Unit 1 - 4 Flashcards
Diffusion
Passive process, particles move from an area of higher concentration to a lower one
Equilibrium
State of balance where particles are distributed evenly
Semipermeable cell membrane
Only some things can cross, prevents harmful toxins from entering
Ion
Charged atom
Cation
Positively charged
Anion
Negatively charged
Positive Ions
Sodium (Na+)
Potassium (K+)
Calcium (Ca2+)
Negative Ions
Chlorine (Cl-)
Ions concentrated inside of cell
K
Ions concentrated outside of cell
Na and Ca (Cl)
Electrostatic pressure
Force that arises from the distribution of electrical charges 
Charge inside of cell =
Negative
Resting potential
Potential difference between the inside and outside of the cell when one is not firing (-65mV)
Electrochemical gradient (5)
- Ion concentrations are different in and out of cell
- Inside of cell = negative
- Electro - ions want to move toward opposite charges
- Chemical - ion wants to move down their concentration gradient
- This instability results in fast changes of ion concentrations
Depolarization
Inside cell is becomes more positive
Hyper polarization
Inside becoming more negative
Threshold
Depolarized voltage where action potential will fire
All or none property
Cell with either fire action potential or not; binary choice
Refractory period
Time where cell cannot fire another action potential because of sodium channel inactivation
Action Potential Phase 1
Open K+ channels create resting potential
Action Potential Phase 2
Depolarization (more positive) brings membrane potential closer to threshold
Action Potential Phase 3
Na+ channels open, causes rapid change in polarity (action potential (massive influx of positive charge)
Action Potential Phase 4
Na+ channels close, K+ channel open, hyperpolarizing cells (more negative)
Action Potential Phase 5
All channels close and bring cell back to resting pontential
Myelin Sheath
Fatty layer around axon, critical for propagating action potential efficiently
Node of Ranvier
Break in myelin sheath (where concentrations of sodium allow positive influx charge)
Positive charge comes from stimulus (2)
- Sensory
- Neurotransmitters releasing onto dendrites
EPSP (excitatory postsynaptic potentials)
Push neuron to firing threshold (causes depolarization when fired)
IPSP (inhibitory postsynaptic potentials)
Push neuron more negative, away from firing threshold (causes hyper polarization when fired)
Spatial summation of EPSP
Arriving at 3 different parts of dendrite
Temporal Summation of EPSP
Many EPSP arrive quickly creating an overlap through one synapse
