Histology

Question 1

What is the key cell of the nervous system?

Answer 1

The neuron

Question 2

What are neurons supported by?

Answer 2

Glial cells

Question 3

What are the 5 different glial cells of the nervous system?

Answer 3

Astrocytes

Oligodendrocytes

Schwann cells

Ependymal cells

Satellite cells of ganglia

Question 4

What are the immune cells of the nervous system?

Answer 4

Microglia

Question 5

True or false: Microglia are a type of glial cell?

Answer 5

False!

Question 6

How many layers of neurons are there in the neocortex?

Answer 6

6

Question 7

What are the 2 specialised regions of the CNS?

Answer 7

Ventricular system and choroid plexus

Question 8

What is the role of the ventricular system?

Answer 8

Formation and passage of CSF

Question 9

What is the choroid plexus?

Answer 9

Vascular structure arising from the wall of each ventricle.

Forms the CSF

Question 10

What are ependymal cells?

Answer 10

Low columnar or cuboidal cells that line the central canal of the spinal cord and the ventricles within the brain.

Question 11

What do ependymal cells have in some places?

Answer 11

Cilia on apical surface to aid CSF flow.

Question 12

How are ependymal cells different to epithelial cells?

Answer 12

They are non basal laminar

Question 13

How are neurons specialised for signalling?

Answer 13

• Morphologically distinct
• Electrically active
• Rapid communication
• Long distance projections (axons)
• Specialised (e.g. transduction mechanisms for the various senses)

Question 14

How do neurons differ from other cells?

Answer 14

Specialised for signalling

High level of protein synthesis

Metabolically active

Terminally differentiated

Question 15

What will neurons that are morphologically distinct from one another have?

Answer 15

Different functions

Question 16

What are the 3 components of the neuron responsible for its morphology?

Answer 16

Actin

Intermediate filaments

Microtubules

Question 17

What role does actin play in regulating neuromorphology?

Answer 17

Dynamic assembly/disassembly, allowing for shape changes and movement (e.g. spines and growth cones).

Question 18

Which component of the neuron underpins the changes in spines and growth cones seen in plasticity?

Answer 18

Actin

Question 19

What are the properties of intermediate filaments found in neurons?

Answer 19

In all neuronal processes

Permanent

Question 20

What are the properties of microtubules found in neurons?

Answer 20

Dynamic

Composed of tubulin

Axon transport

Question 21

Which component of the neuronal cytoskeleton plays a role in axonal transport?

Answer 21

Microtubules

Question 22

What are the 3 different functional divisions to the neuron?

Answer 22

Dendrites - Inputs

Soma - Maintenance (also inputs, too)

Axon & axon terminal - Output

Question 23

Where is a high proportion of the total cell volume of the neuron found?

Answer 23

In the axons and dendrites.

Question 24

What is axonal transport critical in the supply of?

Answer 24

Cell-body derived elements

The axon terminal requires so many components but can’t synthesise them

Question 25

Which part of the neuron is often involved in damage?

Answer 25

The axon - because it is so long and often traverses long distances.

Question 26

What type of potentials does the membrane carry?

Answer 26

Graded potentials

Question 27

What must be present within and on either side of the neuronal membrane for graded potentials to be conducted?

Answer 27

Unequal distribution of positively charged ions on either side of the membrane. Membrane must contain Na+/K+-ATPase pumps and ion channels

Question 28

Which part of the neuron is specialised for inputs?

Answer 28

Dendrites

Question 29

What type of signal is that which travels along the dendrites?

Answer 29

Graded potential - passive electrotonic current

Question 30

What type of signal is that which travels along the axon?

Answer 30

Action potential

Question 31

What is the difference between graded potentials and action potentials in terms of signal conductance?

Answer 31

Action potentials propagate much further than graded potentials.

Question 32

What is the output signal of the axon?

Answer 32

Exocytosis of chemical neurotransmitter at the synapse.

Question 33

Which components of the neuron are visualised with a Nissl stain?

Answer 33

Organelles, e.g. free ribosomes and organelles

Question 34

Where are all proteins of the neuron synthesised? Why is this a problem?

