Neuro Lecture B1

Question 1

CNS

Answer 1

1. Brain

2. Spinal Cord

Question 2

PNS

Answer 2

1. Peripheral Nerves, all cranial nerves, except CN II

2. Neurons in ganglia outside of brain and spinal cord

Question 3

Neurite

Answer 3

An axon or dendrite

Question 4

Perikaryon

Answer 4

Cell body or soma

Question 5

Afferent Neuron

Answer 5

Neuron with an axon carrying impulses inward to the CNS

Question 6

Efferent Neuron

Answer 6

Neuron with an axon carrying impulses outwards from the CNS

Question 7

Synapse

Answer 7

specialized junction where neuron has functional contact with another cell

Question 8

Presynaptic Neuron

Answer 8

A neuron that releases transmitter at a synapse with another neuron

Question 9

Postsynaptic Neuron

Answer 9

A neuron that receives transmitter at a synapse

Question 10

Membrane Potential

Answer 10

The difference in electrical potential recorded across the cell membrane.

Question 11

What the two major cell types in the CNS and PNS?

Answer 11

Neurons and Glia

Question 12

At a very basic level, what are the two major structural components of a neuron?

Answer 12

Membrane and cell body

Question 13

Is the membrane of a neuron permeable?

Answer 13

semi permeable that is embedded with protein complexes

Question 14

what does the cell body of a neuron house?

Answer 14

the nucleus and many other organelles

Question 15

what extends from the cell body of a neuron?

Answer 15

Neurites (axons and denrites)

Question 16

explain the basic role of a dendrite and axon that extend off the neuron

Answer 16

denrites —> listen for signals from other cells
signals from dendrites pass on to the cell body of the neuron then influences the
axon —–> which send their signals to other neurons

Question 17

Nucleus (organelle) of a Neuron

Answer 17

porous double layered membrane encapsulates the chromatin-rich machinery for synthesis of RNA

Question 18

Nissl Substance (organelle) of Neuron

Answer 18

consists of RNA granules which is responsible for creation of proteins so the neuron will work properly

Question 19

Mitochondria (organelle) of Neuron

Answer 19

Involved in generation of ENERGY (ATP)

Question 20

Golgi Apparatus (organelle) of Neuron

Answer 20

Aggregated vesicles that package and allow controlled modification and transport of products of the Nissl substance.

Question 21

Lysosomes (organelle) of Neuron

Answer 21

Scavenger Vesicles loaded with decretory enzymes (basically they are the trash disposals of the neuron)

Question 22

What is the importance of cytoskeletal filaments for a neuron?

Answer 22

1. Maintain the shape of a mature cell

2. Important in transporting materials within the cells

Question 23

Microtubules function in a neuron

Answer 23

1. Transport tracks for two axonal transport system that move materials in opposite directions between the somata and the axonal endings.
   (side note they are stabilized by Tau Proteins)

Question 24

Kinesin is a fast ATP dependent process, describe its mechanism of action

Answer 24

Anterograde transport from the soma toward the + end of the microtubules.
Binding sites allow attachment of large structures (vesicles or mitochondria)

Question 25

When Kinesin becomes inactivated in the nerve ending what happens?

Answer 25

returns to the soma by retrograde axonal transport

Question 26

Dynein is also an ATP dependent process, describe its mechanism of action

Answer 26

Retrograde transport from nerve ending toward the negative end of the microtubule.

Question 27

How does dynein become reactivated?

Answer 27

becomes inactivated in the soma an d returns to the nerve ending for reactivation

Question 28

what trophic molecule, released by cells, is taken up by endocytosis in the axonal terminals and transported to the soma to promote growth in developing or regenerating axons?

Answer 28

Nerve Growth Factor

Question 29

what are the most common filaments in neurons and astroglia ( but absent from oligodendrocytes)

Answer 29

Neurofilaments/ intermediate filaments

Question 30

How are neurofilaments different from microtubules and microfilaments?

Answer 30

They undergo very little turnover

Question 31

what role do neurofilaments play in neurons?

Answer 31

Axonal diameter

Question 32

what role do microfilaments play in neurons?

Answer 32

form a network just beneath the cell membrane, through the use of actin (helps hold the shape of the cell) participate in advancement of the growth cone during neuronal growth or repair after injury.

Question 33

Describe the specific orientation of microtubules in axons?

