Nerve Tissue: Neurons + Glial Cells Flashcards

1
Q

Nerve Tissue

A

is composed of cells (neurons) that are specialized at conveying information and their support cells (glial)

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2
Q

What is the Neuron doctrine (1891)?

A

individual neurons serve as the signaling elements of the nervous system

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3
Q

How many neurons are in the human body?

A

> 100 billion neurons that vary in size and shape

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4
Q

How do neurons receive, process, and transport signals?

A

Neurons utilize electrical and chemical mechanisms

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5
Q

What are electrical signals used for?

A

To convey information rapidly from one neuron to another

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6
Q

What are chemical signals used for?

A

To carry information between part of one neuron and part of a second neuron or effector cell (via synapse)

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7
Q

Why are neurons structured into regions?

A

So that organelles are distributed in a pattern that supports neuronal function

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8
Q

Neurons-Regions: Cell body (a.k.a Perikaryon)

A

Contains the nucleus and surrounding cytoplasm, but does NOT include cell processes

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9
Q

Neuron-Regions: Cell Body Structure

Nucleus

A

-Euchromatic (pale-staining; active in RNA synthesis) with a prominent nucleolus–> 92% of the human genome is euchromatic.

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10
Q

Neuron-Regions: Cell Body Structure

Cytoplasm

A
  • Abundant rough endoplasmic recticulum (a.k.a RER & Nissl substance) and polysomes
  • Well developed cytoskeleton
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11
Q

Neuron-Cell Body Functions

A

(1) Trophic (related to nutrition/metabolism) center of the cell
(2) Receptive to stimuli

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12
Q

Neuron-Regions: Dendrites

A

Elongated processes emanating from the cell body; most neurons have multiple dendrites

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13
Q

Neuron-Regions: Dendrites Structure

A

Short, tapered, and highly branched

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14
Q

Neuron-Regions: Cell Body Structure

A

Large and spherical in shape

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15
Q

Neuron-Regions: Dendrites Structure

Cytoplasm

A

Organelles are similar to cell body except their are NO Golgi complexes

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16
Q

Neuron-Regions: Dendrites Structure

Dendritic Spines

A

Specializations at some synapses

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17
Q

Neuron-Regions: Dendrites Functon

A

(1) Receptive to stimuli, transmit signals towards cell body

18
Q

Neuron-Regions: Axons

A

Elongated processes emanating from the cell body

**Most neurons only have one axon

19
Q

Neuron-Regions: Axons Structure

A

Long, cylindrical and not highly branched

20
Q

Neuron-Regions: Axons Structure

Cytoplasm

A

Organelles similar to the cell body except NO RER or polysomes

21
Q

Neuron-Regions: Axons Structure

Axon Hillock

A

Pyramid shaped region where the axon emanates from the cell body, devoid of Nissil substance (area w/o purple staining)

22
Q

Neuron-Regions: Axons Structure

Terminal Aborization

A

Branched distal portion of axon

23
Q

Neuron-Regions: Axon Function

A

(1) Generate and conduct signals

(2) Receptive to stimuli

24
Q

Neuron-Regions: Presynaptic Terminal (a.k.a Terminal Bouton or Terminal Bud)

A
  • Dilated termination of an axon on another cell at a chemical synapse
  • NO myelin sheath
25
Q

Neuron-Regions: Presynaptic Terminal Structure

Cytoplasm

A

Organelles similar to cell body, except more mitochondria and the presence of small, spherical, membrane-bound synaptic vesicles containing NT

26
Q

Neuron-Regions: Presynaptic Terminal Structure

Active Zones

A

Regions along the presynaptic membrane concentrated with voltage-gated calcium (Ca2+) channels and synaptic vesicles

27
Q

Neuron-Molecular Transport Systems

A

Composed of the well-developed cytoskeleton

Function: to transport substances b/w the cell body and the processes at slow, intermediate, and fast speeds

28
Q

Neuron-Molecular Transport Systems: Types

A

Anterograde: carries materials from the cell body to the periphery
Retrograde: carries materials from the periphery to the cell body–> ex. can lead to transmission of viruses!!

29
Q

Neuron-Categories

Motor

A

General Somatic Efferent
General Visceral Efferent
Special Visceral Efferent

30
Q

Neuron-Categories

Sensory

A

General Somatic Afferent
General Visceral Afferent
Special Somatic Afferent
Special Visceral Afferent

31
Q

Neuron-Categories

Interneuron

A

Local-all processes are confined to a small area

Projection-long axons connecting different areas

32
Q

Neuronal Processes: Types

A
Multipolar = more than one dendrite and one axon 
Bipolar = one dendrite and one axon
Pseudounipolar = a single process that is close to the cell body and gives off two branches (central + peripheral axons)
33
Q

Glial Cells: Structure

A

10x more abudndant than neurons

vary in size and shape

34
Q

Glial Cells: Function

A

-surround and support neurons, but do NOT participate directly in synapse interactions and electrical signaling

35
Q

Glial Cells: Type-Function/Location

Macroglia

A

Astrocytes (CNS): structural support, repair processes and form blood brain barrier
Oligodendryocytes (CNS)-produce myelin
Schwann (PNS)produce myelin and ensheath axons
**Oligodendryocytes and Schwann cells that do not produce myelin or ensheath axons–>called satellite cells & are associated with neuronal cell bodies

36
Q

Glial Cells: Type-Function/Location

Microglia

A

-Macrophagic activity (CNS)

37
Q

Glial Cells: Type-Function/Location

Ependymal

A

-Line cavities (ventricles) (CNS)

38
Q

Myelin Sheath: Structure

A
  • Segmented, multimellar, lipid rich, wrapping of axon

- Formed by the plasma membranes of Oligodendrocytes and Schwann cells

39
Q

Myelin Sheath Structure: Internode vs Node of Ranvier

A
  • Internode = segment of axon covered w/myelin)

- Node of Ranvier = interval at which axon is NOT covered by myelin; b/w internodes

40
Q

Myelin Sheath: Function

A
  • Provides electrical insulation

- Increases speed of impulse conduction by saltation