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Neurology Year 3 > Physiology > Flashcards

Flashcards in Physiology Deck (91)
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1

Where on the neurone decides whether to initiate an all or nothing action potential?

Axon Hillock

2

Unipolar neurones occur where?

Peripheral autonomic

3

Pseudounipolar neurones occur where?

Dorsal root ganglion

4

Bipolar neurones occur where?

Retinal bipolar neurone

5

Multipolar neurones occur where?

Lower motor neurones

6

What triggers the upstroke within a neuronal AP?

Na + influx
Voltage gated Na+ channels

7

What triggers the downstroke within a neuronal AP?

K+ efflux
Voltage gated K+ channels

8

Why if signalling was passive would the AP diminish as it travels along the neurone?

The membrane is leaky allowing ions to exit the axon and reducing the concentration gradient reducing speed of transmission.

9

Saltatory Conduction is enabled by what?

The nodes of Ranvier formed between myelin sheath.

10

Why does myelination increase the speed of conduction?

As it insulates the axons preventing leakage of ions and maintaining the concentration gradient.
Ion channels only located at nodes thus conduction jumps from one node to the next.

11

How would you increase the passive conduction speed of a neurone?

Decrease Ri - Increase axon diameter
Increase Rm - Add insulating material

12

Influx of what ion causes the exocytosis of vesicles containing the neurotransmitter?

Ca 2+

13

What types of synapse are there?

Axodendritic
Axosomatic
Axoaxonic

14

Axodendritic

Synapse between axon and dendrite

15

Axosomatic

Synapse between axon and Soma ( cell body )

16

Axoaxonic

Synapse between axon and axon

17

What is the main excitatory neurotransmitter?

Glutamate

18

How does Glutamate cause an increased +ve AP?

Activates postsynaptic Cation selective channels

19

What is the main inhibitory neurotransmitter?

GABA

20

How does GABA cause an increased -ve AP?

Activates postsynaptic anion selective channels
Influx of Cl- ion

21

What are the two main forms of synaptic summation?

Spatial and Temporal Summation

22

What is the purpose behind summation?

Calculation of excitatory and inhibitory AP that responds too many stimuli from the surroundings allowing a proportionate response.

23

Spatial Summation

Convergence of many inputs upon a neurone to determine its output.
Determined by the axon hillock whether the sum of the AP input is enough to surpass the threshold to trigger an all or nothing response.

24

Temporal Summation

If a single input fires frequently enough it can trigger an all or nothing response.

25

Direct postsynaptic membrane potential is activated by...

Ionotropic receptors

26

Why do inotropic receptors result in rapid opening of the ion channels?

Ionotropic receptors are integral to the ion gates

27

Indirect postsynaptic membrane potential is mediated by

Metabotropic receptors

28

Metabotropic receptors result in rapid opening of ion channels? T/F

False - Activation results in slow opening of ion channels

29

Why does metabotropic receptors cause a slow opening of ion channels?

G - protein coupled receptor
Receptor is separate to the ion channel

30

Muscarinic receptors are usually

Metabotropic