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Body Logistics > Lecture 20+21: CNS, PNS, ANS & sensory networks > Flashcards

Lecture 20+21: CNS, PNS, ANS & sensory networks Flashcards

1
Q

Give an outline of the anatomy of the CNS

A

CNS consists of the brain and spinal cord.

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2
Q

Give an outline of the anatomy of the PNS

A

PNS consists of cranial, spinal nerves

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3
Q

Give an outline of the ANS

A

Subunit of the PNS which involves ganglia and nerves related to them.

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4
Q

Give the different classes you can separate the ANS into and a brief description of each class.

A

Sympathetic: whole body response fight/flight/freeze

Parasympathetic: localised response rest/digest
Enteric: nervous system of the gut

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5
Q

Identify the anatomy of spinal cord.

A

2 Dorsal horns
2 ventral horns
Central grey matter (unmyelinated axons, dendrites)
Peripheral white matter (myelinated axons)
Central canal
2 Dorsal roots
2 Ventral roots

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6
Q

Why do myelinated axons/ nerves appear white?

A

Myelin is made of mostly lipid and water. Lipids don’t stain or are stripped away when stained.

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7
Q

What is a ganglion?

A

A cluster of cell bodies in the PNS not the CNS.

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8
Q

The ventral and dorsal side of the spinal cord tend to either a sensory/motor role. Which side favours which?

A 
Ventral = motor
Dorsal = sensory
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9
Q

If a junior doctor performs a knee jerk reflex test on a patient, can you describe how the knee jerks up?

A
  1. Stimulus = knee hits hammer
  2. Sensory receptors in the muscle detect this
  3. Sensory neuron sends electrical signals to the L3 + L4 in the spinal cord.
  4. Electrical signals sent to the motor neuron.
  5. This signal then send to the muscle (effector)
  6. Response is that the muscles contract = knee jerks
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10
Q

Give an outline of how a reflex arc works involving the structures of the spinal cord.

A
  1. Stimulus–>Receptor–>spinal nerve–> sensory neuron
  2. SENSORY= DR ganglion–>dorsal root–>dorsal horn–>
  3. MOTOR= Ventral horn–>ventral root–>spinal nerve–>
  4. effector –> response
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11
Q

The ANS is made up of the sympathetic and parasympathetic nervous system. Describe the 2 types of neurons between the CNS & target organ regarding both NS.

A

Pre-ganglionic found in CNS whereas post ganglionic in PNS.

Sympathetic: shorter pre-ganglionic (sympathetic chain) & longer post ganglionic nerves to target muscles.

Parasympathetic: longer pre-ganglionic and shorter post ganglionic (attached/near muscle surfaces)

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12
Q

Where are the autonomic preganglionic neurone somas found in the CNS?

A

Sympathetic: lateral horn in T1-L2 cord segment
Parasympathetic: S2-S4 cord segments and brainstem

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13
Q

Describe briefly how sympathetic chain communicates with the spinal nerves after:
1. sensory neurone synapses with the motor neurone.

A
  1. MOTOR= myelinated sympathetic pre-ganglionic soma in lateral horn—> ventral horn, root–> white ramus communicans
  2. White ramus communicans = myelinated so motor neurone goes through here first
  3. Synapses –> unmyelinated post ganglionic nerves in sympathetic ganglion.
  4. Exits ganglion via grey ramus communicans
  5. Post ganglionic nerve –> effector–> response
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14
Q

The sympathetic preganglionic arise in T1-L2 cord segments to supply the skin with dermatomes via 3 routes. How does the sympathetic nervous system supply the trunk of the body (T1-L2)?

A

Sympathetic pre-ganglionic nerves exist only in between T1-L2 cord segments of the body. As the trunk is where T1-L2 is found, the postganglionics can synapse directly to their target organs.

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15
Q

The sympathetic preganglionic arise in T1-L2 cord segments to supply the skin with dermatomes via 3 routes. How does the superior part of the body (head & neck) get supplied with dermatomes?

A

Sympathetic pre-ganglionic nerves exist only in between T1-L2 cord segments of the body. The pre-ganglionics enter & ascend the sympathetic chain. The pre-ganglionics can synapse with the postganglionics and supply the superior dermatomes.

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16
Q

The sympathetic preganglionic arise in T1-L2 cord segments to supply the skin with dermatomes via 3 routes. How odes the inferior part of the body (lower limbs) get supplied with dermatomes?

A

Sympathetic pre-ganglionic nerves exist only in between T1-L2 cord segments of the body. Pre-ganglionics enter & descend sympathetic chain. Pre-ganglionics synapse with the postganglionics and supply the inferior dermatomes.

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17
Q

How does the sympathetic nervous system supply the abdominal viscera with pre-ganglionic input?

A

Sympathetic pre-ganglionics go through the sympathetic chain and use specialised splanchnic nerves to synapse with the postganglionics. Postganglionics get to their targets along blood vessels (pre-aortic ganglion).

