4 Nerve Flashcards

1
Q

Q: What are the 4 primary components of the CNS?

A

A: cerebral hemisphere

brain stem

cerebellum (hindbrain)

spinal cord

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2
Q

Q: What is the structure of the cerebral hemisphere? Surface? 4 functional regions?

A

A: There are lots of fold - there is lots of white matter so the brain folds up to make sure that it can fit in the cranium.

highly convoluted surface of gyri (ridges) and sulci (valleys)

  1. Frontal - front
  2. Occipital - back
  3. Temporal - side
  4. Parietal - middle top
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3
Q

Q: What’s the role of the parietal lobe?

A

A: Sensory and motor function (proprioception)

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4
Q

Q: What’s the role of the frontal lobe?

A

A: executive function

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5
Q

Q: What’s the role of the temporal lobe?

A

A: sound perception and speech recognition

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6
Q

Q: What’s the role of the occipital lobe?

A

A: visual processing

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7
Q

Q: What is the brain stem primarily made of? Consists of which 3 structures? Relation to cranial nerves?

A

A: Primarily grey matter (cell bodies)

Descending Order:

  • Midbrain
  • Pons
  • Medulla

target or source of all cranial nerves

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8
Q

Q: What is the cerebellum also called? It’s attached to? Importance in?

A

A: Hindbrain

structure attached to the brainstem

Important in fine-tuning motor function (balance and posture)

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9
Q

Q: Which one of the 4 main structures of the brain can you live without?

A

A: You can exist without the cerebellum but life will be more difficult

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10
Q

Q: Where does the spinal cord extend out from? Conduit for? Coordinates?

A

A: Extends down from the medulla in the brain stem

Conduit for neural transmission

Co-ordinates some reflex actions

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11
Q

Q: Name 4 neurones and an additional 3.

A

A: unipolar
Pseudo-unipolar
bipolar
multipolar (Pyramidal Cells, Purkinje Cells, Golgi Cells)

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12
Q

Q: What are unipolar neurones made of? Found? (2) Important in?

A

A: Has a cell body and one axon in one direction.

Rarely found in the CNS
Mainly found around the retina (front)

important in visual processing

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13
Q

Q: What is the structure of pseudo-unipolar neurones? Found? (2)

A

A: Single axonal projection which splits into two (bifurcates)

Rarely found in the CNS
Mainly found in the pain pathway in the PNS

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14
Q

Q: What is the structure of bipolar neurones? Found?

A

A: Two projections from the cell body (axon and dendrite)

Rarely found in the CNS

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15
Q

Q: What is the structure of multipolar neurones? Morphologies? (3)

A

A: Numerous projections coming from the cell body
ONLY ONE AXON - the rest are dendrites

Multipolar neuronal cells can have many morphologies

  • Pyramidal Cells - pyramid shaped cell body
  • Purkinje Cells - GABA neurones found in the cerebellum
  • Golgi Cells - GABA neurones found in the cerebellum
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16
Q

Q: Which neurone type is most abundant?

A

A: multipolar

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17
Q

Q: How many axons and dendrons can a neurone have?

A

A: only 1 axon

can have many dendrites

18
Q

Q: What are the 3 properties of a neurone?

A

A: Excitable - ability to change membrane potential and send action potentials along axon (only ones in CNS)

Heterogenous Morphology - lots of different types of cells

Non-dividing

19
Q

Q: Describe 3 common structural features between neurones.

A

A: Soma (cell body, perikaryon)

  • contains nucleus and ribosomes
  • Neurofilaments - type of intermediate filament provides structural support and transport

Axon (only one)

  • Originates from soma at axon hillock
  • Can branch off into collaterals
  • usually myelinated
  • send signals to other cells

Dendrites

  • NOT MYELINATED
  • highly branched cell body
  • Receive information
20
Q

Q: What are astrocytes? Appearance? Abundance? Proliferate? Excitation? Functions (4)

A

A: Neuroglia - ‘neuro glue’
Astrocytes - ‘astro’ like appearance

MOST ABUNDANT CELL TYPE IN THE MAMMALIAN BRAIN

able to proliferate

don’t excite

Functions:

  • Structural cells - support by acting as a ‘glue’
  • Repair - provide nutrients for repair of neuronal cells when damaged
  • Facultative Macrophages - can turn into macrophages when necessary (are immune cells)
  • Homeostasis - mop up neurotransmitter and other substances that are released within the CNS - sort of like a sponge
21
Q

Q: What are the 2 myelin producing cells? Key difference? Draw.

A

A: schwann cells and Oligodendrocytes

ONE OLIGODENDROCYTE MYELINATES MANY AXONS

ONE SCHWANN CELL MYELINATES ONE AXON SEGMENT

22
Q

Q: What are glial cells (neuroglia)? Examples? (6)

A

A: cells in the CNS that are not neurones

role of supporting neuronal cells

oligodendrocytes, astrocytes, ependymal cells, Schwann cells, microglia, and satellite cells.

