Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Human SF > Histology of the Nervous System > Flashcards

Histology of the Nervous System Flashcards

1
Q

what is the nervous tissue composed of?

A
  • Neurons
  • Glia (supporting cells)
  • Blood vessels with their surrounding connective tissue
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The basic unit of the nervous system and each neuron consists of:

A
  • Cell body (soma or perikaryon)

- Processess that extend out from the soma which are dendrites and an axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Functional Characteristics of Neurons:

A
  • Irritability - capability to respond to physical and chemical stimuli and initiate a response (signal reception)
  • Conductivity- ability to transmit the impulse from one region of the cell to another (signal transmission)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Can mature Neurons undergo Mitosis?

A

NO!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Neuron Cell doctrine:

A

The nervous system is composed of countless neurons which are structurally and nutritionally independent of one another but are functionally related at synapses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe cell body or soma of a neuron:

A

In most HE preparation the cell body is the only portion of the neuron observed
-Nucleus- large, spherical and prominent nucleolus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Nissl Substance

A

Free ribosomes and RER in basophillic clumps. Extend throughout the cell and dendrites but not into the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Microtubules and neurofilaments in cell body..

A

they form a network within the cytoplasm for structural integrity and intracellular transport

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Lipofuscin Granules

A

Residues of lysosomal activity that accumulates with age

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Other things the cell body or soma of neuron has…

A

mitochondria, lysosomes, and Golgi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Neuron in the Substantial Nigra of the brainstem contain what?

A

Melanin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Dendrites

A
  • Are single or multiple depending on the neuron type
  • same cytoplasmic content as soma but no Golgi
  • Increase receptive area and may have dendritic spine to further increase surface area for synaptic input
  • Conduct the impulse towards the cell body and most enter the cell body (exception is the pseudounipolar neuron)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Axon

A
  • Only one axon per neuron, but axons give off collaterals
  • Most originate directly from the cell body and conduct the impulse away from the cell body
  • Arise from axon hillock (impulse generating region)
  • microtubules and neurofilaments are arranged longitudinally for functioning in axoplasmic transport (retrograde and anterograde)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Axon Hillock

A

Have a large amount of microtubules, neurofilaments, and mitochondria- but there is no Nissl substance or Golgi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the terminal branches of the axon called?

A

Telodendria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are axon segments?

A

Initial-short, start fro axon hillock
conductive-longest and may or may not be myelinated
transmissive-terminal end that divides into telodendira with terminal boutons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Unipolar (pseudounipolar) Neurons

A
  • true unipolar neurons are only found in development
  • pseudounipolar neurons are found in the adult and have one process (most consider it to be axon) that bifurcates with one serving an afferent function (dendritic) and the other serving an efferent function (axon)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Where are unipolar (pseudo unipolar) neurons found?

A 
Cranial ganglia (V, VII, IX, and X) 
-Dorsal root ganglia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Bipolar Neurons

A

Have an axon and dendrite at opposite poles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where are bipolar neurons found?

A

Olfactory epithelium (CN I), retina (CN II) and vestibulocochlear ganglion (CN VIII)

21
Q

Multipolar Neurons

A

-Have multiple dendrites and one axon

22
Q

What are the two types of Multipolar neurons?

A
  • Golgi type I: largest neuron found in - cerebra cortex (pyramidal cells), cerebellar cortex (purkinjee), motor nuclei of cranial nerves (III, IV, V, VI, VII, IX, X, XI, and XII) and the ventral orn of the spinal cord (LMN, a-motor neurons,)
  • These axons project from one region of the CNS to another or from CNS to periphery.
23
Q

Describe Golgi Type II type of multipolar neuron:

A

Small neuron found in - cerebral cortex (satellite cells, cells of Martinotti, horizontal cells of the Cajal), cerebella cortex and intermediate zone of spinal cord (interneurons)
-Their axons project locally usually staying in one region of the CNS

24
Q

Describe a synapse:

A

Neurons communicate with each other and with effector cells (muscle and gland cells) by means of synapse
-specialized for the transmission of a chemical message in response to an action potential

25
Q

What are the three components of a synapse?

A
  • presynaptic membrane-has synaptic vesicles containing NT
  • Synaptic Cleft-space b/w the two neurons or neuron and effector cell
  • postsynaptic membrane- has receptor mediated ion channels
26
Q

what are the types of synapses?

A
  • Axodendritic
  • Axosomatic
  • Axoaxonic
27
Q

Desribe NTs:

A

-molecules that are released at the presynaptic membrane and activate receptors on the postsynaptic membrane

28
Q

Three groups of NTs?

A
  • ACH or cholinergic
  • AA (glutamate, GABA, aspartate and glycine)
  • Biogenic Amines (NE or adrenergic, Epi, serotonin, and dopamine)
29
Q

Is axonal transport bidirectional?

