Cell Types of the Nervous System

Question 1

How many neurones are there in the human brain?

Answer 1

10^10 - 10^12

Question 2

How many more non-neuronal cells are there than neurones?

Answer 2

Ten times as many

Question 3

What are unipolar neurones? Give an example

Answer 3

Neurones with one process

Dorsal root ganglia

Question 4

What are bipolar neurones? Give an example

Answer 4

Neurones with two processes

Retinal bipolar cells

Question 5

In a motor neuron, what kind of space do the dendrites occupy?

Answer 5

A spherical space known as a symmetrical dendritic field

Question 6

What kind of space do the dendrites of Purkinje cells occupy?

Answer 6

Planar dendritic field

Question 7

What kind of cells have apical dendrites?

Answer 7

Pyramidal cells

Question 8

Which cells have a planar dendritic field?

Answer 8

Purkinje cells

Question 9

Which cells have a symmetrical dendritic field?

Answer 9

Motor neurons

Question 10

What are the most common type of neurones in the brain?

Answer 10

Cerebellar granule cells

Question 11

Are olfactory granule cells unipolar, bipolar or multipolar?

Answer 11

Bipolar with cilia

Question 12

What kind of synapses do olfactory granule cells form, why?

Answer 12

Dendrodendritic synapses as they are anaxonic

Question 13

What are the 3 main types of glial cells?

Answer 13

• Macroglia
• Microglia
• Ependyma

Question 14

Give an example of one of the major subclasses of macroglia

Answer 14

Astrocytes

Also, oligodendrocytes and Schwann cells

Question 15

What type of glial cell are astrocytes?

Answer 15

Macroglia

Question 16

Astrocytes can be ______ or ________

Answer 16

Fibrous, protplasmic

Question 17

What shape are astrocytes?

Answer 17

Star-shaped

Question 18

Are astrocytes unipolar, bipolar, or multipolar?

Answer 18

Multipolar, has lots of long processes

Question 19

How are astrocytes associated with blood vessels?

Answer 19

Enwrap blood vessels to form an extra layer

Question 20

What do astrocytes form?

Answer 20

Glia limitans - lies between cerebral cortex and pia mater

Question 21

What does the glia limitans lie in-between and what is it formed by?

Answer 21

In-between the cerebral cortex and pia mater. It is formed by astrocytes

Question 22

Do astrocytes make connections with synapses?

Answer 22

Yes

Question 23

Where are fibrous astrocytes found?

Answer 23

In white matter

Question 24

Where are protoplasmic astrocytes found?

Answer 24

In grey matter

Question 25

Difference between the intermediate filaments in fibrous and protoplasmic astrocytes

Answer 25

Fibrous astrocytes have many intermediate filaments whereas protoplasmic astrocytes have shorter, fewer intermediate filaments

Question 26

Which type of astrocytes have shorter, fewer intermediate filaments?

Answer 26

Protoplasmic astrocytes

Question 27

Give 2 examples of specialised astrocytes

Answer 27

- Retinal Müller cells | - Radial glia e.g. Bergmann glia

Question 28

Retinal Müller cells

Answer 28

Columnar cells that spand width of the retina

Question 29

Bergmann Glia

Answer 29

These are multipolar and span from pia mater to Purkinje cell layer. Stem cells in adult brain

Question 30

Roles of astrocytes

Answer 30

- Spatial buffering - Neurotransmitter uptake - Glucose metabolism

Question 31

Roles of astrocytes: Explain the process of spatial buffering

Answer 31

- Active neurones release K+ - Astrocytes are very permeable to K+ so astrocytes act like functional syncitium - Astrocytes span from synapse to blood vessel Spatial buffering regulate [K+]

Question 32

Why is the homeostatic balance of K+ important in the brain?

Answer 32

Could alter firing of action potentials

Question 33

Astrocytes are permeable to which ion?

Answer 33

K+

Question 34

What do astrocytes span from?

Answer 34

Synapse to blood vessel

Question 35

What does spatial buffering regulate?

Answer 35

The concentration of potassium ions

Question 36

Spatial buffering in the retina

Answer 36

1. Photoreceptors release K+ when stimulated 2. Müller cells take up K+ 3. [K+] reduced near the photoreceptors

Question 37

Which glial cell aids in the homeostatic balance of K+ in the retina?

Answer 37

Retinal Müller cells

Question 38

Roles of astrocytes: Neurotransmitter uptake

Answer 38

- important inactivation mechanism | Glutamate and GABA is taken into astrocytes rather than being broken down

Question 39

Which neurotransmitters are taken up by astrocytes?

Answer 39

Glutamate and GABA

Question 40

Roles of astrocytes: Glucose metabolism

Answer 40

Glucose = main energy substrate Astrocytes store most glycogen in the CNS Glycogen metabolised and some lactic acid (3 carbon) passed to neurones Neurons prefer 3-carbon energy source

Question 41

Which cells store the most glycogen in the CNS?

Answer 41

Astrocytes

Question 42

What do astrocytes metabolise? What is produced as a result?

Answer 42

Glycogen and glucose maybe. Lactic acid is produced

Question 43

What kind of carbon energy source do neurones prefer?

Answer 43

3-carbon energy source

Question 44

What are microglia processes like?

Answer 44

Short and spiky

Question 45

What kind of cells are microglia derived from?

Answer 45

Circulating monocytes

Question 46

Are microglia phagocytic?

Answer 46

Yes

Question 47

Are microglia enucleate?

Answer 47

No

Question 48

Microglia

Answer 48

- Short, spiky processes - Wide distribution - Derived from circulating monocytes - Phagocytic

Question 49

What is ependyma?

Answer 49

Epithelia lining brain ventricles and central canal of the spinal cord

Question 50

What lines the brain ventricles and central canal of the spinal cord?

Answer 50

Ependyma

Question 51

What is ependyma composed of?

Answer 51

Ependymocytes | Can also get tanycytes in the hypothalamic region

Question 52

What are tanycytes?

Answer 52

Special ependymal cells found in the third ventricle of the brain, and on the floor of the fourth ventricle and have processes extending deep into the hypothalamus

Question 53

Choroid plexus

Answer 53

- Modified ependymal cells - Chloride epithelial cells - CSF formation and flow

Question 54

How is ependyma associated with the choroid plexus?

Answer 54

Consists of modified ependymal cells

Question 55

Do glial cells make specialised junctions with each other, if so, what kind?

Answer 55

Yes, gap junctions

Question 56

How many non-neuronal cells are there?

Answer 56

10 times as many neuronal cells