chapter 2: cells of the nervous system

Question 1

cells present in nervous system

Answer 1

neurons

neuroglial cells = glia

Question 2

CNS consists of

Answer 2

gray matter: contains cell bodies of neurons, embedded in neuropil
white matter: long processes of neurons, surrounded by myelin sheath

Question 3

classification of neurons by Erlanger and Gasser

Answer 3

myelinated Aα, β, γ, δ, B fibers

unmyelinated C fibers

Question 4

classification of neurons by Lloyd and Hunt

Answer 4

Aα = type Ia
Aβ = type Ib or II
Aδ = type III
C = type IV

Question 5

neuroglial cells: central neuroglia are …

Answer 5

astrocytes
oligodendrocytes
ependyma
microglia

Question 6

cytoplasm of astrocytes

Answer 6

contains intermediate filaments (neurofilaments) composed of glial fibrillary acidic protein (GFAP)

Question 7

2 types of astrocytes

Answer 7

fibrous astrocytes: in white matter and GFAP- filaments

protoplasmatic astrocytes: in gray matter

Question 8

functions of astrocyte

Answer 8

• surround capillary blodd vessels with perivascular end feet
• other end feet connect to pia mater
• connections to ependymocytes in ventricular system
• synapses and nodes of Ranvier absorb neurotransmitters (excitatory and inhibitory)

Question 9

excitatory and inhibitory neurotransmitters are …

Answer 9

+: glutamate, acetylcholine, noradrenaline, serotonin and dopamine
-: GABA, glycine, dopamine

Question 10

characteristics of oligodentrocytes

Answer 10

• small nuclei
• small rim of cytoplasm: contain granular endoplasmic reticulum and polyribosomes
• few long thin processes
• filaments are absent, but has numerous microtubules

Question 11

3 types of oligodendrocytes

Answer 11

• interfascicular oligodendrocytes
• satellite oligodendrocytes
• third type contacts the nodes of Ranvier

Question 12

ependyma =

Answer 12

the simple cuboidal/ columnar epithelium than lines the ventricular system

Question 13

3 types of cells in ependyma

Answer 13

• ependymocytes
• tanycytes
• choroidal epithelial cells

Question 14

characteristics of resting microglial cells

Answer 14

• small, elongated nuclei
• not a lot of cytoplasm
• several short- branched processes with spiky appedages
• enevly spaced throughout gray and white matter
• no overlapping or intertwining

Question 15

reactive microglial cells

Answer 15

• formed from resting microcglial cells

- are distended with lipid- rich phagocytosed material

Question 16

neuroglial cells: peripheral neuroglia are …

Answer 16

Schwann cells = neurolemmocytes

Question 17

Schwann cells

Answer 17

• elongated nuclei
• ensheath all axons in all parts of the PNS
• each axon is suspended in the cytoplasm of its Schwann cell by a dubble layer of surface membrane
• 1 Schwann cell ensheaths either 1 myelinated axon or surrounds several unlyelinated axons
• gaps between the cells = nodes of Ranvier

Question 18

neurons are…

Answer 18

cells specialized for sending and receiving chemically mediated electrical signals
their axons carry the encoded output of information fron the region containing their cell bodies to other parts of the nervous system

Question 19

basic concepts of neurons

Answer 19

• cell body with nucleus
• cytoplasma = perikaryon
• neurite = any neural process (axon or dendrite)
• neuron doctrine = each neuron is a structural and functional unit

Question 20

different shapes and sizes of neurons

Answer 20

• size of cell body: 5 μm- 135 μm
• neurons occur in ganglia (PNS) and in laminae and nuclei (CNS) together they are principal cells
• small local circuit neurons = interneurons

Question 21

types of neurons

Answer 21

• multipolar neurons
• unipolar neurons
• bipolar neurons

Question 22

myelin sheath =

Answer 22

apposed layers of glial plamsa membranes

• begins near origin of axon & ends short of its terminal branching
• laid down by neuroglial cells
• interruptions are nodes of Ranvier

Question 23

saltatory conduction

Answer 23

• AP jumps from one node to the next
• signaling is faster in a myelinated exon than in an unmyelinated axon
• the greater the diameter of a nerve fiber, the faster the conduction of the nerve impulse

Question 24

synapses =

Answer 24

a point of functional contact between 2 neurons or between a neuron and and effector cell

Question 25

presynaptic neurite = synaptic terminal

Answer 25

has synaptic vesicles that contain neurotransmitters

Question 26

neurotransmitters can be excitatory or inhibitory

Answer 26

excitatory: stimulates postsynaptic cell
- -> EPSP: excitatory postsynaptic potential = depolarization
inhibitory: inhibits postsynaptic cell
- -> IPSP: inhibitory postsynaptic potential = hyperpolarization

Question 27

neuromodulator =>

Answer 27

modifies the responsiveness to transmitters

Question 28

what is axonal transport?

Answer 28

enzymes, membrane lipoproteins, cytoplasmic structural proteins

Question 29

what is anterograde transport?

Answer 29

• from cell body to synapses

- 2 rates: slow pace or fast pace

Question 30

what is retrograde transport?

Answer 30

• from synaptic terminals to cell body
• absorbed proteins from extracellular space
• rate is variable

Question 31

what are the responses of neurons to injury?

Answer 31

• breakdown of axons and myelin sheath distal to an injury site