Neurotransmission Flashcards

1
Q

Describe the basic anatomy of a neuron.

A

Cell body/Soma (perikaryon and nucleus)
Dendrites and dendritic spines (80-90% of neuron surface area)
Axon (hillock, initial segment, collateral)
Telodendria

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2
Q

Name the four types of neuronal circuits.

A
Diverging
- Motor neurons
Converging
 - Sensory neurons
Reverberating (impulses from later cells repeatedly stimulate early cells)
- Short-term memory, breathing
Parallel after discharge - single cell stimulates a group of cells that all stimulate a common postsynaptic cell)
- Maths problem
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3
Q

Name the four structural classifications of neurons.

A

Anaxonic
Unipolar
Bipolar
Multipolar

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4
Q

Anaxonic neurons

A

Small, multiple cell processes, cannot distinguish axons

Brain and sensory organs

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5
Q

Unipolar neurons

A

Very long axons with cell body located off to the side

Sensory neurons of PNS

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6
Q

Bipolar neurons

A

Small, two processes separated by cell body

Special sensory organs (sight, smell, hearing)

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7
Q

Multipolar neurons

A

Very long axons, multiple dendrites, classical image of neuron
CNS, all skeletal muscle

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8
Q

Where can synapses occur?

A

Dendrites - axodendritic
Soma - axosomatic
Axon terminal - axoaxonic

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9
Q

What is a connexon?

A

Synaptic membrane channel allowing ions to pass in an electrical synapse

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10
Q

Where are electrical synapses found?

A

Areas of brain
Eye
Ciliary ganglia

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11
Q

Which is faster, chemical or electrical synapses?

A

Electrical

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12
Q

Electrical synapses are bidirectional.

True or False?

A

True

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13
Q

Where are chemical synapses found?

A

Most synapses between neurons

All synapses between neurons and other cells

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14
Q

In a chemical synapse, what does the triggering of a postsynaptic action potential depend on?

A

Amount of neurotransmitter released

Excitability of postsynaptic cell

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15
Q

Chemical synapses cannot become stronger.

True or false?

A

False

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16
Q

What do excitatory neurotransmitters do?

A

Cause depolarisation

Promote AP generation

17
Q

What do inhibitory neurotransmitters do?

A

Cause hyperpolarisation

Suppress AP generation

18
Q

What two types of membrane receptors are found on postsynaptic cells?

A

Ionotropic (ligand-gated) receptors
- Open or close channel proteins
Metabotropic Receptors
- Linked to g-protein

19
Q

Name 6 common neurotransmitters.

A
Acetylcholine
Dopamine (monoamine)
GABA (amino acid)
Glutamate (amino acid)
Serotonin (monoamine)
Norepinephrine (monoamine)
20
Q

Describe ACh

A

Widely distributed
Muscle contraction
Hormone excretion

21
Q

Describe dopamine

A

Excitatory or inhibitory
CNS
Movement and posture

22
Q

Describe GABA

A

Inhibitory

Neurons of cortex

23
Q

Describe glutamate

A

Excitatory

Learning and memory

24
Q

Describe serotonin

A

CNS

Regulate body temperature, sleep, mood, appetite, pain

25
Q

Chemical synaptic potentials are graded potentials, so they can be depolarising or hyperpolarising.
True or false?

A

True

26
Q

What happens at the neuromuscular junction when an AP arrives at the presynaptic terminal?

A

See notes

27
Q

How long is the synaptic delay?

A

0.2-0.5ms

28
Q

Why are chemical synapses one way?

A

Dendrites do not have neurotransmitter vesicles

Synaptic delay

29
Q

What is synaptic fatigue?

A

Neurotransmitter cannot recycle fast enough to meet demands

30
Q

What 4 factors classify a substance as a neurotransmitter?

A
  • Synthesised in a neuron
  • Exist and released from pre-synaptic terminal in sufficient quantities
  • Can be applied externally to same effects
  • Has a mechanism for removal
31
Q

Describe norepinephrine

A

Excitatory
Released by adrenergic synapses
Brain and ANS

32
Q

What are neuromodulators?

A
Affect pre or postsynaptic membrane
Have a long term effect
Slow to appear
Responses involve multiple intermediate steps
e.g. neuropeptides, opioids
33
Q

What are opioids and what are their four classes?

A
Neuromodulators which bind to the same receptors as opium and morphine
Relieve pain
- Endorphins
- Enkephalins
- Endomorphins
- Dynorphins
34
Q

What is curare?

A

Blocks nicotinic ACh receptor

Muscle relaxant

35
Q

How does ecstasy work?

A

Increases release of seratonin

36
Q

Which neurotransmitters effect G-proteins?

A

E, NE, dopamine, GABA

37
Q

Which neurotransmitters effect intracellular enzymes (adenylate cyclase)?

A

Lipid soluble gases
NO, CO
Brain cells

38
Q

What are adrenergic receptors?

A

Sympathetic system
Norepinephrine or epinephrine
alpha and beta receptors

39
Q

What are cholinergic receptors?

A

Parasympathetic system
ACh
Muscarinic and nicotinic