Saltatory Conduction and synaptic transmission Flashcards
How do signals travel so far an so fast?
The Scwann cells (myelin sheath) prevent ions from flowing through into axon and it forces the signals to “jump” from node to node
What is Saltatory Conduction
Describes the way an electrical impulse skips from node to node speeding the arrival of the impulse.
Brifely explain the findings of Otto Loewi’s experiment
Otto used two hearts placed in a connecting chamber filled with saline solution, one was connected to the vagus nerve which caused it to slow down. Despite the 2nd heart not being connected to the stimulator it slowed down. This is becuase an electrical stimulation of the vangus nerve relased a chemical into the fluid. This is known as a neurotransmitter.
What is Acetylcholine
It is a chief neurotransmitter of the parasympathetic nervous system. The part of the autonomic nervous system that contracts smooth muscles, dilates blood vessels, increases bodily secretions and slows the heart rate.
What are neurotransmitters?
They are chemical messengers that transmit signals from neuron to target cells (maybe muscles, glands or other neurons)
What are the three types of neurotransmitters
1) Exicotatory: encourages the target cell to take action
2) Inhibitory: decrease the likelihood of the target cell taking action (relaxing).
3)Modulatory: sends messages to many neurons at the same time and can affect other neurotransmitters.
What does Acetylcholine do
this is EXITATORY
triggers muscle contractions stimulates hormones, and controls heartbeat has a role in memory formation and brain function.
What does Dopamine do
this is Modulator
involved in memory, learning, behaviour & movment; released during plesurable activites
What is GABA
mood regulator, stops neurons from being overstimulates, low levels can cause anxiety. INHIBITORY
What is Serotonin
regulates mood, appetite and sleep, low levels can cause depression INHIBITORY
What are endorphins
Involved in pain reduction, stress control and positive emotions
What does synapses mean
it’s the gap between 2 neurosn
What happens when AP reaches the axon terminal
When the AP reaches the axon terminal it causes the ca2+ channels to open.
2) the ca2+ flows in stimulates vesicles filled with NT (acetylcholine) to bind with the pre-synaptic mb
3) NT is released by exocytosis into the synaptic cleft.
What is the second step of synaptic transmission
NT diffuses across the synaptic cleft
and binds to specific post-synaptic receptors (gated Na+ channels)
Neurotransmitters are released by…into the synaptic cleft
exocytosis
