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
the 4 SNARE proteins are divided into 2 groups: which are:
v- SNARE proteins which are Synaptotagmin and synaptobrevin
t-SNARE proteins which are syntaxin and SNAP-25
how many SNARE proteins are there which are important for the vesicle fusion to the presynaptic membrane?
there are 4 SNARE proteins which are impportant when it comes to the fusion of vesicles to the presynaptic membrane
SNARE proteins help with ___ to the presynaptic membrane
vesicle fusion
what is the cause of inhibitory postsynaptic potential?
the influx of Cl- or outflux of K+ will make the postsynaptic membrane negative and it will lead to hyperpolarization, the membrane potential is negative. the hyperpolarization of the postsynaptic membrane is called as the inhibitory postsynpatic potential.
what will happen when the ligand gated channels such as K+ and Cl- are opened on the postsynaptic membrane?
since the K+ concentration is greater in the cell, the opening of these channels will cause K+ outflux of the cell and since the Cl- concentration is greater outside the cell the Cl- particles will flow into the cell. Since positive particles, K+ leave postsynaptic cell or negative particles, Cl-, will flow into the postsynaptic cell, the membrane potential will be more negative, hyperpolarization. the cell are then called inhibitory postsynaptic potential (IPSP).
the bidning of the inhibitory neurotransmitters to the ionototropic receptors will open the____ channels and cause the influx of these particles into the cell.
ligand gated Cl-channel
which channels will open if inhibitory neurotransmitters bind to the ionotropic receptors? name the neurotransmitters as well.
neurotransmitters such as GABA or Glycine which are inhibitory neurotransmitters will open K+ or Cl- channels if they bind to the ionotropic receptors.
neurotransmitters such as GABA and Glycine are excitable neurotransmitters which will excite the synpases. true or false?
False
GABA and Glycine will inhibit the synapses
neurotransmitters such as glutamate and aspartate are inhibitory neurotransmitters. true or false?
False
glutamate and aspartate are neurotransmitters which will excite the synapses.
place the events in correct order:
- synaptotagmin - which in response stimulates vesicle fusion with the presynaptic membrane and neurotransmitter exocytosis.
1: neurotransmitter crosses synaptic cleft and binds to the corresponding receptor.
3: action potential opens voltage gated Ca2+ channels in the presynaptic terminal.
5: calmodulin - which in response cleaves synapsin and stimulate vesicle transport towards the presynaptic terminal.
2: ionotropic - opening Na+ or Ca2+ ligand gated channels –> Na+ or Ca2+ diffuses into the postsynaptic terminal, that´s causes depolarization which is named as excitatory postsynaptic potential (EPSP). If it reaches treshold the action potential in axon hillock is generated.
4: Ca2+ diffuses into presynaptic terminal and binds to two calcium binding proteins.
3: action potential opens voltage gated Ca2+ channels in the presynaptic terminal.
4: Ca2+ diffuses into presynaptic terminal and binds to two calcium binding proteins.
5: calmodulin - which in response cleaves synapsin and stimulate vesicle transport towards the presynaptic terminal.
- synaptotagmin - which in response stimulates vesicle fusion with the presynaptic membrane and neurotransmitter exocytosis.
1: neurotransmitter crosses synaptic cleft and binds to the corresponding receptor.
2: ionotropic - opening Na+ or Ca2+ ligand gated channels –> Na+ or Ca2+ diffuses into the postsynaptic terminal, that´s causes depolarization which is named as excitatory postsynaptic potential (EPSP). If it reaches treshold the action potential in axon hillock is generated.
which two classical neurotransmitters causes impulse conduction in excitatory synapses?
glutamate and aspartate
the neurotransmitter which can cause impulse conduction in excitatory synapses are ____ and _____
glutamate and aspartate
if neurotransmitter bind to metabotropic receptor then it leads to the production of _____ in excitatory synapses.
second messenger
such as: cAMP, IP3, DAG
the second messenger is triggered when a ligand binds to ionotropic receptor. true or false?
false
second messenger is triggered when ligand l binded to metabotropic receptor. den är felskriven, korrigera på chat.
G-protein is coupled to ionotropic receptor.
true or false?
false
G-protein is coupled to metabotropic receptor.
the depolarization of the postsynaptic membrane is called as excitatory postsynaptic potential, EPSP.
true or false?
true
the influx of Na+ and Ca2+ to the postsynaptic terminal will make the postsynaptic membrane more positive, this is called ______
depolarization
if Ca2+ binds to the ______ receptor it will either open ____ or _____ ligand gated channels allowing the influx of these particles into the postsynaptic terminal.
ionotropic receptor
Na+
Ca2+
_________ receptors are channels which has iron receptors for neurotransmitter
ionotropic receptor
what is the names of the two receptors on the postsynaptic membrane?
ionotropic receptor
metabotropic receptor
how many types of receptor are there on the postsynaptic membrane?
