KHA258 Lecture Notes - Lecture 3: Schwann Cell, Neurotransmitter Receptor, Cannabinoid
3 Jul 2018
School
Department
Course
Professor
Behavioural Neuroscience week 3: Neurons
Basic information:
- Communication among neurons gives rise to all behaviour
oNormal and abnormal behaviour may be explained
oTreating
oThe mind is created by the brain: not separate
oWe have physical matter, their properties gives unified subjective
conscious
- Different to other cells:
oCan change electrical potential depending on circumstances
surrounding them at the time
oTissue around that makes them a unitary structure
- Be alert to reality that there are exceptions to this
oCharacter of ideal most common neuron
Resting membrane potential:
- Recording the membrane potential
oMeasure the difference in electrical charge between inside and outside
of a cell
oInside is negatively charged in relation to outside
oMolecules inside and outside
Ions: electron added or removed
This give charge
o-70mV
oMembrane is polarized: carries a charge
This can change
- Ionic basis of resting potential:
oFactors contributing to even distribution of ions
oCharged particles want to keep charge balanced around them
Repel
Random motion: move down the concentration gradient
Density of particular ions that are closely packed
Move until the distance apart is even
Barrier may prevent this occurring
Trying to move apart but something stops them
They have a potential to move
Electrostatic pressure: like repels like
Abundance of like charge ions trying to move with
opposite charges but something is preventing them
Opposites attract
When there is a large amount of like charge ions that
are trying to move away from one another but there is
something stopping this happening
Preventing: things that contribute to uneven distribution
Membrane: selectively permeable
oSome move through with little difficulty
oSome ions can some cannot move through
oPermeable to potassium, not to sodium
find more resources at oneclass.com
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oThis developed but concentration gradient and
electrostatic pressure
Sodium-potassium pump:
oGradient
Sodium is outside cell
Chloride (CL-) outside: combined with Na, salty area
Potassium inside
Therefore, like sodium has fewer electrons
All of these can move across a membrane, this leads to a charge
Negatively charged proteins (A-) inside
Cannot move across membrane
Anions: negatively charged
oIons can move through pumps
Some can move in and out without trouble readily
Channels are permeable to K: leave cell and becomes
increasingly negative inside
Pressure
Excess negative charge inside
Electrostatic pressure as well as concentration gradient
Measured in charges
Na: cell membrane not permeable to Na at resting state
Channels in resting state are close
Not easy to move across
Inside low, outside high concentration: Na wants to
move down concentration gradient
Negatively charged anions inside so there is negative
internal structure
This create electrostatic pressure
Chlorine more concentrated outside than inside
Leads to overall charge imbalance
oEquilibrium potential of ion: Hodgkin-Huxely model
The potential at which there is no net movement of an ion
The potential it will move to achieve when allowed to move
freely
Na: 120mV
K: 90mV
Cl: -70mV
Same as resting potential
This means that electrostatic forces that trying to pull Na inside
the cell
Concentration gradient: if cell become permeable it will move
Electrostatic forces try to more K in the cell but at the same
time K is moving outside the cell because of less charges there
Cl is at equal
Balances charges
Na-K pump:
Metabolically active pump takes Na out, K in
find more resources at oneclass.com
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3 Na to 2 K
Uses ATP
oGeneration and conduction of Postsynaptic potentials:
Neurotransmitter binds at postsynaptic receptor
These chemical messengers bind and causes electrical changes:
Depolarization: making less negative
Hyperpolarization: making more negative
EPSP’s and IPSPs are passive processes:
oChanges within and outside of relative position
of ions
oSite of orientation
oCan move along the membrane
Decrement: not an active process
oLosses energy over time
oCan only travel short distance
When the neuron is at rest it is -70mV less that the outside
oIntegration of postsynaptic potential:
Single EPSP is too small to cause action potential
Need an integration of IPSP and EPSPs
Must depolarize neuron to about -65mV in order to generate
action potential
Summation
Two types of summation:
Spatial: multiple inputs onto a neuron simultaneously
oAt different locations on the neuron
oNet
oMight mistakenly think nothing is happening
oDifficult to conclude nothing happening
Temporal Summation:
oSingle synapse activated at different times
3.2: Action potentials
- As opposed to action potentials
Conduction of action potentials:
- All or none:
oWhen threshold is reached neuron fires and the action potential either
occurs or it does not
oFixed amplitude
Rapid occurrence
oDo not summate
oDoesn’t drop over distance as it occurs from initiation point or beyond
- Uses energy
- Ions move across the membrane
- Uses energy
- Results in ions crossing membrane
- Threshold:
oChange in membrane itself: proteins change
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Communication among neurons gives rise to all behaviour: normal and abnormal behaviour may be explained, treating, the mind is created by the brain: not separate, we have physical matter, their properties gives unified subjective conscious. Different to other cells: can change electrical potential depending on circumstances surrounding them at the time, tissue around that makes them a unitary structure. Be alert to reality that there are exceptions to this: character of ideal most common neuron. Recording the membrane potential: measure the difference in electrical charge between inside and outside of a cell, inside is negatively charged in relation to outside, molecules inside and outside. This give charge: -70mv, membrane is polarized: carries a charge. Ionic basis of resting potential: factors contributing to even distribution of ions, charged particles want to keep charge balanced around them. Random motion: move down the concentration gradient. Density of particular ions that are closely packed. Move until the distance apart is even.
