WEEK 2: NEURONS

Question 1

What percentage of the mass of the brain is the cerebral cortex?

Answer 1

81.8%

Question 2

What percentage of the neurons in the brain are in the cerebral cortex?

Answer 2

19%

Question 3

What percentage of the mass of the brain is cerebellum?

Answer 3

10.3%

Question 4

What percentage of the neurons in the brain are in the cerebellum?

Answer 4

80.2%

Question 5

How many neurons are there in the brain?

Answer 5

86.06 billion

Question 6

How many cells are there in the brain?

Answer 6

~170.68 billion

Question 7

What does the nucleus contain?

Answer 7

DNA

Question 8

What do mitochondria provide to a cell?

Answer 8

Energy

Question 9

Soma

Answer 9

Cell body

Question 10

Draw the structure of a cell body

Answer 10

Question 11

Axon

Answer 11

Connects neuron to other neurons

Question 12

Axon hillock

Answer 12

Joins axon to cell body

Question 13

Presynaptic terminal

Answer 13

Meets postsynaptic terminal of another neuron to communicate

Question 14

Dendrites

Question 15

Draw a neuron

Answer 15

Question 16

Nodes of Ranvier

Answer 16

Gaps of exposed axon between myelin

Question 17

What function do the Nodes of Ranvier perform?

Answer 17

Allow the signal to jump along the axon

Question 18

Myelin

Answer 18

–Fatty substance
–Insulates neurons

Question 19

Myelin sheath

Answer 19

Myelin forms sheath that insulates the axon

Question 20

How do signals travel down the axon?

Answer 20

By jumping between the unexposed parts

Question 21

Draw a unipolar neuron

Answer 21

Question 22

Draw a bipolar neuron

Answer 22

Question 23

Draw a multipolar neuron

Answer 23

Question 24

Draw a pyramidal neuron

Answer 24

Question 25

Draw a cell connected to another cell

Answer 25

Question 26

Action potential (2)

Answer 26

–Brief change in electrical potential across the membrane of an axon –Causes inside of neuron to become +ve charged

Question 27

What voltage is resting membrane potential?

Answer 27

-70 million volts

Question 28

Graph how membrane potential changes when a neuron is activated

Answer 28

Question 29

At rest, are there more positively or negatively charged ions in a neuronal membrane?

Answer 29

Negative

Question 30

What 2 negative ions are there in a neuron?

Answer 30

Cl- = chloride A- = anions

Question 31

What 3 positive ions are there in a neuron?

Answer 31

Na+ = sodium Ca2+ = calcium K+ = potassium

Question 32

At rest, are there more positively or negatively charged ions outside a membrane?

Answer 32

Positive

Question 33

What is an ion pump?

Answer 33

–Inside membrane –Fit specific ions –Move ions around to change concentration of +ve and -ve

Question 34

Describe action potential (5)

Answer 34

–Neuron stimulated -> Membrane potential changes –Ion pumps -> sodium enters, potassium exits –+ve ions -> -70 millivolts to +20 –Sodium stops entering, potassium keeps exiting –+ve ions decrease until resting state

Question 35

Where is action potential triggered?

Answer 35

At each Node of Ranvier

Question 36

What happens when action potential gets to the terminal?

Answer 36

Neurotransmitters released

Question 37

Depolarization (3)

Answer 37

–Sodium enters membrane –Potassium exits –Concentration of +ve ions increases

Question 38

What's one important effect of the refractory period?

Answer 38

Signal can only travel in one direction down a neuron

Question 39

Absolute refractory period

Answer 39

–Neuron can't be stimulated –Another signal won't great through

Question 40

Relative refractory period

Answer 40

–Neuron can be stimulated –Requires stronger signal

Question 41

Draw the phases of action potential

Answer 41

Question 42

Repolarization (of membrane)

Answer 42

–Sodium stops entering –Potassium exits –Concentration of +ve ions decreases

Question 43

What type of cell does the immune system attack in MS?

Answer 43

Ogliodendrocytes

Question 44

What do ogliodendrocytes create?

Answer 44

Myelin

Question 45

What does MS do to signals passing along neurons?

Answer 45

Damages or disrupts

Question 46

Rising phase

Answer 46

Sodium enters

Question 47

Falling phase

Answer 47

Potassium exits