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ESA1 - Tissues Of The Body > Nervous System > Flashcards

Nervous System Flashcards

1
Q

Define multipolar, unipolar and bipolar neurones

A
  • MULTIPOLAR have 1 axon and MULTIPLE dendrites
  • BIPOLAR have 1 axon and 1 dendrite
  • UNIPOLAR have 1 axon and NO dendrites
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2
Q

Describe the arrangement of neurones in a nerve

A
  • Single axons bundled together surrounded ENDONEURIUM
  • Multiple bundles of axons form fascicles surrounded by PERINEURIM
  • Multiple fascicles make up nerves surrounded by EPINEURIUM
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3
Q

Describe the structure of a myelinated neurone axon and how this relates to function

A
  • Contains SCHWANN CELLS wrapped around multiple times forming a MYELIN SHEATH
  • Discontinuous sheath which is separated by gaps called NODES OF RANVIER
  • Nodes allow speedy transmission of action potentials via SALTATORY CONDUCTION
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4
Q

Describe the myelination of cells of the PNS and CNS

A
  • Cells of PNS are myelinated by SCHWANN CELLS

- Cells of CNS are myelinated by OLIGODENDROCYTES

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5
Q

Are the nerve cells of the somatic nervous system myelinated?

A
  • YES

- Myelination allows speedy conduction of action potentials to stimulate voluntary skeletal muscle contractions

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6
Q

What neurotransmitters are released from excitatory and inhibitory neurones respectively?

A
  • EXCITATORY neurones release GLU/ASP neurotransmitters

- INHIBITORY neurones release GLY/GABA (gamma-aminobutyric acid) neurotransmitters

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7
Q

How does demyelination of neurones lead to a decrease in conduction velocity?

A

DECREASED SALTATORY PROPAGATION OF ACTION POTENTIALS so impulse has further to travel

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8
Q

Describe the pathophysiology of multiple sclerosis

A
  • DESTRUCTION OF MYELIN SHEATH of axons which is replaced by SCAR TISSUE
  • Damage to oligodendrocytes and axon
  • SALUTATORY PROPAGATION CANNOT OCCUR and scar tissue does not permit conduction so renders the axon useless
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9
Q

Describe the components of a nerve cell body

A
  • Nucleus
  • Nucleolus
  • Dendrites (some)
  • NISSL SUBSTANCE (aggregations of RER)
  • Golgi body
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10
Q

Explain the function of Schwann cells and the nodes of Ranvier

A
  • Schwann cells are lipid laden and wrap around the axon INSULATING it
  • Schwann cells CANNOT CONDUCT action potentials due to their lipid content
  • Gaps between Schwann cells allow transmission of action potentials via SALUTATORY PROPAGATION at nodes of Ranvier
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11
Q

Explain the roles of glial cells

A
  • SUPPORT NEURONES
  • Maintain homeostasis
  • FORM MYELIN SHEATH which insulate the axons
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12
Q

What is the role of oligodendrocytes?

A

GLIAL CELLS that are involved in MYELINATION of axons (up to 250 axons per cell)

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13
Q

What is the role of MICROGLIA?

A

IMMUNE AND INFLAMMATORY FUNCTIONS of both CNS and PNS

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14
Q

What is the role of astrocytes and where are they located?

A
  • Form the BLOOD-BRAIN BARRIER in CNS

- Assist in the transfer of nutrients and waste

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15
Q

Name 3 types of glial cells present in the CNS

A
  • Astrocytes
  • MICROGLIA (also in PNS)
  • Oligodendrocytes
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16
Q

What is a ganglion?

A

Swelling on nerve fibre formed from a collection of many nerve cell bodies in the PNS

17
Q

Describe the structure of the nervous system

A
  • Nervous system split into CNS and PNS
  • PNS split into SOMATIC (voluntary) and AUTONOMIC (involuntary)
  • AUTONOMIC split into SYMPATHETIC and PARASYMPATHETIC
18
Q

What is the difference between grey and white matter of the CNS?

A
  • Grey matter consists mainly of NERVE CELL BODIES (dark staining nuclei)
  • White matter consists mainly of AXONS (light staining myelin)
19
Q

How do Schwann cells associate with the axon?

A
  • Wrap around the axon 100s of times to provide INSULATION
  • 100μm in length separated at 1μm intervals known as NODES OF RANVIER which allows saltatory conduction of action potentials
20
Q

What is the difference between a sensory neurone and a motor neurone?

A
  • Sensory neurones carry signals FROM CNS TO TISSUES

- Motor neurones carry signals FROM TISSUES TO CNS

21
Q

What is the difference between a pre-ganglionic and post-ganglionic neurone?

A
  • PRE-GANGLIONIC neurones are immediately PROXIMAL TO GANGLION
  • POST-GANGLIONIC neurones are immediately DISTAL TO GANGLION
22
Q

What is the role of the autonomic nervous system?

A
  • INVOLUNTARY CONTROL OF THE PNS including control of respiratory, cardiac, GI, urogenital and thermoregulatory systems
  • MAINTAINS HOMESTASIS
23
Q

Describe the layout of the autonomic nervous system

A
  • 1 neurone in the CNS known as a PRE GANGLIONIC NEURONE which originates from the spinal cord
  • 1 neurone in the PNS known as a POST GANGLIONIC NEURONE which connects to the EFFECTOR
24
Q

Describe the neurotransmitter use of pre and post ganglionic neurones

A
  • Pre-ganglionic neurones are CHOLINERGIC so use acetylcholine
  • Post-ganglionic neurones are NORADRENERGIC so use noradrenaline
25
Q

How do the length of neurones differ in the sympathetic and parasympathetic nervous systems?

A
  • SYMPATHETIC has short pre-ganglionic neurone and longer post-ganglionic neurone
  • PARASYMPATHETIC has long pre-ganglionic neurone and shorter post-ganglionic neurone
26
Q

Describe the difference between the sympathetic and parasympathetic nervous systems

A
  • Sympathetic nervous system is involved in the FIGHT OR FLIGHT response and post-g neurones are noradrenergic
  • Parasympathetic nervous system is involved in relaxation and sleep and post-g neurones are cholinergic
27
Q

Describe the physiological changes that occur during the fight or flight response

A
  • Pupils dilate
  • Increased heart rate
  • Increased cardiac output
  • Increased ventilation
  • Diversion of blood flow away from GI tract to muscles
  • Increased sweat production
  • Secretion of adrenaline from adrenal medulla
28
Q

What are the advantages of the design of the nervous system?

A

Allows FLEXIBILITY

29
Q

What stain is used to stain myelinated neurones?

A
  • OSMIUM TETROXIDE

- Stains lipids dark brown/black

ESA1 - Tissues Of The Body (19 decks)

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