Nervous System Flashcards

1
Q

What are the two cell types in the nervous system?

A

Glia and Neurons.

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2
Q

What is the difference between macroglia and microglia?

A

Macroglia can be split into different subtypes depending on division of the nervous system whilst microglia are the same all over the body.

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3
Q

What is an astrocyte?

A

This is a cell of the CNS which constitutes the blood-brain barrier. It can transfer waste and nutrients between the neurone and blood, and also has phagocytic functions.

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4
Q

What is the role of microglia?

A

Immunity and inflammation.

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5
Q

Name the cell type which is responsible for myelination in the CNS?

A

Oligodendrocyte. These are capable of myelinating 250 axons at a time, this means if they are damage it affects a large number of cells.

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6
Q

What is an ependyma cell?

A

Line ventricles and central canal of the spinal cord for circulation of spinal fluid.

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7
Q

What cell types are found in the PNS and what are their functions?

A

Schwann cells - myelination
Satellite cells - physical support for Neurons
Microglia - immunity and inflammation.

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8
Q

Name the four parts of a neurone.

A

Axon terminal, axon, cell body, dendrites.

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9
Q

What is found in the cell body of a neurone?

A

Nucleus, Nissl substance and Golgi apparatus.

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10
Q

What takes place in Nissl substance?

A

Protein synthesis.

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11
Q

What is grey matter of the nervous system?

A

This is cell bodies. They look grey because they absorb light.

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12
Q

What is a ganglia?

A

This is a swelling where there is a collection of cell bodies.

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13
Q

Where is the initiation segment found on an axon?

A

This is the closest point to the cell body.

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14
Q

What is a node of ranvier?

A

This is a point on the axon of a neurone which is not surrounded by myelin sheath.

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15
Q

What does the level of myelination determine about a nerve?

A

Speed of conduction of electrical impulses.

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16
Q

How can the structure of axons vary?

A

Axons vary in both length and thickness. Some axons are myelinated but not all.

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17
Q

What is the purpose of myelination?

A

Myelination increases nerve conductance, for nerves above 1um in length. The nerve impulse jumps the distance between the nerves of ranvier.

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18
Q

How many times, on average does a Schwann cell wrap around an axon?

A

100.

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19
Q

What is a nerve fasicle?

A

This is a collection of axons which stem from cell bodies of common origin.

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20
Q

What is white matter in the PNS?

A

White matter is peripheral nerve cells. This is because the axons are myelinated and this contains a lot of lipid so they look white on micro graphs.

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21
Q

Describe the locations of the epineurium, perineurium and endonerium.

A

The endonerium surrounds an individiual axons. These collect into fasicles which are surrounded by perineurium, and then the entire nerve is surrounded by epineurium.

22
Q

In the CNS, what are meninges?

A

These are membranous envelopes of the fibrous tracts which are continuous with coverings of the brain and spinal cord.

23
Q

What are the three layers of a meninge?

A

(Outside) Dura mater, arachnoid mater, pia mater (inside)

24
Q

How does a neurone respond when an axon is severed?

A

Proximal section seals up to prevent leakage of contents and a nerve stump forms.

25
Q

What is Wallerian degeneration?

A

This is where the distal part of an axon has been cut off from the nutritional supply, and so it dies and is degenerated.

26
Q

What is chromatolysis?

A

This is where a nerve cell body puffs up with increased contents and displaces the nucleus from its central position to the periphery.

27
Q

What is the term used where an axon of a nerve regrows?

A

Wallerian regeneration.

28
Q

How many pairs of cranial nerves are there?

A

12 pairs

29
Q

What can be said about structures of the CNS?

A

They are all encased within body structures and they are I cases in meninges and surrounded by cerebrospinal fluid.

30
Q

What is the role of the PNS?

A

The role of the periphery nervous system is to carry signals from the CNS to target organs.

31
Q

What is the somatic nervous system?

A

This is under voluntary control. One neurone carries the signal from spinal/cranial locations to the effector organ.

32
Q

What is the behaviour of the somatic nervous system in sleep?

A

It is inactive except for the respiratory system and the eyes.

33
Q

What is the autonomic nervous system?

A

This is in control of control systems in the body. It stimulates fundamental life functions and controls function by changing outputs in two opposing systems.

34
Q

What is meant by intermittent change in bias with relation to the autonomic nervous system?

A

This is where it promotes excretory mechanisms as and when the body needs to and at appropriate times.

35
Q

What is meant by the constancy nature of the autonomic nervous system?

A

The autonomic nervous system controls homeostasis of the internal environment of the body constantly.

36
Q

State the synapsal arrangement in the autonomic nervous system.

A

In the CNS there is a preganglionic nerve, which enters the PNS and synapses at a ganglia. From here there is the post ganglionic nerve which synapses on the effector organ.

37
Q

What can be said about the action of the parasympathetic and sympathetic nervous systems on organs?

A

Generally these two systems act reciprocally on target organs. Autonomic tone is the balance between these two systems. Sweat glands are an exception as they are only stimulated by the sympathetic nervous system.

38
Q

What occurs if there is over activity of the Parasympathetic nervous system?

A

This causes dilation of blood vessels, and lack of substrate for the brain.

39
Q

What is a consequence of over activity of the sympathetic nervous system?

A

This leads to constriction of blood vessels and therefore a shortage of substrate to the tissues which can lead to necrosis.

40
Q

In the autonomic nervous system, what can be said about post ganglionic nerves?

A

These are non myelinated and are called grey rami communicantes.

41
Q

Are preganglionic nerves of the autonomic nervous system myelinated?

A

Yes they are, and they are called white rami communicantes. Axon length is variable between the sympathetic and parasympathetic systems.

42
Q

Which nervous system is seen predominantly in stressful situations?

A

Sympathetic nervous system.

43
Q

What does activity of the sympathetic nervous system lead to?

A

Energy expenditure, increased pulse, increased BP, diversion of blood away from gut and towards muscles.

44
Q

What two hormones are post ganglionic nerves affected by?

A

Adrenaline and noradrenaline, they express nicotin receptors.

45
Q

In the sympathetic nervous system, where do most of the nerves synapse?

A

In the paravertebral chain, close to the spinal cord. This means their preganglionic fibres are short.

46
Q

Which nerve in the sympathetic nervous system is cholinergenic?

A

The pre ganglionic nerve.

47
Q

What is the parasympathetic nervous system responsible for?

A

Relaxation and comfort. This means low heart rate and contraction force and promotion of bodily functions promoting digestion and sleep.

48
Q

Where do nerves of the parasympathetic nervous system generally synapse?

A

In the walls of effector organs. This means that there are long preganglionic nerves and short post ganglionic nerves.

49
Q

In the parasympathetic nervous system, which nerve is cholinergenic?

A

In this case both pre and post ganglionic nerves are affected by choline.

50
Q

What can cause the ANS to become dysfunctional?

A

Lesions on the spinal cord.