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Body Logistics > Nervous Tissue Structure And Function > Flashcards

Nervous Tissue Structure And Function Flashcards

1
Q

What can the nervous system be divided into

A

Central nervous system and the peripheral nervous system

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2
Q

What does the CNS make up of ?

A

The brain and spinal cord ( incl the relay neurone)

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3
Q

What does the peripheral nervous system make up of ?

A
  • cranial nerves, spinal nerves , peripheral nerves

- sensory neurones and motor neurones

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4
Q

In a cross section for the human spinal cord , where would you find the white and gray matter ?

A

The gray matter is roughly in the form of a butterfly ( central bit)

  • the white matter surrounds the gray matter.
  • ventral horns (VF) are found in the anterior section of the spinal cord
  • dorsal horns Are found in the posterior section of the spinal cord.
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5
Q

Where is the main cell body , dendrites and proximal part of the axon found in the nervous system ?

A
  • they are found within the central nervous system
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6
Q

Where is the distal axon and terminal arborisations in the nervous system ?

A

Peripheral nervous system

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7
Q

In the CNS, the myelin sheath surrounding the axon is produced by what cell?

A

Oligodendrocyte

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8
Q

In the PNS, the myelin is produced by and is part of what type of cell !
.

A

Schwann cell

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9
Q

What are the 4 types of neurones ?

A

1) motor neurone
2) sensory neurone
3) integrative neurone
4) Anaxonic neurone

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10
Q

What is the function of motor neurones?

A

Send signals to the effector tissues

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11
Q

Where is the location of motor neurones ?

A

Their cell body is found in the CNS , their axons project into the peripheral nervous system.

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12
Q

Where is the location of sensory neurones ?

A

Start off in the peripheral nervous system then move towards the central nervous system

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13
Q

Where are integrative neurones found ?

A

CNS

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14
Q

What is the function of integrative neurones ?

A

Collate all information

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15
Q

Where is the location of axaxonic neurone ?

A

Retina ( some parts of the CNS)

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16
Q

What is the function of anaxonic neurones

A

Act as relays

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17
Q

What are the variations of neurones?

A
  • unipolar
  • multipolar
  • bipolar
  • anaxonic neurone
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18
Q

What is the cause of multiple sclerosis

A
  • an autoimmune condition when’re the body attacks the myelin sheath in the brain and spinal cord.
  • this causes the myelin sheath to become inflamed.
  • this causes nerve signals to be slowed down , disrupted or sent the wrong way.
  • THIS IS RESULTS IN LOSS OF CONDUCTION VELOCITY!
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19
Q

What are symptoms of multiple sclerosis

A
  • fatigue
  • slurred speech ( dysarthria)
  • vision problems ( Diplopia )
  • mobility issues ( muscle spasms )
  • constipation
  • urinary retention
  • erectile dysfunction or inability to ejaculate.
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20
Q

What is anterograde transport

A
  • movement of molecules / organelles from the cell body to the synapse or neurolemma
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21
Q

Outline the process of anterograde transport in an axon :

A

1) Kinesin ( a transport protein attached to Microtubule structures in the axon) carries secretory vesicles along the axon towards the terminals.

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22
Q

What does an immature vesicles contain moving in the anterograde direction?

A
  • an enzyme in their membranes
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23
Q

What is retrograde movement in neurones?

A
  • movement of organelles/molecules ie veciscles away from the axon terminal towards the cell body
24
Q

What are the two fates of vesicles ?

A

1) lost to the neurolemma

2) recycled through Clathrin-coated endocytosis

25
Q

What type of nerves fibres can peripheral nerves contain ?

A

Sensory

Integrative

Motor

26
Q

What are the three connective tissue layers that are found in peripheral nerves ?

A

1) epineurium
2) perineurium
3) endoneurium

27
Q

Epineurium

A

Dense irregular connective tissue

  • separates different types of nerves and fills spaces between fascicles
28
Q

Perineurium

A

Specialised connective tissue - transport proteins

  • surrounds clusters of axons ( fascicles )
29
Q

Endoneurium

A

Loose connective tissue

  • surrounds single nerve cells
30
Q

Each fasicle in a peripheral nerve contains ——how many types of neurones ?

A

ONE type eg one fascicle could have motor neurone whilst another could have sensory neurones

31
Q

What doestoluidine blue stain ?

A

fats eg myelin sheath

32
Q

How does myelination occur in the PNS

A
    • axon sitting in a groove is surrounded by a Schwann cell
  • the mesaxon membrane ( pair of parallel plasma membranes of a Schwann cell) initiates myelination by surrounding the embedded axon
  • sheet like extension of the mesaxon membrane then wraps around the axon forming multiple membrane layers
  • cytoplasm is extruded from the two opposing plasma membranes of the Schwann cell , which then become compacted to form myelin
33
Q

How does an oligodendrocyte produce meylin in the CNS?

A
  • a1) axon of the nerve is sitting in a groove surrounded by an oligodendrocyte
    2) the plasma membranes of the oligodendrocyte initiates myelination by surrounding the axon.
    3) a sheet like extension of the plasma membrane then wraps around successively around the axon , forming multiple membrane layers.
    4) the cytoplasm is extruded from the two opposing plasma membranes of the oligodendrocyte s , which then becomes compacted to form myelin.
34
Q

What is the only difference between myelination in an oligodendrocyte and a Schwann cell ?

