Exam 1 - PNS (Everything not Brain & Spinal Cord) Flashcards
What are the 2 main nerves in the PNS?
Cranial nerves and Spinal nerves.
Cranial nerves (12) come directly off the brain Spinal nerves come directly off the spine
What is the list of Cranial nerves? List the correct numbers and whether they are sensory, motor, both, and/or Parasympathetic.
- Olfactory Nerve (S)
- Optic Nerve (S)
- Occulomotor Nerve (M) (Para)
- Trochlear Nerve (M)
- Trigeminal Nerve (B)
- Abducens Nerve (M)
- Facial Nerve (B)
- Auditory Nerve (S)
- Glossopharyngeal Nerve (B) (Para)
- Vagus (B) (Para)
- Spinal Accesory Nerve (M)
- Hypoglossal Nerve (M)
Oh Oh Oh To Touch And Feel A Great Vagina Seems Hot
Some Say Marry Money But My Brother Says Big Books Matter More
Which are the 3 nerves that participate in the Parasympathetic system?
- Occulomotor nerve
- Glossopharyngeal nerve
- Vagus nerve
OGV!
What are the functions of each of the 12 Cranial Nerves?
- Olfactory Nerve (S) - Smell
- Optic Nerve (S) - Vision
- Occulomotor Nerve (M) (Para) - Eye Movement, tears, pupil constriction
- Trochlear Nerve (M) - Often attached to dorsal surface of Trigeminal
- Trigeminal Nerve (B) - Large, sends Motor info that moves jaw and brings in sensory info from Tongue.
- Abducens Nerve (M) - External rectus muscles of eyeball
- Facial Nerve (B)
- Auditory Nerve (S)
- Glossopharyngeal Nerve (B) (Para) -Mouth and tongue
- Vagus - Controls smooth muscles of the gut, lungs, and brings information from those muscles.
- Spinal Accesory Nerve (M) - Muscles of head, neck, shoulder
- Hypoglossal Nerve (M) - Tongue and neck
What are the 2 different ways to distinguish functions of PNS?
Anatomical (cranial and spinal nerves) and Functional (autonomic and somatic).
Where in the body does the somatic nervous system (of the PNS) affect functionally?
Is it voluntary or involuntary?
Where does it receive sensory information from?
The output of the Somatic Nervous system (voluntary) innervates the skeletal muscles.
It’s voluntary because these muscles move only when we plan on it.
It receives information from the skin senses and the striated muscles.
Where in the body does the autonomic nervous system (of the PNS) affect functionally?
Is it voluntary or involuntary?
Where does it receive sensory information from?
The muscle component is smooth (organs) and cardiac (heart).
It’s involuntary.
It brings in information from all of my senses: ears, eyes, tastes, smells.
What are the subdivisions of the PNS?
What is the subdivision of the Autonomic Nervous System?
Explain what activation to each component will do.
How do they differ anatomically in where they exit the CNS?
How do they differ in terms of first and second stage neurons?
Somatic and Autonomic.
Autonomic subdivides into Sympathetic and Parasympathetic.
-Both systems innervate the same target organs, BUT, they have opposing affects on the same organs.
ex.
Activation to the Parasympathetic (slows heart, independent activation of neurons)- Pupil Constriction
Sympathetic (speed heart, coordinated and quick activation of neurons)- Pupil Dilation
-They differ anatomically in where they exit the CNS:
Parasympathetic exits through Cranial or Sacral of spine
Sympathetic NS exits spine from Thoracic and Lumbar portion
——————————————————————————-
-The first stage neurons that come out of the the CNS in the Parasympathetic is relatively LONG and second stage that makes contact with the target organs is SHORT
The first stage neurons that come out of the the CNS in the Sympathetic is SHORT and second stage that makes contact with the target organs is LONG
> The point of contact between first and second stage ganglia are all lined up adjacent to the spinal cord and all in contact (string of beads) with each other.
Why is there a different Anatomical set-up between the systems in the Autonomic Nervous System?
hint: which one has a coordinated activation, and why is that important?
Fight or Flight.
For the Sympathetic NS, the response must be coordinated and happen AT THE SAME TIME. We will have to speed up our heart rate to pump oxygen and glucose into our blood, so that it can feed the muscles that will let us RUN!
When we are in a relaxed state listening to a bio psych lecture, which one of the systems is more dominant:
Sympathetic or Parasympathetic?
Parasympathetic.