2 types:
ionotropic receptor
metabotropic receptor
Ca2+ + ____________ = vesicle fusion with the presynaptic membrane
synaptotagmin
Ca2+ + _________ = cleavage of the vesicles
calmodulin
which protein promotes the vesicles fusion with the presynaptic membrane?
synaptotagmin
synapisn is cleaved by which protein?
calmodulin
Ca2+, calcium, influx in the presynaptic terminal lead to calcium binding proteins. the second protein the calcium will bind to is ____ and this complex will stimulate ____ with the presynaptic membrane and neurotransmitter exocytosis.
synaptotagmin
vessicle fusion
Ca2+, calcium, influx in the presynaptic terminal lead to calcium binding proteins. The first protein the calcium will bind to is ___ and this complex will cleave ____ and vesicles will go towards ______.
Calmodulin
synapsin
presynaptic membrane
the influx of which particle happens when an action potential hits the presynaptic terminal?
calcium, Ca2+
which channels in the presynaptic terminal open when an action potential comes along?
voltage gated Ca2+ channels.
there is receptors in the presynaptic terminal.
true or false?
False
there is receptors on the postsynaptic terminal
the vesicles in the ___ are bound to a protein which is called as ___.
presynaptic synapses
synapsin
what is the name of the protein that holds together the vesicles in the presynaptic terminal?
synapsin
name 3 functional parts of the synapses:
presynaptic terminal
postsynaptic terminal
synaptic cleft
protein and polypeptide transmitters are synthesized where?
they are synthesized in the cell body in the ribosomes.
where is the neurotransmitter synthesized?
in the presynaptic terminal
very shortly describe the chemical synaptic process
impulse conduction from one cell to another is done by the help of a specific chemical substance called neurotransmitter which is released and it binds to the receptor on the other cell and causes its activation.
if we destroy electrical synapses with surgery it is possible to active them again by drugs.
true or false?
False
once electrical synapses are destroyed they are gone forever
how can we influence the electrical synapses in hospitals?
most common influence is by surgery. so if we dont want impulses to be conducted to the electrical synapses we have to destroy them. we destroy them by destroying one cell in between 2 other cells and that stops impulse conduction. Once we have destroyed the electrical synapse it is lost forever.
electrical synapses can be influenced by drugs.
true or false?
false
they cannot be influenced by drugs because they dont have receptors for drugs
can you give one negative property of electrical synapses
it is hard to influence impulse transmission. meaning it is hard to influence impulse transmission to the electrical synapses.
in general we cannot influence the electrical synapses with drugs because on these channels there is no receptors for different drugs.
where can we find only excitatory electrical synapses?
such synapses can be found in between cardiac muscle cells, between specific smooth muscle cells, in central nervous system during embryonic life.
how is electrical synapses build? their characteristics
electrical synapses are gap junction or connection which connects together 2 neighboring cells cytoplasm. It allows ions to flow from one cell to another.
in the case of inhibition of electrical synapses all the neighboring cell will also be inhibited. true or false?
False
if the case of inhibtion of electrical synapses the neighboring cells will not be inhibited.
can you give one negative property of electrical synapses?
it is hard to influence impulse transmission. meaning it is hard to influence impulse transmission to the electrical synapses. in general we cannot influence the electrical synapses with drugs because on these channels there is no receptors for different drugs.
where can we find only excitatory electrical synapses?
such synapses can be found in between cardiac muscle cells, between specific smooth muscle cells, in central nervous system during embryonic life.
how is electrical synapses build? their characteristics
electrical synapses are gap junction or connection which connects together 2 neighboring cells cytoplasm. it allows ions to flow from one cell to another.
in the case of inhibition of electrical synapses all the neighboring cell will also be inhibited. true or false?
False
if the case of inhibition of electrical synapses the neighboring cells will not be inhibited.
electrical synapses can conduct impulses in one direction. true or false?
False
electrical synapses can conduct impulses in both directions.
what is the difference between chemical and electrical synapses?
the difference between chemical and electrical synapses is that electrical is fast conducting. electrical synapses can aslo conduct impulses in both directions.electrical synapses are only excited synapses meaning only in the case where the first cell is excited it can transmit the charge to next cell and excite it as well, however if the first cell is inhibited it will not transfer impulse to the next cell.
depending on the mechanism of impulse transmission we can divide all synapses into 2 classes: ______ and ____
electrical and chemical
_______ _______ are between the axon presynaptic neuron and cell bodoy of post synaptic neuron.
axonsomatic synapses
synapses are contact places between ___ which are designed for impulse transmission
cells
in electrical synapses if we activate one cell all the other cells will also be activated. true or false?
true
