Synapse Flashcards
What 3 factors determine the electrical activity of the cell?
- How well ions move across the membrane
- Gradients
- When the ions move
Which ion is the membrane more permeable too?
Potassium (rather than sodium)
What are the 2 gradients that influence ion movement?
- Concentration
- Electrical
Why is a neuron negatively charged at rest?
There is more negative ions inside the cell than outside
Where are neurotransmitters stored?
In the presynaptic terminal
What happens to the equilibrium when the neuron is stimulated?
The equilibrium is upset and if the excitatory stimulation is large enough (above 50mV), the resting potential becomes an action potential
What happens when an AP reaches the presynaptic terminal?
A chemical (neurotransmitter) is released into the junction between the neurons
How is the synapse formed?
The termination of an axon from one neuron onto the dendrite of another neuron
Where do most synapses occur?
Between neurons (that result in neuron becoming excited or inhibited)
What is the area between neurons and muscles?
Neuro-muscular junction
What is the function of synapses at the neuromuscular junction?
Cause muscles to contract and allow us to move
Where are the axons from neurons that activate muscles located?
In the spinal chord
What is the disease that effects neurons that activate muscles?
ALS
- gradually restricts movement
Where are neurotransmitters made?
Cell body
Where are neurotransmitters packaged?
Vesicles
When do vesicles release their contents?
When AP reaches those vesicles (dormant until then)
What type of ion channels open at the synapse?
Calcium (Ca++)
Where does the incoming Ca++ bind to?
Binds to the synaptic vesicles, causing them to release their neurotransmitters into the synapse
What do the neurotransmitters bind to once they are released?
They bind to receptor sites that then become activated
How does habituation/adaptation occur e.g. n sea snails that begin to withdraw their gills less in a defensive manner when confronted with water?
This process can result from a reduction in the influx of calcium at the axon’s pre-synaptic terminal and the release of less neurotransmitter
What are neurotransmitter receptors?
Proteins that are found on dendrites
What are ionotropic neurotransmitter receptors composed of?
1) Binds neurotransmitter
2) Ion channels
What happens when a neurotransmitter binds to a receptor?
The ion channel opens, allowing ions into the cell
How to metabotropic neurotransmitter receptor influence ion channels indirectly?
When a neurotransmitter binds to a binding site, a subunit detaches and causes the ion channel to open allowing ions to pass through