Mnemonics: Paramedics will tell you to chill… relax…
Which part of the Autonomic nervous system are the ganglia, or the point of connection between the first and second stage neurons, connected?
In the Sympathetic nervous system, connected and lined up as a string of beads outside the spinal cords - when you activate 1 ganglion, you activate all of them.
What’s the difference between a nerve and a tract?
Tract = CNS Nerve = PNS
What bilayer is the neural membrane cell comprised of?
What is the process that created these cells called?
What’s the benefits of this type of cell structure?
Neural membrane of a cell is comprised of a Phospholipid bilayer. It’s made by head and tails of a phosphate group… Since the heads are hydrophilic (water lover) and tails are hydrophobic (water hater)- the pressure between them caused them to fold in on each other in a process called Invagination.
The benefit of this type of cell is that it’s fluid. It is semi-permeable because SOME things can go through this layer and some cannot. It is also ‘fluid mosaic’ so that ions and proteins can travel freely without wasting energy.
What are the 2 pores that go through the cell membranes?
Ion channels which allow specific ions to go into and out of cells.
Ion pumps look the same but use energy to “pump” where ion channels don’t.
Explain the internal structures of the cell body starting from:
Nucleus DNA Cytoplasm Endoplasmic Reticulum ---> Ribosomes (2) Golgi Apparatus ----> Enzymes Mitochondria Lysosomes Cytoskeleton ---> Microtubials and Microfilaments ---> Kinesin
> The nucleus, encased in it’s own phospholipid bi-layer, and unlike the cell bodies, it has holes in it to allow for the ion channels.
> The DNA for every single cell is INSIDE the nucleus.
> Cytoplasm fills the cell to give shape and allow travel throughout the cell.
> Endoplasmic reticulum surrounds the Nucleus because it is considered the factory of the cell. It makes the product that the cells themselves need AND what the cells need to export.
There are 2 types of Endoplasmic reticulum:
1) Smooth - No Ribosomes, manufactures Lipids
2) Rough - Ribosomes (why it’s rough texture).
Ribosomes (factory) are protein based molecules that MAKE protein and attach to the Endoplasmic reticulum as well as float freely in the Cytoplasm.
> Once the protein and lipids are made, it needs to be exported outside of the cells and must be packaged - Golgi Apparatus is lipid based packagers that transport around and export out of cell. Packaging the cell is important because there are Enzymes in the cytoplasm that will tear things apart and recycle them.
> Mitochondria produces the cells energy. It has it’s own DNA separate from the nuclear DNA… is Mitochondria alien?? It IS providing us energy while we provide it nutrients and protection…
> Lysosomes are produced by the Golgi Apparatus, inside of the Cytoplasm. They are vesicles filled with enzymes that are used for cell maintenance. They destroy portions of the cell itself (apoptosis).
> Within the Cytoplasm and throughout the cell, the Cytoskeleton resides - Microtubials (extends across space within cell) and Microfilaments (attach to structures within the cell). Microtubials are the roads of the cell. It’s found along Axons to give structure and allow for transportation of the proteins. Vesicles move along the Microtubials by binding to Kinesin (strands of twisted protein and their free ends on both top and bottom attach to a vessicle and walk up and down a microtubial). This is a nano-machine!
If a substance (neurotransmitter) is moved from cell body down to axon terminal - Anterograde transport
If a substance (neurotransmitter) is moved from the axon terminal to cell body - Retrograde transport
Through a chemical signal, Microfilaments can detach and push parts within the cell.
When a cell is signaling that it’s ready to die, which component within the cell body will help it on it’s way?
Lysosomes are produced by the Golgi Apparatus, inside of the Cytoplasm. Lysosomes are vesicles filled with enzymes that are used for cell maintenance. For injured cells that are beyond the point of repair, Lysosomes will split themselves open to release the enzymes into the cytoplasm and the cells are consumed completely in response to a chemical signal produced by the dying cell… aka Apoptosis (cell suicide).
Basically, Lysosomes help to “euthanize” cells and assist in their suicide by using their own enzymes (they shoot up the cell). They guard the cell by recycling the cells.
Mnemonics: LYSOL-somes - LYSOL kills bacteria.
Describe the 4 main parts of a Neuron.
- Soma - Houses Nucleus
- Dendrites - Receptors of information either directly from sensory (skin), or through other Neurons.
- Axons - Electrical signal (Action Potential)
- Axon Terminals - Communicates with the other neurons, muscles, or glands.
Where is the Action Potential generated?
