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BRS Term 1 > Cells of the nervous system and neuromuscular junctions (1) > Flashcards

Cells of the nervous system and neuromuscular junctions (1) Flashcards

1
Q

What are the 4 areas in the CNS?

A

Cerebral hemispheres (highly convoluted surface of ridges- gyri and sulci)
Brainstem
Cerebellum
Spinal cord

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2
Q

What are the 4 functional regions of the cerebral hemisphere?

A
  • frontal lobe
  • parietal lobe
  • temporal lobe
  • occipital lobe
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3
Q

What parts make up the brainstem?

A

midbrain, pons and medulla

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4
Q

What is the cerebellum?

A

hindbrain structure attached to brainstem

–>motor coordination, balance and posture

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5
Q

What is the spinal cord?

A

extends down from medulla

  • -> conduit for neural transmission
  • -> coordinates some reflex actions
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6
Q

What are the 4 different shapes of neurons?

A
  • unipolar–> 1 axonal projection
  • pseudo-unipolar–> single axonal projection that divides into 2
  • bipolar–> 2 projections from cell body
  • multipolar–> numerous projections from cell body (e.g. pyramidal, Purkinje, Golgi)
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7
Q

What are the common features of neurons?

A
  • non-dividing cells
  • soma/cell body: contains nucleus and ribosomes…neurofilaments provide structure and transport
  • axon: long, usually myelinated, originates from soma at axon hillock, can branch off
  • dendrites: highly branched cell body, NOT myelinated, can receive signals from other neurons
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8
Q

What are astrocytes?

A
  • most abundant cell type in CNS
  • can proliferate
  • structural function: blood-brain barrier
  • maintain homeostasis: remove/reuptake neurotransmitter
  • cell repair: synthesise neurotrophic factors
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9
Q

What is an oligodendrocyte?

A
  • large glial cell found in CNS
  • produce myelin sheath insulating neuronal axons
  • analogous to Schwann cells in PNS
  • 1 oligodendrocyte–> myelinated many axons (bc feet), but 1 Schwann cell–> myelinates 1 axon
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10
Q

What are microglial cells?

A
  • specialised population of macrophages in CNS

- perform immune functions (remove damaged neutrons and infections)

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11
Q

What are ependymal cells?

A
  • specialised epithelial cells
  • line fluid-filled ventricles of brain
  • regulate production and movement of CSF
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12
Q

What are the types of neuroglia?

A
  • astrocytes (support cells)
  • oligodendrocytes (myelin)
  • microglia
  • ependyma
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13
Q

What are the 4 major physiological ions?

A

K+, Na+, Cl- and Ca 2+

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14
Q

What is the uneven ion distribution in a neutron at resting membrane potential (RMP)?

A
  • high extracellular sodium (and chloride)
  • low extracellular potassium
  • high concentration gradient for calcium (more extracellular)
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15
Q

Does a negative charge in a cell make it more or less excitable?

A

less excitable

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16
Q

Describe the process of generating an action potential at a molecular level.

A
  • at RMP, VGSCs and VGKCs are closed
    1. Membrane depolarisation- VGSC open–> Na+ influx–> further depolarisation
    2. VGKCs open at slower rate and cause efflux of K+ from cell–> membrane repolarisation
    3. Na+/K+ ATPase pump restores ion gradients:

resting configuration–>Na+ enter pump, phosphorylated by ATP–> conformational change–> active configuration - Na+ released outside cell and K+ bind–> dephosphorylated–> back to resting configuration–> K+ released into cell

17
Q

What is the purpose of myelin in saltatory conduction?

A

myelin has high resistance and low capacitance (charge build up), so prevents AP conducting through it–> therefore AP transmitted along axon faster

18
Q

What is the purpose of Nodes of Ranvier?

A

small gaps (no myelin) intermittently along axon

19
Q

What is saltatory conduction?

A

AP ‘jumping’ between nodes

20
Q

How does communication between nerve cells work?

A

autocrine- cell targets itself

paracrine- cell targets nearby cell

21
Q

What is the axondendritic synapse?

A

connection between presynaptic terminal and neuronal dendrite

22
Q

What is the axosomatic synapse?

A

connection between presynaptic terminal and neuronal soma

23
Q

What is the axoaxonic synapse?

A

connection between presynaptic terminal and neuronal axon

24
Q

What is the neuromuscular junction?

A
  • specialised structure w/axon terminal and muscle membrane
  • unidirectional chemical communication between peripheral nerve and muscle
  • paracrine NT release
  • nicotinic ACh receptors on skeletal muscle–> change in end-plate potential
25
Q

What is the sarcolemma?

A
  • the skeletal muscle membrane: nAChR activation–> depolarisation–> generates AP
26
Q

What are T-tubules?

A

continuous w/sarcolemma and closely connected to sarcoplasmic reticulum
* AP travels through T-tubules

27
Q

What is the sarcoplasmic reticulum?

A
  • surrounds myofibrils- contractile units of muscle
  • stores Ca2+ –> released following sarcolemma depolarisation
  • Ca2+ –> myofibril contraction + muscle contraction

BRS Term 1 (10 decks)

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