Brain Bee Chapter 2 - Jacey

Question 1

What is something all neurons have in common?

Answer 1

their activity is electrical and chemical.

Question 2

true or false? neurons cooperate and compete with each other in regulating the overall state of the nervous system

Answer 2

true

Question 3

neurons consist of which four things?

Answer 3

dendrites, cell body, axon and synaptic terminals.

Question 4

what is a neuron’s outer membrane made out of?

Answer 4

fatty substances

Question 5

inside neurons are many different layers of _______, and they consist of ______.

Answer 5

compartments, proteins

Question 6

true or false? Tiny
protuberances that stick out from the dendrites called
dendritic spines. These are where incoming calls make
most of their connections.

Answer 6

false

Question 7

true or false? Proteins transported to the
spines are important for creating and maintaining neuronal
connectivity.

Answer 7

true

Question 8

The end-points of the ____ also respond to molecules called growth factors.

Answer 8

axons

Question 9

true or false? These factors are 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

Answer 9

true

Question 10

On the receiving side of the cell, the dendrites have __________ with incoming axons of other cells

Answer 10

close contacts

Question 11

These junction spots are
named ____, from classical Greek words that mean “to
clasp together”

Answer 11

synapses

Question 12

What are communication between nerve cells at these contact points is referred to as?

Answer 12

synaptic transmission

Question 13

When the dendrite receives one of the chemical messengers
that has been fired across the gap separating it from the
sending axon, miniature _____ are set up inside the receiving dendritic spine

Answer 13

electrical currents

Question 14

define ‘excitation’

Answer 14

miniature electrical currents that come into the cell

Question 15

define ‘inhibition’

Answer 15

currents that move out of the cell

Question 16

True or false?

All these positive and negative waves of current are accumulated in the dendrites and they spread down to the cell body.

Answer 16

true

Question 17

If they don’t add up to very much activity, the currents soon die down and nothing further happens. However, if the currents add up to a value that crosses a threshold, the neuron will
________________.

Answer 17

send a message to the other neurons

Question 18

To communicate from one neuron to another, the neuronal

signal has first to travel along the _______.

Answer 18

The axons of neurons transmit electrical pulses called action potentials

Question 19

name two channels and their ions.

Answer 19

potassium (K) and sodium (Na)

Question 20

these channels are kept in balance by an ____

Answer 20

ion pump

Question 21

what is an ion pump’s job?

Answer 21

to bale out excess sodium ions.

Question 22

the action potential is an ______ event

Answer 22

electrical

Question 23

what do nerve fibres behave like?

Answer 23

electrical conductors

Question 24

what is an analogy that can help think about action potentials?

Answer 24

the movement of energy along a

firework sparkler after it is lit at one end.

Question 25

what do you call "the marvellous feature of nerve fibres is that after a very brief period of silence"

Answer 25

the refractory period

Question 26

True or false? In many axons, action-potentials move along reasonably well, but not very fast

Answer 26

true

Question 27

Define myelin sheath

Answer 27

a fatty, insulating blanket, | made out of the stretched out glial cell membranes

Question 28

which two people won the Nobel Prize for discovering the mechanism of transmission of the nerve impulse?

Answer 28

Alan Hodgkin and Andrew Huxley

Question 29

the mylin sheath prevents the ____ ____ from leaking out in the wrong place

Answer 29

ionic currents

Question 30

Every so often, glial cells leave a little gap - the axon concentrates its ___ and ___ ion channels.

Answer 30

Sodium (Na) and Potassium (K)

Question 31

what do these ion channels do?

Answer 31

They function as amplifiers that boost and maintain the action potential as it skips along the nerve.

Question 32

Fun fact: In myelinated neurons, action-potentials can race along at ____!!

Answer 32

100m/s

Question 33

what is the distinctive characteristic of the action potential?

Answer 33

all or nothing (they don’t vary in size, only in how often they occur.)

Question 34

true or false? the only way that the strength or duration of a stimulus can be encoded in a single cell is by variation of the frequency of action potentials.

Answer 34

true