Peripheral nervous system Flashcards

1
Q

What is the peripheral nervous system divided into?

A

Somatic and autonomic nervous systems

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2
Q

Which neurones transmit information towards the CNS?

A

Sensory afferent nerves

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3
Q

Which neurones transmit information away from the CNS?

A

Motor efferent nerves

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4
Q

How many pairs of spinal nerves are there?

A

31

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5
Q

What is a neural plexus?

A

Derived from multiple spinal cord segments, and is an intricate network of nerves

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6
Q

Which layer sheaths the entire nerve?

A

Epineurium

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7
Q

Which layer surrounds the bundles of nerve fibres?

A

Perineurium

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8
Q

Which layer is intermediate of individual nerve fibres?

A

Endoneurium

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9
Q

Which meningeal layer is continuous with the epineurium?

A

Dura mater

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10
Q

Which two meningeal layers are continuous with the endoneurium and the perineurium?

A

Pia mater and the arachnoid layer

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11
Q

What is a dermatome?

A

An area of skin that is supplied by a single spinal nerve (strips of skin consists of a single nerve)

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12
Q

What is a myotome?

A

Group of muscles innervated by a single spinal nerve

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13
Q

What nerves conduct sensory impulses from the viscera?

A

Visceral afferent nerves

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14
Q

Do parasympathetic efferent nerves innervate the blood?

A

No

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15
Q

Which structure contains multiple cell bodies existing outside the CNS?

A

Ganglia

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16
Q

Which structure contains a collection of cell bodies inside the CNS?

A

Nucleus

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17
Q

Where are afferent somatic and visceral fibre cell bodies?

A

Reside within spinal ganglia

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18
Q

Which nerve fibres synapse with the peripheral ganglion?

A

Peripheral nerves

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19
Q

How are peripheral nerves arranged?

A

Bundled in fasiciuli, comprised of three connective tissue layres: (Epineurium, perineurium, and endoneurium)

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20
Q

Which layer sheaths individual fasicules?

A

Perineurium

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21
Q

Which layer sheaths individual axons?

A

Endoneurium

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22
Q

What two parameters are used to classify peripheral nerves?

A

Based on conduction velocity

Based on axonal diameter

23
Q

What classification system is used to classify nerves based on conduction velocity?

A

Letters (ABC)

A- fastest

24
Q

Which classification system is used to classify nerves based on axonal diameters?

A
Roman numerals (I-IV)
1 fastest
25
Q

Which nerves are classified under the axonal diameter system?

A

Sensory nerves exclusively

26
Q

What effect does myelination have on conduction velocity?

A

Increases conduction velocity due to the principle of saltatory conduction

27
Q

What are exteroceptors

A

Detect pain, touch, pressure and temperature

28
Q

Which receptors detect movement and joint position?

A

Proprioceptors

29
Q

Which receptors detect the internal environment (Blood pH,and gastrointestinal movement)?

A

Interoceptors

30
Q

What are chemoreceptors?

A

Specialised sensory receptors transduce a chemical substance and subsequently generates an electrical
signal

31
Q

Where are chemoreceptors located?

A

Medulla = environmental pH
Peripheral= Aortic arch and carotid sinus
Olfactory bulb

32
Q

Which receptors detect light in retina (rods and cones)?

A

Photoreceptors

33
Q

What are mechanoreceptors?

A

Detects opening of ion channels

34
Q

What are nociceptors?

A

Detects signals from damaged tissue or threat of damage indirectly respond to chemicals released from damage tissue

35
Q

Which proprioceptor in muscle detect changes in length?

A

Muscle spindles

36
Q

What happens during muscle stretch in terms of electrical transmission? (reflex)

A

Stimulates reflexively, a muscle contraction to counteract overstretching and muscle fibre damage (Myotatic reflex)
Stretching causes the muscle fibre to transmit an electrical impulse to the spinal cord to stimulate a muscular response.

37
Q

What is the static component of myotatic reflex?

A

Persists during the time of muscular stretch

38
Q

What is the dynamic component of the myotatic reflex?

A

Lasts momentarily in response to the initial sudden increase in muscle length

39
Q

Which proprioceptor detects changes in tension in tendons?

A

Golgi tendon organs

40
Q

Which neurotransmitter is released at an inhibitory interneuron?

A

Glycine, hyperpolarises motor neurone, causes muscle to relax

41
Q

What is a neuromuscular junction?

A

Specialized synapse between a motor neuron and a muscle fibre
Motor neurone axon approaches innervated muscle

42
Q

What is a motor unit?

A

Single motor neurone in conjunction with corresponding muscle fibres that it innervates.
Smallest functional unit to produce force

43
Q

What is a motor pool?

A

Collection of motor neurones collectively coordinate together to stimulate contractions of a single muscle, all of the motor units within a muscle is considered as a motor pool.

44
Q

Where do sympathetic neurones arise?

A

Thoracolumbar

45
Q

What effects does sympathetic innervation have on the body?

A

Direct blood to muscles, dilation of pupils, increases respiratory rate, dilation of airways, increased heart rate

46
Q

What effect does parasympathetic innervation have?

A

Rest, increased gastric secretions decreased respiratory and heart rate

47
Q

Where do preganglionic efferent axons leave the spinal cord?

A

Through the ventral nerve roots joining the mixed spinal nerve

48
Q

How do preganglionic sympathetic fibres enter the sympathetic chain of ganglia?

A

Through the white ramus communicans

49
Q

What do paravertebral trunks contain?

A

Post-ganglionic neurone cell bodies

50
Q

Fibres concerned with innervation of structures in the head and thorax terminate where?

A

Terminate in synaptic contact with postganglionic celll bodies in the sympathetic chain

51
Q

Fibres concerned with innervation of structures of pelvic and abdominal viscera terminate where?

A

Pass uninterrupted through the sympathetic chain and travel to plexuses

52
Q

What does the mixed spinal nerve contain?

A

Mixed spinal nerve contains pre and post-ganglionic fibres. Synapse, postganglionic neurone can ascend or descend

53
Q

Where do postganglionic nerve fibres leave the sympathetic chan?

A

Gray ramus communicans

54
Q

Why is the gray ramus communicans gray?

A

Unmyelinated