Action Potential

intracellular fluid

fluid inside a cell

extracellular fluid

fluid outside a cell

nucleus

stores the cell’s DNA

endoplasmic reticulum

synthesizes proteins, lipids, and steroids

golgi

sorts proteins from the ER

cell membrane

made of phospholipid bilayer and charged molecules cannot go through

axon terminal

the ends of axons which transmit messages to other cells

myelin sheath

bands wrapped around the axon that allow for faster ion travel

mitochondria

generates energy

DNA

stores genetic info

ribosomes

synthesizes proteins

How many and what ion does sodium potassium pump bring in the cell?

2 potassium

How many and what ion does sodium potassium pump out the cell?

3 sodium

gradient

flow of substance in one end to another

channel

moves ions from high to low concentration

transporter

moves ions against the gradient with energy/ATP

NA⁺

sodium

K⁺

potassium

glia

Break down and remove dead neurons and waste

equilibrium constant

satisfies concentration gradient

cytoplasm

liquid inside the cell

neurons

brain cells

EPSP

excitatory postsynaptic potential

IPSP

inhibitory postsynaptic potential

axon hillock

adds up EPSP + IPSP charges

threshold

-55 mV

resting

-70 mV

when do the voltage gated sodium channels open?

when the vertex is reached

when do the voltage gated sodium channels inactivate?

absolute refractory period

when do the voltage gated sodium channels close?

relative refractory period

what is the vertex of action potential?

20-40 mV

Are VGKc’s fast or slow?

slow

are voltage gated potassium channels fast or slow?

Slow

depolarization

sodium rushes in the cell, voltage keeps rising until the vertex

repolarization

once vertex is reacher, voltage is positive, so potassium wants to leave and the voltage starts decreasing

hyperpolarization

Because the VGKC are slow to close, the charge becomes slightly more negative than resting but then slowly goes back up to resting potential

action potential

change in voltage when a cell is activated by stimulus

neuronal membrane

keeps two fluids separate

membrane potential

difference in charge between the two fluids

neurotransmitters

small molecules released from the axon terminal

What are vesicles?

membrane bound spheres filled with neurotransmitters and has proteins branching out

What is a vesicle when it’s proteins are attached with the cell membrane?

docked

Ca²⁺

calcium

What kind of molecule is calcium?

signaling molecule

signalling molecule

interacts with proteins to do a job

synapse

Space across two neurons

presynaptic terminal

another way to say axon terminal

synaptic bouton

same as axon terminal

dendritic spine/post synaptic neuron

receives ions

ligand gated ion channels

proteins that allow ions to pass through when binded to a neurotransmitter

nodes of ranvier

spaces in between myelin sheaths on the axon

saltatory conduction

“skipping” of one node to the next

absolute refractory period

no AP’s possible

What happens during the absolute refractory period?

VGNA channels are inactivated

What happens during the relative refractory period?

NA channels close

What is the relative refractory period?

when action potential is possible, but needs more EPSPs

How can VG channels help move AP from the axon to the axon terminal?

When the first NA channel responds, the EPSPs go in both directions and open the next NA channels to the right.

Why can’t action potential move towards the soma?

The VGNA channels open and inactivate from towards to away from the soma so the sodium is blocked.

What is the benefit of myelin to helping AP move quickly?

Myelin is an insulator, helps move the current more quickly. There are no channels, so the sodium skips to the next band.