1-4 nuerons, action potentials, neurotransmitters

Question 1

nueron

Answer 1

nerve cell

“signaling cell” of nervous system

communicate via synapses – through neurotransmitters

Question 2

myelin sheath

Answer 2

speed message transmission

CNS - created by oligodendrocytes
PNS - created by Schwann cells

Question 3

axon terminal

Answer 3

end boutons

releases neurotransmitters into the synapse

Question 4

cell membrane

Answer 4

phospholipid bilayer

proteins span the layer forming channels or receptors

molecules can pass through these channels

Question 5

what stimulates channels / receptors

Answer 5

electrical activity

ligands (neurotransmitters)

heat, mechanical stiumulation

Question 6

voltage difference (at rest)

Answer 6

more positive ions outside the cell body than inside

the voltage inside the body is negative (relative to outside)

Question 7

resting voltage inside body

Answer 7

-70mV

Question 8

why is the membrane negative at rest

Answer 8

ions move down the electrostatic gradient

ions flow from higher to lower concentration

Question 9

sodium potassium pump

Answer 9

a protein pump in the neuron cell membrane

uses ATP energy

pumps Na+ out
K+ in
at the same time

Question 10

ion contribution to resting potential

Answer 10

negatively charged ions mostly inside the cell

Na+ mostly outside, K+ inside

membrane is leakier to K+ than Na+ –> more positive ions leave the cell interior than get in

net result is the interior of the cell body at rest is negatively charged

Question 11

how do cells generate electrical signal

Answer 11

all living cells are polarized (have a charge)
neurons are negatively charged at rest

cells have semi-permeable membrane
charged particles can cross
when they cross, changes charge of the cell

nueron can alter polarization for brief period of time –> brief change = action potential

Question 12

action potential

Answer 12

where the neuron rapidly changes its resting electrical potential form negative to positive & back to negative

electrical change travels down axon

change at axon terminals causes release of neurotransmitters

Question 13

threshold voltage

Answer 13

where action potentials are generated

when stimulated, ligand-gated ion channels open & change the membrane voltage

Question 14

action potential generation

Answer 14

stimulus increases membrane permeability

conductance to Na+ increases & sodium rushes into cell

decrease of Na+ outside cell & membrane potential moves toward 0

Na+ concentration inside = greatest, Na+ conductance drops & K+ conductance increases

potassium moves rapidly out of cell

cell membrane potential moves back toward rest state

Question 15

hyperpolarization

Answer 15

negative intracellular potential is more negative than it is at rest

brief interval at the end of the voltage change

Question 16

refractory period

Answer 16

when the cell is hyperpolarized

more difficult to depolarize the cell during this brief interval

Question 17

saltatory conduction

Answer 17

nerve signals jump from one gap (node of ranvier) in the myelin sheath to another

instead of traveling smoothly along the entire length of the nerve

this jumping action speeds up the transmission of signals along the nerve fiber

Question 19

tetrodotoxin

Answer 19

blocks sodium channels

membrane can’t depolarize

leads to weakness & numbness
can be fatal

Question 20

multiple sclerosis

Answer 20

damage to myelin sheath

nerves can’t jump as efficiently due to damage

muscle weakness, numbness, trouble w/ coordination

Question 21

exocytosis

Answer 21

release of neurotransmitter into synaptic cleft

Question 22

post-synaptic potential

Answer 22

like action potential, but smaller

Question 23

excitatory (EPSP)

Answer 23

leads to depolarization & perhaps action potential (if threshold is met)

when Na+ or CA2+ enters the cell

Question 24

inhibitory (IPSP)

Answer 24

leads to further negative polarization or no change & no action potential happens

when K+ leaves the cell or Cl- enters the cell after stimulatioin

serves as an active “brake” that suppresses excitation

Question 25

temporal summation

Answer 25

repeated stimuli can have a cumulative effect

can produce a nerve impulse when a single stimuli is too weak

Question 26

spatial summation

Answer 26

synaptic input from several locations can have a cumulative effect

can trigger a nerve impulse

Question 27

spontaneous firing rate

Answer 27

periodic production of action potentials despite synaptic input

EPSP - increases # of action potentials above spontaneous firing rate

IPSP - decreases # of action potentials below spontaneous firing rate

Question 28

graded potentials

Answer 28

liklihood of an action potential depends on the ratio of IPSPs to EPSPs at a given moment

graded potentials are summed –> either cell reaches threshold (action potential occurs) or it doesn’t

Question 29

classes of neurotransmitters

Answer 29

amino acids
a modified amino acid
monoamines (also modified from amino acids)
peptides (chains of amino acids)
purines
gases

Question 30

termination of neurotransmitters

Answer 30

if it is:

1. degraded by enzymes
2. transported back into the cell & repackaged
3. combination of 1 & 2

Question 31

ionotropic

Answer 31

neurotransmitter attaches to the receptor causing the immediate opening of an ion channel

occur very quickly & are very short lasting

most use glutamate or acetylcholine

open sodium ion channel
sodium enters cell –> depolarization
potassium ion channel opens
potassium leaves cell –> hyperpolarization (more negative)

Question 32

metabotrophic effects

Answer 32

when a neurotransmitter attaches to a recpetor & initiates a sequence of metabolic reactions that are slower & longer lasting

hunger, fear, thirst, & anger

bends the rest of the protein inside the neuron
allows it to react w/ other molecules

Question 33

neuromodulation effects

Answer 33

increasing or decreasing the release of other neurotransmitters

altering the response of postsynaptic cells to various inputs

Question 34

antagonistic

Answer 34

block neurotransmitter effects

Question 35

agonist

Answer 35

mimic or increase the effects

Question 36

affinity

Answer 36

a drug has an affinity for a particular type of receptor if it binds to that receptor

Question 37

efficacy

Answer 37

the efficacy of the drug is its tendency to activate the receptor

Question 38

drugs at the synapse

Answer 38

increasing the synthesis

causing vesicles to leak
increasing release

decreasing reuptake

blocking the breakdown

directly stimulating or blocking postsynaptic receptors