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140 . Foundations of Anatomy and Clinical Practice > Nervous Tissue > Flashcards

Nervous Tissue Flashcards

1
Q

What is the function of neurons?

A

Send and receive information through electrical impulses

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2
Q

What are common structural features of a neuron?

A 
Nucleus
Soma (cell body)
Dendrite
Axon
Axon terminals
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3
Q

What are the three main functions of the brain?

A 
1. Autonomic Functions 
(heartbeat, breathing, digestion, temp)
2. Cognitive skills 
(planning, thinking, emotions, behaviours)
3. Sensorimotor function
(sensation and movement)
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4
Q

What is the functional unit of the nervous system?

A

Neuron

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5
Q

What is the most common type of neuron in human nervous systems?

A

Multipolar

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6
Q

What are the three main categories of neuron structure

A

Multipolar
Pseudo-Unipolar
Bipolar

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7
Q

A motor neuron is an example of which type of neuron structure?

A

Multipolar

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8
Q

A sensory neuron is an example of which type of neuron structure?

A

Pseudo-Unipolar

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9
Q

A retina neuron is an example of which type of neuron structure?

A

Bipolar

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10
Q

What is an anaxomic neuron?

A

A neuron without an axons, therefore, it cannot propagate an action potential

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11
Q

What are glial cells?

A

Cells which provide supporting functions to the nervous system in various ways

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12
Q

List the glial cells which exist in the CNS:

A

Astrocyte
Oligodendrocyte
Microglia
Ependymal cell

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13
Q

List the glial cells which exist in the PNS:

A

Satellite cell

Schwann cell

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14
Q

What is the function of oligodendrocytes?

A

Produce myelin to be wrapped around the axon (for neurons in the CNS)

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15
Q

Compare the electrical conduction speed of myelinated axons with that of non-myelinated axons:

A

Myelinated axons have a much faster conduction speed

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16
Q

What is the function of myelin?

A

Wraps around axon to prevent electrical signals escaping and speed up conduction rates through the axon

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17
Q

What is the function of schwann cells?

A

Produce myelin to be wrapped around the axon (for neurons in the PNS)

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18
Q

What is the function of an astrocyte?

A

Maintain chemical concentrations in extracellular space
Remove waste products
React to damage
Acts as a blood-brain barrier

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19
Q

What is the function of the blood-brain barrier?

A

Selectively control which molecules can pass between the bloodstream and nervous tissues

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20
Q

What substances can pass through the blood brain barrier?

A

Gases (CO2 and O2)
Lipid soluble molecules
Water and certain ions - with helps from proteins!

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21
Q

Why may a malfunctioning blood-brain barrier be dangerous / undesirable?

A

Unwanted proteins may cause disruptive neural activity and can lead to a number of CNS diseases

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22
Q

Explain how the Astrocytes maintain the blood brain barrier:

A

Astrocytes produce more tight junctions to make sure the permeability of the barrier remains relatively low

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23
Q

What is the function of ependymal cells?

A

Produce cerebrospinal fluid (CSF)

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24
Q

Which PNS cell performs a similar role as astrocytes?

A

Satellite cells

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25
Q

What is the function of microglia?

A

Similar to that of a macrophage, migrate and engulf pathogens found in the CNS

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26
Q

What is the function of a satellite cell?

A

Maintain chemical concentrations in extracellular space
Remove waste products
React to damage
Acts as a blood-brain barrier

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27
Q

Ionic concentrations at rest create an extracellular environment with what charge?

A

Net +ve charge

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28
Q

Ionic concentrations at rest create an intracellular environment with what charge?

A

Net -ve charge

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29
Q

What is the resting membrane potential?

A

(-70 mV)

It is generated by the unequal distribution of Sodium, Potassium and Chloride ions

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30
Q

What is the result of the Sodium Potassium pump?

A

3 Sodium ions are pumped out of the cell and 2 Potassium ions are pumped into the cell

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31
Q

What is an action potential?

A

A significant but transient rise in the membrane potential

32
Q

Explain how a stimulus triggers depolarisation:

A

Stimulus causes an influx of +ve ions
Change in the voltage from -ve to +ve
This is depolarisation

33
Q

What is repolarisation?

A

The stage directly following depolarisation where there is a sustained efflux of Potassium ions from the membrane

34
Q

What is hyperpolarisation?

A

Directly following polarisation, the membrane potential is more negative than it typically is and another action potential cannot be created until resting membrane potential is restored

35
Q

Where in a neuron is the action potential generated?

A

The axon hillock, (where the axon is connected to cell body)

36
Q

How does an action potential propagate (move) through an axon?

A

A wave of depolarisation as voltage-gated Sodium channels produce a regenerative current to retain the amplitude of the action potential

37
Q

Where are voltage-gated Sodium channels found?

A

At gaps in the myelin sheath known as the Nodes of Ranvier

38
Q

What factors may affect the speed of an action potential moving down an axon?