At the Axon Hillock
What’s the difference between Unipolar, Bipolar, and Multipolar Neuron?
Where are they found?
Unipolar - Has 1 process that leaves the Soma. It splits into 2 portions, 1 dendrite and 1 terminal. Found in Sensory, Motor, PNS.
Bipolar - 2 processes that leaves the Soma. 1 has Dendrites on one end and terminals on the other end. Found in Sensory (retina, cochlea).
Multipolar - Multiple processes that leaves the Soma. 1 single Axon with multiple dendrites. The Axon itself can split into multiples.
What is it called when an Axon splits?
Collateral
What are the 3 types of functional variations of Neurons?
hint: how do neurons transmit information??
- Sensory (Afferent) neurons transmit info INTO the CNS from sensations
- Motor (Efferent) neurons transmit into AWAY from CNS into muscles and glands
- Interneurons that act as a bridge between sensory and motor neurons. They don’t directly work with sensory or motor. This is the most common.
How are Glial cells different from neurons?
Glial cells make up about 10 to 1.
They don’t conduct electrical signals like neurons do.
What are the 2 divisions of the Glial Cells?
Microglia
Macroglia - Astrocytes, Oligodendrocytes, Schwann
What is Microglia’s main 2 functions?
hint: phagocytes
Main function is in the immune support of the brain - inflammatory response.
> They are phagocytes which engulf and destroy things in the extracellular fluid.
Pretty much the “police” and check to make sure the cell belongs there (do you have a brain tag?) - if not, it eats it up and then spits up the cell’s amino acids and carbo chains back into the extracellular fluid for recycling or waste.
> Within the extracellular fluid, Microglia regulates and stabilizes concentration of ions which allows us to use chemical signaling.
Mnemonics: (P)hagocytes - (P)olice
Micro-(PH)one - Micro - (PH)ag… sounds catchy?
What are the functions of Astrocytes? hint: communicates, recycles, balances glucose, BBB.
Astrocytes wrap around blood vessels within the brain and neurons - forms connection between the blood and the neuron and it wraps around the points of connection bw 2 neurons to isolate the individual synapses so things remain private…
Recycles: Pulls neurotransmitters out of synapses and send it back to the neurons as well as hold onto them and release them at will.
Astrocytes keep blood sugar balanced: Astrocytes pre-process glucose and oxygen from the blood to deliver to the neuron so it’s in an instantly usable form. It also stores the glucose (energy) to give it to the neuron!
Blood brain barrier: Layer of protection like the pia mater to keep bad things away from neurons.
Are astrocytes capable of communicating?
Yes, astrocytes can pull and release chemicals from synapses. They can affect the communication. For example, if the neuron releases too much chemical signal, the astrocyte can make the signal weaker and vice versa.
What is the epithelial cells referring to in connection to Blood Brain Barrier?
Epithelial cells make up blood vessels. These cells have gaps between them which allow things like glucose to freely flow in and out of the blood.
However, cells in the brain does not have the gaps, so large protein cells cannot penetrate through the epithelial cells.
Another layer coming from the astrocyte regulates what can get out of the brain tissue.
Give an example of an area with a “weak” blood brain barrier with less astrocyte covering blood vessels in the area. Why would we have a system like this?
The Area Postrema is there to accurately evaluate what is in my blood. It is near the 3rd ventricle and area that induces vomiting when toxins are detected. It’s important to get rid of the poisons before it gets worse.
Glial cell Oligodendrocytes function, structure, and appearance.
Produces Myelin for CNS neurons.
Paddle-like.
Function: Myelinates multiple axons.
Glial cell Schwann Cell function and appearance.
Produces Myelin for PNS.
Flat, pancake-like.
Function: Myelinates 1 axon at a time.
Explain Mitochondria’s role within the cell.
> Mitochondria produces the cells energy. It has it’s own DNA separate from the nuclear DNA… is Mitochondria alien?? It IS providing us energy while we provide it nutrients and protection…
Mnemonics: MIGHTY-chondria - It’s mighty, full of energy!
Explain the Endoplasmic Reticulum and what it’s considered within the cell structure. What do they produce?
> Endoplasmic reticulum surrounds the Nucleus because it is considered the factory of the cell. It is PRODUCER and makes the product that the cells themselves need AND what the cells need to export.
There are 2 types of Endoplasmic reticulum:
1) Smooth - No Ribosomes, manufactures Lipids
2) Rough - Ribosomes (why it’s rough texture).
