Unit 2 - Nerve and Synapse

Question 1

the basic building blocks of the human brain

Answer 1

neurons

Question 2

all brain functions involve the generation and transmission of __________ by and between nerve cells at ___________

Answer 2

electrical signals, neuromuscular junctions

Question 3

what are the two key components of the central nervous system?

Answer 3

the brain and spinal chord

Question 4

what are the two key components of the peripheral nervous system?

Answer 4

the crainial nerves and spinal nerves

Question 5

a set of twelve nerves connected directly to the brain which are responsible for things like facial expressions and movements

Answer 5

cranial nerves

Question 6

a set of nerves connected directly to the spinal chord that are responsible for modulating motor and sensory information

Answer 6

spinal nerves

Question 7

neurons recieve synaptic inputs from other cells at their _________

Answer 7

dendrites

Question 8

what are the three types of neurons?

Answer 8

1) sensory neuron
2) motor neuron
3) interneuron

Question 9

all neurons have __________ for recieving/integrating inputs, conducting action potentials, and for sending __________ at synapses

Answer 9

specialized sub-regions, chemical signals

Question 10

what is the equation for membrane potential?

Answer 10

Vm = Vi - Vo

Question 11

by convention, the outside of the nerve cells is considered to be _____mV because ________

Answer 11

0, it is very stable

Question 12

what is the resting membrane potential of a nerve cell?

Answer 12

-70mV

Question 13

what is the net current of the resting membrane potential?

Answer 13

I = 0

Question 14

the membrane is impermeable to what three key ions?

Answer 14

Na+, K+, Cl-

Question 15

what is the Nerst equation?

Answer 15

Ex = (58/z)log([X]o/[X]i)

Question 16

concentration gradients are maintained by _______, notably the ______ pump

Answer 16

ATPases, Na/K

Question 17

compared to the outside of the cell, the inside has a __________ charge

Answer 17

negative

Question 18

what are the four basic steps of an action potential?

Answer 18

1) depolarization
2) repolarization
3) hyperpolarization
4) return to rest

Question 19

when negative ions move outside of the nerve cell, and positive ions move inside the nerve cell, this creates a _______

Answer 19

negative current

Question 20

when negative ions move inside the nerve cell, and positive ions move outside the nerve cell, this creates a _______

Answer 20

positive current

Question 21

a measure of easiness of ion flow across a resistor, with units in siemens

Answer 21

conductance (G)

Question 22

the inverse of conductance, with units in ohms

Answer 22

resistance (R)

Question 23

the electrival driving force to move charges

Answer 23

Voltage (V)

Question 24

what is Ohm’s Law according to cell physiology?

Answer 24

I = G(Vm - Vrest)

Question 25

the magnitude of a chemical driving force is proportional to the _______

Answer 25

concentration gradient

Question 26

the electrical driving force on ions is provided by the _______

Answer 26

membrane potential

Question 27

what does it mean for an ion channel to be selective?

Answer 27

the channels are permeable only to specific ions

Question 28

what does it mean for ion channels to be non-selective?

Answer 28

the channels are permeable to most if not all ions

Question 29

what does it mean for an ion channel to be gated?

Answer 29

has a specific trigger to open/close it, very regulated and controlled

Question 30

ion flow across a membrane is driven by:

Answer 30

electrochemical gradient

Question 31

how many ions flow through an open ion channel per second?

Answer 31

10^7-10^8

Question 32

- ligands - post-translational modifications - depolarization/ hyperpolarization - stretch, pressure, flow - non-gated these are all types of:

Answer 32

channel gating

Question 33

ATPase is an example of what type of transport?

Answer 33

primary active transport

Question 34

symporters and antiporters are an example of what type of transport?

Answer 34

secondary active transport

Question 35

uniporters and ion channels, which are driven by their own electrochemical gradient, are an example of what type of transport?

Answer 35

passive transport

Question 36

what is a symporter?

Answer 36

an ion channel where the driving molecule and the transport molecule move in the same direction

Question 37

what is an antiporter?

Answer 37

an ion channel where the driving molecule and transporter molecule move in the opposite direction

Question 38

in a transport cycle, the transporters undergo:

Answer 38

conformational changes

Question 39

different cells have different _____ for their action potentials

Answer 39

shapes

Question 40

what are the three main phases of an action potential?

Answer 40

1) depolarization 2) repolarization 3) hyperpolarization/ refractory period

Question 41

the giant squid has an axon how large?

Answer 41

1mm

Question 42

what is the role of tetrodotoxin (TTX)?

Answer 42

blocks voltage-gated Na+ channels

Question 43

what is the role of tetraethylammonium (TEA)?

