Cell Neuroscience - Neurons and Glia - Part 2

Question 1

This MAP is an ATPase responsible for retrograde transport from nerve ending towards the negative end of the microtubule, soma. It is also the motor protein causing movement of cilia and flagella. It becomes inactivated in the soma and is carried back to the nerve ending to be re-activated. What is it?

Answer 1

Dynein

Question 2

Slowing down of the ___ transport may lead to neurodegeneration and cell death, and also may play part in the development of some neurodegenerative diseases

Answer 2

retrograde dynein dependent

Question 3

What are the functions of Astrocytes in the CNS?

Answer 3

role in

• maintaining homeostasis at the synapse,
• regulating neuronal signalling,
• protecting neurons from oxidative damage by releasing antioxidant enzymes
• determining the fate of endogenous neural precursors by e.g. releasing growth factors

Question 4

Which antioxidant enzymes are released by Astrocytes to protect neurons from oxidative damage

Answer 4

• Mn- and CuZn

- superoxide dismutase, SOD

Question 5

Why is it important that astrocytes in the CNS release cholesterol?

Answer 5

important for increasing the number of synapses and thus the synaptic activity and plasticity of neurons

Question 6

What are the four morphologic classes of GFAP (glial fibrillary acidic protein) positive astrocytes present in the human brain?

Answer 6

• interlaminar astrocytes
• protoplasmic astrocytes
• varicose projection astrocytes
• Fibrous astrocytes

Question 7

Where in the CNS are interlaminar astrocytes found?

Answer 7

Densely packed in cortical layer 1.

Question 8

Where are protoplasmic astrocytes found in the CNS?

Answer 8

Cortical layers 2-6

Question 9

Where in the CNS are varicose projection astrocytes found?

Answer 9

Cortical layers 5-6

Question 10

Where in the CNS are Fibrous astrocytes found?

Answer 10

White matter

Question 11

There are also astrocytes in the ___, which have recently been suggested to have functional roles in pathological pain partly by modulating synaptic transmission between neurons and nociceptive pathway.

Answer 11

spinal cord

Question 12

Astrocytes display ___, which can then trigger the release of gliotransmitters, such as ___, ___ and___.

Answer 12

• spontaneous and neuronal activity-evoked oscillations in their intracellular Ca2+ concentration
• glutamate
• D-serine
• ATP

Question 13

The excitability of astrocytes are not based on action potentials (as in neurons) but rather on changes in the ___.

Answer 13

-intracellular Ca2+ ion concentration.

Question 14

Astrocytes associated with the neurovascular unit are responsible for ___ in the brain. Damage to the neurovascular unit may be a factor in ___, where vascular ___ deposits are often found.

Answer 14

• maintaining cerebral blood flow and ionic and osmotic balances
• e.g. the pathogenesis of Alzheimer’s disease
• amyloid

Question 15

In Alzheimer’s disease, as well as in head trauma and ischemia, astrocytes are known to ___ and also form ___, isolating neurons from each other

Answer 15

• become reactive

- glial scars (glial boundaries)

Question 16

Astrocytes are also known to be ___ during ischemia and head trauma, but also are known to be able to ___.

Answer 16

• swelling

- regulate their volume back to normal.

Question 17

Astrocytes store ___ and supply neurons with ___ in the CNS.

Answer 17

• glycogen
• lactate

(Astrocytes are the sole storage depot for glycogen, which can be converted to lactate and transferred to neurons as an alternate source for ATP production. If glucose supply is interrupted, neuronal activity can survive this loss but only until glycogen is used up (within about 10 minutes of glucose supply interruption).)

Question 18

Astrocytes regulate ___ in the Microenvironment of Neurons.

Answer 18

[K+]o

Question 19

What is spatial buffering or potassium siphoning?

Answer 19

Potassium ions taken up at one region of the astrocyte are then distributed throughout the cytoplasm of the cell, and further to its neighbours via gap junctions. This sharing of the K+ ion load is called spatial buffering or potassium siphoning.

Question 20

Astrocytes take up ___ from the extracellular fluid.

Answer 20

neurotransmitters

Question 21

Which neurotransmitters are taken up by Astrocytes from extracellular fluid?

Answer 21

• Glutamate
• Glycine
• Noradrenaline