Lecture 21 - Nervous Tissue Structure And Function Flashcards

(88 cards)

1
Q

What are the 2 parts/systems of the Nervous System?

A

Central Nervous System (CNS)
Peripheral Nervous System (PNS)

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

What is the CNS comprised of?

A

The Brain and spinal cord

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

What are the main type of Neurone found in the Central Nervous System?

A

Relay neuron

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

What is the Peripheral Nervous System comprised of?

A

Cranial Nerves, Spinal Nerves and Peripheral Nerves

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

What are the 2 types of Neurone found in the Peripheral Nervous System (PNS)?

A

Sensory Neurons
Motor Neurons

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

What are the 2 types of matter located in the brain and the spinal cord?

A

Gray matter
White matter

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

What is white matter made of and why is it white?

A

It consists of myelinated axons
Myelination is mainly made up of lipids which are white

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

How is white matter distributed in the brain?

A

It is central

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

How is white matter distributed in the spinal cord (transverse/longitudinal section)?

A

Peripheral

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

What is Grey matter made of?

A

Nerve cell bodies
Dendrites
Non-myelinated axons
Axon terminals
Neuroglia

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

How is grey matter distributed in the brain?

A

Peripheral
Also in areas called nuclei

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

How is grey matter distributed in the spinal cord (transverse/longitudinal section)?

A

Central Butterfly shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a dendrite?

A

Extensions of the nerve cell body which receive signals so the nerve cell body can receive inputs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a Perikaryon?

A

The cell body of a neurone

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

Describe the structure of the grey matter in the spinal cord

A

Butterfly shape
Prongs/Wings on either side of spinal cord
Posterior prongs called Dorsal Horns (DH)
Anterior prongs called Ventral Horns (VH)
Grey Commissure (GC) is the branch that connects the 2 wings together

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

What is the role of the white matter?

A

Contains nerve fibres that form ascending and descending tracts

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

What is the Pia mater?

A

The outer connective tissue layer of the brain
Blood vessels are here

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What cell is part of and produces the myelin for axons in the CNS?

A

Oligodendrocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What cell is part of and produces the myelin for axons in the PNS?

A

Schwann cell

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

What are Nissl bodies?

A

Granules in the cytoplasm of the Perikaryon (Cell body of neurone) made of aggregations of Rough ENdoplasmic Reticulum (lots of ribosomal RNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Basic structure of a neuron

A

Main cell body (Perikaryon)
Cytoplasmic projections (Dendrites and axon)

Perikaryon, dendrites and proximal part of axon in CNS
Distal axon in PNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the 4 Types of Neuron?

A

Sensory
Integrative
Motor

(Anaxonic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the function of a sensory neuron?

A

Sends environmental signals to integrative centre

Periphery towards CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the function of an integrative neuron?

