Neurotransmission Flashcards
What are the key structures in a neuron?
- dendrites
- soma
- axon
- terminal boutons
- neuronal membrane
Describe a dendrite
The recipient of information from other neurons, have a large receptive field due to their branch like structure
What is the cell soma?
The body of the cell which control processing in the cell and integrates information
Describe an axon
Carries information (action potentials) from the soma to the terminal boutons connecting to multiple neurons
Describe terminal boutons
They are found at the end of the axon, the communication point of a neuron connecting to multiple neurons
What is the neuronal membrane?
It separates the extracellular and intracellular environment, allowing certain substances into the cell
What is the membrane potential?
The difference in charge from the inside to the outside of the cell, the inside is more negatively charged
Why is there a membrane potential?
The force of diffusion - molecules moving from an area of high to low concentration
The force of electrostatic pressure - like charges attract, opposite charges repel
What is the sodium-potassium pump?
It maintains the ionic concentration gradients across the membrane, ATP is broken down releasing energy which forces ions to move against their concentration gradient
What is happening when the cell membrane is at rest?
More potassium channels are open than sodium channels so more potassium is leaving than there is sodium coming in hence the negative charge
What does the oligodendroglial cell do?
form myelin around axons in the brain and spinal cord
What do Schwann cells do?
wrap around peripheral nerves to form myelin
What are nodes of ranvier?
the ends of myelinated sections on axons
What is myelin and its purpose?
a fatty coating which causes action potentials to jump along the axon thus requiring less energy
What is the result of myelin sheath damage?
multiple sclerosis; problems with nerve impulses
What is a tetrodotoxin?
a toxin which blocks voltage gated Na+ channels leading to paralysis and death
What is a dendrotoxin?
a toxin which blocks village gated K+ channels leading to intense convulsions
How are neurotransmitters released?
synaptic vesicle is docked at the synaptic membrane, presynaptic depolarisation opens Ca+ channel, vesicles bind to postsynaptic membrane and release neurotransmitter and then the vesicle detaches
Describe the key physical feature os ionotropic receptors and what this achieves
doughnut shaped; allows ions to flow through the receptor, protein subunits surround the central pore
What is the function of a metabotropic receptor?
indirect transmission via a G-coupled protein receptor, amplifies the signal
How do G-coupled protein receptors transmit signals?
the neurotransmitter binds to the receptor and activates the G-protein, the protein splits and activates other enzymes
How are neurotransmitters deactivated?
reuptake into the synaptic cleft or by enzymes which break the neurotransmitter down
What are the features of Glutamate?
it is the major excitatory neurotransmitter in the CNS, activates both ionotropic and metabotropic receptor
What are the features of GABA?
it is the major inhibitory neurotransmitter in the NCS, activates the ionotropic receptor only
What are autoreceptors?
receptors which respond to neurotransmitters in the synaptic cleft; act as a negative feedback mechanism
What do autoreceptors do?
regulate internal processes controlling the synthesis and release of neurotransmitter