A

In an oligodendrocyte, it wraps more than one axon simultaneously whereas in Schwann cells , it myelinates axons one by one.

35
Q

What is the structure of unmyelinated nerve cells ?

A
  • the individual axons are engulfed by the cytoplasm of a Schwann cell - but there is NO myelin sheath that surrounds the axon.
  • this results in slower propagation of action potentials.
36
Q

Which cells are bigger - oligodendrocyte dendrocytes or schwann cells ?

A

Schwann cells as oligodendrocyte are incredibly small.

37
Q

What are a few examples of Neuroglial cells ?

A
  • these comprise of all non-neural cells of the CNS.

oligodendrocyte

  • astrocytes
  • microglial cells
  • ependymal cells
38
Q

Astrocytes

A
  • star like structure
  • largest of the glial cells.
  • have perineural feet that contains gap junctions which help with :
  • the biochemical support for endothelial cells
  • transport nutrients from blood to nerve cells.
  • regulate nerve impulses by release glutamate which is an inhibitory neurotransmitter
  • contribute to the blood -brain barrier which prevents blood from entering the brain.
  • they play a role in repair and scarring process of the brain and spinal cord following traumatic injuries.
39
Q

Microglial cells

A
  • smallest and rarest of the glial cells
  • Elongated , flattened nucleus.
  • found throughout the CNS
  • they act as the first and main form of active immune defence in the CNS.
  • they have unique potassium channels that respond to even small changes in extracellular potassium concentrations which indicates the presence of ruptured cells , such as brain injury.
  • they can also phagocytise the dead cells / pathogens then act as antigen-presenting cells at the blood-brain barrier to monocytes in circulation.
40
Q

Ependymal cell function

A

Synthesis and secrete cerebrospinal fluid through the ventricles to the spinal cord

  • microvilli absorbs cerebrospinal fluid for removal of pathogens
  • present pathogens to microglial cells and astrocytes
  • have modified right junctions between ependymal cells which control fluid release into the brain, usually they are closed but when cerebrospinal fluid increases , they open.
  • They are NOT epithelia because they do not have a basal lamina
41
Q

Ependymal cell structure and location

A
  • neuronal support cells that forms epithelial lining of the ventricles in the brain and the central canal of the spinal cord.
  • they are derived from the neuroectoderm during embryology.
  • they look like columnar epithelial cells
  • the apical surface have both cilia and microvilli
42
Q

What are the three main classifications of neurones ?

A
  • unipolar
  • bipolar
  • multipolar
43
Q

UniPolar neuron

A
  • these don’t actually exist in humans

- instead , humans have a psuedounipolar neurone

44
Q

An example of pseudo unipolar neurone

A

Restricted to sensory neurones only

  • located outside the CNS
45
Q

Structure of pseudo- unipolar neurone

A
  • 2 axonal branches , one extends from the periphery eg the hand and one extends to the spinal cord.
  • one process leaving from the cell body.
  • there are NO dendrites
  • located outside the CNS
46
Q

Bipolar neurone

A
  • two branches extending from the cell body
  • one axon , one dendrite
  • found in the retina of the eye and olfactory epithelium.
  • located outside the CNS
47
Q

Multipolar neurone

A
  • accounts for all the rest of the neurones in the body
  • one axon extending from the cell body and several dendrites
  • located outside the CNS
48
Q

Anaxonic neurone

A
  • no axons
  • cannot send out action potentials throughout the body.

-

49
Q

Within the cytoplasm of the cell body , what granules are found ?

A

Nissl substance which are aggregations of rough endoplasmic recticulum which are basophillic ( stain with basic dyes)

50
Q

In the CNS, grey matter contains almost all the …

A

Neuronal cell bodies and their associated fibres

51
Q

In the CNS, white matter consists mainly of …

A

Nerve fibres

  • the white appearance is due to the presence of large amounts of myelin.
52
Q

Compare the locations of grey and white matter in the spinal cord and brain

A
  • in the spinal cord , the grey matter lies centrally , surrounded by white matter.
  • however , In the brain a secondary migration occurs during development , such that the cerebrum and cerebellum the grey matter forms the outer layer called the cortex.
53
Q

Where are astrocytes located ?

A

In the CNS.

  • they are found between a nerve cell and a brain capillary.
  • they transport glucose and lactate directly to the neuron from the capillary.
54
Q

Relapsing-remitting MS

A

Most common form of the disease multiple sclerosis

  • this is where some patients will have a particular symptom for a while and then it may disappear for several weeks or months.
55
Q

What occurs during the relapse ( diseased) stage of MS

A

Demyelination of the myelin around axons in the CNS by autoimmune destruction of the myelin sheath laid down by oligodendrocytes.

  • The current idea is that T cells are directed towards an antigen on the surface of myelin that probably mimics a protein present in a virus,
56
Q

What occurs during the remission stage ( disease absent )

A

Oligodendrocyte lay down new layers of myelin to protect the axons of the neurones within the CNS.

57
Q

Is there any cure for MS?

A
  • there is no common cure .
  • however , girls who have severe forms of MS are often advised to become pregnant because pregnancy tends to reduce MS symptoms and relapse.
  • this is similar to other autoimmune diseases such as Graves’ disease.

Body Logistics (20 decks)

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