Midterm 1 Flashcards
Brain, Neuron, Perception
Neuron Structure
Input -> Dendrite -> Cell Body -> Axon Hillock -> Axon -> Output
Node of Ranvier
Inbetween myelin sheath
3 types of Synapses
Axosomatic: axon - cell body
Axodendritic: axon - dendrite (most common)
Axoaxonic: - axon - axon
The Neuron as a Battery
Uses the Difference in electical potential ( more positive ions outside the cell) (more negative ions inside the cell) to give the neuron a resting potential of -70mv
Ion Channels vs Ion Pumps
Passive transport via gradient (Na, K, Ca, Clvs Active transport (Na, K, Ca)
K+ Electrochemical Equilibrium
Electrical Gradient brings K+ into Cell
Concentration Gradient pushes K+ out of Cell
Nernst Equation
calculates potential bt inside and outside of cell when K+ ions are in balance.
Eion = Equilibrium potential for ion R = Universal gas constant F = Faraday constant T = Temperature z = Valence ln() = natural logarithm [ion]o = outside concentration of ion [ion]i = inside concentration of ion
Na+ Electrochemical Equilibrium
both push in bc more sodium outside the cell ( conc. gradient) and more -ive inside = elec. gradient
Na/K Pump
For 1 molecule of ATP
(adenosine triphosphate):
● 2 K+ in
● 3 Na+ out
Result:
Concentration gradients
● Greater Na+ outside
● Greater K+ inside
Electrical gradient
● Higher potential outside
ACTION POTENTIAL EVENTS
- At threshold, voltage-gated Na+ channels open, and positive Na+ ions flow into cell
- As depolarization continues, even more voltage-gated Na+ channels open, increasing depolarization
- Voltage-gated K+ channels open, and K+ ions flow out of cell
- Voltage-gated Na+ channels close, while voltage-gated K+ channels are still open
During hyperpolarization, another action potential cannot be generated (absolute refractory period) - Voltage-gated K+ channels close when the membrane is hyperpolarized (below resting potential), and the membrane potential returns to steady state at the resting potential (relative refractory period)
Propagation of Action Potential (long distance)
second way the action potential travels through the neuron.
long distance signal transmission
spiking of potential conducts to nearby tissue which then excites the nearby tissue = action potential goes and so on and so on.
Glutamate
Excitatory neurotransmitter
GABA
Inhibatory Neurotransmitter
Ionotropic Receptors
Short response time
Metabotropic Receptors
Long Response time
Strength of Post Synaptic Potential Depends on:
Strength of PSP at the synapse ● Timecourse of PSP at the synapse ● Distance to the synapse ● Time since the action potential`