23
Q

Q: What’s the role of a schwann cell?

A

A: Produces myelin for peripheral nerves

ONE SCHWANN CELL MYELINATES ONE AXON SEGMENT

24
Q

Q: What are the 3 differences between oligodendrocytes and astrocytes?

A

A: Oligodendrocytes are smaller

Oligodendrocytes have a denser cytoplasm and nucleus

Absence of intermediate filaments and glycogen in the cytoplasm

25
Q

Q: Describe oligodendrocyte morphology. Projections?

A

A: variable morphology and function

numerous projections that form internodes of myelin

ONE OLIGODENDROCYTE MYELINATES MANY AXONS

26
Q

Q: What are microglia? Similar to?

A

A: Immune cells of the CNS

Similar to macrophages

27
Q

Q: What are ependymal cells? Full of? Role?

A

A: Epithelial Cells of the CNS

Line fluid filled ventricles - full of cerebrospinal fluid

Regulate production and movement of cerebrospinal fluid

28
Q

Q: Summarise the neurones and neuroglia. (5)

A

A: Neurone: Excitable cells of the CNS (Responsible for electrical transmission)

Oligodendrocyte: Glial cell - produces myelin

Astrocyte: Most abundant cell type in the CNS (provide support to neurones)

Microglia: Neuronal macrophages (functional during immune response and inflammation)

Ependymal Cells: Epithelial cells lining ventricles

29
Q

Q: What are the 4 major ions involved in neurotransmission and resting membrane potential? Cell permeability? Causes?

A

A: Na+

K+

Ca2+

Cl-

Cell membranes are impermeable to these ions - transport is regulated by pumps and channels

This causes uneven distribution of ions

30
Q

Q: Describe the uneven distribution of the 4 major ions? What does this cause?

A

A: High Extracellular - Na+ and Cl-

Low Extracellular - K+

High concentration gradient into the cell of Ca2+ because of very low concentrations inside the cell

The differences in concentration creates a potential difference across the membrane

31
Q

Q: What are the normal values for K+ concentration (mM) inside and outside a cell?

A

A: Conc outside/mM

4

Conc inside/mM

150

32
Q

Q: What are the normal values for Na+ concentration (mM) inside and outside a cell?

A

A: Conc outside/mM

140

Conc inside/mM

10

33
Q

Q: What are the normal values for Ca2+ concentration (mM) inside and outside a cell?

A

A: Conc outside/mM

2

Conc inside/mM

0.0001

34
Q

Q: What are the normal values for Cl- concentration (mM) inside and outside a cell?

A

A: Conc outside/mM

120

Conc inside/mM

5

35
Q

Q: What is the resting membrane potential of neuronal cells?

A

A: Negative Charge Inside (intracellular)

Resting Membrane Potential = -40 to -90mV

36
Q

Q: What happens when an AP leaves a cell/area? What happens as a result? (3)

A

A: NA+ and K+ imbalance -> need to be restored
-Na+K+ATPase (pump) restores the ion gradients

  1. resting configuration: Na+ enters vestibule and upon phosphorylation -> ions are transported through protein
  2. active configuration: Na+ removed from cell-> K+ enters the vestibule
  3. pump returns to resting configuration -> K+ is transported back into the cell
37
Q

Q: What a Na K pump exchange? Uses?

A

A: 3 Na+ leave cell
2K+ enter cell
uses 1 ATP

38
Q

Q: What is happening with the VGSC and VGKC at rest? How is an action potential created?

A

A: at resting membrane potential
-voltage gated Na+ channels (VGSCs) and voltage gates K+ channels (VGKCs) are closed (-70mV)

  1. membrane depolarisation: opening of VGSC (around -40mV) -> Na+ influx -> further depolarisation
  2. VGKCs opens at slower rate and causes -> efflux of K+ from cell-> membrane repolarisation
39
Q

Q: Without myelination, what is electrical conduction like? What does myelin do?

A

A: get slow movement of action potentials along the axon via cable transmission

Myelin prevents the action potential from spreading because it has high resistance and low capacitance

40
Q

Q: What is saltatory conduction?

A

A:
Nodes of Ranvier have a dense concentration of VGSCs and VGKCs

Action Potentials jump between Nodes of Ranvier allowing faster conduction

41
Q

Q: What happens in a synapse? (3)

A

A: neurotransmitter is released from vesicles

  • AP opens voltage gated Ca2+ channels at presynaptic terminal
  • Ca2+ influx -> vesicle exocytosis

activation of post synaptic receptors

  • NT bind to receptor on post synaptic membrane
  • receptors modulate post-synaptic activity

neurotransmitter reuptake

  • NT dissociates from receptor and can be:
    i) metabolised by E in synaptic cleft
    ii) recycled by transporter protein