Lecture 1-4 Flashcards
1
Q
Cells of the Nervous System (2)
A
- Glial Cells: Support cell
- Neurons: communication + main functional part
2
Q
Type of Glial cells (2):
A
- Microglia: macrophages (garbage collectors)
- Macroglia: astrocytes, oligodendrocytes, schwann cells
3
Q
Astrocytes (2)
type + major function
A
- Most abundant macroglia
- Two major functions:
1. Support Neurons (nutritive such as growth factors and physical)
2. Fundamental component of the BBB (wraps around blood vessels)
4
Q
Oligodendrocytes (3)
structure + creates + location
A
- contain projections from the central cell body and wrap around the axon of neurons to help neurons function
- Creates myelin sheath and assists in conduction velocity (increase)
- Confined to CNS (brain + spinal cord)
5
Q
Shwann Cells (3)
Diff from + what they do +location
A
- Different from oligiodendrocytes as there are no projections to make myelin shealth on multiple axons, as the schwann cell only wrap around 1 axon and makes myelin sheath
- Wrapping around increase condution velocity making signal faster
- Only in PNS
6
Q
Neuron Components (4)
A
- Dendrites = Input
- Soma/Cell body = Integration: take vast input and determine if the info will be sent to axon and to next neuron
- Axon: Conduction
- Synapic Bouton = OUTPUT, axon ends, close contact with other neuron/organs
7
Q
The vast majority of neurontransmiters come at ….
A
the dendrite but can come at the axon or cell body
8
Q
Phospholipid molecule components (2)
A
- Polar head: Hydrophillic, charges on head portion and binds to free water molecules
- Nonpolar tails: Hydrophobic, hydrocarbon tail
9
Q
Hydration shell + ex
A
- Sodium ion has charge causing water molecules to surround. It has an hydration shell causing it to be hard to pass through the membrane.
10
Q
Membrane potential
A
- Voltage across membrane = seperation of charges.
- Membrane acts like a circuit
11
Q
Properties of the — and —– allow for the development of the membrane potential
A
- membrane
- hydration shells
12
Q
How does a voltmeter work?
A
- Measures the charge between 2 distinct area. The reference electrode and the recording electrode are placed at two distinct area and sees if the charge is the same/diff between the 2 electrode.
13
Q
Source of membrane potential:
A
- Seperation of electrical charges (charges = ions)
- Charged components that are seperated by membrane leads to resting membrane
14
Q
Tell me the location of the ions in the cell:
Na+
K+
A-
A
15
Q
Sodium/Potassium Pump (2)
Energy + function
A
- Energy dependent on hydrolyzing ATP and using ADP
- The pump moves three sodium ions out of the cell for every two potassium ions it brings in. The pump makes sure K+ is on the inside of the cell
16
Q
Concentration differences lead to:
A
- a force for ion movement
Area of high concentration -> Area of low concentration
17
Q
Ion will —- move down a concetration gradient
A
naturally
18
Q
—- is key to the development of the membrane potential
A
Ion movement
19
Q
Talk about the ion inclination in membrane potential in terms of quantitivity (2):
K+ and Cl-
A
K+ = More on inside, force to get out
Cl- = More on outside so try to get inside
20
Q
What function does the membrane serve?
A
- A barrier, prevents ions to move except for potassium which can move down concentration gradient due to leak channels
21
Q
What happens when you decrease K+ permeability?
A
Less K+ will leave the cell making the inside less negative. This will result in higher (less -) resting membrane potential
22
Q
Driving force
what + aka + Direction of Na+ and K+
A
- Powered by concentration differences
- Diffusion
23
Q
Couluomb’s Law (3)
What + charges + Formula
A
- Describes the magnitude of the electrostatic force of attraction or repulsion between two point charges at rest that is directly proportional to the product of the magnitudes of charges and inversely proportional to the square of the distance between them
- Like charges repel, opposite attract
24
Q
EMF
What + Direction of Na+, K+, Cl-
A
- ## the sum of the electric potential differences produced by a separation of charges (electrons or ions) that can occur at each phase boundary (or interface) in the cell
25
Equilibrium potential
When Driving force = EMF
Net movement is 0 for ions
26
Talk about DF and EMF on K+ ions with infinite leak channels
1. Potassium starts to move down it's concentration gradient outside of the cell.
2. Leaves more and more negativity inside of the cell. This makes the electromotive force even bigger. The more - the inside, the more EMF acting.
3. Driving force tries to move K+ out of the cell making membrane potential more negative where EMF is going to pull potassium back into the cell.
