Physiology of neurons Flashcards
What is an electrical synapse?
A synapse that transmits information electrically with no chemical involvement, they are bidirectional and they have smaller gaps and don’t allow for amplification.
What is a consequence of no amplification in an electrical synapse
the signal is always weakened as it is transmitted from presynaptic to the postsynaptic cell.
What is the refractory period
A period of time during which a neuron is incapable of reinitiating an AP, the amount of time it takes for neurons membrane to be ready for a second stimulus once it returns to its resting state following excitation.
What is AHP
After-hyperpolarisation: at the end of an AP the voltage inside temporarily goes slightly more negative than at rest.
How do neurons code the intensity of their synaptic input and how can this be controlled
Firing frequency represents intensity of activity. increasing threshold lowers firing frequency and one way to do this woul be to block some sodium channels.
What is excitability
how easy it is to start nervous signalling and threshold determines excitablilty
What is lignocaine
Local anaesthetic, works by blocking sodium channels in their inactivated state and it raises the threshold and thus lowers excitability and stops action potentials locally
What is carbamazepine
blocks sodium channels, raises the threshold and lowers excitability
What is Ek the equilibrium potential
The moment when the two forces (chemical and electrical) are equal and opposite. It is also known as the reversal potential. When the k+ flowing out = k+ flowing into the cell.
What is Ena
+60 mV
What is Ek
-90 mV
What is Eca
+123 mV
What is Ecl
-40 mV
What is a graded potential
graded potentials have a varying potential difference in a graded way. electrically localised, last a long time and decrease as they move along an axon. Occurs in the eyes at receptors.
