E1-L3: Nerve

Question 1

Describe the difference between White & Gray matter.

Answer 1

Although grey matter has a greater quantity of neurons (and glia) when compared to white matter, the neurons in white matter are highly myelinated (oligodendrocytes), which also gives white matter it’s “white” appearance.

Question 2

Describe the organization & composition of Grey & White matter

Answer 2

Within the Brain, white matter makes up the deep cortex, while grey matter is primarily superficial (i.e. cerebral cortex).​

Question 3

Describe the Grey & White matter orientation & composition in the spinal cord.

Answer 3

Grey & White matter orientation is reversed in the Spinal cord relative to the Brain;

The gray matter is primarily deep (dorsal, ventral, & lateral horns) composed of neuronal soma & interneurons, while the white matter is superficial, composed on afferent & efferent (ascending/descending) nerve tracts.

Question 4

Describe what is indicated in the image.

Answer 4

Gray matter:

Composition:

N: Neurons; Usually the largest cells

G: Glia cells; (microglia, astrocytes, & oligodendrocytes)

Np: Neuropil; tangles of neuronal processes

Question 5

How can Neuropils be emphasized?

Answer 5

Using a Gold stain emphasizes the tangles of neuronal processes (neuropil)

Question 6

Describe what the image is of & the composition.

Answer 6

White matter:

N: Neuron (myelinated)

G: Glia cells

A: astrocytes?/* verify

Question 7

Describe the layers of the Meninges from superficial to Deep

Answer 7

The meninges is 3 layers of connective tissue, covering the CNS

1. Dura Mater: Tough outer CT
2. Arachnoid Mater: Contains CSF
3. Pia Mater: Impermeable to CSF

Question 8

What is this referred to as?

Answer 8

A tumor of the meninges is referred to as a Meningioma

Question 9

Describe the characteristics of Neurons:

Answer 9

Function: Receive (neurotransmitters) & transmit (electrical) information through the activation & inactivation of voltage gated sodium & potassium channels & Sodium/Potassium Pump.

Electrochemical Gradient:

Intracellular: Low Na+, High K+

Extracellular: High Na+, Low K+

Resting Potential: ~-65mV

Question 10

Describe the characteristics of an Action potential

Answer 10

Action potentials are “all or nothing” once the threshold has been reached.

Question 11

Describe what occurs at the synapse

Answer 11

The synapse is the end of the neuron connecting the neuron to another neuron or to a muscle.

The Action potential (impulse) activates Voltage-gated calcium channels, allowing the influx of Calcium into the neuron.

The calcium initiates fusion of Acetylcholine vesicles to the synaptic membrane and release into the synaptic cleft.

Acetylcholine binds with the neuron/muscle receptors, triggering a signal/contraction cascade.

Question 12

How does Botulism toxin affect neuronal signalling?

Answer 12

Botulism toxin (from Clostridium Botulinum) blocks acetylcholine release at the Neuromuscular Junctions (NMJ) resulting in flaccid paralysis

Question 13

How does Tetanus toxin effect neuronal signaling?

Answer 13

Tetanus toxin (from Clostridium tetani) blocks GABA release at inhibitory synapses, resulting in Spastic Paralysis

Question 14

What is this an image of?

Answer 14

Cerebral Cortex

Question 15

What is this slide?

Describe organization & function

Answer 15

Cortex: Numerous folds & neurons

Medulla: White matter

Functions: Coordination of body movements

Question 16

Describe the layer organization of the Cerebellar Cortex

Answer 16

1. Molecular layer (Parallel fiber)
2. Purkinje layer (purkinje cells)
3. Granular layer (mossy fiber)
4. White matter