zohraz flashcards lecture 3
what is renshaw cells? what do renshaw cells secrete?
renshaw cells are inhibitory cells that transmit inhibitory signals to the surrounding motor neurons.
spatial summation occurs when _____ presynaptic neurons release neurotransmitter at ______ locations onto the repetitive segment thus generating EPSPs, IPSPs or both in the postsynaptic neuron.
Multiple
temporal summation involves a single presynaptic neuron rapidly and intensely stimulating the postsynaptic neuron in a given time period. true or false?
TRUE
spatial summation involves presynaptic neurons collectivelly stimulating the postsynaptic neuron within a given time period.
true
what is divergence?
a single presynaptic neuron may synapse with several postsynaptic neurons.
what is the main effect of convergence?
convergence allows summation of information from different sources, and the resulting response is a summated effect of all the different types of information.
what is convergence?
convergence means signals from multiple inputs uniting to excite a single neuron.
Convergence is when signals from different sources come together to make one neuron excited. It’s like multiple messages or signals reaching a neuron at the same time and causing it to get active or fired up.
is acetylcholine excitatory or inhibitory neurotransmitter?
acetylcholine is an excitatory neurotransmitter
which SNARE proteins are sensitiive against Ca2+?
synaptotagmin becuase it works as a sensor for exocytosis when Ca2+ is present
the postsynaptic neuron converts the chemical signal back into an electrical signal (postsynaptic potential). true or false?
true
at a chemical synapse, a presynaptic neuron converts an electrical signal (nerve impulse) into a chemical signal (neurotransmitter release). true or false?
true
name the two main advantages of electrical synapses?
- Faster communication: In electrical synapses, the signals called action potentials can travel directly through special connections called gap junctions. This direct pathway makes electrical synapses faster compared to chemical synapses, where signals need to cross a small gap. It’s like having a high-speed highway for communication between cells.
- Synchronization: Electrical synapses have the ability to synchronize or coordinate the activity of a group of neurons or muscle fibers. When these cells are connected by gap junctions, they can generate action potentials together, acting in perfect harmony. It’s like a synchronized team of dancers performing a routine in perfect time because they are physically connected.
what is the 5 things to remember when it comes to electrical synapases?
- synpases are directly connected
- fast
- excitatory
- two way conduction
- hard to influence impulse
- transmission
what is a synapse?
a synapse is a site where information is transmitted from one cell to another.
A synapse is a specific location where information is passed from one cell to another. It acts as a connection point between two cells, allowing them to communicate with each other. This communication occurs through chemical or electrical signals that are transmitted across the synapse. Think of a synapse as a bridge that enables information to travel from one cell to another, helping cells in the body to work together and send messages.
what is divergence?
Divergence refers to a situation where one single sender neuron connects with multiple receiver neurons by forming synapses with them. This branching out of connections allows information to spread and have a broader impact in our body. When the sender neuron communicates with several receiver neurons, it leads to a wider response throughout the body. Think of it as one sender neuron sending its message to multiple recipients, amplifying the reach and effect of the information being transmitted.
what is the benefit of convergence?
Convergence refers to a process in the brain where multiple neurons come together to stimulate a single neuron. The benefit of convergence is that it allows us to amplify the response from the output neuron. In other words, when we stimulate multiple neurons at the same time, the combined effect produces a stronger response in the output neuron.
Additionally, convergence enables cells to conserve and share pathways. This means that the same muscle fiber, for example, can receive stimulation from multiple sources or input neurons. This sharing of pathways allows for more efficient and flexible communication within the brain.
what is the name of the property which allows several presynaptic neurons to make synapses with one common postsynaptic neuron?
convergence
The property you’re referring to is called “convergence.” It’s a way for several small units in the brain, called presynaptic neurons, to connect and send signals to a single central unit, called a postsynaptic neuron. In simpler terms, convergence means that multiple input neurons can come together and send their signals to one output neuron. This allows information from different sources to be combined and processed in a single neuron, enhancing communication and integration in the brain.
what is convergence?
Convergence is a property found in groups of neurons, known as neuronal pools. It refers to the ability of multiple input neurons, called presynaptic neurons, to connect and send their signals to a single output neuron, known as a postsynaptic neuron. In simple terms, convergence means that many small input neurons can come together and send their signals to one big output neuron. This allows information from different sources to be combined and processed in a single neuron, which helps in integrating and transmitting information within the brain.
why is there a synaptic delay?
