The Dynamic Neuron

Question 1

When information supposedly is processed only in one direction called?

Answer 1

Polarization

Question 2

Describe the structure of the neuron (3)

Answer 2

An outer membranes of neurons, made of fatty substances
Draped around a cytoskeleton that is built up of rods of tubular and filamentous proteins that extend out into dendrites and axons alike

Question 3

Dendrites change shape sprouting new ___________ and ___________ others

Answer 3

Connections

Withdrawing

Question 4

Axons grow new _______

Answer 4

Endings

Question 5

What are inside neurons?

Answer 5

Many inner compartments

Question 6

Tiny protuberances that stick out from the dendrites called _________ ______

Answer 6

Dendritic spines

Question 7

Where do incoming axons make most of their connections?

Answer 7

Dendritic spines

Question 8

What do the end-points of the axons also respond to?

Answer 8

Growth factors

Question 9

What do growth factors do? (3)

Answer 9

Taken up inside and then transported to the cell body
Where they influence the expression of neuronal genes and hence
The manufacture of new proteins

Question 10

What does “synapse” mean in Greek?

Answer 10

To clasp together

Question 11

What are the junctional spots when dendrites receive contacts from incoming axons?

Answer 11

Synapses

Question 12

What are the communication between nerve cells at synapses called?

Answer 12

Synaptic transmission

Question 13

Where are most synapses located in the cerebral cortex?

Answer 13

On the dendritic spines, sticking out like little microphones

Question 14

What are currents that come into the cell called?

Answer 14

Excitation

Question 15

What are currents that move out of the cell called?

Answer 15

Inhibition

Question 16

The axons of neurons transmit electrical pulses called:

Answer 16

Action potentials

Question 17

How do action potentials move along nerve fibers? Why?

Answer 17

Like a wave travelling down a skipping rope

Axonal membrane contains ion channels

Question 18

What do ion channels do?

Answer 18

They can open and close to let through electrically charged ions

Question 19

What do the ion channels let in?

Answer 19

Some let in sodium ions (Na+) while others let through potassium ions (K+)

Question 20

What happens when ion channels open?

Answer 20

The Na+ or K+ flow down opposing chemical and electrical gradients, in and out of the cell

Question 21

The Na+ or K+ flow down opposing chemical and electrical gradients, in and out of the cell, in response to:

Answer 21

Electrical depolarisation of the membrane

Question 22

What is the first channels to open when an action potential starts at the cell body?

Answer 22

Na+ channels

Question 23

Step 1 (when an action potential starts at the cell body) (2)

Answer 23

Na+ channels open

A pulse of sodium ions flashes into the cell and a new equilibrium is established within a millisecond

Question 24

Step 2 (when an action potential starts at the cell body)

Answer 24

In a trice, the transmembrane voltage switches by about 100mV
Flips from an inside membrane voltage that is negative to one that is positive

Question 25

In step 2 (when an action potential starts at the cell body), what is the negative and positive voltage?

Answer 25

-70 mV

+30 mV

Question 26

Step 3 (when an action potential starts at the cell body)

Answer 26

This switch opens K+ channels, triggering a pulse of potassium ions to flow out of the cell, almost as rapidly as the Na+ ions that flowed inwards