Neurohistology

Question 1

The initial segment of the axon is the first ——— μm after the axon leaves the axon hillock

Answer 1

400 μm

Question 2

ž———- is Bundle of axons in PNS

Answer 2

Nerve

Question 3

Nerve
ž
ž
• ———: Loose CT around each axon
ž
•———: CT around a bundle of axons
ž
• ———: CT around a nerve

Answer 3

Nerve
žBundle of axons in PNS
žEndoneurium
• Loose CT around each axon
žPerineurium
• CT around a bundle of axons
žEpineurium
• CT around a nerve

Question 4

Neuronal Cell Body
• also called———
• Variablesize
– ~— to —μm diameter

Answer 4

Neuronal Cell Body
• Soma/Perikaryon • Variablesize
– ~5-140 μm diameter

Question 5

Do dendrites have Rough ER

Answer 5

Yes

Question 6

The ———— is the
primary receiving site for
synaptic information.

Answer 6

Dendritic tree

Question 7

The dendritic surface of many neurons has ————- which further increase the synaptic surface area.

Answer 7

Dendritic spines

Question 8

Abundant neurotubules
and neurofilaments and
components of the rough
endoplasmic reticulum
(Nissl bodies) may extend
into the base of the ———.

Answer 8

Dendrite

Question 9

———- is the Last site where membrane potentials propagated from synaptic inputs are summated before being transmitted to axon

Answer 9

Axon hillock

Question 10

——— is a Barrier for lateral diffusion of transmembrane proteins & lipids embedded in plasma membrane

Answer 10

Axon hillock

Question 11

Do axons have Nissl bodies

Answer 11

No

Question 12

Classification of neuron based on Dendrite structure

Answer 12

Pyramidal
Stellate

Question 13

Most neurons of brain & spinal cord are ——— type of neuron

Answer 13

Multipolar

Question 14

Multipolar neurons are >—% of neurons

Answer 14

99

Question 15

How many processes do the following have:
Multipolar
Bipolar
Pseudounipolar

Answer 15

Multipolar- >2 processes
Bipolar- 2
Pseudounipolar- 1 process;quickly forms 2 processes

Question 16

Which neurons are rare

Answer 16

Bipolar neuron

Question 17

Anterograde transport of a vesicle along a microtubule is mediated by ———.

Answer 17

kinesin.

Question 18

Retrograde transport of a vesicle along a microtubule is mediated by cytoplasmic ———.

Answer 18

dynein.

Question 19

Pseudounipolar neuron are (sensory/motor?) neurons – located mainly in ————

Answer 19

Sensory neurons – located mainly in dorsal root ganglia

Question 20

Classification based on Cell Body & Dendrites
-———-cells : Pyramid-shaped
-————- cells: —Star-shaped

—Cells can also be classified by whether the dendrites have spines or not
—Those that do are called —— Neurons —Those that don’t are called ———-
Neurons
—

Answer 20

Classification based on Cell Body & Dendrites
—Pyramidal cells —Pyramid-shaped
—Stellate cells —Star-shaped
—Cells can also be classified by whether the dendrites have spines or not
—Those that do are called Spiny Neurons —Those that don’t are called Aspinous
Neurons

Question 21

Classification based on Cell Body & Dendrites

———— cells are spiny, while ——- cells can be spiny or aspinous

Answer 21

Classification based on Cell Body &
—Pyramidal cells are spiny, while stellate cells can be spiny or aspinous

Question 22

Neuron Classification by Axon Length
—

Answer 22

Neuron Classification by Axon Length
—Golgi type I Neurons —Long axon

—Golgi type II Neurons —Have short axon
—

Question 23

Neuron Classification by Axon Length
—Golgi type I Neurons —Long axon include:

—Golgi type II Neurons —Have short axon
— Greatly outnumber type I
—Numerousin ——— &———
— Often (inhibitory/excitatory?) in function

Answer 23

Neuron Classification by Axon Length
—Golgi type I Neurons —Long axon:
— Pyramidal cells
— Purkinje cells
— Motor cells of spinal cord

—Golgi type II Neurons —Have short axon
— Greatly outnumber type I
—Numerousin cerebral&cerebellarcortex — Often inhibitory in function

Question 24

Classification of neurons By Axon Diameter

Answer 24

By Axon Diameter
1. Sensory afferents
-Size: largest -> smallest
-Aa,Ab,Ad,C
2. C: small, unmyelinated
-pain & temperature
3. Aa:
- Proprioceptors in muscle

Question 25

Neuron Classifications By Function

Answer 25

Neuron Classifications By Function 1. Sensory receptors in PNS 2. Motor/efferent neurons 3. Inter neurons/ association neurons

Question 26

Neuron Classifications By Function 1. Sensory receptors in PNS -Send AP to —— -———soma -Located in ganglia in —— 2. Motor/efferent neurons - ——— soma -Soma in CNS - Except —— -Send AP to —— or —— 3. Inter neurons/ association neurons -Located in —— ->—% of all neurons -~ all ——— soma

Answer 26

Neuron Classifications By Function 1. Sensory receptors in PNS -Send AP to CNS -Pseudounipolar soma -Located in ganglia in PNS 2. Motor/efferent neurons - Multipolar -Soma in CNS - Except ANS -Send AP to muscle or gland 3. Inter neurons/ association neurons -Located in CNS ->99% of all neurons -~ all multipolar -Integration of information