Ribosomes (factory) are protein based molecules that MAKE protein and attach to the Endoplasmic reticulum as well as float freely in the Cytoplasm.
Mnemonics: Endo PRODUCER (R)eticulum - EndoPLASMIC (R)IBOSOMES.
Explain what the Cytoskeleton does and it’s 2 parts. Be specific about each role.
If a substance is moved from cell body down to axon terminal - it is considered what type of transport?
If a substance is moved from the axon terminal to cell body - it is considered what type of transport?
hint: nano-machines
> Within the Cytoplasm and throughout the cell, the Cytoskeleton resides - Microtubials (extends across space within cell) and Microfilaments (attach to structures within the cell). Microtubials are the roads of the cell. It’s found along Axons to give structure and allow for transportation of the proteins. Vesicles move along the Microtubials by binding to Kinesin (strands of twisted protein and their free ends on both top and bottom attach to a vessicle and walk up and down a microtubial). This is a nano-machine!
If a substance is moved from cell body down to axon terminal - Anterograde transport
If a substance is moved from the axon terminal to cell body - Retrograde transport
Through a chemical signal, Microfilaments can detach and push parts within the cell.
How does MS occur?
Immune system attacks Myelin.
MS can resolve itself if the immune system stops attacking myelin, the myelin can grow itself back with immune suppressors.
Apoptosis can send signals to lysosomes to totally kill off the neurons-permanent apoptosis.
What is Myelin?
What is it made of?
Allows electrical signals move faster, saves neurons energy by keeping ionic concentration stable.
Made of lipids and small protein.
What are the 2 different Neural Communications?
What is Neural communication considered?
Between neurons - Chemical (neurotransmitter, signal goes TO neurons)
Within neurons - Electrical (signal goes THROUGH the neuron)
Neural communication is Electrochemical.
Define ‘ion’. How does ion affect the way cells move?
A charged particle that is either positive or negative.
Depending on whether the cell is positive or negative, it will move differently.
What makes intercellular and extracellular fluid different from one another?
The concentrations of ions!
Describe Resting Membrane Potential. What does it mean i
Define depolarization and hyper-polarization.
What does it mean if the RMP is -65mV?
Measurement of the electrical potential INSIDE of the cell relative to the OUTSIDE of the cell. Just a measurement of difference, not an absolute value.
> Depolarization - what happens to the RMP if you apply positive charge to membrane, making the difference between in and out more same.
Hyperpolarization - the membrane becomes more negative during hyperpolarization so the diff. bw inside and out is GREATER.
> ie; If the RMP is -65mV, it just means that the difference of electrical potential on the inside of the cell is -65mV LESS than the outside.
What type of transport is it when a substance is removed from the cell body down to the axon terminals?
Terminal to the cell body?
Anterograde transport is when a substance is removed from the cell body to the axon terminal.
Retrograde transport is when a substance is removed from the axon terminal to the cell body.
Describe the structure of a sensory neuron. Explain where this neuron might reside in and how it would transmit information.
Sensory neurons are the most simple - they are bipolar neurons and found in the retina of the eye for example.
It has a single dendrite and single short axon.
The bipolar neurons transmit afferent sensory info from the retina’s light receptors to the neurons that carry the information to the visual centers of the brain.
Describe the structure of an interneuron. Explain where this neuron might reside in and how it would transmit information.
They are also called association cells because they have an association between the sensory and motor neurons.
The pyramidal cell has 2 sets of dendrites - one from the apex of the cell body and one from its sides. These interneurons carry information from the cortex to the rest of the brain and spinal cord.
Describe the structure of a unipolar neuron.
What type of process do they have?
Where would you find these neurons?
There’s only 1 process that leaves the soma, but splits into one portion (dendrites) and one portion (axons).
Found in sensory and motor neurons - so the dorsal horn’s dendrites extend out to the skin, the cell bodies are in the dorsal horn, and the terminals are in the spine.
Describe the structure of a multi-polar neuron.
What type of process do they have?
Where would you find these neurons?
Multi-polar neurons have multiple processes coming off the soma - all but one is dendrites. The single one is axon (the axon itself can split into multiple axons or axon collateral).
What is happening with neurons during someone who suffers from MS?
Neurons are dying because they are not getting a “talk back” signal due to lack of myelin (since the system is attacking it’s own myelin due to odd immune system issue). They die without communication. They are hella social.
How does Dr. Trevitt define neurocommunication?
What allows us to move our muscles and to respond to our environment.
