Exam #1: Histology Review--Self Study Flashcards Preview

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Flashcards in Exam #1: Histology Review--Self Study Deck (44):
1

What is the Perikaryon?

Cell body of a neuron, also known as the some

2

List the histological characteristics the perikaryon.

- Prominent round to oval euchromatic nucleus (protein synthesis is constant)
- Rich in free ribosomes & rER--> contains nissil bodies
- Dark nucleolus
- Rich in mitochondria to meet high energy requirements

*Remember that euchromatic= loosely packed & active

3

What are nissil bodies?

Stacks of rER that stain dark blue with acidophilic stains

4

What are microtubules? What is the function of microtubules?

- Long, rigid, & flexible structures that form the skeleton of the neuron
- Also aid in transport of materials to & from the soma

5

What are neurofilaments?

- Intermediate filaments of neurons
- "Muscles" of the neuron b/c of contractile properties

6

What is the axon hillock?

- Proximal end of the axon
- Funnel-shaped
- Pale staining b/c lacking rER
- Contains microtubules & microfilaments

7

What is lipofuscin?

- Old degenerated plasma membrane that cannot be fully degraded by lysosomes & accumulates in the cytoplasm
- Accumulates with age; thus, commonly called the "age pigment"

8

What is neuromelanin?

Byproduct of DA synthesis that commonly accumulates in the Substantia Nigra

9

What is the function of dendrites?

Increase the receptive surface area of the neuron

10

What is the initial segment of a neuron?

Part of the axon where the nerve terminal is generated (proximal)

11

What are the function of myelin?

- Increases conduction velocity
- Insulates axons

12

Does the axon contain rER?

NO!

13

What is Anterograde Transport? What facilitates anterograde transport?

- Flow of substances away from the cell body
- Kinesin micotubule motor protein
- Slow= No ATP
- Fast= ATP

14

What substances are transported via slow anterograde transport?

- Tubulin
- Actin
- Neurofilament proteins

15

What is Retrograde Transport? What facilitates retrograde transport?

- Flow of substances from the axon terminal to the cell body
- Dynein mitrotubule motor protein
- Fast Transport only (ATP)
- Viruses & toxins

16

What substances are transported via fast retorgrade transport?

- sER
- Vesicles
- Mitochondria
- Amino Acids
- Sugars
- Nucleotides
- Ca++

17

List the characteristics of bipolar neurons.

- Associated with the special senses (vision, hearing, balance, smell)
- Dendrite in the periphery
- Axon terminates in brainstem

18

List the characteristics of pseudo-unipolar neurons.

- Cell body is located in sensory ganglia
- Axon terminal is in the brainstem
- E.g. Cranial Nerves

19

List the characteristics of astrocytes.

- Star shaped with astrocytic feet that cover the surface of capillaries
- Form the BBB
- Form scar tissue in response to a lesion
- Monitor ionic & chemical composition of the CSF

20

What is microglia?

- Phagocytic cells of the nervous system
- Derived from monocytes

21

What is an astrocytoma?

- Most common type of brain tumor
- Arises from astrocytes
- Deforms ventricles

22

What are ependymal cells?

Type of neuroglia that lines the ventricles

23

What is an Ependymoma?

- Tumor of the 4th ventricle that compresses the surrounding structures
- Rare type of tumor that arises from ependymal cells

24

What is the difference between an unmyelinated axon in the CNS vs. PNS?

- "naked" in the CNS
- Sit in a Schwann cell groove in PNS

25

What are the differences between Schwann cells & Oligodendrocytes?

Oligodendrocytes
- Myelinate axons in the CNS
- 3 foot-like processes myeliante 3 axons

Schwann Cells
- Myelinate axons in the PNS
- Myelinate 1-to-1

26

What is myelin?

- Fatty & white b/c of lipid content (Lipoprotein)
- NOT secreted; rather, wraps around the axons

27

What is the difference between an internode and a Node of Ranvier?

Internode= myelinated portion of an axons
Node of Ranvier= gap between two internodes

28

What are Clefts of Schmidt-Lanterman?

Schwann cell cytoplasm that gets trapped in the concentric layers of the call membrane myelinating the axon

29

What is the difference between: endonerium, perineurium, & epineurium?

Endonerium=
- Connective tissue surrounding individual axons in the PNS
- Contains collagen

Perineurium= connective tissue surrounding a fascile in the PNS

Epineurium
- Connective tissue surrounding an entire nerve in the PNS
- Dense irregular collagenous tissue sleeve
- Contains blood & lymphatic vessels

30

What is Multiple Sclerosis (MS)?

- Autoantibodies generated against oligodendrocytes
- Triggered by oligodendrogliopathy

31

What is Optic Neuritis?

Inflammation of the optic nerve

- Presents with papilledema
- Most common cause is MS

32

What is papilledema?

Swelling of the optic disc

33

Outline the different locations of Gray & White Matter.

Gray
- Cerebellar Cortex & Cerebral Cortex
- Nuclei deep to Cerebral Cortex
- Nerve cell bodies

White
- Myelinated axons
- Tracts
- Nerve cell axons

34

How many cranial nerves are there? What about spinal nerve?

12 & 31

35

What is the difference between the voluntary nervous system & involuntary nervous system?

Voluntary= brain, spinal cord, & motor neurons in peripheral nerves

Involuntary= ANS

36

What is "craniosacral outflow" referring to? What about "thoracolumbar outflow?"

PNS vs. SNS

37

What is an axodendritic synapse?

- most common type of synapse
- axon terminal & dendrite

38

What is an axosomatic synapse?

Synapse between an axon terminal & membrane of a cell body

39

What is an axoaxonic synapse?

- Least frequent type of synapse
- Synapse between two axon terminals

40

What is the difference between collapse & "kiss & run" neurotransmission?

Kiss & Run= Brief attachment & release of only a portion of the contents of a vesicle

Collapse= Vesicle attaches & completely empties all of its contents into the synaptic cleft

41

Describe the flow of CSF.

1) Choroid Plexus
2) 2x lateral ventricles
3) 3rd Ventricle
4) Cerebral Aqueduct of Sylvius
5) 4th Ventricle
6) Most leaks into the subarachnoid space
7) Remainder goes into the central canal of the spinal cord

42

Outline the anterograde changes that occur in response to injury.

- Distal segment of axon degenerates
- Elimination of debris by phagocytic cells (Schwann cells & macrophages)
- Schwann cells form tunnels for the axon sprouts to go through

43

Outline the reterograde changes that occur in response to injury.

- Swelling of the cell body
- Chromatolysis (Nissil bodies & rER breakdown/ nucleus moves aside)
- Protein synthesis
- Nucleus moves back
- Axon sprouts

44

What is the difference between a fibrous & a protoplasmic astrocyte?

Fibrous= white matter
Protoplasmic= gray matter