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Neuroscience Year 2 > Introduction - Neural Conduction and Synaptic Transmission > Flashcards

Introduction - Neural Conduction and Synaptic Transmission Flashcards

1
Q

Neurons resting potential

A

-70mV

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2
Q

Ionic basis of resting potential

A

Random motion of ions

Electrostatic pressure

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3
Q

Ions which contribute to resting potential

A

Chloride
Potassium
Sodium
Negatively charged proteins

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4
Q

Properties of neural membrane responsible for uneven distribution of ions

A

Differential permeability of ions (K+ and Cl- pass readily through, Na+ with difficulty, proteins not at all)
Sodium potassium pump (3 Na+ for 2 K+)

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5
Q

Depolarisations are

A

EPSPs

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6
Q

Hyperpolarisations are

A

IPSPs

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7
Q

Post synaptic responses are what type of response?

A

Graded

Weak signals elicit small potentials and vice versa

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8
Q

Postsynaptic potentials characteristics

A

Rapid

Decremental - decrease in amplitude as they travel through the neuron

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9
Q

Action potentials are

A

All or nothing

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10
Q

Threshold of excitation

A

-65mV

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11
Q

Ionic basis of AP

A

Na+ channels open and Na+ moves into cell
Triggers opening of K+ which moves out of the cell
Na+ channels close
Repolarisation occurs due to continued efflux of K+
K+ channels gradually close causing hyperpolarisation for a brief time

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12
Q

Absolute refractory period

A

Period where it is impossible to cause an action potential

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13
Q

Relative refractory period

A

Period where an AP can be initiated but only with higher than normal levels of stimulation

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14
Q

Antidromic conduction

A

If an electrical stimulation of sufficient intensity is applied to the terminal end of the axon, an AP will be generated and travel back along the axon to the cell body

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15
Q

Orthodromic conduction

A

Axonal conduction in the natural way from cell body to terminal buttons

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16
Q

Conduction is faster when

A

Axons are myelinated

Axons are larger in diameter

17
Q

Two categories of neurotransmitter

A

Small

Large

18
Q

Small neurotransmitters

A

Several types
Typically synthesised in the cytoplasm of the terminal button and packaged into synaptic vesicles by the button’s Golgi complex
Stored in clusters next to the presynaptic membrane

19
Q

Large neurotransmitters

A

Neuropeptides
Assembled in the cytoplasm on ribosomes and packaged into vesicles by Golgi complex
Transported by microtubules to the terminal buttons at a rate of 40cm per day
Don’t congregate as close to the presynaptic membrane as small vesicles do

20
Q

Release of neurotransmitter molecules

A

AP causes Ca2+ channels to open
Ca2+ entry causes vesicles to fuse with the presynaptic membrane and empty their contents into the synaptic cleft
Small-molecule neurotransmitters tend to be released in a pulse each time there is an influx of Ca2+
Neuropeptides tend to be released gradually in response to gradual increase in Ca2+ which may occur due to a general increase in neuron firing rate

21
Q

Activation of receptors by neurotransmitters

A

Neurotransmitters produce signals in postsynaptic neuron by binding to receptors on the postsynaptic membrane
Many neurotransmitters can bind to multiple receptor types
Allows different messages to be transmitted in different parts of the brain by one neurotransmitter

22
Q

Ionotropic receptors

A

Ligand-activated ion channels

Binding causes opening or closing of channel

23
Q

Metabotropic receptors

A

Associated with signal or G-proteins
Slower effects
Longer lasting
More diffuse and varied
Binding causes subunit of g-protein to break away
Subunit may bind to nearby ion channel and induce IPSP or EPSP
Or may trigger synthesis of second messenger which influences the neuron in many ways

24
Q

What is an autoreceptor?

A

Metabotropic receptor
Binds to neuron’s own neurotransmitter molecules
Regulate the amount of neurotransmitter molecules in the synapse - reduces release when too high, increases it when too low

25
Q

Astrocytes have been shown to communicate with neurons and other cells using…

A

Gap junctions

26
Q

Neurotransmitter types

A 
Amino acids 
Monoamines 
Acetylcholine 
Soluble gas neurotransmitters
Neuropeptides 
Endocannabinoids
27
Q

Amino acids

A

Glutamate - most prevalent neurotransmitter in mammalian CNS
GABA - most prevalent inhibitory neurotransmitter in mammalian CNS

28
Q

Monoamines

A

Catecholamines

  • Dopamine
  • Norepinephrine
  • Epinephrine

Indolamines
- Serotonin (5-HT)

29
Q

Acetylcholine

A

Neurotransmitter at neuromuscular junction

30
Q

Soluble gas neurotransmitters

A

Nitric oxide

Carbon monoxide

31
Q

Endocanabinoids

A

Similar to THC (main psychoactive constituent of marijuana)

32
Q

Neuropeptides

A 
Pituitary peptides 
Hypothalamic peptides 
Brain-gut peptides 
Opioid peptides 
Miscellaneous peptides
33
Q

What is an agonist?

A

Drug that facilitates the effect of a particular neurotransmitter

34
Q

What is an antagonist?

A

Drug that inhibits the effects of a particular neurotransmitter

35
Q

Atropine

A

Receptor blocker which exerts antagonistic effect by binding to muscarinic receptors, blocking ACh’s effect on them

36
Q

Curare

A

Receptor blocker at cholinergic synapses at nicotinic receptors
Binding blocks transmission at neuromuscular junction, paralysing recipient and killing them by blocking respiration
Used to prevent muscle contraction during surgery when patient is maintained by a ventilator

37
Q

Botox

A

Blocks release of ACh at neuromuscular junction and is therefore a deadly poison
Injected in minute doses has applications in medicine and cosmetics

38
Q

The existence of opioid receptors in the brain suggests that

A

Opioid chemicals occur naturally in the brain

39
Q

Families of endogenous opioids

A

Enkephalins

Endorphins

Neuroscience Year 2 (5 decks)

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