Module Part 4 Cell Membrane Flashcards
Function of the Cell Membrane (3)
Separates components from environment
Gatekeeper, selectively permeable
Maintains homeostasis
For homeostasis to be maintained you need to balance (4)
pH
temperature
glucose
water balance
Homeostasis:
When a pH solution is unbalanced, you need a ____
BUFFER
Cell membrane is made up of ___, ___, and ___ which is why its called a phospholipid bilayer
The bilayer is only made up of ___ and ___
However, the specific parts once formed include the ___, ___, and ___
Phosphate
Proteins
Lipids
Phosphates and Fats
Lipid Bilayer
Protein Channel
Protein Pump
Does not require energy to move molecules from a HIGH water conc to LOW water concentration
Requires energy (ATP) to move molecules from a LOW water conc to HIGH water concentration
Passive Transport
Active Transport
Passive Transport kinds (3):
____ Movement of small particles across the cell membrane until homeostasis is reached. Sometimes, Molecules spread out into a more free environment, tightly packed if in high conc
____ Like (1) but ___ and ___ proteins aid in pushing the molecules across
___, the movement of WATER through a selectively permeable membrane. HIGH WATER to LOW WATER
Diffusion
Facilitated Diffusion, Carrier Proteins, Channel Proteins
Osmosis
Osmosis:
____ Solutions have high concentration of solute, causing it to make a cell____. Water diffuses ___
____Solutions have low concentration of solute, causing it to make a cell ___. Water diffuses ____
____ Solutions Same concentration. Water diffuses ___
Hypertonic, Shrivel, out
Hypotonic, Swell, In
Isotonic, Into and Out
Active Transport types (4)
Materials EXIT the cell
Materials ENTER the cell
SMALL Materials ENTER the cell
LARGE materials ENTER the cell
Exocytosis
Endocytosis
Pinocytosis
Phagocytosis
Proteins involved in active transport are known as ____
Blood vessels are ____ in carbon dioxide compared to the cells so energy is used to pull the carbon dioxide from LOW SOLUTE concentration to HIGHER SOLUTE CONCENTRATION so the carbon dioxide can go with the blood vessels
Protein pumps
High
a distribution of charge across
the cell membrane
A. The body as a whole is electrically ___
B. All fo the cells of the body have an electrical potential across their membrane, a ____
C. Membrane potentials develop because of ____ between the inside and outside of the cell
Membrane potential
Neutral
Voltage Difference
Differing Ion Concentrations
Membrane potential:
Commonly reported resting membrane volt value of cells
Is in unit of ___
____ is always measured between two points
-70 mV
Millivolts
Voltage
Membrane potential:
____ Flow of electrical charges from one point to another
- ___ charges repel ____ attract
- Ions tend to move from areas of ____ to areas of ____
- Movement of a ____ ion from one side of a membrane to the other implies a ____ charge is left behind
Current
like, unlike
greater concentration, least concentration
positive, negative
Membrane potential:
____the voltage across a conductor is directly proportional to the current flowing through it, provided all physical conditions and temperature, remain constant
I=
E=
R=
Subsequent equation:
Ohm’s law
Current Flow
Electrical potential
Resistance
(I=E/R)
Membrane potential:
____ = Aqueous solution + good conductor
____ = A few charged groups can not carry current - high electrical resistasnce - good insulator
___ and ___ - both have low electrical resistance
Cell
Lipid Membrane
Extracellular Fluid, Intracellular Fluid
____ Describes the steady state of the cell
BY convention the ECF is assigned a voltage of ___
____ of the membrane is stated in terms of excess charge ____ the cell
Resting Membrane Potential
Zero