A

Collates all information

CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the function of a motor neurone?
Sends signals to effector tissues CNS to Periphery
26
What are the 2 different structures sensory neurones can have?
Bipolar Psuedounipolar
27
Describe the structure of a bipolar neuron
Perikaryon (cell body) is inline with the signal/impulse Has 1 axon and 1 dendrite
28
Describe the structure of a psuedounipolar neuron
The Perikaryon is not inline with the signal The Perikaryon use not found in CNS
29
What is the function of an Anaxonic neurone?
They act as relays Found in the retina and some parts of the CNS
30
What is the structure of an Anaxonic neurone
NO AXON Many DENDRITES Dendrites releases neurotransmitter
31
Where are the cell bodies of pseudounipolar, bipolar and postsynaptic autonomic neurones found?
Outside the CNS
32
Where are Purkinje and pyramidal cells (both integrative neurones) found?
In CNS
33
What colour do Nissl bodies get stained with Cresyl violet?
PURPLE (stains the Ribosomal RNA) So nucleolus and Nissl bodies easy to see
34
What does Anterograde mean?
Moving towards the axon/away from the perikaryon nucleus
35
What does retrograde mean?
Moving back towards nucleus
36
What is the axon hillock?
The hill like structure between the main cell body of the neuron and the axon
37
Where is lots of Golgi apparatus found in neurone?
The axon hillock
38
Why is there lots of Golgi at the axon hillock?
Enzymes in Golgi vesicles make neurotransmitter which need to travel down the axon
39
How does neurotransmitter travel down an axon to the synapse?
The microtubule shuttle system The negative (retrograde) end of the microtubule removed and added onto the positive (anterograde) end A Kinesin with anterograde vesicle attached and a Kinesin with mitochondria attached walk down the microtubule
40
What is Kinesin?
Protein associated with the microtubule
41
What is the role of Kinesin?
It walks the vesicle containing the neurotransmitter (anterograde vesicle) and a mitochondria to the terminal bouton of the axon
42
What happens to the microtubule once it reaches the terminal bouton?
It dissolves so vesicle with neurotransmitter and mitochondria are deposited at the terminal
43
How is the empty (retrograde) vesicle transported back to the cell body?
Microtubule with Dynactin associated to it walks along the microtubule as the positive (anterograde) end of the microtubule is removed and added to the negative (retrograde) end
44
What is dynactin and what is its function?
Protein associated with microtubule which is transported the empty retrograde vesicle back to the perikaryon
45
Why do the mitochondria which have been transported to the terminal bouton remain there?
They provide the Ca2+ needed for neurotransmitter to fuse with he plasmalemma
46
What happens to neurotransmitter once its been released from its vesicle into he synaptic cleft?
Binds to postsynaptic neuron receptor If not bound recycled back into synaptic knob by pinocytosis
47
What’s are the 4 connective tissue layers found in nerves?
Endoneurium Perineurium Epineurium Paraneurium (fascia separating nerves from surrounding structures
48
What is the Endoneurium
Loose connective tissue surrounding a single axon Endoneurium = myelination created by schwann cells
49
What is perineurium?
Specialised connective tissue which contains transport proteins to control the ionic concentration of a fascicle Surrounds clusters of axons to form a FASCICLE
50
What is Epineurium?
Dense Irregular connective tissue Contains all the fascicles
51
What is the Paraneurium?
Dense regular connective tissue Spiral connective tissue which surrounds multiple nerves. Fascia that separates nerves from surrounding structures
52
What does damage to the myelin in the CNS cause?
Multiple Sclerosis
53
What does damage to myelin in the PNS cause?
Gillian Barre syndrome
54
How does an axon of the PNS become myelinated by a Schwann cell?
Axon surrounded/engulfed by a Schwann cell Mesaxon membranes surround embedded axon 1 mesaxon membrane successively wraps axon in concentric circles stimulated by Neuregulin 1 (NRG1) Cytoplasm of Schwann cell squeezed out , this compaction forms the finished myelin
55
What is Neuregulin 1?
An epidermal growth factor
56
What does Neuregulin 1 do?
Stimulates a mesaxon of the Schwann cell to wrap around the embedded axon in successive concentric circles about 20 times
57
What does a mutation in the Neuregulin-1 gene (NRG-1) cause?
Schizophrenia
58
How does an Oligodendrocyte myelinate a nerve in the CNS?
Produces MULTIPLE cytoplasmic processes that wrap around MULTIPLE axons
59
What is the key difference in the myelination process of a Schwann cell (PNS) and Oligodendrocyte (CNS)?
The cell body of the Oligodendrocyte sits outside of the neuron The cell body of a Schwann cell wraps itself around the neuron
60
How do Myelinated peripheral never appear with Toluidine blue stain?
Thick continuous blue layer (indicates the myelination) Toluidine stains fat blue
61
How do unmyelinated peripheral nerves appear with Toluidine stain?
2 separate blue layers Inner layer is membrane of nerve/axon Outer layer is membrane of Schwann cell The Schwann cell is not contiguous
62
What are the gaps between 2 schwann cells called?
Nodes of Ranvier
63
What is the small amount of cytoplasm that can be found at the nodes of Ranvier called?
Schmidt Lanterman Clefts
64
Do myelinated or unmyelinated nerves transmit nervous impulses the fastest?
Myelinated Saltatory conduction can occur
65
What is saltatory conduction?
When the electrical impulse jumps from 1 node of Ranvier to the next since the myelination insulates the axon so depolarisation can only happen at these regions
66
Why is the conduction of an electrical impulse in an unmyelinated axon slower than a myelinated one?
Depolarisation has to continuously progress all the way down the axon which is slower than jumping between nodes of Ranvier in a myelinated axon
67
How does diameter of an axon affect the speed it conducts nervous impulses?
Larger the diameter the faster the speed of impulse transmission
68
Why do axons with larger diameters conduct electrical impulses faster?
Less resistance to flow of ions The gaps between Nodes of Ranvier are larger in myelinated axons
69
Describe the structure of an unmyelinated nerve
The axons are engulfed by the cytoplasm of the schwann cell There are gaps between the axons
70
What are the support cells of the CNS called?
Neuroglial cells (Glia)
71
What are the 4 types of Neuroglial cells in the CNS
Oligodendrocytes Astrocytes Microglial cells Ependymal cells
72
Role of Oligodendrocytes
Myelinate/insulate axons in the CNS
73
Describe the structure of an Astrocyte
Star like structure Have feet which attach to blood vessels (peri vascular feet) in the brain and feet which attach to nerves (perineural feet)
74
What is the role of an Astrocyte?
Contributes to blood brain barrier Transports nutrients (lactate) from blood to nerve cells Release Glutamate near to Nodes of Ranvier regulating/stimulating nervous impulses
75
What is the strucutre of a Microglial cell?
Large cell with FLAT ELONGATED NUCLEUS
76
What is the role of Microglial cells?
They are macrophages which reside in the CNS They have immune function Remove damaged nerve cells Digest protein tangles associated with senile DEMENTIA and ALZHEIMERS
77
Where are Ependymal cells located in the CNS?
They are located in the spinal canal which is at the centre of the Grey Comissure which is Posterior to the Ventral Median Fissure
78
What type of tissue are Ependymal cells derived from?
neural tissue and neural crest
79
What structures do Ependymal cells have on their Apical surface?
Cilia Microvilli
80
What is the function of Ependymal cells?
Produce and secrete Cerbrospinal Fluid (CSF) Cilia moves CSF through ventricles to spinal cord Microvilli absorb CSF for removal of PATHOGENS CSF also protects brain and spinal cord from sudden impacts
81
What is the importance of the modified tight junctions of Ependymal cells?
Control release of CSF into brain
82
What is Multiple Sclerosis (MS)?
Autoimmune degradation of the myelin sheath Patchy loss, some parts of axon also destroyed Is remmiting and relapsing
83
MS affects which part of the nervous system?
CNS Degrades myelin in CNS
84
What are the Symptoms of MS?
Fatigue Vision problems (Diplopia) Slurred speech (Dysarthria) Mobility issues Dysphagia (Difficulty eating and swallowing) Numbness and tingling
85
What is Guillian Barré syndrome?
Demyelination of motor neurones Affects the PNS
86
What type of symptoms does Guillain Barré syndrome cause?
Produces bilateral symptoms affecting both sides of body Numbness Pins and needles Weakness Pain Balance and coordination
87
Why can Guillain Barré syndrome be deadly?
May affect Neurons leading to intercostal muscles and diaphragm leading to breathing issues
88
Why are symptoms produced from MS and GBS?
Speed of conduction of impulses down axons are affected