Cellular Neuroanatomy (1)

Question 0

Structural and functional unit of the NS

Answer 0

Neuron

Question 1

2 principal cell types in nervous system

Answer 1

Neurons and glia

Question 2

3 functions of glia

Answer 2

1. Physical support ( protection)
2. Electrical insulation
3. Metabolic exchange b/n vascular system and NS

Question 3

Function of neuronal cell body. Other name?

Answer 3

Produces proteins and provides metabolic function. Also called soma

Question 4

Which neuronal structures receive input from other neurons.

Answer 4

Dendrites

Question 5

What kind of inputs are are preferentially on to dendrites and dendritic spines?

Answer 5

Excitatory synaptic inputs

Question 6

What three functions do dendritic spines serve as the anatomical substrate for?

Answer 6

1. Synaptic transmission
2. Synaptic plasticity
3. Memory storage

Question 7

How many axons does each neuron have? Function?

Answer 7

One and ONLY ONE axon. Axons conduct electrical output from one neuron to another.

Question 8

How many dendritic spines may be on a dendrite?

Answer 8

Hundreds to thousands. Remember they are the small membranous protrusions from the dendrites themselves, sort of like microvilli.

Question 9

Soma of neurons is esp. rich in what organelle?

Answer 9

Rough ER

Question 10

What are Nissl bodies?

Answer 10

Basophilic masses consisting primarily of rough ER and ribosomes. Function is protein synthesis.

Question 11

Positive Nissl stain indicates what 2 neuronal structures.

Answer 11

1. Cell bodies

2. Proximal dendrites

Question 12

Where is Nissl substance not found in neurons?

Answer 12

In the axon, beginning at the axonal hillock

Question 13

Gray matter is _________ tissue and consists primarily of what two neuronal structures?

Answer 13

Unmyelinated; consists of Somas and Dendrites

Question 14

White matter is ______ tissue; what neuronal structure does it primarily consist of?

Answer 14

Myelinated; consists of myelinated Axons

Question 15

What organelles are present in the axonal hillock.

Answer 15

None!

Question 16

What is the axonal initial segment?

Answer 16

Portion of axon from axonal hillock to beginning of myelination

Question 17

Pseudounipolar neurons are typically found where?

Answer 17

In the PNS, as part of sensory neurons. Ex. - sensory neurons with cell bodies in the dorsal root ganglia

Question 18

Where are multipolar neurons typically found

Answer 18

In the CNS. Ex. - pyramidal cells of cortical regions, Purkinje fibers of the cerebellum, or motoneurons

Question 19

Local circuit interneurons, such as those in the retina are usually what type of neuron?

Answer 19

Bipolar

Question 20

What type of cells integrate information and send long axons to other brain areas? Other two names for these?

Answer 20

Principal cells; also called projection neurons or Golgi type I cells

Question 21

What is unique about interneurons? What other two names are they known as?

Answer 21

They do not send their axons out of the local brain area. Also called Local Circuit neurons or Golgi Type II cells (either no axon or short, local axon)

Question 22

What are the two types of synaptic transmission?

Answer 22

Electrical and chemical

Question 23

What structures are needed for electrical synapses to function?

Answer 23

Gap junctions

Question 24

Most excitatory synapses in the brain are located on what structures?

Answer 24

Dendritic spines

Question 25

What are the 4 types of synapse types?

Answer 25

1. Axosomatic 2. Axodendritic 3. Axoaxonic 4. Dendrodendritic The neuromuscular junction is also one; axospinous is a subtype of axodendritic

Question 26

What is unique about chemical synapses in vertebrates compared to electrical synapses?

Answer 26

Chemical synapses transmit information unidirectionally

Question 27

What is the presynaptic bouton or axonal varicosity?

Answer 27

Portion at end of axon where synaptic vesicles containing NT reside

Question 28

What are two examples of excitatory NTs?

Answer 28

Acetylcholine and glutamate

Question 29

How do excitatory NTs work?

Answer 29

Depolarize the postsynaptic neuron to increase probability of firing

Question 30

What are two main inhibitory NTs?

Answer 30

Glycine and GABA

Question 31

What are two examples of modulatory NTs?

Answer 31

Dopamine and NE

Question 32

Excitatory synapses are also called what? These are asymmetric, what does this mean?

Answer 32

Gray's Type I. Asymmetric means they have a more pronounced density in the postsynaptic membrane than in the presynaptic membrane

Question 33

Where are type I synapses normally found?

