3: SIGNALS Flashcards
electrical charge across a cell membrane (diff in charge inside + outside cell)
MEMBRANE POTENTIAL
2 TYPES OF MEMBRANE POTENTIALS THAT AXONS HAVE
- RESTING MEMBRANE POTENTIAL
- ACTION POTENTIAL
membrane potential of a neuron when it is AT REST (not being altered by excitatory/inhibitory postynaptic potentials)
RESTING MEMBRANE POTENTIAL
brief electrical impulse that provides basis for conduction of info along axon
ACTION POTENTIAL
2 WAYS MEMBRANE POTENTIAL CAN CHANGE
- HYPERPOLARIZATION
- DEPOLARIZATION
incr in membrane potential of cell relative to normal resting potential (inside axon become more NEGATIVE than outside)
HYPERPOLARIZATION
reduction (toward 0) of membrane potential of a cell from its normal resting potential (inside of axon becomes more POSITIVE than outside)
DEPOLARIZATION
value of the membrane potential that must be reached to produce an ACTION POTENTIAL
THRESHOLD OF EXCITATION
VALUE OF RESTING POTENTIAL
-70 mV
VALUE OF THRESHOLD OF EXCITATION
-55 mV
VALUE OF ACTION POTENTIAL
+40 mV
VALUE OF HYPERPOLARIZED NEURON
-90 mV
movement of molecules from regions of HIGH concentration to regions of LOW conentration
DIFFUSION GRADIENT
substances that split into 2 particles w opposing electrical charge when dissolved in water
ELECTROLYTES
notion that oppositely charged atoms attract + alike atoms repel = due to ____
ELECTROSTATIC PRESSURE
notion that CATIONS (+) + ANIONS (-) move towards areas of unlike charge (away from highly +/- areas)
ELECTROSTATIC GRADIENT
notion that gradients can balance one another + this is maintained by SODIUM-POTASSIUM PUMP
DYNAMIC EQUILIBRIUM
pump that pushes SODIUM ions out of axon in exchange for POTASSIUM ions
SODIUM-POTASSIUM PUMP
fluid within cell
INTRACELLULAR FLUID
fluid outside cell
EXTRACELLULAR FLUID
charge INSIDE cell = more ____
NEGATIVE (MORE ANIONS)
charge OUTSIDE cell = more ____
POSITIVE (MORE CATIONS)
IONS INSIDE CELL:
LOW concentration of ___ + ___
HIGH concentration of ___ + ___
LOW: Cl- + Na+
HIGH: K+ + A-
IONS OUTSIDE CELL:
LOW concentration of ___ + ___
HIGH concentration of ___ + ___
LOW: K+
HIGH: Cl- + Na+
Cl- uses ____ to get INSIDE cell + ____ to get OUTSIDE cell
DIFFUSION; ELECTROSTATIC PRESSURE
Na+ uses ____ + ____ to get INSIDE cell + ____ to get OUTSIDE CELL
DIFFUSION; ELECTROSTATIC PRESSURE; SODIUM-POTASSIUM PUMP
K+ uses ____ to get INSIDE cell + ____ to get OUTSIDE cell
ELECTROSTATIC PRESSURE; DIFFUSION
- THRESHOLD OF EXCITATION PASSED/DEPOLARIZATION: Na+ channels OPEN + Na+ enters cell
- REPOLARIZATION: K+ channels OPEN + K+ leaves cell
- PEAK: Na+ channels become REFRACTORY (no more Na+ enters cell)
- HYPERPOLARIZATION: K+ continues to leave cell + membrane pot returns to RESTING level
- RESTING: K+ channels CLOSE + Na+ channels RESET
- extra K+ outside diffuses away
ION MVMTS DURING ACTION POTENTIAL
where is an action potential generated?
at AXON HILLOCK
ion channel that opens/closes acc to the value of the MEMBRANE POTENTIAL
VOLTAGE-DEPENDENT ION CHANNEL
sodium channel blocker that pufferfish contain that PREVENTS ACTION POTENTIALS
TETRODOXIN
principle that once an AP = triggered in an axon it CANT be stopped (impulse travels till end of axon)
ALL-OR-NONE LAW
principle that variations in INTENSITY of a stimulus/other info being transmitted in an axon = represented by variations in RATE at which axon fires
RATE LAW
HIGH rate of AP firing = ___ muscular contraction + STRONG stimulus (bright light) causes ___ rate of firing in axons of eyes
STRONG; HIGH