4. If the permeability of the membrane is inifinite, K+ move out of cell until EMF= DF which is Equilibrium potential.
27
Talk about DF and EMF on Na+ ions with infinite leak channels
| Explain proocess + Membrane potential + EP
1. More sodium on outside of the cell, driving force moves Na+ inside of cell
2. EMF also tries to move Na+ inside of the cell due to inside being negative
3. If we allow freeflow, Na+ will move inside of the cell. The inside of cell becomes positive (positive membrane potential).
4. The EMF force will switch direction once inside of cell is positive (repel Na+).
5. Free flow will cause membrane potential to be positive.
6. Equilibrium potential for sodium will be a positive value.
28
For a cell where there is only one permeant ionic species (only one type of ion that can cross the membrane), the resting membrane potential will equal the ----- for that ion.
- equilibrium potential
29
The steeper the concentration gradient is, the ---- the electrical potential that balances it has to be.
larger
*You can get an intuitive feeling for this by imagining the ion concentrations on either side of the membrane as hills of different sizes and thinking of the equilibrium potential as the force you'd need to exert to keep a boulder from rolling down the slopes between them.*
30
In neurons, however, the resting membrane potential is close but not identical to the K+ equilibrium potential. Instead, under physiological conditions (conditions like those in the body), neuron resting membrane potentials are ----- negative than the K+ equilibrium potential.
slightly less
*The reason K+ equilibrium potential is more negative is because the inside of the cell is left with fewer positive ions, making it more negatively charged relative to the outside. If K+ were the only ion involved, the resting membrane potential would settle at this -90 mV. However, other ions like Na leak in, making the resting membrane potential slightly less negative (around -70 mV). Permeability to Na+ in particular, is the main reason why the resting membrane potential is different from the potassium equilibrium potential.*
31
In a resting neuron, both Na+ and K+ are permeant, or able to cross the membrane. Na+ will try to drag the membrane potential toward its (-----) equilibrium potential. K+ will try to drag the membrane potential toward its (-----) equilibrium potential.
- positive
- negative
32
The real membrane potential will be in between the
----- equilibrium potential and the ---- equilibrium potential. However, it will be closer to the equilibrium potential of the ion type with ------
- Na+ and K+
- higher permeability (the one that can more readily cross the membrane).
33
Adding more sodium to the outside of the cell, the sodium equilibrium potential will ----- because....
- Increase
- The equilibrium potential represents the voltage at which the electrical and chemical forces driving Na⁺ in and out of the cell are balanced. By increasing the sodium concentration outside the cell, there is now a stronger concentration gradient pushing Na⁺ into the cell, meaning that a higher (more positive) membrane potential is needed to counterbalance this increased gradient.
34
Nernst Equation
| What it is + the equation
Relation between the concentration difference of a permeating ion across a membrane and the membrane potential at equilibrium.
| Na+, K+, Cl- by itself
## Footnote
0°C + 273.15 = 273.15K
35
Nernst equation (temp)
- Temp isnt changing, steady-state
36
Nernst Equation Shortcut for 18°C, valence 1
| mv and V
37
Nernst Equation Shortcut for 37°C, valence 1
38
Explain to me what the Nernst equation number means (3):
| What + ex + equilibrium ex
- At what voltage the ion's movement across the membrane will be at equilibrium, meaning that the chemical driving force (due to the concentration gradient) is perfectly counteracted by the electrical driving force (due to the charge difference across the membrane).
- In this case, -75 is the equilibirum potential or Nernst/reversal potential for a specific ion across a membrane, such as sodium (Na⁺), potassium (K⁺), or chloride (Cl⁻). This equilibrium potential is the electrical potential (voltage) difference across the membrane that exactly balances the chemical gradient for that ion.
- Membrane will go to -75 before equilibirum is reached.
39
For sodium (Na⁺), if the Nernst potential is calculated to be +60 mV, this means:
1. If the membrane potential is at +60 mV, sodium ions will -------.
2. If the membrane potential is more negative than +60 mV, sodium ions will ------
3. If the membrane potential is more positive than +60 mV, sodium ions will ------
1. have no net movement across the membrane (the electrical force pulling Na⁺ out of the cell balances the chemical force pushing Na⁺ into the cell due to its higher concentration outside)
2. tend to flow into the cell because the concentration gradient is stronger than the electrical force keeping it out.
3. tend to flow out of the cell, as the electrical force pushing them out overcomes the concentration gradient pulling them in.
40
In the Nernst equation, it is an artificial situation where permeability is ----- and the equilibroium value is based solely on -----
- infinite
- concentration
41
Calcium Nernst equation anomalie:
42
Chloride Nernst equation anomalie:
Flip out and in
43
Nernst equation is for use with just 1 ion, In physiological systems, multiple ions are present, what can we do?
- use Goldman Equation
