Exam #1

Front 1

absolute refractory period

Back 1

time immed after the action potential when sodium gates close ad the membrane cant produce another action potential (also prevents current from moving backwards)

Front 2

action potential

Back 2

rapid depolarization followed by slight hyperpolarization. increase from -70mV to -55mV (threshold) then beyond - opens voltage gated Na+ and K+, propagates down axon at same level

Front 3

active transport

Back 3

protein mediated process that expends energy to pump chem from blood to the brain (ex: happens in blood brain barrier w/ glucose)

Front 4

afferent axon

Back 4

("a" admission) neuron that brings sensory info to (the CNS), every sensory neuron is afferent from the nervous system

Front 5

all-or-none law

Back 5

either an action potential will happen or it wont - electrical gradient must reach threshold in order for it to happen. size and intensity of AP are independet of the size of stimulation

Front 6

astrocyte

Back 6

star shaped glial cell. wraps around presynaptic terminals helps synchronoze activity by taking up chem released by axon and sending them back, also helps in waste removal when neurons die, and helps regulate blood flow to the brain

Front 7

axon

Back 7

thin fiber that extend form cell body. carries information from cell body (often myelinated)

Front 8

axon hillock

Back 8

at the "top" of the axon - where an action potential starts (after rcvng info from cell body)

Front 9

blood-brain barrier

Back 9

keeps harmful chemicals and viruses from reaching the brain, but also keeps useful meds (ie chemotherapy) from brain. O2, CO2 diffuse, glucose, A Acids vitamins , etc need active transport to reach brain

Front 10

cell body, or soma

Back 10

contains nucleus, ribosomes, mitochondria, neural membrane - neural membrane uniquely specialized for neural functions

Front 11

concentration gradient

Back 11

process where molecules travel from Hi to Low concentration area in order to reach equilibrium

Front 12

dendrite

Back 12

branches (covered w synaptic receptors) used to rcv info from other neurons

Front 13

dendritic spine

Back 13

increase surface area allowing more info to be passed on

Front 14

depolarization

Back 14

process where inside (of neural membrane) becomes more positive. from -70mV resting, to -55 threshold, if thrshold reached action potential is possible

Front 15

efferent axon

Back 15

("e" exit) carries info away from the CNS to motor neurons / muscles. every motor neuron is efferent from the nervous system

Front 16

electrical gradient

Back 16

diff in + / - chargs across membrane (ie: + attracted to -)

Front 17

glia

Back 17

most numerous type of neuron. DOES NOT conduct impulses to other cells - types: astrocytes,microglia, oligodendricytes (CNS) schwann (PNS), radial glia guide migration @ embryonic stage

Front 18

graded potential

Back 18

membrane potential that varies in magnitude (ex NT's from synapse cause graded potential in dendrites) gradually decreases in intensity

Front 19

hyperpolarization

Back 19

increased negative charge (drops below -70mV resting potential) in AP due to K+ leaving and Cl- entering

Front 20

interneuron

Back 20

cell who's axon and dendrites contained within a structure (interneuron in thalamus has axon and dendrite contained in thalamuc

Front 21

local anesthetic

Back 21

attach to Na+ channels and block it from entering cell, therefore blocks action potentials (that could signal pain messages) scorpion venom keeps Na+ open therefore too much Na+ comes and / toxic

Front 22

local neuron

Back 22

small neuron w small or no axon, therefore they exchange info though graded potential (astrocytes and glial cells act like local neurons)

Front 23

membrane

Back 23

structure that separates inside from outside of cell structure.phospholipid bi-layer of neural membrane is only semi permeable, voltage or chem gated protein channels allow certain ions to flow in/out at certain rate

Front 24

microglia

Back 24

small glial cell that remove waste material and microorganisms from the CNS

Front 25

mitochondrion

Back 25

structure w/in neuron (soma and axon) that performs metabolic activity that provides "fuel" (ATP) for the cell

Front 26

motor neuron

Back 26

efferent neuron / conducts impulses from its soma in the sp cord to muscle or gland

Front 27

myelin / myelin sheath / myelinated axon

Back 27

insulated material (oligo in CNS, schwann in PNS), sheath conducts impulses faster via saltitory conduction

Front 28

neuron

Back 28

cell that rcvs and xmits info to other cells by conducting electro-chemical impulses

Front 29

node of Ranvier

Back 29

short unmyelinated spaces btwn myelin segments - AP jumps to nodes (Na+ channels are open at the nodes) and propagates

Front 30

nucleus

Back 30

2 defs: structure within cell that cotains chromosomes, & cluster of cell bodies in the CNS

Front 31

oligodendrocyte

Back 31

glial cell that produced myelin sheath in the CNS

Front 32

polarization

Back 32

the electrical gradient across a membrane.

Front 33

presynaptic terminal

Back 33

tip of the axon. NT's are released to cross synapse and activate receptors on the postsynaptic terminal (of dendrite)

Front 34

propagation of the action
potential

Back 34

happens via saltitory conduction. AP doesnt vary in "strength"

Front 35

relative refractory period

Back 35

period after absolute refractory period when K+ gates are open wider than usual requiring a stronger than usual stimulus to create AP

Front 36

resting potential

Back 36

-70mV, electrical potential across membrane when cell is not being stimulated. inside is more negative, due to negatively charged proteins

Front 37

ribosome

Back 37

located in the soma - ribosomes synthesize new protein molecules, proteins provide bldg materials for the cell and facilitate various chemical rxns

Front 38

saltatory conduction

Back 38

how the AP travels down myelinated axon - it jumps from node to node following the flow of positive ions (Na+)

Front 39

Schwann cell

Back 39

glial cells that produce myelin sheaths on (some) axons in the PNS

Front 40

selective permeability

Back 40

the ability for some chemicals to pass freely across cell membrane (ex: blood brain barrier) (ex: Na+ must be pumped in but Cl- can diffuse slowly)

Front 41

sensory neuron

Back 41

afferent neuron, takes sensory info TO a structure, ex: if hand is burned, afferent neuron takes info from nerve on hand to dorsal side of sp cord

Front 42

sodium-potassium pump

Back 42

after AP / absolute refractory period, it pumps (3) Na+ ions out and (2) K+ ions in. pump is used to restore resting potential/homeostasis

Front 43

threshold of excitation

Back 43

level of depolarization at which stimulation beyond this point will produce massive depolarization (AP), Na+ channels open and Na+ rushes in (further depolarizing), AP can only happen if depolarization reaches threshold

Front 44

voltage-activated channel

Back 44

channels in the membrane that depend in voltage differences to open /close them (ex Na+ channels are voltage gated)