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18
Q

Where do parasympathetic preganglionic neurones synapse with the target organs proximity wise?

A

The neurones synapse in ganglia that is close to the target organs/tissues.

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19
Q

Them major source of input to the thoracic & abdominal viscera is the ……………………

A

Vagus nerve

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20
Q

The head has 4 specialised parasympathetic ganglia. Can you name which ganglia receives pre-ganglionics from:

  • the oculomotor nerve
  • facial nerve
  • glossopharyngeal nerve
A
  • oculomotor = ciliary ganglion
  • facial = pterygopalatine ganglion/ submandibular ganglion
  • glossopharyngeal = otic ganglion
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21
Q

The head has 4 specialised parasympathetic ganglia. Can you name what target tissue would receive postganglionics from:

  • ciliary ganglion
  • pterygopalatine ganglion
  • submandibular ganglion
  • otic ganglion
A
  • ciliary = eye
  • pterygopalatine = lacrimal gland
  • submandibular = submandibular & sublingual gland
  • otic = parotid gland
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22
Q

2yrs boy has neurological disorder where neurotransmitters not released efficiently at axon terminals. Further investigation indicates the storage vesicles are not being transported from perikaryon/soma to the axonic bouton in adrenergic neurons.

Which type of fibre in these neurons normally carries vesicles to the nerve terminal?

A

Microtubules
They attach to anterograde vesicles (have neurotransmitters) via kinesin and they “walk” the secretory vesicles in anterograde transport.

When the neurotransmitters have been released at the axon terminal, the empty vesicles fuse with the pre-synaptic plasma membrane and are transported back towards the soma. They use the retrograde system in which the retrograde vesicles attach to the microtubules via dynactin.

23
Q

A post-mortem biopsy of the spinal cord of a 39yrs woman shows inflammatory brain tissue and rows of cell nuclei aligned between demyelinated axons within the white matter.

The observed nuclei are evidence of the presence of which cell type?

A

The rows of nuclei indicate that oligodendrocytes are present. They are the cells that create the myelin in the CNS and are restricted to sites within the nerve fibres. Hence you see the characteristic rows of nuclei.

24
Q

A patient has developed Alzheimer’s disease and one of the characteristics is a decrease in synaptic neurotransmitter vesicular recycling.

What is the normal fate of the synaptic vesicle after it has released a neurotransmitter into the synaptic cleft?

A

The synaptic vesicle will fuse with the pre-synaptic plasma membrane so that it can be reused for more anterograde transport.

25
Q

A man develops a tingling sensation in both arms and worsens to bilateral limb weakness and mild respiratory problems. Further examination shows he has Guillain-Barre syndrome and some of his Schwann cells have already been damaged.

Which histological and structural components of his peripheral nerves have contributed to his loss of motor neuron control?

A

The Nodes of Ranvier have been compromised.

Transmission of a nerve impulse is dependent on saltatory conduction: impulses jump from node to node. If a node is missing or damaged, this slows the speed of impulse transmission so it causes these symptoms.

26
Q

Which key nerve cell type is involved in the (short circuit) knee-jerk reaction and forms the basis of a reflex arc?

A

The interneuron (in CNS) is the most significant as it allows an immediate response without any other signals from other information.

27
Q

A man presents with brain damage due to excessive alcohol consumption (alcohol encephalopathy), A biopsy of spinal tissue shows central chromatolysis (axonal Nissl bodies are destroyed).

What structures and substances are the Nissl bodies composed of?

A

RER and polyribosomes.

Nissl bodies are cells in neurons, somas and neuroplasm where they produce and secrete proteins.

28
Q

A 35yrs man has episodes of demyelination of nerves in his CNS. This is characteristic of a particular disease.

Which disease does he have?

A

Multiple sclerosis.

This is an autoimmune disease that can cause chronic and progressive dysfunction of the nervous system due to demyelinated axons in the CNS then remission periods of re-myelination by oligodendrocytes.

KEY = episodes of demyelination

29
Q

Sympathetic innervation results in the fight or flight response.

Which physiological actions and responses indicate sympathetic activation has occurred?

A 
Increased heart rate
increased pupil dilation
Decreased rest and digestion
Increased sweating
increased lung function
decreased defecation
30
Q

Sensory neurones have their cell bodies in which neuronal structure?

A

The dorsal root ganglion

31
Q

The vagus nerve is one of the cranial nerves that innervates a number of organs of the body and is designated a Roman numeral to identify it. This designation is relative to the other cranial nerves.

What is its designation?

A

X as it is the 10th cranial nerve

32
Q

The nervous system can be effectively studied using 2 top level divisions of organisation.

What are those divisions?

A

Central and peripheral

These can be divided further into autonomic and somatic, sympathetic and parasympathetic, sensory and motor output

33
Q

How many nerves are there in the cervical, thoracic, lumbar and sacral groupings?

A 
cervical = 8
thoracic = 12
Lumbar = 5
sacral = 6
34
Q

What is the aetiology of Parkinson’s disease?

