Chapter 4

Question 1

Electricity

Answer 1

A flow of electrons from a body that contains a higher charge to a body that contains a lower charge

Question 2

Negative pole

Answer 2

The source of electrons- higher charge

Question 3

Positive pole

Answer 3

Location to which electrons flow- Lower charge

Question 4

Do nerves carry electrical stimulation

Answer 4

Yes (Galvani 18th century)

Question 5

Electrical stimulation

Answer 5

Passing a electrical current from the tip of an electrode through the brain tissue, changing the electrical activity in the tissue

Question 6

Fritsch and Hitzig found

Answer 6

Electrical stimulation of the neocortex causes movement

Question 7

Bartholow found

Answer 7

First report of human brain stimulation

Question 8

Caton studies

Answer 8

First attempt in measuring electrical currents of the brain using a voltmeter and electrodes to the skull

Question 9

Electroencephalogram

Answer 9

Graph that records electrical activity through the skull or from the brain and represents graded potentials of many neurons

Question 10

von Helmholtz studies

Answer 10

Flow of info in the nervous system is too slow to be a flow of electricity

Question 11

Bernstein found

Answer 11

Ions don’t travel along the axon but rather a wave of charge

Question 12

Electrical potential

Answer 12

An electrical charge measured in volts: stored energy

Question 13

Volt

Answer 13

A measure of a different in electrical potential

Question 14

Voltmeter

Answer 14

A device that measures volts

Question 15

What was used to measure a neuron’s electrical activity

Answer 15

A giant squid because of its large axon

Question 16

Microelectrodes

Answer 16

A set of electrodes small enough to go into an axon. Can be used to measure a neurons neural activity or deliver a current to a single neuron

Question 17

DIffusion

Answer 17

Movement of ions from higher concentration to lower

Question 18

Concentration gradient

Answer 18

Differences in concentration of a substance that allow substances to diffuse

Question 19

Voltage gradient

Answer 19

Difference in charge between two regions that allows a flow of current if the two regions are connected

Question 20

Equilibrium

Answer 20

Occurs when concentration gradients and voltage gradients are balances

Question 21

Resting potential

Answer 21

Electrical charge of the membrane in the absence of stimulation. The inside of the membrane is at rest (-70mV) relative to the outside

Question 22

What four charged particles take part in a resting potential

Answer 22

Na+, Cl-, K+, and large proteins (A-)

Question 23

Ion distribution across a resting membrane

Answer 23

A- ions and K+ ions have higher concentration inside the axon while Na+ and Cl- have higher concentration outside the axon

Question 24

Na+-K+ pumps

Answer 24

Intrude Na+ from the intercellular fluid and extrude K+

Question 25

Graded potentials

Answer 25

Small voltage fluctuations across the cell membrane

Question 26

Hperpolarization

Answer 26

- Increase in electrical charge across a membrane (more negative) - Usually due to the inward flow of Cl- (signalled by GABA) and outward flow of K+

Question 27

Depolarization

Answer 27

- Decrease in electrical charge across a membrane | - Due to inflow of sodium

Question 28

Action potential

Answer 28

Large brief reversal in polarity of an axon

Question 29

Threshold potential

Answer 29

Voltage of neural membrane at which an action potential is triggered. Opening of Na+ and K+ voltage activated channels to -50mV leads to it

Question 30

Voltage activated ion channels

Answer 30

Gated channels that open or close only at specific membrane voltages. Na+ channels are more sensitive and open sooner and both are closed at resting

Question 31

Repolarization

Answer 31

Returning to a polarized state (K+ out)

Question 32

Tetrodotoxin

Answer 32

Blocks sodium channels and causes a slightly different action potential due to an efflux of potassium recorded

Question 33

TEA on action potential

Answer 33

TEA surrounding the axon blocks the potassium channels, a smaller than normal but longer action potential is recorded

Question 34

Absolute refractory period

Answer 34

The state of an axon in the repolarizing period in which a new action potential cannot be fired because the channels are closed

Question 35

Relative refractory period

Answer 35

The state of an axon in the later phase of an action potential, during which a stronger current is required to produce another action potential, Potassium channels are still open

Question 36

Nerve impulse

Answer 36

Propagation of an action potential down an axon and only down. Refractory periods produce a single discrete impulse that travels along the axon in one direction only. Size and shape of potential remain constant along the axon

Question 37

Myelin

Answer 37

Produced by oligodendroglia in the CNS and Schwann cells in the PNS, speed up nerve impulses

Question 38

Node of Ranvier

Answer 38

Part of an axon that is not covered in myelin, enables interaction with the extracellular fluid and leads to action potentials

Question 39

How many connections can dendritic spines create for a neuron

Answer 39

Over 50k

Question 40

Excitatory postsynaptic potential (EPSP)

Answer 40

Brief depolarization of a neuron membrane in response to stimulation, making the neuron more likely to fire an action potential (Influx of Na+)

Question 41

Inhibitory postsynaptic potential (IPSP)

Answer 41

Brief hyper-polarization of a neuron membrane in response to stimulation, making it less likely to fire an action potential (Efflux of K+ or influx of Cl-)

Question 42

Summation

Answer 42

Cell body adding IDSP and EDSP impulses, need both temporal and spatial summation to increase action potential

Question 43

Temporal summation

Answer 43

Pulses that occur approximately the same time on a membrane that are summed

Question 44

Spatial summation

Answer 44

Pulses that occur at approximately the same place on a membrane are summed

Question 45

The axon hillock

Answer 45

Junction of the cell body and axon, rich in voltage activated channels, EDSPs and IPSPs and action potentials are initiated here

Question 46

Where do action potentials not occur

Answer 46

On its dendrites although some neurons have voltage activated channels on the dendrites that do enable action potentials

Question 47

Back propagation

Answer 47

Reverse movement of an action from the axon hillock into the dendritic field

Question 48

Optigenetics

Answer 48

Some ion channels respond to light rather than voltage

Question 49

Ways we receive information about the world

Answer 49

- Bodily sensations - Auditory sensations - Visual sensations - Chemical sensations

Question 50

Neurons in relation to the ways we receive info

Answer 50

All neurons related to the way we receive info have ion channels on their cell membrane, these ion channels initiate chain of events that produce a nerve impulse

Question 51

Touch neuron example

Answer 51

Hair displacement when touched opens stretch-activated channels in the dendrites membrane allow for an action potential

Question 52

How nerve impulses produce movement

Answer 52

Spinal motor neurons send nerve impulses to synapses on muscle cells, axon of each motor neuron makes on or more synapses with target muscle and sends to end plate (Part of the muscle membrane that is contacted by the axon terminal)

Question 53

Acetylcholine

Answer 53

Chemical transmitter that the axon terminal releases at the muscle end plate. This allows channels to open causing a membrane to depolarize the muscle to the threshold, which then leads to an action potential causing muscle contraction