Task 3 Flashcards
What is a synapse?
A synapse consists of the specialized junction where one part of a neuron contacts and communicates with another neuron or cell type (such as a muscle or glandular cell)
What are the two sides of a synapse? And what is the usual direction of information flow?
Presynaptic side consists of an axon terminal
Postsynaptic side may be a dendrite or the soma of another neuron
The usual direction of information flows from pre to post
What is an axon terminal?(also called synaptic bouton)
Is the end of an axon or axon collaterals which grins a synapse on a neuron or other target cell
What is synaptic transmission
The transfer of information at the synapse from one neuron to another
How do synapses communicate?
Mostly chemically usually using chemical messengers
The action potential triggers the presynaptic neuron to release neurotransmitters
These molecules bind to receptors on the postsynaptic cell and make it more or less likely to fire an action potential
If not chemical synapses what is the other way?
Electrical synapses where ions flow directly between cells
How is a synapse constructed?
The axon terminals form synapses with the dendrites ir somata of other neurons
What are the three principal components of a synapse?
The presynaptic membrane of the axon terminal of the presynaptic neuron
The synaptic cleft gap (20-40 nanometers) that separates the presynaptic and postsynaptic membranes
Specialized postsynaptic membrane on the surface of the dendrite or cell body of the postsynaptic neuron.
What is inside the axon terminal of a sending cell?
Synaptic vesicles that are filled with neurotransmitter molecules
Each vesicles contains a neurotransmitter (chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons
The neurotransmitter carries information from the presynaptic neuron (sending neuron) to the postsynaptic cell(receiving cell)
What are the two types of synapses again?
Electrical and chemical both types relay information but do se by very different mechanisms
What is signal transmission?
Steps required for the transmission of information from one neuron to another
Delay between arrival of information at presynaptic terminal and its transfer to the postsynaptic cell reflects this steps required
What is the presynaptic element?
The presynaptic side of the synapse.Consists of an axon terminal
What are synaptic vesicles?
Vesicles within within axon terminals that contain neurotransmitters
What are secretory granules,
Larger vesicles that contain soluble protein appearing dark so they are called dense core vesicles
What is the active zone?
Sites of neurotransmitter release
Synaptic vesicles are clustered in the cytoplasm adjacent to this zone
What is the postsynaptic element what the postsynaptic density?
Postsynaptic element is the postsynaptic side of te synapse
The postsynaptic density is the protein accumulated in and under the postsynaptic membrane
What are the two functions of the postsynaptic element?
1 to anchor receptors for neurotransmitters in the postsynaptic membrane
2 Transduction : the neurotransmitter receptors will convert intercellular chemical signal (neurotransmitter) into intracellular signal(change in membrane of potential/chemical change) in the postsynaptic cell
What does the nature of a postsynaptic response depend on?
Depends on the type of protein receptor activated by the neurotransmitter
What is te anatomy of a chemical synapse?
They lack cytoplasmic continuity
There’s an extracellular space between cells
The axon of the presynaptic cell is highly branched and terminates in terminal knobs aka synaptic buttons
Pre and postsynaptic cells have membrane specializations
What are the different types of chemical synapses in the CNS?
Axodendritic synapses
Axosomatic synapses
Axoaxonic synapses
Dendrodentric synapses
Location of axodendritic synapses?
Presynaptic neurons synapse along dendritic spines of the postsynaptic neuron
The presynaptic membrane is on axon
The postsynaptic membrane is on dendrite
Where are axosomatic synapses located?
Presynaptic neurons synapse along the cell body (soma) of the postsynaptic neuron
The presynaptic membrane is on axon
The postsynaptic membrane is in soma