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Neuroanatomy Mod 1 > 1.2 > Flashcards

1.2 Flashcards

1
Q

Anatomy of a neuron

A

Dendrite
Soma
Axon
Axon hillock
Myelin sheath
Node of Ranvier
Axon terminal/synaptic bouton

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2
Q

Soma

A

Contains organelles responsible for
- protein synthesis
- protein modification and packaging
- Ca2+ storage
- energy production of the cell

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3
Q

Cytoskeleton

A

Support for the neuron
Multiple proteins function as elements of the cytoskeleton
- microfilaments
- neurofilaments
- microtubules

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4
Q

Pathology of the cytoskeleton: Alzheimer’s disease

A

Tau proteins support normal microtubule structure
Abnormal phosphorylation results in abnormal microtubules, tau becomes a neurofibrillary tangle within the neuron.

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5
Q

Dendrites

A

Send signal to the soma
Dendritic spines increase surface area and provide greater number of synapses

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6
Q

Pathophysiology of dendrites

A

Fewer dendrites, fewer dendritic spines are associated with
- schizophrenia
- neurodegeneratice diseases
- reduced mental capacity

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7
Q

Axons

A

Specialized areas:
- initial segment
- axon hillock
- axon proper
- node of ranvier
- axon terminal
- axoplasm

Longest axon is in the big toe… reaching from T12 to big toe

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8
Q

Axonal transport

A

Proteins carry substances along the microtubules
Anterograde - toward axon terminal
Retrograde - toward cell body

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9
Q

Pathophysiology of axonal transport: Multiple Sclerosis

A

Inflammatory products disrupt microtubules –> disrupted axonal transport

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10
Q

Electrical synapses

A

Gap junctions of the nervous system are found only in specific tissues such as retina, cerebrum, and brainstem
Creates a system where multiple cells function as one, with immediate transmission of a signal throughout the area
Cardiac muscle

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11
Q

Chemical synapses

A

Required components:
- a messenger molecule = neurotransmitter
- synaptic vesicle (holds neurotransmitters)
- a receptor on the receiving cell

An action potential is transmitted along the axon to the axon terminal, where the neuron releases a chemical messenger which will act on a different cell.

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12
Q

Synaptic configurations

A
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13
Q

Presynaptic membrane

A

On the axon terminal of the neuron which is carrying the action potential
Docking complexes allow NT vesicles to be in place in preparation for release into the synapse when the signal arrives.

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14
Q

Presynaptic membrane: steps

A

A. Axon at rest.
B. Ca2+ channels open, vesicle docks on axon membrane.
C. Vesicle containing NT fuses with cell membrane.
D. Vesicle opens, releases NT.
E. Clathrin takes up the vesicle membrane to reform another vesicle.

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15
Q

Postsynaptic membrane

A

The postsynaptic membrane contains receptors which bind neurotransmitters.
Two types
- ionotropic receptors: fast and short lived
- metabotropic receptors: several step process, long lasting

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16
Q

Neurotransmitters vs. neuromodulators

A

Neurotransmitters directly influence the postsynaptic cell.
Neuromodulators indirectly influence the postsynaptic cell by acting on a third neuron.

17
Q

How are neurons classified?

A

Dorsal root ganglion is pseudounipolar

18
Q

Types of neuroglia

A

CNS:
- astroglia
- oligodendroglia (produce myelin)
- microglia
- ependymal cells

PNS:
- schwann cells (produce myelin)

19
Q

Astroglia/Asctrocytes

A

Expand between neural elements
- support and insulate (contributes to the blood brain barrier)
- communicate

Pathophysiology of astrocytes is involved in:
- alzheimer’s
- parkinson’s
- major depression

Located in gray matter
Originates in neural tube

20
Q

Microglia

A

Derived from monocytes
- phagocytosis of damaged, aging tissue

Pathophysiology:
- alzheimer’s
- multiple sclerosis

Originates in bone marrow

21
Q

Ependymal cells

A

Lines the ventricles of the brain and central canal of the spinal cord
- facilitate CSF circulation

Pathophysiology
- susceptible to viruses
- involved in hydrocephalus

Originates in neural tube

22
Q

Nerve impulses

A

All cells have a negative interior charge, maintained by the Na/K pump (2 Na+ out, 1 K+ in) which results in a polarized cell.
Resting membrane potential: -70mV

23
Q

Action potentials

A

Voltage-gated Na+ ion channels are guarded by activation and inactivation gates.
Rest: the activation gate is closed and the inactivation gate is open
Voltage change: both gates open
Absolute refractory period; inactivation gate closes

24
Q

Depolarization

A

Action potentials occur when Na+ ions move into the neuron through voltage-gated Na+ ion channels = depolarization

25
Q

Repolarization

A

Na+ ion movement across into the cell causes depolarization, which triggers voltage-gated K+ ion channels to open and remain open

26
Q

Hyperpolarization

A

Though the gate opens slowly, the K+ rushes out quickly causing hyperpolarization.

27
Q

Phases of the action potential

A
  1. Voltage gated Na+ channels open: Na+ rushes into the cell
  2. Peak voltage: Na+ channels close
  3. Voltage gated K+ channels open and K+ rushed out
  4. Hyperpolarization can result because K+ efflux causes a transiently lower MP.
28
Q

Propogation of action potentials

A
  1. Na+ influx spreads away from the site of the action potential
  2. Positive charge in neighboring part of the axon
  3. Triggers voltage gated Na+ channel
  4. Propogation of action potential toward the axon terminal
29
Q

Speed of action potential signal depends on

A

Diameter of axon
Presence of myelin

30
Q

Nerve impulses: Postsynaptic potentials

A

Postsynaptic potentials can be excitatory or inhibitory.
Excitatory postsynaptic potential: membrane of the effector cell is depolarized making an AP more likely
Inhibitory postsynaptic potential: membrane of the effector cell is hyperpolarized making an AP less likely

31
Q

Mechanics of synaptic transmission

A

Action potential arrives at the axon terminal.
1. Synaptic vesicle fuses with presynaptic membrane.
2. Ca2+ flows into cells which causes the synaptic vesicle to spill its contents into the synaptic space.
3. Synaptic vesicle membrane is recycled.

32
Q

Overview of neurotransmitters

A

Most neurotransmitters are proteins.
They can be synthesized in the soma and carried to the axon terminal.
After release, NTs can be taken back up by the axon or broken down in the synaptic cleft.

33
Q

Schwann cells

A

Originate in the neural crest
Myelinate axons
Function during degeneration and regeneration of axons

34
Q

Which neurotransmitters are excitatory?

A

dopamine
glutamate

35
Q

Which neurotransmitters are inhibitory?

A

GABA

36
Q

Which neurotransmitters are both excitatory and inhibitory?

A

acetylcholine
serotonin

Neuroanatomy Mod 1 (7 decks)

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