Answer 33

positive ends situated distally

Question 34

Describe the specific orientation of microtubles in dendrites

Answer 34

Mixed Orientation. Half having positive ends near soma and the other half oppositely directed. (therefore this allows some materials to move toward dendrites instead of down axons)

Question 35

Multipolar neurons

Answer 35

1. Multiple Dendrites attached to soma | 2. Central or Peripheral special sensory function

Question 36

Golgi Type I and Golgi Type II

Answer 36

1. Multipolar Neurons with long axons= type I | 2. Multipolar Neurons with short axons= type II

Question 37

Bipolar Neurons

Answer 37

1. Elongated Cell Body and 2 processes * 1 process=forms axonal structures * 2 process= conveys information from the dendrites to the soma 2. Linked to CN VIII (found in the retina)

Question 38

Pseudo-Unipolar Neurons

Answer 38

2 processes: *1. carries information to the soma from the periphery * 2. Other away from the soma toward and into the CNS Remember example in class he gave about the hot stove! THERMAL ENERGY ---> INFO ABOUT ENERGY --> INFO TO CNS then further communication

Question 39

There are three different Neuron types, efferent/afferent and interneuron, most neurons work in which type?

Answer 39

Interneuron (Example: lots of enteric nervous system in the GI tract)

Question 40

what two factors does the speed of axons depend on?

Answer 40

diameter (The bigger the better) and electrical insulation (myelinated fibers are faster)

Question 41

Neurons can be grouped according to axonal diameters, which correlate with conduction velocity, which neuron fibers considered class IV fibers

Answer 41

``` Class IV fibers, in addition to being the smallest, are unmyelinated also considered class C ```

Question 42

Transmitter released by excitatory neurons tend to depolarize or polarize membranes?

Answer 42

depolarize membranes of other neurons

Question 43

CNS, type of Glia: Astrocytes

Answer 43

1. Most numerous cell type within the CNS 2. Maintains ionic homeostasis 3. Maintains synaptic homeostasis 4. Regulates cerebral blood flow 5. Protects neurons from oxidative damage 6. Supplies lactate to glucose-deprived neurons 7. Direct differentiation of neuronal precursors 8. Release cholesterol (increase # of synapses) 9. Release Gliotransmitters (glutamate, ATP) 10. Blood brain barrier protection 11. Formation of gliotic scars (after injury)

Question 44

Explain the Astrocyte Ca++ current system

Answer 44

creates a calcium wave or current and this is important between neuronal activity and blood supply

Question 45

Explain spatial buffering or potassium siphoning

Answer 45

Neuronal activity elevates K+ however large extracellular amounts of K+ can disturb intercellular signaling by depolarizing neurons. Astrocytic K+ ion channels take up the excessive ions for shunting to neighboring astrocytes via gap junctions.

Question 46

Radial glia become what in the cerebellum? And what in the retina?

Answer 46

Cerebellum: Bergman Glia Retina: Muller Cells

Question 47

CNS; type of glia: Microglia

Answer 47

1. Immunocompetent and phagocytic 2. Protect neurons from micro-organisms and toxic effects of cellular debris 3. Secrete neurotrophic or neuron survival factors upon activation 4. Contributes to initiation of pathological neuron degeneration 5. Releases Cytotoxic molecules

Question 48

CNS; type of glia: Oligodendrocytes

Answer 48

1. Myelinate central axons | 2. Many demyelinating neuro disorders are due to oligodendrite degeneration

Question 49

CNS; type of glia; Ependymal Cells

Answer 49

1. Form the walls of ventricles 2. Produce neurons and glial cells after stroke 3. Contribute some to glial scars (with astrocytes) 4. Shield the brain from CSF (with astrocytes)

Question 50

CNS; type of glia; Choroid Plexus Epithelial Cells

Answer 50

secrete CSF

Question 51

CNS; type of glia; Tanycytes

Answer 51

derived from radial glia | interface between blood and CSF

Question 52

PNS; type of glia; Schwann Cells

Answer 52

Myelinate peripheral axons

Question 53

immature schwan cells arise from what?

Answer 53

precursors of neural crest cells

Question 54

PNS; type of glia; Enteric Glial Cells

Answer 54

plentiful neurons of the enteric nervous system

Question 55

PNS; type of glia; Satellite Glial Cells

Answer 55

Surround neurons in sensory, sympathetic and parasympathetic ganglia, regulating the chemical environment

Question 56

describe the processor regeneration of axons in the PNS by schwann cells

Answer 56

1. Proliferate, forming a guide tube 2. Release nerve growth factors, encouraging axonal regeneration 3. Re-myelinate the regenerating axon (rate of 2mm/day) 4. Target cells may die unless reinnervated within denervated cells may die after 3 weeks

Question 57

Chromatolysis

Answer 57

reflects post traumatic neuronal swelling and dilution of organelles

Question 58

Anterograde degeneration

Answer 58

reflects the transynaptic death of the denervated (postsynaptic) cell

Question 59

Retrograde degeneration

Answer 59

reflects the death of the presynaptic cell

Question 60

why is there no regeneration of CNS axons?

Answer 60

central glial cells do not secrete significant amounts of nerve growth factor. oligodendrites do not form guide tubes gliotic scars block axonal growth

Question 61

Virtually all PNS tumors are???

Answer 61

Schwannomas

Question 62

50% of brain tumors are of what origin?

Answer 62

Glial origin

Question 63

Guillain-Barre Syndrome or Multiple Sclerosis

Answer 63

loss of myelin