Answer 43

blocks voltage-gated K+ channels

Question 44

the slow inactivating of K+ channels while the Na+ channels are already inactivated explains the prescence of:

Answer 44

hyperpolarization

Question 45

as depolarization increases from 0 - +52 mV, the fast inward Na+ current ______, and the slow outward K+ current _______

Answer 45

decreases, increases

Question 46

at +65mV, the fast Na+ current becomes:

Answer 46

positive

Question 47

4 identical proteins embedded in the cell membrane that form the voltage gated K+ channel

Answer 47

tetramer

Question 48

4 non identical proteins embedded in the cell membrane that form the voltage gated Na+ channel

Answer 48

monomer

Question 49

how many activation segments does a K+ tetramer have?

Answer 49

4

Question 50

how many activation segments does an Na+ monomer have?

Answer 50

1

Question 51

in the Na+ channel, the voltage center moves up during _______, then down during ________

Answer 51

depolarization, repolarization

Question 52

during the refractory period in the Na+ channel, what happens to the voltage centers?

Answer 52

the voltage centers are closed even tighter than at rest in order to prevent another depolarization

Question 53

membrane potential at which a spike is initiated. always more positive than the resting potential

Answer 53

threshold

Question 54

magnitude varies with the strength of the stimulus

Answer 54

graded potentials

Question 55

true or false: graded potentials can be either depolarizing or hyperpolarizing

Answer 55

true

Question 56

the time during which the axon is resistant to generating a spike. it results from Na+ channels being inactivated and relatively irresponsive to depolarization.

Answer 56

refractory period/ hyperpolarization

Question 57

passive spread of current down a dendrite/axon depends on:

Answer 57

resistance to flow of current

Question 58

smaller dendrites/axons have _________ and current flows with ________ down a smaller dendrite/axon.

Answer 58

higher resistance, difficulty

Question 59

electrically insulating and mechanically supporting layers formed by the plasma membrane of a glial (or schwann) cell

Answer 59

myelin sheath

Question 60

nodes of ranvier are:

Answer 60

"naked" or without myelin

Question 61

what is the benefit of myelination along the axon?

Answer 61

the action potential 'jumps' and increases conduction speed by 100-10K folds

Question 62

chemical synapses are _________, whereas electrical synapses are _________

Answer 62

unidirectional, bidirectional

Question 63

the presence of vesicles in presynaptic terminals is indicative of:

Answer 63

chemical synapses

Question 64

during the process of recycling neurotransmitters, the import of neurotransmitters to a vsicle requires:

Answer 64

ATP

Question 65

during the process of recycling neurotransmitters, presynaptic uptake of a neurotransmitter requires:

Answer 65

the cotransport of the neurotransmitter with Na+

Question 66

synaptic transmissions can be either _______ or _______

Answer 66

excitatory, inhibitory

Question 67

what is an example of excitatory postsynaptic potential (EPSP)

Answer 67

the neurotransmitter glutamate causing Na+ channels in the postsynaptic neuron to open, causing depolarization

Question 68

what is an example of inhibitory postsynaptic potential (IPSP)

Answer 68

the neurotransmitter GABA causes Cl- channels in the postsynaptic neuron to open, causing hyperpolarization

Question 69

the neurotransmitter acetylcholine (ACh) opens non-selective cation channels, which conduct both Na+ and K+ ions, at the:

Answer 69

neuromuscular junction

Question 70

which enzyme breaks down acetylcholine for recycling?

Answer 70

acetylcholinase (AChE)

Question 71

what is the effect of acetylcholine opening a nonselective cation channel?

Answer 71

depolarization occurs because there is more Na+ entry than K+ efflux at rest

Question 72

neurotransmitters and voltage-gated channels work together to create:

Answer 72

postsynaptic action potentials

Question 73

presynaptic voltage-gated Ca2+ channel activation leads to:

Answer 73

postsynaptic currents

Question 74

binds to calcium inside of the nerve terminal. this has no effect on presynaptic voltage spike, but blocks the postsynaptic potential by blocking the release of neurotransmitters.

Answer 74

Ca chelator

Question 75

what is an end-point potential (EPP)?

Answer 75

an EPSP in a muscle cell

Question 76

true or false: EPSPs decay in size over long distances

Answer 76

true

Question 77

results from the release of a very small amount of a neurotransmitter, contained in a single vesicle:

Answer 77

miniature endplate potential (MEPP)

Question 78

neurotransmitters are released in ________ packets: the smallest ________ will release a 0.4mV depolarization

Answer 78

quantal, quantum

Question 79

one quantum of neurotransmitters is equivalent to:

Answer 79

one vesicle of neurotransmitters

Question 80

the time between the onset of the presynaptic spike and the onset of EPSP

Answer 80

synaptic delay

Question 81

what are the five basic steps of a reflex arc?

Answer 81

1) arrival of stimulus and activation of receptor 2) activation of a sensory neuron 3) information processing in the CNS (by interneurons) 4) activation of motor neuron 5) response by effector