neurons and synaptic transmission Flashcards
what are neurones?
nerve cells that process and transmit messages through electrical and chemical signals
describe the action of the sensory neurone
carry messages from the PNS or receptor site to the CNS
describe the action of the relay neurone
connect the sensory neurones to the motor neurones and other relay neurones. In CNS
describe the action of the motor neurone
connect the CNS to effectors such as muscles and glands
describe the action potential of a neurone
when the neurone is activated by a stimulus, the inside of the cell becomes positively charged for a split second causing an action potential to occur. this creates an electrical impulse that travels down the axon towards the end of a neurone
what is excitation within neurones?
when a neurotransmitter, such as adrenaline, increases the positive charge of the postsynaptic neurone. This INCREASES the likelihood that the postsynaptic neurone will pass on the electrical impulse
what is inhibition within neurones?
when a neurotransmitter, such as serotonin, increases the negative charge of the postsynaptic neurone. This DECREASES the likelihood that the postsynaptic neurone will pass on the electrical impulse
how do neurones communicate with each other?
neural networks
what is the gap between 2 neurones called?
a synapse
what is a synapse?
a gap between 2 neurones
how are signals WITHIN the neurones transmitted?
electrically
how are signals BETWEEN neurones transmitted?
chemically
what happens when the impulse reaches the end of the neurone?
neurotransmitters are released from tiny sacs called synaptic vesicles
what is the end of the first neurone called?
presynaptic terminal
explain synaptic transmission
The synapse is the gap between two neurones. The axon carries the electrical impulse to the presynaptic terminal. Here, the impulse is converted to a chemical impulse. Synaptic vesicles on the presynaptic terminal release neurotransmitters. These carry the impulse across the synapse. Once the neurotransmitter reach the post synaptic receptor site membrane, they bind to the receptor sites. Any that don’t bind experience re-uptake by the presynaptic terminal or are dissolved by enzymes. Then the impulse is taken electrically by the dendrites on the next neurone to begin the process again
which part of the neurone takes the impulse TO the synapse?
axon
which part of the neurone takes the impulse AWAY from the synapse?
dendrites
in which direction can an impulse travel?
one way
what is summation?
Summation is the addition of positive and negative post-synaptic potentials. A nerve cell can receive both positive and negative potentials simultaneously. These potentials are added and if the net effect on the postsynaptic neurone is inhibitory, the neurone will be less likely to fire, and if the net effect is excitatory, the neurone will be more likely to fire
what is the role of dendrites?
carry nerve impulses from neighbouring neurones to the cell body
what is the role of axons?
carries the impulse from the cell body down the neurone to the pre synaptic terminal
what is the role of the myelin sheath?
protects the axon and speeds up the electrical transmission of the impulse
what is the role of the nodes of ranvier?
speed up the transmission of the impulse by making it jump across the gaps on the axon. the gaps are the nodes
Why can neurones only transmit info in one direction at a synapse?
The synaptic vesicles containing the neurotransmitter are only present on the presynaptic terminal. The receptors the neurotransmitter bind to are only present on the post synaptic neurone. The signal can only be passed on if it binds. Diffusion of the neurotransmitter mean they go from high to low concentration so can only travel one way
