Histology Test Two

Front 1

Nervous Tissue:
- Anatomical Classification
- Functional Classification

Back 1

* Anatomical Classification:
- Central Nervous System (CNS)
- Peripheral Nervous System (PNS)

* Functional Classification:
- Somatic Nervous System (SNS)
- Autonomic Nervous System (ANS) (visceral- unconsciously controlled)

Front 2

Tissue components of nervous tissue

Back 2

- neuron
- supportive cells:
In CNS: neuroglia
In PNS: Schwann cells; Satellite cells
- Vasculature

Front 3

Neuron Categories

Back 3

* Sensory Neurons (senses and position):
- somatic afferent fibers
- visceral afferent fibers

* Motor Neurons
- somatic efferent fibers
- visceral efferent fibers

* Interneurons- connections, help integrate sensory and motor neurons

Front 4

Neuron Anatomy

Back 4

- cell body
- axon (longer, away from the cell)
- dendrites (bring impulses into the cell)

Front 5

Neuron Types

Back 5

1. Multipolar- one axon, multiple dendrites
2. Bipolar- one axon, one dendrite
3. Unipolar (aka pseudopolar)- one axon, no distinct dendrites (only in certain places)

Front 6

Neuron Cell Body

Back 6

- Nissl bodies- free ribosomes involved in protein synthesis

- Axon hillocks- an organelle-free region at the base of the body leading out into the axon

- Perikaryon- nerve cell body; has machinery like mitochondria, etc.

Front 7

Cell Processes- dendrites (bring signal to the body)

Back 7

- dendrites found near the cell body (short)
- branch to form dendritic trees
- unmyelinated
- wider in diameter than axons
- dendritic spines (nubs where axon attaches)

Front 8

Cell Processes- axons (take signal away from cell body to interact with another neuron)

Back 8

- one axon per cell
- very long
- not branched
- originate from axon hillock
- not many organelles present

Front 9

Morphological Types of Synapes

Back 9

1. Axodendritic- occurring btwn axons and dendrites
2. Axosomatic- occurring btwn axons and cell body
3. Axoaxonic- occurring btwn axons and axons
4. Dendrodendritic- occurring btwn dendrites and dendrites

Front 10

Transmission Types of Signals

Back 10

- Chemical (release of chemical substances)
- Electrical (travels through gap junction; no chemicals- common in invertebrates)

Front 11

Channels

Back 11

- voltage gated (open based on a charge)
- ligand gated (ligand (neurotransmitters) open it)

Front 12

Axonal Transport

Back 12

- most protein synthesis occurs in cell body and get transported out there by motor proteins traveling along microtubules

- Kinesin: carry molecules toward the positive end of the microtubule (toward synapse)
&
- Dynein: carry them back to the cell body (negative end)

Front 13

Supportive Cells

Back 13

PNS:
- Schwann cells
- Satellite cells

CNS:
- Neuroglial cells

Front 14

Schwann cells and myelin sheaths

Back 14

- in PNS
- actual cells that are found along the length of axons and produce myelin sheath
- it envelops the axon and continues to wrap around it (can wrap up to 19 times)
- insulation allows signals to jump

Front 15

Unmyelinated PNS nerves

Back 15

- axon gets embedded in the sides of Schwann cell
- can get up to 20 axons embedded in one Schwann cell

Front 16

Satellite Cells

Back 16

- they are cuboidal cells- on periphery
- they surround cell bodies of ganglia
- they are functionally similar to schwann cells (help insulate)

Front 17

Neuroglia Cells

Back 17

1. Astrocytes- supportive; provide nutrition; create barriear in blood vessels by end feet

2. Microglia- small, phagocytic

3. Oligodendrocytes- maintain myelination in CNS

4. Ependymal cells- line spinal canal and ventricles of brain (maintain area and produce cerebralspinal fluid)*

Front 18

Oligodendrocytes

Back 18

- doesn't wrap its body around it
- process extends out and wraps around the axon (so it can myelinate more than one axon)

Front 19

Peripheral Nerve Organization

Back 19

- Schwann cells around axon
- Connective Tissues involved:
1. Perineurion
2. Endoneurion
3. Epineurion- outermost layer

- vasculature associated with this region

Front 20

CNS Organization

Back 20

- Gray matter- cell bodies for neurons (perikaryons); axons and dendrites

- White matter- pretty much only myelinated axons present

- Tracts: groups of axons heading to a specific location

Front 21

Connective Tissues of CNS (surround the brain):

Back 21

1. Dura mater- directly underneath skull; interacts with periosteum

2. Arachnoid- more delicate tissue; subarachnoid space is underneath (blood vessels run through subarachnoid space)

3. Pia mater- in direct contact with cerebral cortex

Front 22

Blood-Brain Barrier

Back 22

- tight junctions of endothelium
- foot processes of astrocytes (interact with capillaries)
- basal lamina associated with area

Front 23

Neuron Injury

Back 23

- nerve cells cannot replicate, so depending on how axon is injured, it may or may not be able to repair itself
- Schwann cells can divide and repair (but sometimes schwann cells don't do a good job at repairing)