Answer 34

In the soma. A problem because the axon terminal is a great distance from the soma.

Question 35

What are the passive support functions of astrocytes?

Answer 35

Neurotransmitter uptake and regulation K⁺ homeostasis Neuronal energy supply Maintenance of the blood brain barrier Aid in myelination Injury response and recovery

Question 36

What are the active support functions of astrocytes?

Answer 36

Modulation of neuronal function and blood flow

Question 37

How do glial cells regulate neurotransmitter uptake and degradation?

Answer 37

They express glutamate and GABA transporters used to shunt neurotransmitter out of the synapse.

Question 38

What happens to neuronal excitability when glutamate transporters in glial cells are inhibited?

Answer 38

Neurons become more depolarised, increasing excitability.

Question 39

Glia show modulations in which intracellular ion?

Answer 39

Calcium

Question 40

What is the calcium wave?

Answer 40

A propagating wave of calcium influx throughout the astrocyte, used as the signal both in and between glia when an external stimulus is applied.

Question 41

What can calcium waves in astrocytes be initiated by?

Answer 41

Neurotransmitters (e.g. ATP, Glutamate) Trauma Spontaneous Inflammatory mediators

Question 42

How can astrocytes modulate neuronal function?

Answer 42

Via vesicular excretion of glutamate or ATP onto neuronal membrane.

Question 43

What effect does the calcium wave have on the neuron? How?

Answer 43

Neurons are inhibited by calcium wave. ATP is released from the astrocyte onto the neuron

Question 44

How do astrocytes regulate the vasculature?

Answer 44

Calcium waves initiated within an astrocyte cause vasoconstriction or vasodilation via the release of ATP.

Question 45

What do oligodendrocytes and Schwann cells do?

Answer 45

Myelinate axons

Question 46

Where in the nervous system are oligodendrocytes found?

Answer 46

In the CNS

Question 47

Where in the nervous system are Schwann cells found?

Answer 47

In the peripheral nervous system

Question 48

What effect does myelination have on the neuron?

Answer 48

Provides electrical insulation for neurons. Increases conduction velocity.

Question 49

Other than their location, what is a major difference between oligodendrocytes and Schwann cells?

Answer 49

Oligodendrocytes extend processes that wrap around parts of several neurons, whereas Schwann cells wrap around one axon only.

Question 50

What are the small gaps between the myelin sheathings of an axon?

Answer 50

Nodes of Ranvier

Question 51

Of what origin are the microglia?

Answer 51

Haematopoietic origin Mesodermal derivative

Question 52

What percentage of cells in the mouse brain are microglia?

Answer 52

5-20%

Question 53

Which immune cell do microglia resemble?

Answer 53

Macrophages - they are phagocytic

Question 54

What do microglia do?

Answer 54

Constantly survey they CNS and change rapidly in response to inflammation or injury Upregulate cytokines/growth factors.

Question 55

What are peripheral nerves composed of?

Answer 55

One or more bundles (fascicles) of nerve fibres.

Question 56

What is each fascicle of a peripheral nerve fibre surrounded by?

Answer 56

Perineurium - collagenous tissue

Question 57

What is generally present in a peripheral nerve fibre if there is more than one fascicle present?

Answer 57

A further layer of collagenous tissue - the epineurium

Question 58

What is the endoneurium?

Answer 58

The loose vascular supporting tissue surrounded each nerve fibre and Schwann cell within each individual fascicle.

Question 59

What are ganglia?

Answer 59

Aggregations of cell bodies of neurons outside the CNS

Question 60

What are the 2 types of ganglia?

Answer 60

Sensory and autonomic ganglia

Question 61

What do the sensory ganglia house?

Answer 61

The somata of sensory neurons

Question 62

Where are the sensory ganglia found?

Answer 62

In the dorsal root of the spinal cord (dorsal root ganglia)

Question 63

What do the autonomic ganglia house?

Answer 63

The somata of post-ganglionic neurons

Question 64

What do ganglia contain?

Answer 64

Cell bodies, nerve fibres and satellite cells (supporting cells in ganglia)