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IMS > Neurophysiology and Neurosecretion > Flashcards

Neurophysiology and Neurosecretion Flashcards

1
Q

Describe the anatomy of the neuron?

A

Cell body from which high branched nerve processes called dendrites and a single axon extend

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2
Q

What are dendrites covered by?

A

Dendritic spines

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3
Q

What does dendritic spines do?

A

form connections or synapses with dendritic spines of other neurons

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4
Q

Where does the Axon arise from?

A

Axon hillock

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5
Q

Describe an axon?

A

At its end an axon will branch forming telodendria

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6
Q

How is telodendria terminated?

A

By small swellings called presynaptic terminals or boutons

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7
Q

What does Presynaptic terminals contain?

A

Small vesicles

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8
Q

What does the Vesicles contain?

A

Chemical messengers or neurotransmitters

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9
Q

Describe the Process of Axonal transport?

A

neurotransmitters are synthesised in the nerve cell body and transported down the axon

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10
Q

What are the 3 major neuron types?

A

Multipolar, Unipolar and Bipolar

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11
Q

What is the Resting Membrane Potential?

A

is when the Inside of a nerve cell has negative potential in relation to the positive electrical potential contained in extracellular fluid

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12
Q

How is an Electrical gradient created?

A

Cells pump NA from interior to exterior fluid to swap NA for K, the high extracellular conc of NA and High intracellular conc of K causes this

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13
Q

What happens when the cell reaches RMP?

A

Cell becomes polarised

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14
Q

How does the Cell become polarised?

A

When K enters cell following electrical gradient but move out the cell along its own conc gradient and the forces are balanced

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15
Q

How can RMP value be calculated?

A

Nernst equation, average -70 to -90mV

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16
Q

What is the C0 and C1 (conc in and out of k) normally?

A

5mM and 140mM respectively

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17
Q

How can NA channels open in localised changes of RMP?

A

Through voltage gated channels

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18
Q

How can NA channels open in Neurotransmitter activation?

A

Ligand gated channels

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19
Q

How does the Cell become depolarised?

A

During an Action potential when NA channels open and NA enters cells

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20
Q

What are the small internal electric currents set up by the AP called?

A

Intrinsic/local currents

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21
Q

How does Intrinsic currents conduct AP?

A

Open voltage gated NA channels initiate another AP

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22
Q

What prevents the backflow of excitation?

A

The inactive/refractory period

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23
Q

How is a Inactivation period created?

A

Once voltage gated NA channels has opened and closed it goes through period of inactivation

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24
Q

How is conduction velocity enhanced?

A

Myelination of Axons

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25
Q

How is the myelin sheath formed?

A

Cells called Schwann cells

26
Q

What does the myelin sheath do?

A

Wraps around axons to form 1mm sheath leaving short stretch of unmyelinated axon before next schwann cell

27
Q

How does Myelin sheath function?

A

Increasing the conductivity of the axon which increases conductivity of intrinsic currents increasing conduction velocity

28
Q

What do local anaesthetics target?

A

Voltage gated ion channels as have high affinity for NA ion channels in open state

29
Q

What increases the effect of the local anaesthetic?

A

Exhibit use dependant block which creates more channels to open, maintains in inactivated state

30
Q

What does maintenance in inactivated state mean?

A

Cell cant be re-stimulated

31
Q

What is a synapse?

A

Junction between a neuron and target cell

32
Q

Whar are the 2 types of Synapses?

A

Electrical and Chemical

33
Q

How does Electrical Synapses work?

A

Transmission via pores (gap j), allows rapid communication between neurons found in smooth and cardiac muscle

34
Q

What does the Chemical synape consist of?

A

Pre-synaptic membrane at pre-syn terminal of an axon and post-syn membrane

35
Q

What seperates the pre- and post-synaptic membranes?

A

Synaptic cleft

36
Q

How is a post-synaptic potential initiated?

A

AP in presyn activates release of neurotransmitter molecules into synaptic cleft that bind to specific receptors opening ligand gated channels

37
Q

What happens if the post-syn potential is large enough?

A

Elicit an AP in the target neuron

38
Q

What are 3 classical neurotransmitters?

A

AA, Monoamines, Purines

39
Q

Give me an example of AA neurotransmitters?

A

Glutamate, Gabba, Glycine

40
Q

Give me an example of Monoamine neurotransmitters?

A

ACh, Dopamin, NA, Adrenaline, Sertonin, Histamine

41
Q

Give me an example of a Purine Neurotransmitter?

A

Adenosine, ATP

42
Q

When fired where the does AP reach?

A

Synaptic bouton

43
Q

What enters and opens the boutons?

A

Calcium channels open to release calcium

44
Q

What protein is Calcium detected by?

A

Synaptotagmin

45
Q

What does Synaptotagmin do?

A

Promotes formation of SNARE complex between snare proteins

46
Q

What is the SNARE protein embedded in the vesicle membrane?

A

Protein Synaptobrevin

47
Q

What are the SNARE proteins associated with pre-syn membrane?

A

Protein Synatacin and SNAP-25

48
Q

How does a neurotransmitter release at an active zone?

A

Vesicle and pre-syn membranes fuse - then diffuse across synapse

49
Q

How does a neurotransmitter get back into the neuron?

A

It binds to the receptor and is broken down and recycled back

50
Q

Where do neuropeptides release?

A

From any location of the terminal membrane

51
Q

What do neuropeptides require to be released?

A

High concentrations of calcium to increase cell firing rate

52
Q

What is co-transmission?

A

More than 1 neuropeptide being released from single synapse

53
Q

What is the control of neurosecretion mediated by?

A

Autoreceptors and heteroreceptors

54
Q

What do Autoreceptors do?

A

Monitors self secretion

55
Q

What does hetroreceptors do?

A

Transmission from other synapses

56
Q

What do the receptors function as part of?

A

Localised negative feedback system

57
Q

What are sub-threshold potentials?

A

Inhibitory postsyn (ISPS) or Excitatory postsyn (ESPS)

58
Q

What are the 3 Mechanisms behind neurotransmitter inactivation?

A

Reuptake
Enzymes
Diffusion

59
Q

How does Reuptake mechanism work?

A

Ion gradients with high affinities

60
Q

How does Enzyme mechanism work?

A

AchE (acetate and choline) blocked by organophosphates

61
Q

How can Diffusion mechanism work?

A

Route for peptides as they are large so have prolonged effects

IMS (53 decks)

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