Answer 33

On dendrites

Question 34

Gray's type II synapses are what kind? Where are they found?

Answer 34

Inhibitory. Usually found on somas

Question 35

What proteins are gap junctions composed of?

Answer 35

Connexons

Question 36

What molecules make up connexons? How many?

Answer 36

Connexins. 6 connexins make up a connexon

Question 37

What protein is responsible for anterograde axonal transport?

Answer 37

Kinesin

Question 38

What protein is responsible for retrograde axonal transport?

Answer 38

Dynein

Question 39

What cells provide myelination in the PNS?

Answer 39

Schwann cells

Question 40

What cells provide myelination in the CNS?

Answer 40

Oligodendrocytes

Question 41

What cells provide metabolic exchange and serve as a part of the BBB? What two types are there?

Answer 41

Astrocytes. Fibrous and protoplasmic types exist.

Question 42

What cells serve as phagocytic and inflammatory cells in the CNS? What germ layer are they derived from?

Answer 42

Microglia. Derived from mesoderm, like monocytes.

Question 43

What cells are the stem cells for glia and neurons?

Answer 43

Polydendrocytes

Question 44

What cells line ventricles?

Answer 44

Ependymal cells. Are cuboidal to low columnar epithelial cells

Question 45

How many internodes does a Schwann cell form? Does Schwann cell myelin contact the Schwann cell soma?

Answer 45

1. (Schwann cells myelinate only one portion of one neuron). The Schwann cell myelin IS in contact with the Schwann cell soma

Question 46

What is a Schmidt-Lanterman cleft, or incisure?

Answer 46

Small folds of cytosol that support the myelin; allow for continuity of cytoplasm despite the cell being wrapped tightly around the axon

Question 47

What two Schwann cell pockets overhang the paranormal and nodal portion of the axon?

Answer 47

1. Microvilli | 2. Schwann cell pockets ( or paranormal loops)

Question 48

What is endoneurium?

Answer 48

Thin layer of CT that surrounds each individual nerve fiber

Question 49

What is perineurium?

Answer 49

CT layer covering entire nerve fascicle

Question 50

How many internodes can one oligodendrocyte form? What similarity do they have to Schwann cells?

Answer 50

30-50 internodes, but like Schwann cells, oligodendrocytes can only form one internode per neuron. What is different is that they can myelinate several axons per oligodendrocyte.

Question 51

What is different about unmyelinated neurons in the PNS compared to those in the CNS?

Answer 51

In the PNS, they are protected by Schwann cells (one Schwann cell can loosely envelope a few unmyelinated nerve, but they do not tightly wrap around, so don't really insulate them). In the CNS, unmyelinated neurons are completely unprotected.

Question 52

Other than maintenance of BBB, what 2 processes are astrocytes involved in?

Answer 52

1. Angiogenesis | 2. Synaptogenesis

Question 53

What is the purpose of the metabolic exchange astrocytes carry out?

Answer 53

Maintain constant ionic concentrations for optimal neuronal function

Question 54

What are Radial glia?

Answer 54

Sub population of astrocytes that provides direction and scaffolding for axon migration and development

Question 55

How are astrocytes involved in the tripartite synapse?

Answer 55

They are involved in NT release into the synaptic cleft and also have NT receptors themselves

Question 56

How do astrocytes communicate with each other?

Answer 56

Via Ca2+ release, spread by gap junctions

Question 57

Which astrocytes are found in white matter?

Answer 57

Fibrous. These have vascular feet that connect them to outside of vascular walls

Question 58

What astrocytes are found in grey matter?

Answer 58

Protoplasmic. These are the most common overall

Question 59

What are two types of radial astrocytes that persist into adulthood?

Answer 59

1. Mueller cells ( in retina) | 2. Bergman glia ( cerebellum)

Question 60

Which cells function as astrocytes in the PNS? What cells are they derived from?

Answer 60

Satellite cells. Derived from neural crest cells. Usually surround the entire soma of ganglia cells ( are around the pseudounipolar cells of peripheral ganglia). Are small cuboidal cells

Question 61

Other than ventricles of the brain, what do ependymal cells line?

Answer 61

Central canal of spinal cord.

Question 62

The apical surface of ependymal cells is covered by what?

Answer 62

Cilia and microvilli

Question 63

What do the basal surfaces of ependymal cells contact?

Answer 63

Astrocytes

Question 64

Why is it important that ependymal cells don't have tight junctions?

Answer 64

Allows for free exchange between CSF and neural tissue