Question 27

Types of Synapses

Answer 27

Synapses Axodendritic synapses Axosomatic synapses Axoaxonic synapses

Question 28

Synaptic cleft ~— nm; shorter than — to — nm distance that separates cells at chemical synapse

Answer 28

Synaptic cleft ~3.5 nm; shorter than 20-40 nm distance that separates cells at chemical synapse

Question 29

CNS Neuroglia include

Answer 29

CNS Neuroglia • Astrocytes – Control [ion] • Microglia – Phagocytic • Ependymal cells – Line ventricles • Oligodendrocytes – Form myelin

Question 30

Astrocytes ——— -shaped ̈Bind neurons to ——— & ——-

Answer 30

Astrocytes ̈Star-shaped ̈Bind neurons to capillaries & pia mater

Question 31

——— is the Most abundant glial cells

Answer 31

Astrocytes

Question 32

Astrocytes functions:

Answer 32

Functions 1) Supportive 2) Insulating, particularly with regard to synapses 3) Electrolyte balance, particularly regarding K+ ions 4) pH balance of extracellular milieu 5) Sequestration of neurotransmitters 6) Communicate with capillary endothelial cells 7) Interactions with immune system

Question 33

Types of astrocytes

Answer 33

Fibrous astrocytes Protoplasmic astrocytes

Question 34

Fibrous astrocytes -prominent in ——- matter -describe the processes: Protoplasmic astrocytes -prominent in —— matter -describe the processes:

Answer 34

Fibrous astrocytes -prominent in white matter -fine, long, straight processes Protoplasmic astrocytes -prominent in gray matter -wavy, thin, fluffy processes

Question 35

Ependyma ž———-epithelial cells lining the ventricles of the brain & central canal of the spinal cord

Answer 35

Low columnar

Question 36

Myelin is —% lipid & —% protein & allows for efficient conduction of action potentials down the axon

Answer 36

Myelin is 80% lipid & 20% protein & allows for efficient conduction of action potentials down the axon

Question 37

Oligodendrocytes (II) •Unlike ——— cells, form segments of myelin sheaths of numerous neurons at once

Answer 37

Oligodendrocytes (II) •Unlike Schwann cells, form segments of myelin sheaths of numerous neurons at once

Question 38

SUPPORTING CELLS IN THE PNS

Answer 38

SUPPORTING CELLS IN THE PNS • Satellite cells • Located around nerve cell bodies in ganglia • Schwann cells / neurolemmocytes • Form myelin around axon in PNS

Question 39

——— disease -Neurons that produces dopamine in the substantia nigra begin to degenerate.

Answer 39

Parkinson’s

Question 40

In people with PD, ———- levels are lower in the brain, specifically in the substantia nigra.

Answer 40

, glutathione

Question 41

Tay-Sachs Disease Autosomal recessive disease Mutations in both alleles of a gene——-on chromosome — HEX A codes for the alpha subunit of the enzyme ———- found in lysosomes Juvenile: symptoms: —- Chronic adult form, symptoms:

Answer 41

Tay-Sachs Disease vAutosomal recessive disease vMutations in both alleles of a gene (HEX A) on chromosome 15 vHEX A codes for the alpha subunit of the enzyme beta- hexosaminidase found in lysosomes vJuvenile: paralysis, dementia, blindness and early death (3 yrs) vChronic adult form: neuron dysfunction and psychosis

Question 42

Shingles (Herpes Zoster) (I) • Shingles is a disease caused by same virus that causes chickenpox called———. After chickenpox, virus remains dormant in —— neurons for life. • The virus can become active again and cause ——- (unusual skin sensation, itching or a burning, tingling, or shooting pain).

Answer 42

Shingles (Herpes Zoster) (I) • Shingles is a disease caused by same virus that causes chickenpox (varicella zoster). After chickenpox, virus remains dormant in DRG neurons for life. • The virus can become active again and cause shingles (unusual skin sensation, itching or a burning, tingling, or shooting pain).

Question 43

Some researchers believe that ——— is the prime candidate for the location of neural stem cells.

Answer 43

ependyma .

Question 44

Neurogenesis predominantly occurs in the ——— and ——— zones of the brain.

Answer 44

Neurogenesis predominantly occurs in the subventricular and subgranular zones of the brain.

Question 45

Multiple sclerosis occurs more in women than in male T or F

Answer 45

T

Question 46

Multiple Sclerosis (II) Two characteristic microscopic features are:

Answer 46

Two characteristic microscopic features are: (1) infiltration of inflammatory cells (T cells and macrophages) inside and around multiple sclerosis plaques; (2) plaques of astrocytic aggregates.

Question 47

Multiple sclerosis — and — cells, recruited to multiple sclerosis lesions, secrete ———

Answer 47

CD8+ and CD4+ T cells, recruited to multiple sclerosis lesions, secrete cytokines (interleukin-2, tumor necrosis factor-o, and interferon-y).

Question 48

Multiple sclerosis T cells secrete ——- which binds to ——- on which glial neuron to induce their programmed cell death.

Answer 48

T cells secrete Fas ligand which binds to Fas receptor on oligodendrocytes to induce their programmed cell death.

Question 49

Leukodystrophy They may be inherited in a ———-, ———, or ———manner, depending on the type of leukodystrophy.

Answer 49

They may be inherited in a recessive, dominant, or X-linked manner, depending on the type of leukodystrophy.