A

Myelination
Axon diameter
Temperature

39
Q 
Place the following 'stages' in order:
Repolarisation
Depolarisation
Stimulus
Hyperpolarisation
A
  1. Stimulus
  2. Depolarisation
  3. Repolarisation
  4. Hyperpolarisation
40
Q

Explain the process of synaptic transmission:

A

Action potential reaches axon terminal
Calcium channels open
Calcium causes vesicles to release a neurotransmitter
Neurotrasmitter diffuses across synaptic cleft and bind to post synaptic receptor
Receptors activated and Sodium channels open in post synaptic cell

41
Q

What is a neurotransmitter?

A

A chemical messenger which transmits signals across a synapse between neurons

42
Q

What is spatial summation?

A

Excitatory potentials from many neurons triggering a stimulus threshold

43
Q

What is temporal summation?

A

Successive stimuli from one neuron triggering a stimulus threshold

44
Q

What is the main difference between spatial and temporal summation?

A 
Spatial = less signals from many neurons
Temporal = many signals from one neuron
45
Q

What structures make up the CNS?

A

Brain and Spinal Cord

46
Q

What structures make up the PNS?

A

All nerves in the body excluding those in the CNS (Brain and Spinal Cord)

47
Q

What is the function of the autonomic nervous system?

A

Regulate the internal environment

48
Q

What are the two divisions of the autonomic nervous system?

A

Sympathetic

Parasympathetic

49
Q

What is the function of the somatic nervous system?

A

Enables us to interact with the external environment

50
Q

What are the two divisions of the PNS?

A

Autonomic nervous system

Somatic nervous system

51
Q

What is the spinal spinal cord?

A

A long, delicate cord of the nervous system which is responsible for transmitting nerve signals to and from the brain

52
Q

Where is the spinal cord located?

A

In the vertebral canal, protected by the vertebral column

53
Q

Explain how spinal nerves leave the vertebral column:

A

A pair of spinal nerves pass through the intervertebral foramen, (one on each side)

54
Q

How many pairs of spinal nerves are there?

A 
31 pairs:
8 Cervical
12 Thoracic
5 Lumbar
5 Sacral
1 coccygeal
55
Q

What is the dorsal root?

A

The supply of afferent (sensory) fibres which provide information to the spinal cord

56
Q

What is the ventral root?

A

The supply of efferent (motor) fibres providing information from the spine to muscles

57
Q

What is the ‘mixed’ spinal nerve and why is it important

A

It is a bundle of afferent and efferent nerves passing in different directions, it exists so both nerves can squeeze through the intervertebral gap

58
Q

What is the dorsal ramus?

A

A branch from the mixed spinal nerve carrying fibres through to the skin and deep muscles of the back

59
Q

What is the ventral ramus?

A

A branch from the mixed spinal nerve carrying fibres through to the anterolateral parts of the trunk and limbs

60
Q

What are grey and white rami?

A

A branch making connections with the ANS via the sympathetic ganglion

61
Q

What is the dorsal root ganglion?

A

A cluster of sensory neurons

62
Q

What is a dermatome?

A

An area of skin supplied by the afferent (sensory) fibres of a single spinal nerve

63
Q

T / F:

Dermatomes are individual and specific to each person

A

False, there may be some tiny differences but can be generally mapped on an anatomical model

64
Q

What is a myotome?

A

A group of muscles which are innervated by the efferent (motor) fibres of a single spinal nerve

65
Q

Why can myotomes be clinically relevant in assessing spinal damage?

A

A change (loss) in muscle strength within a particular myotome may indicate damage to a particular spinal nerve root

66
Q

What is a spinal plexus?

A

A bundle of ventral rami which come together and branch out to form named peripheral nerves.

67
Q

Name the 4 spinal plexuses and give their root values:

A 
Cervical plexus (C1-C4)
Brachial plexus (C5 - T1)
Lumbar plexus (L1 - L4)
Sacral plexus (L4 - S4)
68
Q

What is the nerve formed at the cervical plexus and which muscles does the plexus innervate?

A

Phrenic Nerve:

Innervate the back of the head, neck, shoulders and diaphragm

69
Q

What is the nerve formed at the brachial plexus and which muscles does the plexus innervate?

A

Median Nerve, Radial Nerve, Ulnar Nerve:

Innervate the upper limbs

70
Q

Why can dermatomes be clinically relevant in assessing spinal damage?

A

Impaired sensation of a specific dermatomal region may indicate damage to a particular spinal nerve root

71
Q

What is the nerve formed at the lumbar plexus and which muscles does the plexus innervate?

A

Femoral Nerve:

Innervate the anterior and lateral aspects of the thigh

72
Q

What is the nerve formed at the sacral plexus and which muscles does the plexus innervate?

A

Sciatic Nerve:

Innervate the posterior of thigh and below the knee

73
Q

What structures are present in a peripheral nerve?

A 
Perineurium
Endoneurium
Epineurium
Fascicle
Axons
74
Q

What is a fascicle?

A

A bundle of individual neurons with a shared purpose

75
Q

What is the perineurium?

A

A cell layer surrounding the fascicle

76
Q

What is the endoneurium?

A

The connective tissue in-between axons

77
Q

What is epineurium?

A

The outer layer of a peripheral nerve, it is dense, irregular connective tissue

140 . Foundations of Anatomy and Clinical Practice (12 decks)

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