True or false: Neural communication flows anterograde or retrograde.
False - that applies to neurotransmitters, but NOT neurons. Electrical communication flows just 1 way.
How are neurons unique in the way they transmit their signal?
They have the ability to transmit electrical signals which most cells can’t.
Why is the potential of the extracellular fluid different from the potential of the intracellular fluid?
Because the ion concentrations (and electrical charges) are different!
What are the 2 ways to anatomically categorize neurons?
Shapes: Unipolar, Bipolar, Multipolar
Function: Afferent and Efferent
Why is the inside of the cell more negative than the outside?
The charged particles (ions) concentrations found between the 2 different fluids.
What is more negative, the intracellular or extracellular fluid?
The intracellular fluid is more negative.
What are the ion charges of the following ions:
Sodium
Potassium
Chloride
Sodium - Positive
Potassium - Positive
Chloride - Negative
How is the extracellular fluid similar to sea water?
Since we were made from seawater, our extracellular fluid is composed mostly of positive ion Sodium and negative ion Chloride.
If Potassium is positively charged, why does it hang out inside of the intracellular fluid? How come it doesn’t hang with it’s homie Sodium?
There are protein molecules which are in the cell which are negatively charged.
What does movement of ions in the membranes create?
Electrical signals.
Describe the forces that make Ions move.
Diffusion AND Electrostatic Pressure.
Describe diffusion and which ion participates in this action.
Ions like elbow room and spreads out from like ions.
Move from HIGH concentration to LOW concentration.
Ex) Sodium does NOT like it’s own kind. Does not care about Chloride.
Diffusion is about CONCENTRATION (gradient).
Describe electrostatic pressure and which ion participates.
Seeks out Opposite charges. Repelled by the same charged ions.
Ex) Neg. charged ions are attracted to Pos. charge.
Electrostatic is about CHARGE.
Use sodium as an example and describe its diffusion and electrostatic behavior.
Sodium does not want to be with other Sodium (diffusion - get away from its own) but also doesn’t want to be with Potassium (electrostatic - repelled by same charge)
Attracted to Chloride (negative charge).
What happens to the negatively charged proteins when the ion channels open?
Nothing, they’re too large to go through the channel - they keep the intracellular NEGATIVE.
If we open a Potassium channel when the membrane is at resting potential? Explain what the diffusion and electrostatic forces do.
Due to Electrostatic pressure, K+ will stay inside since opposite attracts.
Makes sense that the force of diffusion will push the potassium out since the concentration of K+ is so high inside, and there IS A LEAK, but overall not much movement.
If we open a Chloride channel, where does it go? Explain what the diffusion and electrostatic forces do.
Diffusion forces pushes it INTO the cell (too many on the outside) while Electrostatic pressure pushes it out (Chloride is negative like the inside)
Not a lot of movement with Chloride.
If we open a Sodium channel, where does it go? Explain what the diffusion and electrostatic forces do.
Diffusion pushes the sodium INTO the cell to spread itself out.
Electrostatic forces also push the sodium INTO the cell because it’s positive charge is attracted to the negativity.
What is the only channel when open, makes a difference in the RMP? Why?
Sodium channels. Because, it’s actually moving due to diffusion and electrostatic pressure.
What are the 3 types of channels?
Describe them all.
Voltage-gated channels: Will open or close when membrane it’s embedded in reaches a specific voltage.
>Depends on the membrane potential
Transmitter-gated: This gate only opens if there is a neurotransmitter bound to it.
Some channels have BOTH gates (ie; the membrane has to be at a certain potential AND it has to have a neurotransmitter bound to it for it to open).
What are ion channels comprised of?
Ion channels are comprised of protein subunits, and span the membrane.
How specific are ion channels?
Very specific. Only let 1 ion per channel.
What is Depolarization also known as?
Excitatory Post-Synaptic Potential
What is Hyperpolarization also known as?
Inhibitory Post-Synaptic Potential.
How are the names EPSP and IPSP derived?
Derived from the effects of these changes in the membrane potential in the next cell in the chain and how likely the next membrane will have an action potential.
Which potential makes it more likely for the next neuron in the chain to have an action potential?
Depolarization (EPSP) makes it more likely for the next neuron to have an action potential, while hyperpolarization (IPSP) makes it less likely.
What does it mean when a cell is depolarizing?
What does it mean when a cell is hyperpolarizing?
Ie: what’s the inside of the cell relative to the outside?
