Neuronal signalling 1 Flashcards
What is the principal unit of signal transduction?
The neuron
Main components of a neuron?
Cell body, dendrites, axon, nerve terminal
What is a synapse?
the small spaces between neuronal cells (~20 nm)
Where can a synapse form?
Pre N onto dendrites
Termini onto a Post n
2 types of synapses?
Electrical and chemical
Electical synapse?
Less common, simpler, no NTs, AP migrates into next cell via gap junction
Chemical synapse?
Common, complex, has NTs
What conversion happens at a synapse?
the point where electrical conduction is converted to chemical conduction
Are synapses 1:1?
No, one cell can have many synapses arriving towards it/leaving it
What is all activity in a neuron based on?
Electric charge of the cytoplasm–> +ve or -ve ions moving across the membrane
What causes selective permeability in neurons?
Channels which open and close to allow specific ions in/out
What can have a charge and thus affect the charge of a cell/across a membrane?
Ions and proteins
What happens when ions cross the membrane?
Change in membrane potential
Difference between AP and graded potential?
AP is the same every time–> reaches x value by opening specific channels whereas a graded potential is more variable
Two main types of electrical response?
Intrinsic and response to external
Intrinsic electrical responses?
Neurons active all the time
Ways intrinsically active axons generate APs?
Silent (none)
Beating (regular pulse to AP)
Bursting (many at a time)
Different ways an AP can be generated in response to an external thing?
Sustained response
Accomodation (signal across synapse is modified)
Delay (cell doesn’t respond to the NT)
How can the electrical activity of isolated neurons be studied?
Connecting them to electrodes and treating the membrane as part of a circuit
Main types of measuring neuronal activity?
Impalement and Patch clamping
Impalement to measure neuronal activity?
Fine electrode (w/ a set amount of resistance) is stuck into a cell
Measures movement of charge into and out of a cell
Patch Clamping to measure neuronal activity?
Larger electrode stuck onto the surface of the cell–> measure changes going on through channels
What is a Faraday cage used for?
Electrically isolating things inside it from the outside
What does resistance do?
Regulates the movement of ions across the membrane
What happens if a channel opens and an ion can now move into that cell?
Drop in resistance to that ion
What can clamping measure?
Voltage or amplitude
Why can only one of voltage and amplitude be measured at once?
One has to be fixed to measure the other one
What must be clamped to measure the change in membrane potential?
The current
What doesnt change if current is clamped?
The rate of flow