Polarity
Inside
Membrane Ion Channels:
___Open all of the time, slow passage of ions, permeability is constant (neurons). Random opening
a. ___,____ & ___
b. Biased towards ____ because it is 75% more permeable to it
c. Accounts for ___ of the resting membrane potential
Leak channels
Sodium, Potassium & Chlorine
K+
95%
Membrane Ion Channels:
____ Unequal transport of POSITIVE IONS makes the ICF more ____ than it would be just from diffusion alone
It is an ____ pump
___Na+ : ___ K+ (NOTE Na+ IN K+ OUT)
Na+K+ATPase Pump
Negative
Electrogenic
3:2
Types of Channels (4)
Always Open (Exterior has the normal positive charge and cytosol has negative) Restign potential
Opens (transiently) in response to CHANGE in the membrane potential (Exterior in this case is negative)
Opens & Closes in response to an EXTRA cellular neurotransmitter
Open & Closes in response to a specific INTRAcellular molecule
Resting K+ Channel — K+
Voltage-gated Channel — Na+
Ligand-gated Channel — Na+
Signal-gated Channel — Na+
Membrane Channels:
Voltage-gated channels are responsible for propagating action potentials along the ____ membrane
While, Ligand-gated and Signal-gated channels found in ____ and ___ are responsible for generating ____ in ____
Axonal Membrane
Dendrites and Cell Bodies
Electric Signals in Postsynaptic Cells
Membrane Potential:
Too much K+ in the blood
Hyperkalemia
Membrane Potentials Ion Gradients:
Generally called a ____
Two Forms include ____ and ____
Electrochemical Gradient
Chemical Concentration Gradient
Electrical Concentration Gradient
Resting Membrane Potential:
In all cells a potential difference across the membrane exists:
The inside is ___ which is why it needs the (Na+K+ATPase)
While the MEmbrane Potentials are usually between ___ and ___
A cell with a resting membrane potential is said to be ___
Both inside and the outside of the cell should be ____
Negative
-40mv to -90mv
Polarized
Electrically neutral
Resting Membrane Potential:
Factors that determine the resting Membrane potential (4)
Selective permeability of plasma membrane
Leak Channels
Na+K+ATPase Pump
Difference in Ion concentrations
Resting Membrane Potential:
Ions that do the most important roles (4)
In the ECF ___ helps to balance ___
In ICF ___(___) balance ___
Na+
K+
Ca++
Cl-
Cl-, Na+
Proteins(neg charge), K+
Resting Membrane Potential:
Selective membrane permeability:
a. At rest - Slightly permeable to ___, ___ times more permeable to ___, and freely permeable to ___
b. ___ moves down its concentration gradient easily & Faster than ___
c. Movement of a ___ out leaves a negative charge
Na+, 75, K+, Cl-
K+, Na+
K+
Membrane potential :
___ aka. ____Ion movements in both directions across the membrane are equally balanced (net movement = zero)
____ implies no net ion movement
Equation:
E(x) = RT/ZF log inside/outside
R=
T=
Z=
F=
Equilibrium Potential
Ion Flux
Nernst Potential
R= Gas constant
T= Temp. Kelvin
Z= Charge on Ion (Valance)
F=Faraday’s Constant
Hwo to use the Nernst’s equation
E(x) = ___ log inside/outside OR outside/inside
-61 mV
Nernsst’s equation Examples
-61mV log [14]/[140]
-61mV log [140]/[4]
Na+
K+
Net Current Flow (I) equation:
I(x) = g(x) {Em - E(x)}
Where
g=
Em =
E(x) =
g = Ion Conductance
Em = Resting Membrane Potential
E(x) Nernst’s potential
Resting Membrane Potential:
At rest, the membrane potential is not changing, so the sum of all currents must equal zero
Otherwise,
Resting Membrane Potential equation:
Em=
R= universal gas constant R=8.314471 J mol -1
T= 0K - 273.15oC
Z= Moles of electrons transferred
F = Faraday’s constant 96, 485.3415 C mol -1
Pa = Permeability of membrane to that ion
Ao = outside
Ai = inside
Em = RT/zF ln ( Pa [A]o + Pb [B]o / Pa [A]i + Pb [B]i )
