nervous system

sensory neurons

• carry sensory info (pain, temp, etc)

interneuron

• connector neuron

• short

cell body

• location of nucleus and organelles

dendrite

• receives info

axon

• carries info away

• long & thin

• cells around the axon insulate the axon & helps move info along

axon terminal

• transmits signals to cells

• vesicles

synaptic cleft

• between axon terminal and other cell

• neurotransmitters are dumped her from vesicles

sodium-potassium pump

• allows central nervous system to work

• 3 NA+ for every 2 K+ pumped in

• creates an electrical gradient // membrane potential

why does the outside have a more positive charge?

more positives are being pumped out (3 NA+) than pumped in (2 K+)

what happens after a signal comes

• sodium channel opens up & sodium comes in

• lessening the positive charge outside the celll

why sodium diffuses in easily

the gradient

inside

negative (2 K+ pumped in)

outside

positive (3 NA+ pumped out)

resting potential

-70 ish

myelin sheath

• layer of phospholipids

• insulates the neurons so that signals don’t get lost + moves faster

schwann cell

• layers of myelin sheath that insulate axons

nodes of ranvier

• signals go from node to node

• between each schwann cell

• depolarized region

resting membrane potential

difference in charge between the interior and exterior of the cell

how the membrane becomes depolarized

stimulus → sodium flows in, lessening the positive charge outside

depolarization across the membrane

sodium channels open and it flows in, making the inside + and the outside -, and this ripples through the neuron

action potential

moving depolarization

restoring the resting membrane potential

sodium channels close and potassium channels open

repolarization

• rapid flow of potassium ions out of the cell

• fully restoring proper concentration of NA+ and K+ in and out of the cell

inside of presynaptic neuron

vesicles filled with neurotransmitter molecules

docking proteins

• where the vesicles (filled with neurotransmitters) dock

• located at the presynaptic terminal

when an action potential (electrical impulse) arrives at synaptic terminal

vesicles fuse with membrane & dump neurotransmitters into synaptic cleft

synaptic cleft

• between axon terminal (presynaptic) and other cell (postsynaptic)

• neurotransmitters are dumped here from vesicles

how the action potential reach the new cell

receptors on the postsynaptic cell open/close ion channels

synaptic vesicles

sacs @ axon terminal that contain neurotransmitters

peripheral NS

carries info from periphery to central NS (brain & spinal cord)

motor division

carries info from the central NS to periphery (muscles)

somatic NS

motor division

autonomic NS

motor division

signals to skeletal muscles, voluntary

somatic NS

regulates internal environment, involuntary

autonomic NS

parasympathetic division

autonomic NS

sympathetic division

autonomic NS

rest and digest

parasympathetic

fight or flight

sympathetic

neurotransmitters are broken down to..

prevent repeated signals

calcium

causes synaptic vesicles to fuse and release neurotransmitters thru exocytosis

depolarization causes..

Ca channels open, calcium rushes in

how depolarization happens

sodium channels open, NA+ rushes into the axon, decreasing the gradient

how depolarization happens

potassium channels open, K+ goes out of axon until gradient is back to resting

hyperpolarization/refractory period

resting period before the next stimulus

what brings membrane potential back to normal/resting

NA+/K+ pump