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Biochemistry/Physiology > Quiz 8 - Graded Potentials and Synaptic Communication > Flashcards

Quiz 8 - Graded Potentials and Synaptic Communication Flashcards

1
Q

Current

A

Flow of electrical forces (opening of ion channels)

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2
Q

Voltage

A

Electrical potential difference (Ion concentration gradient)

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3
Q

Ohm’s law

A

Current = Voltage/Resistance

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4
Q

Resistance

A

Opposition of passage of electrical current (membranes)

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5
Q

Action Potentials

A

Propagation of local depolarization via voltage gated ion channels

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6
Q

Orthodromic conduction

A

Down one direction of axon

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7
Q

Antidromic conduction

A

Back up the axon

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8
Q

Nodes of Ranvier

A

Gaps in myelination, sites of depolarization, saltatory conduction

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9
Q

Myelination

A

Speeds up axon conduction

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10
Q

Graded Potentials

A

Aka Local Potential, Generator Potential, Receptor Potential

Membrane potentials that initiate small local events that in turn trigger an action potential

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11
Q

What stimuli do graded potentials react to?

A

Sensory stimuli via receptor complex

Neurotransmitter signals from a synapse

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12
Q

Which type of potential propagates?

A

Action potentials do via voltage-gated channels

Graded potentials do not, are local

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13
Q

What is the amplitude of potentials?

A

APs - Larger, 100 mV

GPs - Smaller, 3-20 mV

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14
Q

What is the duration of potentials?

A

APs - Shorter, 1-2 ms

GPs - Longer, ms-seconds, occur until summation triggers AP or stimulus ends

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15
Q

What is the localization of potentials?

A

APs - cell-wide

GPs - Localized

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16
Q

Which potentials have a refractory period?

A

APs - yes

GPs - no

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17
Q

Which potentials are decremental?

A

Degrade with distance
APs - no
GPs - yes

18
Q

How do potentials spread?

A

APs - voltage gated channels

GPs - passive electrochemical

19
Q

What is summation?

A

Collective graded potentials together depolarize the membrane and trigger AP. Can be spatial or temporal.

20
Q

What is spatial summation?

A

Collective activity of multiple graded potentials generated by different pre-synaptic neurons.

21
Q

What is temporal summation?

A

Repeated activity of graded potentials from the same pre-synaptic neuron.

22
Q

Types of neurons

A 
Unipolar
Bipolar
Pseudo-unipolar
Motor
Pyramidal
Purkinje
23
Q

What is a bouton and what does it do?

A

Pre-synaptic portion of synapse

Converts electrical signal (AP) into chemical signal (neurotransmitter)

24
Q

What is a dendrite and what does it do?

A

Post-synaptic portion of synapse

Converts chemical signal (neurotransmitter) into electrical signal (AP)

25
Q

How wide is a synaptic cleft?

A

20-40nm

26
Q

What are neurexins?

A

Specialized proteins that hold synapse together.

Originate from presynaptic neuron and bind to receptor on post synaptic neuron

27
Q

Is speed of transmission directly or inversely proportional with the number of neurons in a chain?

A

Inversely

Small latency but it is there

28
Q

What is the active zone?

A

Region of synaptic bouton that is rich in mitochondria and packed with neurotransmitter containing vesicles.

29
Q

How does the active zone work?

A

Action potential arrives causing Ca2+ channels to open
Ca2+ flows in
Ca2+ causes vesicles to fuse with membrane via SNARE proteins
Fusion may or may not be complete - Kiss and Run Hypothesis
Neurotransmitters released into synapse

30
Q

What are the two main SNARE proteins?

A

Synaptotagmin on the vesicle

Syntaxin on the membrane

31
Q

What is orthograde transport?

A

Movement of neurotransmitters from cell body to boutons

Moved in vesicles attached to kinesin proteins down microtubules

32
Q

What is retrograde transport?

A

Movement of vesicles from synapse to cell body

Attached to dynein proteins down microtubules

33
Q

What is fast transport?

A

Movement of vesicles down and back along microtubules

400 mm/day

34
Q

What is slow transport?

A

Movement through cytosol and via cell structural proteins
Not slow, but less constant (on/off)
1-10 mm/day

35
Q

What is the postsynaptic density?

A

Region of post synaptic synapse that is rich with ligand-gated ion channels and other effector proteins
Similar to active zone

36
Q

What is an EPSP?

A

Excitatory post synaptic potential
Causes excitatory effects in post-synaptic cell by either causing excitement (depolarization) or inhibiting inhibition (hyperpolarization)

37
Q

What is an IPSP?

A

Inhibitory post synaptic potential
Causes inhibitory effects in post-synaptic cell by either causing inhibition (hyperpolarization) or inhibiting excitation (depolarization)

38
Q

Does an inhibited neuron pass on information?

A

Yes, often a lack of signal is what causes a downstream effect.

39
Q

What is presynaptic inhibition?

A

Occurs at the axon of the pre-synaptic neuron.

Prevention of neurotransmitter vesicle release.

40
Q

What is post-synaptic inhibition?

A

Occurs at cell body of post-synaptic neuron.

Prevention of action potential by hyperpolarization or other means.

Biochemistry/Physiology (10 decks)

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