The reason for the synaptic delay is because of the necessary conversions that take place during communication between neurons. When an electrical signal, known as an action potential, reaches a synapse, it needs to be converted into a chemical signal called a neurotransmitter. This neurotransmitter is then released into the small gap called the synaptic cleft and travels towards the postsynaptic cell. Once it reaches the postsynaptic terminal, the neurotransmitter is converted back into an electrical impulse that can be understood by the receiving neuron.
These conversions between electrical and chemical signals, and vice versa, introduce a delay in the transmission of information across the synapse. This delay occurs because the electrical signal needs to be converted into a chemical form, transmitted across the synaptic cleft, and then reconverted back into an electrical signal at the postsynaptic terminal. It is this process of signal conversion and transmission that causes the synaptic delay.
chemical synpases conduct impulses faster than electrical synapses. true or false?
false
why is the chemical synapses only conducting impulses one way?
because the vesicles with the neurotransmitter are located only in the presynaptic terms and receptors which are able to change membrane potential are only located in the postsynaptic terminal. however we can also find some receptors located on the presynaptic terminal but they are responsible for the regulation of neurotransmitter release and can not change the membrane potential of the presynaptic terminal.
chemical synapses can transmit impulses in both directions. true or false?
False
chemical synapses can only transmit impulses in one direction.
electrical synapses can transmit impulses in both directions. true or false?
true
what is the function of acetylcholinesterase?
Acetylcholinesterase has the job of breaking down extra acetylcholine in the space between neurons called the synaptic cleft. This enzyme helps make sure that acetylcholine doesn’t stay around for too long, so that the signals between neurons can work properly.
in short: to break down the left of acetylcholine in the synaptic cleft.
which ion flow through the postsynaptic membrane can be caused by the gamma-aminobutyric acid binding to its receptor?
samma fråga men ställd på olika sätt
When gamma-aminobutyric acid (GABA) binds to its receptor on the postsynaptic membrane, it allows a specific type of ion to flow through. Which ion is it?
K+ outflux
what can decrease the neurotransmitter amount in the synaptic cleft?
stimulation of the acetylcholine esterase
destruction of the synaptotagmin
neurotransmitter diffusion out of the synaptic cleft
how can facilitiation be caused in chemical synapses?
- by giving more frequent impulses
- by activating facilitatory synapses
place the events in the correct order:
- vesicle fusion with the presynaptic membrane
- depolarization of the presynaptic terminal
- activation of the calmodulin
- opening of the voltage gated calcium channel
- synaptotagmin acitvation
- calcium concentration increase in the presynaptic terminal.
place the events in the correct order:
- depolarization of the presynaptic terminal
- opening of the voltage gated calcium channel
- calcium concentration increase in the presynaptic terminal.
- activation of the calmodulin
- synaptotagmin activation
- vesicle fusion with the presynaptic membrane
how many classification of neurotransmitter are there?
there is 5 classes of classification of neurotransmitter
name the enzyme which are located in the presynaptic terminal and describe how it can remove neurotransmitter from the synaptic cleft!
monoamine oxidase is an enzyme which is located on the presynaptic membrane terminal. this enzyme will break down norepinephrine in the presynaptic terminal.
describe the removal of neurotransmitter from the synaptic cleft by enzymes which are located on the postsynaptic membrane
the removal of neurotransmitters from the synaptic cleft by enzymes which are located on the postsynaptic membrane is done by destroying the neurotransmitters.
name all the 3 ways neurotransmitters can be removed from the synaptic cleft:
- neurotransmitters can be reuptaken into the presynaptic terminal and packed into vesicles.
- neurotransmitters can be removed by destroying them with specific enzymes. these enzymes can be located on thepostsynaptic membrane which will take up neurotransmitters and break them down and released products are excreted out of the cell.
- removal of neurotransmitters can be done by diffusion, then the neurotransmitters are diffused out of the synaptic cleft. however the first and second way is more used when neurotransmitters are removed from the synaptic cleft.
describe shortly the process where SNARE proteins interact and pull the vesicle to the presynaptic membrane
SNARE proteins such as synaptobrevin, syntaxin, synaptotagmin and SNAP-25 will interact and pull the vesicle to the presynaptic membrane. then this complex waits for the Ca2+ influx to the cytoplasm. Ca2+ which is positively charged particle can interact with the negativity charged proteins and bring them closer. So Ca2+ will interact with the synaptotagmin and allow synaptotagmin to react with the other 3 SNARE proteins and open fusion pore and let neurotransmitters out of the vehicle.
the t-SNARE proteins are:
syntaxin and SNAP-25
the v-SNARE proteins are:
2 synaptotagmin and 1 synaptobrevin
