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Neurology > Neurons & Neurotransmission > Flashcards

Neurons & Neurotransmission Flashcards

1
Q

Name the five key parts of the neuron

A
  • dendrite
  • cell body/soma
  • axon hillock
  • axon
  • synapse
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2
Q

What is the function of a dendrite?

A

Receives inputs from other neurons and convey graded electrical signals passively to the soma

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3
Q

Describe the contents of the soma

A

Synthetic and metabolic centre it contains nucleus, ribosomes, mitochondria and ER

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4
Q

What is the function of the axon of hillock?

A

site of initiation of all or none action potentials

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5
Q

What is the function of the axon?

A

Conducts output signals as action potentials to the presynaptic terminal

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6
Q

In what direction do chemicals move in an axon?

A

Retrograde and anterograde

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7
Q

What happens at the synapse?

A

Point of chemical communication between neurons/other cells

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8
Q

How are neurons classified?

A

According to shape - number and conformation of processes (neurites)

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9
Q

State four types of neuron

A
  • unipolar (one neurite)
  • pseudounipolar (bifurcation of axon gives rise to two terminals)
  • bipolar (two neurites)
  • multipolar (three or more neurites, cell body gives rise to multiple dendrites)
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10
Q

Where are each type of neuron found?

A

Unipolar - peripheral autonomic neuron
Pseudounipolar - dorsal root ganglion
Bipolar - retinal ganglion
Multipolar - lower motor neuron

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11
Q

State four functional regions of a neuron

A
  • input
  • integrative (soma/axon of hillock)
  • conductile
  • output (release of neurotransmitter)
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12
Q

What leads to the shape of the action potential?

A

Upstroke - sodium influx

Down stroke - potassium efflux

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13
Q

What two factors affect how far an action potential will travel?

A 
Membrane resistance (leakiness) 
Axial resistance (impedance)
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14
Q

What happens to the amplitude of the action potential as it moves along the axon?

A

Remains constant

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15
Q

Why do passive signals not travel far?

A

Membrane is leaky due to reduced change in potential

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16
Q

How do you increase the spread of an action potential?

A

Decrease axial resistance (axon diameter)

Increase membrane resistance (insulator)

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17
Q

Name two types of insulator cell

A 
Schwann cell (PNS)
Oligodendrocyte (CNS)
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18
Q

Describe the node of ranvier

A

Concentration of ion channels due to a gap in myelin sheath leads to saltatory conduction which action potentials jump between nodes

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19
Q

What is the general process of neurotransmission?

A
  1. Uptake of precursor
  2. Synthesis of transmitter
  3. Storage of transmitter
  4. Depolarisation by AP
  5. Ca2+ influx by voltage activated channels
  6. Ca2+ induced release of transmitter
  7. Receptor activation
  8. Enzyme mediated inactivation of transmitter or re-uptake of transmitter
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20
Q

Name the two membrane involved in a chemical synapse

A

pre synaptic and post synaptic

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21
Q

What holds the two synaptic membranes together?

A

Matrix of extracellular protein in the cleft

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22
Q

How can you distinguish between pre and post synaptic membranes?

A

Pre - vesicles that store neurotransmitter in active zones

Post - density containing lots of receptors

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23
Q

Name three types of synapse based on the location of the synapse

A
  • axodendritic (very common)
  • axosomatic (common)
  • axoaxonic (rare)
24
Q

Name two types of synapse based on function

A

Excitatory

Inhibitory

25
Q

Describe and give an example of an excitatory synapse

A

CNS most frequently glutamate activates post synaptic cation selective ionotropic receptors and leads to local graded depolarisation

26
Q

What causes an e.p.s.p?

A

Sodium influx

27
Q

Describe and give an example of an inhibitory synapse

A

CNS most frequently GABA/glycine activates post synaptic anion ionotropic receptors to generate a local graded hyperpolarisation

28
Q

What causes an i.p.s.p?

A

Chloride influx

29
Q

State the two types of integration

A

Spatial

Temporal

30
Q

Describe spatial integration

A

Many inputs converge upon a neuron to determine its output

31
Q

Describe temporal integration

A

Single input may modulate output by variation in AP frequency of that input

32
Q

Where are peptides released from?

A

Secretory vesicles

33
Q

Where are amino acids/amines released from?

A

Synaptic vesicles

34
Q

What type of channels mediate fast neurotransmission?

A

Ionotropic ligand gate ion channels

35
Q

What type of receptor mediate slow neurotransmission?

A

G protein coupled receptors

36
Q

Name the one neurotransmitter that does not activate G protein coupled receptors

A

Glycine

37
Q

State the two key types of receptor

A

Ionotropic receptor

Metabotropic receptor

38
Q

Describe the metabotropic receptor

A

Receptor and channel are distinct, slow and indirect

39
Q

Name three artificial glutamate receptors

A
  • AMPA
  • Kainic Acid
  • NMDA
40
Q

Describe non-NMDA receptors

A

Sodium and potassium permeable channel that is fast and excitatory

41
Q

Describe NMDA receptors

A

Sodium, potassium and calcium permeable, slow and excitatory

42
Q

How do glutamate metabotropic receptors work?

A

By secondary messenger cascade, no specific ion channel but can be inhibitory

43
Q

What are the two key types of supporting cell in the nervous system?

A

Ependymal

Glia

44
Q

Describe ependymal cells

A

Ciliated cells that line the ventricles of the brain and central canal of the spinal cord.

45
Q

What is the function of ependymal cells?

A

Contribute to formation and circulation of CSF and have a role in early development

46
Q

Name two types of glial cells

A

Microglia

Macroglia

47
Q

Describe microglia

A

Phagocytes that engulf debris and involved in the relationship between CNS and immune system

48
Q

Name the four types of macroglia

A
  • astrocytes
  • oligodendrocytes
  • schwann
  • capsular
49
Q

What do the astrocyte processes do?

A
  • subpial end feet on the surface of the brain and spinal cord
  • perivascular end feet at the capillaries of blood brain barrier
  • contacts with neurons
50
Q

State five functions of the astrocytes

A
  • control electrolyte balance
  • produce neurotrophins
  • uptake neurotransmitters
  • supply glutamine for synthesis of glutamate
  • regulate tightness of BBB
51
Q

Describe oligodendrocytes

A

Small cells with few processes - processes form myelin sheath around multiple CNS axons and produce neurotrophic factors that are important in repair of damaged axons in CNS

52
Q

Describe Schwann cells

A

Each cell is only a short segment of one axon and cells spiral around the axon to form the lamella

53
Q

What is the purpose of schwann cells?

A

Vital in regeneration of transected axons - they proliferate to form a tube which growth sprouts from the proximal end to re-innervate the de-innervated target

54
Q

Where are capsular cells found?

A

Surround neuronal cell bodies in sensory and autonomic ganglion

55
Q

Describe the structure of capsular cells

A

Flattened cells form an almost complete layer that separates ganglion cell bodies in the DRG and cranial nerves from the surrounding tissue and vasculature

56
Q

Where are capsular cells found?

A

Autonomic ganglion particularly the sympathetic division

Neurology (29 decks)

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