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BRS Neurology & Neuroanatomy > Cells of the Nervous System > Flashcards

Cells of the Nervous System Flashcards

1
Q

What is the Central Nervous System?

A
  • Brain ( cerebral hemispheres, brainstem. cerebellum).
  • Spinal Cord
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2
Q

What is the Peripheral Nervous System?

A
  • Nerve fibres originating from the CNS.
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3
Q

What are gyri and sulci?

A
  • Gyri = ridges of cerebral hemispheres.
  • Sulci = valleys of cerebral hemispheres.
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4
Q

What are the four regions each cerebral hemisphere is separated into?

A
  1. Frontal Lobe
  2. Parietal Lobe
  3. Temporal Lobe
  4. Occipital Lobe
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5
Q

What is the frontal lobe responsible for?

A

Responsible for executive functions such as personality.

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6
Q

What is the parietal lobe responsible for?

A

Contains somatosensory cortex responsible for processing tactile information.

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7
Q

What is the temporal lobe responsible for?

A

Contains:

  • Hippocampus - short term memory
  • Amygdala - behaviour
  • Occipital - processing of visual behaviour
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8
Q

What is the occipital lobe responsible for?

A

Processing of visual information.

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9
Q

What does the brainstem consist of?

A
  • Midbrain
  • Pons
  • Medulla
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10
Q

Where is the cerebellum? What does it do?

A
  • Attached to the brainstem.
  • Important role in motor coordination, balance and posture.
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11
Q

What does the spinal cord do?

A

Extends down from medulla, acts as conduit for neural transmission, but can coordinate some reflex actions.

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12
Q

What is a mature neuron?

A

Non-dividing excitable cell.

Main function is to receive and transmit information in the form of electrical signals.

Heterogenous morphology

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13
Q

What does the fact that neurones are polymorphous mean?

A

Can’t be classified on the basis of shape, location or function.

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14
Q

What do unipolar neurons look like?

A

Cell body (with nucleus) + single axonal projection.

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15
Q

What do pseudo-unipolar neurones look like?

A

Single axonal projection bifurcates (forks into two).

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16
Q

What do bipolar neurones look like?

A

2 projections from cell body = 1 axon + 1 dendrite

17
Q

What do multipolar neurones look like?

A

Most common type of neuron.

Numerous projections from cell body, but only one axonal projection.

3 types:

  • Pyramidal cells
  • Purkynje cells
  • Golgi cells
18
Q

What are the common features of a neuron?

A

Soma/ Cell Body/ Perikaryon

Axon

Dendrites

19
Q

What is the soma?

A

Cell body/perykaryon

  • Contains nucleus (main nucleus & nucleolus) & ribosomes.
  • Neurofilaments —> structure & transport of proteins for e.g. to end of axon/dendrites.
20
Q

What is an axon?

A

Long process (aka nerve fibre).

  • Originates from soma at axon hillock.
  • Can branch off into ‘collaterals’.
  • Usually covered in myelin.
21
Q

What are dendrites?

A

Highly branched cell body.

NOT covered in myelin.

Receive signals from other neurons.

22
Q

What does neurones being excitable cells mean?

A
  • Artificially generated resting membrane potentials.
  • Therefore can generate bio-electrical signals to communicate with other cells.
23
Q

What are ion channels and pumps used for?

A

Cell membranes are impermeable to K+, Na+, Cl- and Ca2+ ions.

Ion channels/pumps regulate the transport of these ions across the membrane.

24
Q

What does the impermeability of the cell membrane to ions and the use of ion channels and pumps result in?

A

Results in an uneven ion distribution.

High extracellular: Na+ & Cl-

Low extracellular: K+

25
Q

What does the uneven ion distribution across a cell membrane result in?

A

Uneven ion distribution = difference in ion concentration —> creates a potential difference across membrane

=

RESTING MEMBRANE POTENTIAL

26
Q

What is the resting membrane potential of a neuron?

A

Negative charge inside compared to outside.

RMP is around -70mV.

Concentrated around the inside of the cell membrane. Outside of cell membrane is around 0mV. —> Resting membrane potential is usually -40mV to -90mV.

27
Q

Describe the concentrations of Ca2+ inside/outside of the cell membrane.

A

Concentration of Ca2+ outside cell is quite low, but concentration of Ca2+ inside cell is very low = high concentration gradient = Ca2+ move down concentration gradient into cell through channel or transporter protein.

28
Q

Describe the Voltage-Gated Channels at RMP.

A

Voltage-Gated Sodium and Potassium Channels are closed at RMP .(VGSCs & VGKCs).

For an action potential, 3 Na in for every 2 K out.

29
Q

What is an Action Potential?

A

Depolarisation and subsequent repolarisation of a membrane.

30
Q

How does membrane depolarisation occur?

A

A change in ion channel configuration opens the VGSC = Na+ influx —> further depolarisation until around +40mV.

Na channels have faster kinetics than K channels, so Na opens (and closes) first.

31
Q

How does membrane repolarisation occur?

A

Na channels begin to close and K channels open —> membrane potential becomes more negative towards -70mV again.

32
Q

What is the role of the Sodium-Potassium-ATPase pump?

A

Restores ion gradient imbalances after an action potential by pumping 3 Na out and 2 K in (against the concentration gradients).

33
Q

How does the Sodium-Potassium ATPase pump work?

A
  1. Resting configuration = Na+ enters vestibule and upon phosphorylation is transported through the protein.
  2. Active configuration = Na+ has been removed, so K+ enters vestibule.
  3. Pump retuns to resting configuration, so K+ is transported back into the cell.
34
Q

What is saltatory conduction?

A

Action potential spreads along the axon by jumping between Nodes of Ranvier.

35
Q

Why is Saltatory Conduction important?

A

Axons are myelinated.

Myelin prevents AP spreading due to its high resistance and low capacitance.

Nodes of Ranvier = small gaps in the myelin intermittently along axon, with high concentrations of Na and K channels.

Saltatory conduction = much faster than cable transmission.

36
Q

What are neurotransmitters used for?

A

AP can’t travel from pre-synaptic terminal to post-synaptic terminal, so bioelectrical signal —> biochemical signal —> bioelectrical signal.

37
Q

What happens when an AP reaches the pre-synaptic terminal?

A

AP opens Voltage-Gated Ca2+ channels at pre-synaptic terminal = Ca2+ influx.

Binds to vesicles containing neurotransmitters.

Vesicles exocytose and release contents into synaptic cleft.

38
Q

What do neurotransmitters after being released into the synaptic cleft?

A

Bind to receptors/ion channels on post-synaptic terminal, causing propagation of the signal.

39
Q

After binding to receptors on the post-synaptic membrane, what happens to the neurotransmitters?

A

Neurotransmitters dissociate from the receptors and are either:

  • Metabolised by enzymes in synaptic cleft.
  • Recycled by transporter proteins

In some cases, taken back to presynaptic terminal.

= Neurotransmitter Reuptake.

BRS Neurology & Neuroanatomy (1 decks)

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