Week 2 - Neurons

Question 1

How many neurons and glia cells?

Answer 1

~100 billion

Question 2

How many more glia cells than neurons?

Answer 2

around 10x more glia

Question 3

What do neurons do?

Answer 3

Communicate!

Question 4

How many interconnections do neurons have with other neurons?

Answer 4

Up to 10,000.

Question 5

How fast can this communication occur between neurons?

Answer 5

500hz but 100hz is typical.

Question 6

What parts of a neuron are the most changeable over time?

Answer 6

The Dendrites (spines extending from the soma).

Question 7

Typically, each DENDRITIC SPINE has what connecting with it?

Answer 7

One or more AXON TERMINALS from other neurons.

Question 8

What does each DENDRITIC SPINE represent?

Answer 8

One or more inputs.

Question 9

What does an APICAL dendrite imply?

Answer 9

Towards the APEX.

Question 10

What does a BASAL dendrite imply?

Answer 10

Towards the BASE.

Question 11

What is the difference between APIC and BASAL dendrites?

Answer 11

APICAL is the dendrite pointing upwards from the soma, the BASAL dendrites are those heading East/West.

Question 12

How do APICAL and BASAL dendrites connect regarding layers?

Answer 12

Since layers are a horizontal strata, APICAL dendrites connect ACROSS/BETWEEN layers, BASAL dendrites connect WITHIN layers.

Question 13

Axons carry what?

Answer 13

An electro-chemical impulse.

Question 14

What defines the difference between a Multipolar, Bipolar and Monopolar neuron?

Answer 14

How many projections from the cell body there are.

• Multipolar may have multiple dendrites and a single axon
• Monopolar will have a single projection from cell body but that projection may split into 2 axons.

Question 15

What type of neuron is AFFERENT?

Answer 15

Sensory.

Question 16

What type of neuron is EFFERENT?

Answer 16

Motor.

Question 17

What does AFFERENT mean?

Answer 17

It gets INPUT from sensors (sensory, peripheral neuron - outside the nervous system).

Question 18

What does EFFERENT mean?

Answer 18

It OUTPUTS signal to CONTROL muscle fibres, glands etc. (motor, also peripheral neuron)

Question 19

What is an Interneuron neuron?

Answer 19

They are NOT peripheral, they are within nervous system. Only interact with other neurons.

Question 20

What are ASTROCYTES?

Answer 20

• maintenance (scaffolding)

- waste/dead cells

Question 21

What do Micro glia do?

Answer 21

• waste
• viruses
• serve to supplement immune system in brain

Question 22

What type of glial cell is most important regarding communication?

Answer 22

Myelinating types:

• Oligodendrocytes - Central nervous system
• Schwann cells - Peripheral nervous system

Question 23

If nerve damage occurs, what type of cells can assist with recovery?

Answer 23

Schwann cells. They are in the periphery.

Question 24

What is the surface of a cell called?

Answer 24

A membrane (or plasma membrane).

Question 25

What can and cannot pass through a cell membrane?

Answer 25

Most chemicals cannot pass through the membrane. Protein channels permit a controlled flow of water, oxygen, sodium, potassium, calcium, chloride and other important chemicals.

Question 26

Which structure contains the chromasomes?

Answer 26

The nucleus.

Question 27

What structure performs metabolic activities, providing the energy that the cell uses for all activities?

Answer 27

Mitochondrion.

Question 28

What are the sites within a cell that synthesise new protein molecules?

Answer 28

Ribosomes.

Question 29

What is the most distinctive feature of a neuron?

Answer 29

Its shape! This varies from one neuron to another.

Question 30

Some neurons lack...

Answer 30

...axons and well-defined dendrites.

Question 31

What type of neuron is specialised at one end to be highly sensitive to a particular type of stimulation, such as light or touch?

Answer 31

A sensory neuron.

Question 32

What is a dendrite's surface lined with?

Answer 32

Synaptic Receptors. This is where dendrites receive information from other neurons.

Question 33

What do dendritic spines do?

Answer 33

Increase the surface area available for synapses.

Question 34

What does the cell body (soma) contain?

Answer 34

The Nucleus, ribosomes, and mitochondria. This is where most of a neuron's metabolic work takes place.

Question 35

What is the thin fibre of constant diameter which conveys an impulse toward other neurons, an organ or a muscle?

Answer 35

the Axon.

Question 36

The axon's length is comparable to the width of a...

Answer 36

dendrite.

Question 37

The insulating material coating some axons are called the...

Answer 37

myelin sheath.

Question 38

What are the interruptions in the myelin sheath known as?

Answer 38

Nodes of Ranvier.

Question 39

A neuron can have only one...

Answer 39

Axon, but an axon can have many branches.

Question 40

The end of each branch of an axon has a swelling called...

Answer 40

a presynaptic terminal, also known as an "end bulb" or "bouton (french for Button)".

Question 41

An afferent axon...

Answer 41

brings information into a structure.

Question 42

An efferent axon...

Answer 42

carries information away from a structure.

Question 43

Every sensory neuron is...

Answer 43

an afferent to the rest of the nervous system.

Question 44

Every motor neuron is..

Answer 44

an efferent from the nervous system.

Question 45

If a cell's dendrites and axon are entirely contained within a single structure, the cell is an ..... or ..... of that structure.

Answer 45

interneuron or intrinsic neuron of that structure.

Question 46

The shape of a neuron determines its...

Answer 46

connections with other cells and thereby determines its function.

Question 47

What is the full title of a Glia?

Answer 47

neuroglia.

Question 48

Where do glia outnumber neurons?

Answer 48

The cerebral cortex.

Question 49

Where do neurons outnumber glia?

Answer 49

The cerebellum.

Question 50

What is an astrocyte (glial cell) and what does it do?

Answer 50

It is wrapped around the synapses of functionally related axons. It shields it from chemicals circulating in the surround.

Question 51

Other than shielding, what else do astrocytes do?

Answer 51

Takes up ions and transmitters released by axons and releases them back, helping to synchronise closely related neurons, enabling their axons to send messages in WAVES.

Question 52

Astrocytes are important for generating...

Answer 52

Rhythms, such as for breathing.

Question 53

What do astrocytes do with blood vessels?

Answer 53

They dilate them to bring more nutrients into brain areas that have heightened activity.

Question 54

What system do microglia act as part of?

Answer 54

The immune system, removing fungi and viruses from the brain.

Question 55

When do microgrlia proliferate?

Answer 55

After brain damage, to remove dead or damages neurons.

Question 56

How do microglia contribute to learning?

Answer 56

They remove the weakest synapses.

Question 57

Where are Oligodendrocytes?

Answer 57

The brain and spinal cord.

Question 58

Where are Schwann cells?

Answer 58

In the periphery of the body.

Question 59

What do Oligodendrocytes and Schwann cells do?

Answer 59

Build the myelin sheaths that surround and insulate certain vertebrate axons, and supply axons with nutrients necessary for proper functioning. They support axons.

Question 60

What do Radial glia do during embryonic development?

Answer 60

Guide the migration of neurons and their axons and dendrites.

Question 61

What happens to radial glia when embryonic development finishes?

Answer 61

Most differentiate into neurons, and a smaller number differentiate into ASTROCYTES and OLIGODENDROCYTES.