Neurons

Question 1

Neurons

Answer 1

specialized cells that can receive and transmit chemical or electrical signals

Question 2

Glia cells

Answer 2

provide support functions for neurons

Question 3

action potentials

Answer 3

electrical signals that transmit information WITHIN a neuron; rapid change in membrane potential
NA+ rushing in and K+ rushing out

Question 4

neurotransmitters

Answer 4

chemical signals that transmit information from one neuron to the next; cause a rapid, temporary change in membrane potential of the adjacent neuron to possibly initiate an action potential

Question 5

dendrites

Answer 5

receive neurotransmitters from other neurons; dendritic spines to increase surface area for possible connections with other neurons

Question 6

synapses

Answer 6

where neurons release signals to the other neurons’ dendrites

Question 7

axon hillock

Answer 7

“integrates” the signals from multiple synapses; junction between the cell body and axon

Question 8

axon

Answer 8

tube-like structure that propagates integrated signal to specialized endings (axon terminals)

Question 9

myelin

Answer 9

insulator to minimize dissipation of electrical signals; increases speed of condition; produced by glial cells; there are periodic gaps in myelin sheath called nodes of Ranvier where signal is “recharged” down the axon

Question 10

astrocytes

Answer 10

nutrients and other substances to neurons, regulate ion and chemical concentration in extracellular fliod, structural support for synapses, blood-brain barrier

Question 11

oligodendrocytes and Schwann cells

Answer 11

form myelin shearth around axons in the CNS or PNS
- single Schwann cell provides myelin for only one axon - surrounds the axon
- one axon can be myelinated by several oligodendrocytes and one oligo can be myelin for multiple neurons

Question 12

resting potential

Answer 12

membrane potential (electric charge; difference in charge inside and out the cell) in a neuron not transmitting a signal
NEGATIVELY charged for neurons - about -70 mV

Question 13

action potential

Answer 13

brief depolarization along the axon; all-or-nothing - can’t change speed or magnitude

Question 14

neurotransmitters

Answer 14

chemical messengers between neurons - help depolarize or hyperpolarize adjacent neurons: will an action potential more or less likely to occur?

Question 15

sodium-potassium pump

Answer 15

maintains the resting potential; pumping out sodium and bringing in potassium
3 sodium out and 3 potassium in

Question 16

potassium leak channels

Answer 16

diffusion in concentration gradient; potassium diffuses out of a cell faster than sodium because there are more
chloride ions tend to accumulate outside of the cell because repelled by negatively charged inside

Question 17

voltage-gated ion channels

Answer 17

channels that open or close in response to changes in membrane voltage

Question 18

hyperpolarization

Answer 18

membrane potential increases in magnitude (more negative)

Question 19

depolarization

Answer 19

membrane potential decreases in magnitude (more positive)

Question 20

threshold potential

Answer 20

specific voltage membrane must reach for an action potential to occur
usually about -55mV
if reached, the action potential is initiated at the axon hillock

Question 21

depolarization

Answer 21

voltage-gated sodium channels open and sodium rushes into axon and inside becomes positively charged

Question 22

repolarization

Answer 22

voltage gated sodium channels close and remain closed; voltage-gated potassium channels open and potassium effluxes out

Question 23

hyperpolarization

Answer 23

potassium leaves until the membrane potential dips below normal resting; sodium channels return to resting state

Question 24

reset resting potential

Answer 24

sodium potassium pump and potassium lleak channels are active and establishing the membrane potential

Question 25

how action potential travels down the axon

Answer 25

wave of depolarization: repeating pattern down the axon
one direction only - never go backward due to refraction period of voltage gated channels that cannot reopen for a period of 1-2 seconds after they close
no change in magnitude or speed - all or nothing
can only change frequency and how many action potential occur in given time

Question 26

speed of action potential between neurons

Answer 26

vertebrates: myelination of axon

Question 27

nodes of Ranvier

Answer 27

gaps in myelin sheath; have voltage-gated sodium and potassium channels: flow of ions result in regenerating the action potential over and over again

Question 28

saltatory conduction

Answer 28

“jumping” of action potential from one to the next; helps save energy since channels only need to be present at the nodes

Question 29

presynaptic vs postsynaptic neuron

Answer 29

neuron sending signal vs neuron receiving signal

Question 30

sypnatic cleft

Answer 30

small gap between two neurons where neurotransmitters are released

Question 31

synaptic transmission

Answer 31

1. action potential depolarizes membrane and opens voltage gated sodium channels, further depolarization
2. voltage-gated calcium channels open in the presynaptic neuron, allowing calcium ions to enter
3. signaling cascade that causes synaptic vesicles to fuse with presynaptic membrane
4. these vesicles hold neurotransmitters and when they fuse with the membrane - they are releases into synaptic cleft

Question 32

excitatory postsynaptic potentials (EPSPs)

Answer 32

makes a postsynaptic neuron more likely to fire an action potential; can cause sodium channels to open and depolarization

Question 33

inhibitory postsynaptic potentials (IPSPs)

Answer 33

less likely to fire an action potential; hyperpolarization

Question 34

neurotransmitters being removed from synaptic cleft

Answer 34

diffuse away, be degraded by enzumes, or recycled by the presynaptic neuron

Question 35

summation

Answer 35

occurs at the axon hillock - basically taking all the signals into account to see if an action potential should be fired
temporal summation - one neurons
spatial summation - many neurons