2 - Neurons & Glia

Question 1

Extracellular space has high concentration of which ions?

Answer 1

Na+ and Cl-

Question 2

Intracellular space has low ….. and high …..

Answer 2

Low [Na+] and high [K+]

Question 3

Why is [Ca2+] kept low in neurons?

Answer 3

Because it’s a critical signalling ion

Question 4

True or false - neurons have low amounts of mitochondria

Answer 4

FALSE - lots of mitochondria because neurons consume lots of energy

Question 5

What are secretory vesicles?

Answer 5

Specialised packages that contain neurotransmitter

Question 6

Define neurotransmitter

Answer 6

Specialised chemical used to communicate info between neurons

Question 7

What are some important parts of a neuron?

Answer 7

• neuronal membrane -> separates intra and extracellular spaces
• ribosomes -> protein synthesis
• rough ER (aka Nissl bodies)
• mitochondria -> provide energy for membrane-bound ion pumps

Question 8

What makes a neuron special?

Answer 8

1. Neural processes that extend away from cell body

2. Mechanisms for electrical and chemical communication

Question 9

What’s a neurite?

Answer 9

A neuronal process (ie: axons and dendrites)

Question 10

Which direction do axons and dendrites transmit info?

Answer 10

Axons transmit info away from soma and dendrites transmit towards soma

Question 11

What are the 3 protein structures in the neuronal cytoskeleton?

Answer 11

• microtubules
• neurofilaments
• microfilaments

Question 12

Microtubules

Answer 12

Run longitudinally down neurites

Mediate intracellular transport

Microtubule associated proteins regulate their assembly and function

Question 13

Neurofilaments

Answer 13

Structural support

Regulate axon diameter

Question 14

Microfilaments

Answer 14

Linked to microtubules and membrane

Comprised of actin

Question 15

What are the 3 important parts of axon?

Answer 15

Axon hillock, axon proper and axon terminal

Question 16

Does the ER extend into the axon?

Answer 16

No - protein synthesis mainly happens in cell body

Question 17

What is transported within an axon?

Answer 17

Proteins, neurotransmitters and metabolites

Question 18

What are 2 methods of axon transport?

Answer 18

1. Fast axoplasmic transport

2. Slow axoplasmic transport

Question 19

Fast axoplasmic transport

Answer 19

• proteins synthesised in soma actively transported towards synapse
• metabolic waste from synapse transported to soma

Question 20

Slow axoplasmic transport

Answer 20

• mechanisms unclear
• active transport
• real slow

Question 21

What are the 2 transport directions in an axon?

Answer 21

• anterograde via kinetic (towards synapse)

- retrograde via dynein (away from synapse)

Question 22

Do axon terminals have microtubules?

Answer 22

No

Question 23

True/false - axon terminals have protein-dense membrane and lots of mitochondria

Answer 23

TRUE

Question 24

What does the pre-synaptic neuron release?

Answer 24

Neurotransmitter

Question 25

Synaptic cleft

Answer 25

Small gap between membranes of 2 neurons

Question 26

Where does neurotransmitter bind after being released?

Answer 26

Binds to proteins in post-synaptic membrane and then converted into electrical signal

Question 27

Spines

Answer 27

Small extensions of cell membrane where axon of another neuron comes in close proximity

Question 28

Density and length of dendritic spines depends on what?

Answer 28

Environment and development

Question 29

What can occur when spines don’t develop properly?

Answer 29

Mental retardation

Question 30

T/F - a neuron’s dendritic arbor limits its function

Answer 30

True

Question 31

Why do neurons vary in structure?

Answer 31

Because structure begets function

Question 32

How do neurons vary?

Answer 32

- number of neurites - shape and dendrites - connections - axon length - neurotransmitter

Question 33

What is a unipolar neuron?

Answer 33

Neuron with one primary axon/dendrite projecting from soma

Question 34

Stellate cells

Answer 34

Collate info locally within a brain region

Question 35

Pyramidal cells

Answer 35

Send info to other brain regions

Question 36

Do stellate cells have long axons?

Answer 36

No they have very short axon

Question 37

Glia

Answer 37

Support neuronal function and may be involved in info transmission

Question 38

Main types of glia

Answer 38

- myelinating glia - astrocytes - Microglia - ependymal cells

Question 39

What are the 2 types of myelinating glia?

Answer 39

Oligodendroglia (CNS) and Schwann cells (PNS)

Question 40

What do myelinating glia produce?

Answer 40

Myelin - electrically insulating sheath around axons

Question 41

What are the gaps in myelin called?

Answer 41

Nodes of Ranvier

Question 42

Why are nodes of ranvier important?

Answer 42

Provide connection between cytoskeleton in axon and extracellular fluid

Question 43

What’s the primary function of myelin?

Answer 43

Increase axonal conduction velocity

Question 44

Astrocytes support and influence what?

Answer 44

Support synaptic signalling, influence neurite growth and regulate chemical content of extracellular space (eg: K+ buffering)

Question 45

More roles of astrocytes

Answer 45

- regulate neurotransmitter in synapse - neuronal communication - ensheath small arterioles and capillaries

Question 46

Microglia

Answer 46

Fight inflammation and form specialised immune system in brain

Question 47

Ependymal cells

Answer 47

Line fluid-filled ventricles Produce CSF so brain floats Control fluid release between brain tissue and CSF in ventricles