Neuro: Neurons, Glia, Histology

Question 1

Soma is the:

Answer 1

Cell body of the neuron

Question 2

Soma is involved in:

Answer 2

-gene expression
-biosynthesis
-cell. Survival mechanisms
-responses to injury
-receives synaptic input

Question 3

Dendrites:

Answer 3

-“fingers”
-receive synaptic input
-can be structurally altered by activity

Question 4

Axons:

Answer 4

Send out action potential that initiates at the axon hillock

Question 5

Terminals:

Answer 5

Where axons send their information to, and terminals release neurotransmitter into synapses

Question 6

Terminal boutons

Answer 6

Site of release of synaptic vesicles and neurotransmitters into synaptic cleft

Question 7

In the terminal bouton, neurotransmitter molecules are stored inside ______________

Answer 7

Synaptic vesicles

Question 8

When an action potential reaches the terminal…

Answer 8

The vesicles fuse with the cell membrane, releasing the stored neurotransmitter into the synaptic cleft where it binds to receptor in cell mem. of postsynaptic neuron

Question 9

Post-synaptic density:

Answer 9

Appearance of the synapse region by electron microscopy

Question 10

In the resting state of pre-synaptic activation:

Answer 10

-few vesicles are already docked at active zone, not yet fused
-most vesicles tethered by actin and not docked

Question 11

In the activated state of presynaptic activation:

Answer 11

-Ca2+ influx allows neurotransmitter release by pre-docked vesicles
-Ca2+ influx causes actin filaments to dis-associate from vesicles

Question 12

Axon terminals can form synapses on what part of the neuron?

Answer 12

Any part!

Question 13

Synapses can mediate either excitatory or inhibitory effects on the post-synaptic neuron. This depends on:

Answer 13

-nature of neurotransmitter
-nature of the receptor for that neurotransmitter

Question 14

Synapses on dendritic spines are…

Answer 14

ALWAYS excitatory

Question 15

At axoaxonic synapses, neurotransmission can excite or inhibit the…

Answer 15

Postsynaptic axon terminal s

Question 16

Sensory/pseudo-unipolar neurons :

Answer 16

-Touch/pain receptors in skin/viscera and taste receptor cells
-Typically located in a ganglion

Question 17

Motor neurons:

Answer 17

Located in the anterior horn of the spinal cord and in cranial nerve motor nuclei in brainstem

Question 18

Local interneuron

Answer 18

Usually very short, unmyelinated axons in PNS and CNS

Question 19

Neuroendocrine neuron

Answer 19

-Mostly in hypothalamus
-release peptide hormone into blood (systemic or portal circulation

Question 20

Antrograde axonal transport:

Answer 20

-from cell body to terminals
-synaptic vesicles
-neurotransmitters, synthetic enzymes

Question 21

Retrograde axonal transport:

Answer 21

-from terminals to target

Question 22

Kinesin is ____________ because it goes toward _____ end

Answer 22

Anterograde, plus end

Question 23

Dynein is ______________ because it goes towards ______ end

Answer 23

Retrograde, minus

Question 24

Clinical significance of axonal transport:

Answer 24

-pathophysiological role in neurodegenerative disorders
-role in viral infections of PNS
-potential tool for viral delivery of gene therapy

Question 25

In PNS, _____________ form the myelin sheath

Answer 25

Schwann cells (glia)

Question 26

Myelin sheath:

Answer 26

Electrical insulation that boosts speed of current down the axon

Question 27

Along the length of the axon, the myelin sheath is normally…

Answer 27

Interrupted by small gaps exposing bare axon

Question 28

Gaps in myelin sheath are called:

Answer 28

Nodes of ranvier

Question 29

Adaptive purpose of nodes of ranvier

Answer 29

-allows electrical signal to renew intensity at each node of ranvier

Question 30

White matter

Answer 30

Region dominated by myelinated axons that give a shiny white color

Question 31

Grey matter

Answer 31

Region dominated by cell bodies and dendrites, few/no axons

Question 32

Disorders that cause demyelination of axons:

Answer 32

-peripheral neuropathy
-multiple sclerosis
-vitamin B12 deficiency
-poor attempts of rehydrating someone too rapidly

Question 33

Microglia

Answer 33

-small glia
-phagocytic cells that attack pathogens
-can alter blood-brain barrier to white blood cells to enter CNS and drive inflammatory response

Question 34

Astrocytes function:

Answer 34

-star shaped cells
-form barrier inside pia material
-part of blood-brain barrier surrounding capillaries
-envelopes parts of neurons to control extracellular environment for normal neurons

Question 35

Ependymal cells

Answer 35

Cells that form a single layer along the deepest part of the brain and spinal cord forming a border between CNS tissue and the ventricular spaces containing CSF

Question 36

Pericyte

Answer 36

Envelopes endothelial cells and control substances moving across endothelial cell membranes

Question 37

What can diffuse across blood brain barrier?

Answer 37

-lipids
-hydrophobic substances in blood

Question 38

What has to be actively transported across blood brain barrier?

Answer 38

Water soluble substances (glucose, nucleotides, some AA)

Question 39

Gliosis stages:

Answer 39

-growth of each astrocyte
-proliferation (mitosis)
-clustering of astrocytes at pathology site
-formation of barrier around damage
-isolates the pathological area

Question 40

Role of Schwann cells in injury

Answer 40

Provide scaffolding and protection for regeneration of axon

Question 41

Is there better regeneration to an axonal injury in CNS or PNS?

Answer 41

PNS

Question 42

Steps after axonal injury in PNS:

Answer 42

-macrophage enters nerve and cleans up debris
-Schwann cells survive and help with axon regrowth

Question 43

Steps after axonal injury in CNS:

Answer 43

-monocytes enter CNA and morph into Microglia to clean up debris
-Oligos often die creating scar tissue that inhibits axonal regrowth