Depolarization aka EPSP (excitatory post synaptic potential) describes when the inside of the cell is becoming more positive. (and more similar because it’s closer to the extracellular fluid).
Hyperpolarization aka IPSP (inhibitory post-synaptic potential) describes when the RMP becomes more negative inside relative to outside.
What does threshhold mean? What happens during threshold?
When a cell is depolarized to threshold, an action potential is produced. This is when the sodium and potassium channels open up.
-65 -> -70 , depolarized or hyperpolarized?
Hyperpolarization of the cell membrane. The resting potential goes down!
-65 -> -60 , depolarized or hyperpolarized?
Depolarization of the cell membrane. The resting potential goes up!
What accounts for the rise and fall of an action potential?
The opening of sodium channels and potassium channels in the neural membrane accounts for the rise and fall seen in a recording of an action potential.
What does it mean when the sodium and potassium channels open up?
Threshold has been reached
Which area, if threshold is met, will trigger an action potential?
What happens with the ions?
If change in Membrane Potential exceeds threshold at the axon hillock, there will be an AP.
This is when the sodium channels open.
What is a refractory period?
Limits cells firing during this time.
How does the axon hillock evaluate whether to trigger an AP or not?
Calculator:
Each synapse will signal the synapse right next to it, changing the membrane potential.
Evaluates (sums) all input to the neuron over a given time period (~msec) and determines if overall change in membrane charge exceeds threshold.
What is passive conduction?
What does this have to do with the axon hillock?
When energy shot from the action potential is super fast but disappears quickly.
The axon hillock sums up all the passive conductions and sums them up to see overall change in the membrane potential.
Therefore, synapses closer to the axon hillock have more of a say than the ones out in the boondocks since their signals are weaker.
What does it mean when synapses are strengthened due to practice or learning?
The synapse connection in certain neurons become stronger because the synapses migrate closer to the axon hillock.
Why is AP considered a transient reversal?
Transient - doesn’t last forever, quick
Reversal - the cell membranes change concentration of ions
What’s happening with ions during AP?
Na+ rushes into cell via voltage-gated channels (diffusion + electrostatic pressure)
Influx of Na+ (100 million ions/sec) raises membrane potential to ~40mV
Voltage-gated K+ channels open
K+ rushes out of cell (diffusion + electrostatic pressure)
At peak of AP, Na+ channels become refractory
K+ continues to leave cell, driving MP down
Membrane becomes hyperpolarized, K+ channels close, Na+ channels reset
Extra K+ outside diffuses away, Na+/K+ pump works to restore MP back to RPM
What does active and passive conduction mean for a myelinated axon?
What are it’s advantages and disadvantages?
What does it mean when there’s a mix of active and passive conduction?
Active AND passive conduction = saltutory conduction.
Myelin (fast) and Nodes of Ranvier (passive)
advantages and disadvantages temporal and spacial summation
Passive conduction: Fast and cheap; Energy Dissipates
Active conduction: Never lose signal; Slow and expensive.
What does the sodium-potassium pump do?
It restores the ion concentrations so that the next time an AP is to start again, sodium can be drawn into the cell by both diffusion and electrostatic pressure. Before the sodium-potassium pump cleans up the mess, there’s too much sodium inside of the cell already, so diffusion would not allow sodium to enter again.
What is going on during absolute and relative refractory period?
During absolute refractory periods, it limits action potentials. The absolute refractory period is when a neuron cannot produce another action potential during this period, since an action potential is already occurring at this time.
During the relative refractory period, the resting membrane is in a hyperpolarized state. Starting an action potential at this state will require a larger depolarization, or a greater stimulus than usual.
Define synapse.
A synapse is a point of communication between two neurons.
What’s the difference between electrical synapse and chemical synapse?
Electrical synapses are characterized by very tiny synaptic gaps crossed by ion channels from the pre- and postsynaptic neurons.
Chemical synapses involve the release of neurotransmitter by the presynaptic cell.
How does calcium act when calcium channels open? Why is this important for the process of changing from an electrical signal to chemical?
When calcium channels open, it acts like sodium since Calcium is in higher concentration outside of the cell and is positively charged (both diffusion and eletrostatic pushes it into the cell)
It causes the vesicles hanging out in the axon terminals to dock /attach to the inner surface of the terminal membrane, once attached it cleaves them open to spill their contents into the space in the synapse between the pre and post- synaptic cell…
The vesicle membrane is continuous with the terminal membrane (made of same stuff).