A

Loss of neurones in the substantia nigra.

35
Q

Compare and contrast oligodendrocytes and astrocytes.

A

Both produce myelin

Oligodendrocytes:

  • CNS
  • wraps around many axons simultaneously
  • affected in MS
Astrocytes:
-PNS
-wraps around one axon
-forms BBB
-removes excess K+ ions 
-involved in physical repair
provide physical support
36
Q

Describe what microglia are.

A

They are specialised phagocytes found in the CNS.

37
Q

What are cell types are affected in Guillain-Barre syndrome?

A

Schwann cells as they usually produce myelin. Any changes mean the Nodes of Ranvier are damaged or absent.

38
Q

What is the purpose of ependymal cells

A

They provide the inner lining of the spinal canal and brain’s ventricles.
They produce and secrete CSF.

39
Q

If a patient is diagnosed with MS, what symptoms would they originally present with?

A

fatigue
Vision problems (diplopia)
Slurred speech (dysarthria)
Numbness and tingling sensations (paraesthesia)
Mobility issues like muscle spasms (myoclonia)
Urinary retention
Constipation

40
Q

What is grey and white matter?

A

Grey matter consists of unmyelinated axons, dendrites, nerve somas, axon terminals.

White matter consists of myelinated materials

41
Q

Where would you find grey and white matter in the brain and spinal cord?

A

Brain:
white = central
grey = peripheral nuclei

Spinal cord:
white = peripheral
grey = central butterfly shaped

42
Q

What is the relation between myelination and the impulse speed of conduction?

A

Myelinated axons allows for faster conduction speed as it allows the impulse to jump to Nodes of Ranvier instead of using continuous conduction throughout the entire axon.

43
Q

Explain the function of Schwann cells and Oligodendrocytes.

A

Both cell types produce myelin which insulates the axons. This allows for faster conduction speed as impulses can jump to exposed axon segments (Nodes of Ranvier). Bypassing majority of the axon length quickens conduction speed.

Schwann cells do this in the PNS
Oligodendrocytes do this in the CNS

44
Q

Name as many glial cells as you can.

A

Microglia
Oligodendrocytes
Ependymal cells
Astrocytes

45
Q

Which neurotransmitters are used in the parasympathetic and sympathetic nervous systems

A

Sympathetic:

  • pre-ganglionic neurotrans. = ACh
  • post-ganglionic neurotrans. = Noradrenaline

Parasympathetic:

  • pre-ganglionic neurotrans. = ACh
  • post-ganglionic neurotrans. = ACh
46
Q

What would be classed as non-myelinated material?

A 
Dendrites
Non-myelinated axons
Nerve somas (perikaryons)
Axon terminals
Neuroglia cells (CNS support cells)
47
Q

A single neuron is extended between the CNS and PNS.

Which structures of the neurone would be found in the CNS and PNS?

A 
CNS:
Dendrites
Proximal part of axon
Soma/perikaryon
Microglia
Oligodendrocytes
Astrocytes
Nissl bodies
Myelin
PNS:
Distal part of axon 
Axon terminal
Schwann cells
Myelin
Nodes of Ranvier
48
Q

There are 4 types of neurons: motor, sensory, integrative, anaxonic. Which one of these is different in terms of which structures they synapse between?

A

Anaxonic as they synapse from dendrite to dendrite instead of the typical dendrite to axon.
They are found in the retina and act as relay neurons.

49
Q

Immature vesicles contain enzymes within its membrane from perikaryons. As the vesicles travel down the axon, neurotrans. are synthesised.

How does the neurotrans. cause the post-synaptic neurone to receive a signal?

A
  1. Neurotrans. vesicles are kept at the pre-synaptic neurone.
  2. The pre-synaptic membrane depolarises and this causes an influx of Ca2+ ions into the axonal bouton.
  3. Influx causes neurotrans. release into the synaptic cleft.
  4. Neurotrans. binds to specific receptors on the post-synaptic membrane.
  5. This excites/inhibits the post-synaptic neuron.
50
Q

A patient comes into the surgery and presents with tingling and numbness in their legs. Their GP decides to do a knee-jerk test to test their reflexes and their sensory neurone function.

What type of synapse is between the sensory neurone and muscle?

A

Axosomatic as it is between the muscle cell and axonal bouton.

51
Q

Where in the body would you find dendro-dendritic synapses?

A

In the retina as dendrites synapse to another dendrite.

52
Q

What are the 4 layers of connective tissue that separate the nerve fibres in peripheral nerves?

A

paraneurium=separates nerves from surrounding structures
epineurium=separates different nerves
perineurium=surrounds axon clusters (fascicles)
endoneurium= surrounds singular axon

53
Q

In order for impulses to be conducted quickly, the axons must be myelinated.
Describe how an axon becomes myelinated.

A
  1. A Schwann cell surrounds an axon.

2. Mesaxon membrane starts myelination by surround the embedded axon.

Body Logistics (13 decks)

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