule attaches to binding site
-Direct channel
Describe metabotropic receptors
-Contains binding site
-Initiates a chain reaction that eventually opens ion channels
-Requires energy
-PSP slower
-Indirect channel
What are the 2 processes in termination?
-Reuptake
-Enzymatic deactivation/degradation
Describe reuptake
-Transmitter is taken back by presynaptic terminal via transporter molecules
Describe enzymatic deactivation/degradation
-Transmitter broken down by an enzyme e.g. acetylcholinesterase breaks down Ach into choline and acetic acid
Describe the 3 neural integration
-Excitatory = increases likelihood of neuron firing
-Inhibitory = decreases likelihood of neuron firing
-Integration = summation of PSPs that control of neuron firing
What are the 5 neurotransmitters?
-GABA
-Glutamate
-Dopamine
-Serotonin
-Acetylcholine (ACh)
Describe GABA
-Most abundant
-Inhibitory (reduce chance of firing)
Describe Glutamate
-Most abundant
-Excitatory
-Binds to lots of receptors
-Learning and memory
Describe Dopamine
-Motor control
-Reward and addiction
Describe Serotonin
-Regulation of mood, eating and sleep
Describe Acetylcholine (ACh)
-Found in CNS and PNS at neurotransmitter junctions (muscle contraction)
Describe an antagonist
-A drug that blocks a neurotransmitter
-An example is Botulinum toxin (Botox) - it blocks the release of acetylcholine and prevents muscle contraction so paralyses muscles
Describe an agonist
-A drug that mimics a neurotransmitter and enhances synapse function
-An example is muscarine (naturally occurs in mushrooms)
-Muscarine imitates acetylcholine
