Neurohistology

Question 1

What are neurons?

Answer 1

• Excitable cells
• Long cytoplasmic extensions specialised for reception of stimuli and conduction of a nerve impulse
• Do not undergo cell division and replication

Question 2

What do dendrites do?

Answer 2

Receive information from adjacent axons.

Question 3

What is the function of axons?

Answer 3

Send information from one end of the neuron to the other (faster if myelinated)

Question 4

Where are signals from the cell soma summated?

Answer 4

Axon Hillock

Question 5

What is the function of the axon hillock?

Answer 5

-Considered as the ‘trigger zone’ which must reach threshold potential to achieve an action potential.

Question 6

What are rich in voltage-gated Na+ channels?

Answer 6

Axon Hillock and Axon Initial segment (AIS)

Question 7

When does myelin start?

Answer 7

After Axon Initial Segment (AIS)

Question 8

What makes a neuron multipolar?

Answer 8

Dendrites
Nucleus
Cell Body
Axon + Axon terminal

Question 9

What stain used for dendrites?

Answer 9

MAP2- Microtubule Associated Protein

Question 10

What stain is used to identify axons?

Answer 10

BetaIV Spectrin

Question 11

What is the function of motor neurons?

Answer 11

Relay commands from brain and spinal cord to muscles and glands.

Question 12

Multipolar neurons- Golgi stains shows..

Answer 12

Spiny Dendrites

Question 13

Where are multipolar motor neurons in the spinal cord found?

Answer 13

Ventral horn of the spinal cord

Question 14

Multipolar motor neurons in the spinal cord display..

Answer 14

Large pale staining nucleus and a prominent nucleolus and nissl bodies.

Question 15

What does Nissl stain show in multipolar neurons?

Answer 15

Stain rough endoplasmic reticulum and polyribosomes important in protein synthesis
Largely absent in axons - axons cannot regenerate

Question 16

Sensory neurons are excited by…

Answer 16

Specific Stimuli

Question 17

What is ganglia?

Answer 17

Aggregations of nerve cells (ganglion cells) outside the CNS

Question 18

Dorsal Root Ganglia are surrounded..

Answer 18

by connective tissue capsule, which continuous with the peripheral nerve

Question 19

What are individual ganglion cells surrounded by?

Answer 19

A layer of flattened satellite (fibroblast) cells

Question 20

What is the function of interneurons?

Answer 20

Integrate information from sensory to motor neurons

Question 21

The cerebral cortex is also known as?

Answer 21

The Neocortex

Question 22

The cerebral cortex is divided into how many layers?

Answer 22

6 layers each housing neurons

whose morphology is characteristic of that layer

Question 23

What are the 6 layers of the cerebral cortex?

Answer 23

1- Molecular layer
2-External Granular Layer
3-External Pyramidal Layer
4-Internal Granular Layer
5-Internl Pyramidal Layer
6-Multiform Layer

Question 24

What neurons found in layer 4 of the Cerebral Cortex?

Answer 24

Internal Granular Layer - Granule (stellate) neurons

Question 25

What is the Cerebral Cortex?

Answer 25

your brain's outermost layer of nerve cell tissue

Question 26

In the cerebral cortex deep to the grey matter is white matter composed of ...

Answer 26

Myelinated Fibres

Question 27

How many layers does the cerebellar cortex have?

Answer 27

Three layers within the gray matter

Question 28

What are the 3 layers of the cerebellar cortex?

Answer 28

Outer Molecular Layer A single layer of Purkinje Cells A Granular Layer

Question 29

What cells are found in the granular layer?

Answer 29

``` Granule cells (most abundant neuron in brain) Golgi Cells ```

Question 30

What cells found Purkinje layer?

Answer 30

Purkinje cells

Question 31

What cells found in the outer molecular layer?

Answer 31

Basket cells, stellate cells

Question 32

What are the largest cells in the cerebellum?

Answer 32

Purkinje Neurons

Question 33

What is the structure of Purkinje Cells?

Answer 33

Pear- shaped cell bodies | distinctive dendritic tree in the molecular layer

Question 34

What the smallest cell type?

Answer 34

Granule cells

Question 35

What is the function of Purkinje fibres in the cerebellum?

Answer 35

Receive afferent information

Question 36

What are neuroglia?

Answer 36

Cells function in the metabolism and support of neurons

Question 37

What type of neuoglia is found in CNS?

Answer 37

Astrocytes Oligodendrocytes Ependymal Cells Microglia

Question 38

What type of Neuroglia is found in PNS?

Answer 38

Schwann Cells | Satellite cells

Question 39

What neuroglia have myelin sheath around axons?

Answer 39

Schwann Cells -PNS | Oligodendrocytes -CNS

Question 40

What is the function of Astrocytes?

Answer 40

Provide structural and metabolic support for neurons

Question 41

What the different types of Astrocytes?

Answer 41

Fibrous - in white matter Protoplasmic - in gray matter Muller glia - In retina Radial Glia - specialised cells in developing CNS

Question 42

Astrocytes help form...

Answer 42

Blood brain barrier

Question 43

How to do astrocytes help form blood brain barrier?

Answer 43

Form glial- limiting membrane around blood vessels and along CNS surface

Question 44

What is the barrier composed of?

Answer 44

Endothelial cells joined by tight junctions

Question 45

What is the integrity of the blood barrier highly dependent on?

Answer 45

Astrocyte 'end feet'

Question 46

Diffusion of what solutes is prevents in blood-brain barrier?

Answer 46

O2 CO2 Lipid Soluble molecules (hormones) >500 daltons MV not permissible

Question 47

What cells serves an immune function within the CNS?

Answer 47

Microglia

Question 48

How do microglia function?

Answer 48

Able to phagocytose cell debris in response to injury

Question 49

How do microglia exist?

Answer 49

Resident Microglia

Question 50

When does microglia get activated?

Answer 50

Upon CNS damage and actively move towards sites of injury

Question 51

What to microglia release in its immune response?

Answer 51

Cytokines | help and hinder recovery

Question 52

What neuron forms myelin sheath around CNS axons?

Answer 52

Oligodendrocytes

Question 53

What is the difference in myelination between Schwann cells and Oligodendrocytes?

Answer 53

Schwann cells myelinate one axon | Oligodendrocytes myelinate several axon

Question 54

What diseases affect oligodendrocytes?

Answer 54

Multiple Sclerosis | Leukodystrophies

Question 55

What is one of the last cell type to form during development?

Answer 55

Oligodendrocytes

Question 56

What cell forms myelin sheath around PNS axons?

Answer 56

Schwann Cells

Question 57

What is the function of Schwann cells?

Answer 57

Key role in the organisation of connective tissue sheaths around peripheral nerves during development and regeneration

Question 58

What percentage lipid in myelin?

Answer 58

80%

Question 59

What does myelin provide?

Answer 59

Insulation | Enhanced conduction velocity for action potentials (saltatory conduction)

Question 60

What type of conduction does unmyelinated axons have?

Answer 60

Continuous Conduction of action potentials due to passive current flow (low conduction)

Question 61

What are examples of unmyelinated axons?

Answer 61

Sensory Fibres carrying pain, temperature, itch

Question 62

In CNS, unmyelinated axons are not associated with...

Answer 62

Glial Cells

Question 63

PNS: Schwann cells '.................' unmyelinated axons contacting............

Answer 63

envelope | 1 or more axons