A

Yes!
Anterograde- carries material from the soma to the axon and dendrites
Retrograde- carries material from the axon and dendrites to the soma

30
Q

What are nerve fibers?

A

Either axons or dendrites

31
Q

What is composed of nerve fibers?

A

peripheral nerves and the white matter of the CNS

32
Q

Describe unmyelinated nerve fibers:

A
  • Not surrounded by a myelin sheath
  • In the CNS they are bare
  • In PNS a number of fibers are embedded in individual recesses (mesaxon) in a single Schwann cell and its basal lamina
  • They are very slow conducting fibers
33
Q

Desribe Myelinated Nerve fibers

A
  • surrounded by a myelin sheath and are found in the CNS and PNS
  • In CNS myelin sheath is formed by oligodendrocytes which can myelinate several axons
  • In PNS Schwann cells wrap their membranes around a single axon to form a myelin sheath
34
Q

There are BLANK Schwann cells or oligodentrocytes along the length of a single axon, and the junction between two cells is called a BLANK

A
  • Several

- Node of Ranvier

35
Q

Does peripheral nerves include bundles of unmyelinated and myelinated nerve fibers in the PNS?

A

True

36
Q

What are connective tissue components of peripheral nerves?

A
  • Epineurium (surronds an entire cranial or spinal nerve)
  • Perineurium (divides the nerve into fascicles)
  • Endoneurium (very thin CT that surrounds individual nerver fibers and their associated Schwann Cells)
37
Q

In white matter within the CNS the unmyelinated and myelinated nerve fibers or the spinal cord and brain enclosed in connective components?

A

NO

38
Q

Describe Schwann Cells:

A
  • produce the myelin sheath of myelinated nerves and engulf axons of unmyelinated nerves in the PNS
  • myelin sheath is multiple layers of the Schwann Cells membrane wrapped around in axon
  • Neurilemma is the small amount of cytoplasm left in the outermost layer
  • myelinated nerve vary from lightly myelinated to heavily myelinated
39
Q

Describe Satellite cells?

A
  • Layer of small cuboidal cells that surround the cell bodies of the ganglia (psuedounipolar neurons located in cranial, spinal, and autonomic ganglia)
  • provide insulation and serve as a pathway for metabolic exchange
40
Q

Describe Astrocytes:

A
  • Star-shaped cells found in the gray matter (Protoplasmic astrocytes_
  • In white matter (fibrous astrocytes) of the CNS
  • They have end feet (perivascular feet) that sit on blood vessels, neurons, and the pia mater
  • They probably function in metabolic transport
41
Q

Describe oligodendrocytes

A
  • produce the myelin of the CNS
  • Can myelinate up to 50 axons
  • nodes of ranvier are bare compared to those in the PNS that are covered with endoneurium and interdigitating schwann cells
42
Q

Microglia

A
  • Macrophages of the CNS
  • Found in both gray and white matter
  • they are mesodermal in origin
  • migrate to the sites of dead neurons and glial cells and phagocytize them
  • regarded as immune protectors of the CNS
43
Q

Ependyma

A
  • simple cuboidal epithelium that lines the ventricles of the brain and the central canal of the spinal cord
  • modified ependymal cells and associated capillaries form choroid plexus which produce CSF fluid
44
Q

Neuron and Nerve fiber regeneration

A

When neurons are destroyed there is minimal replacement by some stem cells

  • Injured cells and their processes in the CNS are phagocytosed by microglia, and glial cells fill the space with the glial scar
  • Limited regeneration of nerve fibers occurs in the CNS by replacement neurons forming new nerve fibers or remaining neurons forming collateral branches.
  • The absence of endoneurial sheaths also contribute to the limited regeneration of nerve fibers
45
Q

Regeneration in PNS

A

an injured or transected nerve fiber undergoes regeneration by a process called the axon reaction
- the extend of damage is impt in determining the amount of functional loss

46
Q

Axon Reaction:

A

Local changes or reaction: - the severed end of the axon retract away from each other and the cut ends close ; macrophages and fiibroblast infiltrate the area, secrete cytokines and growth factors, and phagocytose the debris

Anterograde changes or reaction:- terminal portion of the axon and its myelin sheath degenerate and is phagocytosized by proliferating schwann cells and macrophages (Wallerian degeneration); proliferating schwann cells form schwann tubes within the original endoneurium

Retrograde changes or reaction: the soma of the neuron swells, Nissl bodies disperse and the nucleus becomes eccentric (chromatolysis); proximal portion of the axon degenerates, sprouts form and are guided by schwann cells to the endoneurium to reach the target cells

47
Q

What must be present for regeneration to occur?

A

Schwann cells, macrophages, fibroblasts, and endoneurium

Schwann cells have both myelinated and unmyelinated fibers

48
Q

How fast does regeneration proceed?

A

about 3-4mm per day

Human SF (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions