Foreman 2

Front 1

The 3 types of ion channels are

Back 1

ligand-gated, voltage-gated, mechanically-gated

Front 2

The opening of a channel is called

Back 2

gating

Front 3

The number of ions passing through a channel determines

Back 3

current

Front 4

The number of ions passing through a channel depends on

Back 4

the length of time it is open.

Front 5

In the nervous system, the ligand-gated channels are activated by

Back 5

neurotransmitters.

Front 6

Voltage-gated channels are activated by

Back 6

changes in membrane potential

Front 7

Mechano-sensitive channels are also known as

Back 7

stretch receptors

Front 8

Mechano-sensitive channels are activated by

Back 8

a change in the shape of a cell.

Front 9

Gap junctions are

Back 9

channels between two cells that allow the passage of large molecules.

Front 10

Gap junctions are found in abundance in

Back 10

cardiac muscle and certain smooth muscle.

Front 11

Gap junctions can be regulated by

Back 11

Ca2+, H+, and voltage

Front 12

The pores in Gap junctions close when

Back 12

Ca2+ is elevated and when pH decreases to protect adjacent cells.

Front 13

In neuron anatomy, the cell body

Back 13

contains nucleus and protein synthesis

Front 14

In neuron anatomy, dendrites

Back 14

receive input from other neurons.

Front 15

In neuron anatomy, axons

Back 15

transmit action potentials.

Front 16

In neuron anatomy, the axon hillock

Back 16

is the part of the axon next to the cell body

Front 17

In neuron anatomy, the axon collaterals

Back 17

are branches of the axon

Front 18

In neuron anatomy, the axon terminals

Back 18

are nerve terminals that release neurotransmitters

Front 19

In neuron anatomy, the synapse

Back 19

is the junction between nerve and nerve, muscle, or gland.

Front 20

90% of cells in the central nervous system are

Back 20

Glia (neuroglia)

Front 21

Oligodendrocytes are found in

Back 21

brain and spinal cord

Front 22

The role of oligodendrocytes is

Back 22

to wrap around axons to form myelin sheath and nodes of Ranvier.

Front 23

Schwan cells are found in

Back 23

the peripheral nervous system.

Front 24

The role of Schwan cells is

Back 24

to wrap around axons to form myelin sheaths and nodes of Ranvier.

Front 25

Schwann cells are critical for

Back 25

transmission of axon potential.

Front 26

The role of astroglia is

Back 26

regulate cerebrospinal fluid and form the blood brain barrier.

Front 27

The role of microglia is

Back 27

perform immune functions of the central nervous system.

Front 28

Action potentials are

Back 28

a rapid change in membrane potential.

Front 29

Action potential are a property of

Back 29

excitable cells (nerve, muscle, glands)

Front 30

The excitability in action potentials is provided by

Back 30

opening and closing of voltage-gated channels.

Front 31

For a stimulus to cause an action potential, it must

Back 31

reach a threshold of 55 mV

Front 32

When the action potential threshold is reached

Back 32

Na+ channels open allowing Na+ influx.

Front 33

Influx of Na+ leads to

Back 33

further depolarization of neuron (positive feedback).

Front 34

At the peak of the action potential, channels

Back 34

go from open to inactivated.

Front 35

Na+ channels inactivate after

Back 35

1 msec.

Front 36

Depolarization produced by influx of Na+ causes

Back 36

delayed opening of K+ channels

Front 37

Efflux of K+ after an action potential causes

Back 37

repolarization of neuron

Front 38

Hyperpolarization after an action potential is due to

Back 38

high K+ conductance.

Front 39

The summary of an action potential is

Back 39

1. Neuron at resting potential, 2. Depolarization reaches threshold potential and activates voltage-gated Na+ channels, 3. Influx of Na+ leads to further depolarization, 4. Delayed opening of K+ channels, 5. Na+ channels inactivate, 6. Neuron repolarized by efflux of K+, 7. Hyperpolarization due to K+ conductance, 8. K+ channels close and membrane returns to resting potential.

Front 40

The properties of action potentials are

Back 40

1. All-or-none response, 2. Constant amplitude, 3. Threshold, 4. Refractory period

Front 41

The all-or-none response of action potentials means

Back 41

once it is initiated, it goes to completion.

Front 42

The absolute refractory period is

Back 42

the inactivation of sodium channels immediately after firing.

Front 43

The relative refractory period is

Back 43

when some Na+ channels have returned to resting state, but K+ channels remain open.

Front 44

The purpose of the refractory period is

Back 44

to limit frequency of action potentials to approximately 100/sec and prevent action potential moving backwards.

Front 45

The relative refractory period means subsequence stimuli

Back 45

must be stronger to reach action potential.

Front 46

The spreading currents depolarization in an action potential is propagated through

Back 46

voltage-gated Na+ channels activating.

Front 47

In nerve cells, action potentials propagate

Back 47

from axon hillock to nerve terminal

Front 48

In skeletal muscle fibers, action potentials propagate

Back 48

from middle to ends.

Front 49

Myelin insulates the axon to

Back 49

prevent charge from leaking out of the axon.

Front 50

Voltage-gated sodium channels and Na+/K+ ATPase in the axon are located only

Back 50

at the Nodes of Ranvier.

Front 51

Saltatory conduction is

Back 51

the spread of current from node to node in an axon.

Front 52

Condunction of action potential is much faster in ________ neurons.

Back 52

myelinated.

Front 53

The conduction velocity of an action potential is increased by

Back 53

myelination and increasing the axon diameter.

Front 54

In voltage-gated channels, voltage sensors

Back 54

detect the voltage across the membrane

Front 55

In voltage-gated channels, inactivating gates

Back 55

inactivate the channel on the cytoplasmic side by blocking the opening

Front 56

In voltage-gated channels, are/are not selective for a given ion.

Back 56

are very selective

Front 57

In voltage-gated channels, auxiliary subunits

Back 57

modulate the activity of the channels.