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Flashcards in Neurotransmission Deck (51):
1

What do dendrites convey?

Graded electrical signals passively to the soma

2

What do dendrites receive inputs from?

Other neurones

3

What is the soma?

Synthetic and metabolic centre- containing nucleus, ribosomes, mitochondria, and ER.

4

What does the soma do?

Integrates incoming signals that are conducted passively to the axon hillock

5

What is the axon hillock and initial segment?

Site of initiation of the all or none ap

6

What does the axon do?

Conducts output signals as aps to other neurones (or cells).

7

Between what does the axon mediate transport of materials?

Soma and presynaptic terminal (anterograde direction) and vice versa (retrograde)

8

What is a synapse?

Point of chemical communication between neurones (or other cells)

9

What direction of transport do several virus' exploit to infect neurones?

Retrograde

10

What are the 4 types of neurone?

Unipolar, pseudounipolar, bipolar, multipolar

11

Describe a unipolar neurone and give an example

One neurite. Peripheral autonomic neurone

12

Describe a bipolar neurone and give an example

Two neurites. Retinal bipolar neurone

13

Describe a pseudounipolar neurone and give an example

One neurite that bifurcates. Dorsal Root Ganglion (DRG) neurone

14

Describe a multipolar neurone and give an example

Three or more neurites. Lower motor neurone (LMN) (motoneurone)

15

What are the four functional regions of neurones?

Input, integrative, conductile, output

16

What are Golgi Type I and Type II axons?

Type I is long, type II is short

17

What is overshoot?

Brief period when polarity is reversed to inside postive

18

What occurs in the upstroke of the ap?

Opening of voltage activated Na+ channels and inward Na+ movement

19

What occurs in the downstroke of ap?

Opening of voltage activated K+ channels and outward movement of K+

20

Why do passive signals not spread far from their site of origin?

The nerve cell membrane is leaky (not a perfect insulator). This is due to current loss across the membrane

21

In the axon does the ap have a constant or variable amplitude?

Constant

22

What kind of process is the membrane potential change?

Passive neuronal process that decays exponentially with distance

23

What does the distance over which current spreads depend upon?

Membrane resistance (rm) and axial resistance of the axoplasm (ri)- increased rm/ri increased length constant

24

What does greater local current spread increase?

AP conduction velocity

25

What does the ap do to the charges on each side of the membrane?

Swaps them (-ve on outside, +ve on inside)

26

How would you decrease ri?

Increasing axonal diameter (not feasible though)

27

How would you increase rm?

Adding an insulating material - myelin- provided by Schwann cells in PNS and oligodendrocytes in CNS (both types of macroglia)

28

What is the length constant equation?

Lambda= (rm/ri)^0.5

29

What do many Schwann cells surround?

A single axon

30

What does one oligodendrocyte surround?

Many axons

31

What is saltatory conduction?

When an ap jumps from one node of Ranvier to the next

32

What is the definition of axodendritic?

Presynaptic cell synpases with the post synaptic cell on the back of its dendrite

33

What is the defintion of axosomatic?

Presynaptic axon synapses on the soma of the post synaptic cell

34

What is the defintion of axoaxonic?

Presynaptic terminal of one cell terminates upon one presynaptic terminal of another cell before that cell shows an axosomatic synapse upon a postsynapstic cell

35

What makes a synapse excitatory or inhibitory?

Transmitter used

36

What transmitter is used most in excitatory synpases in the CNS?

Glutamate

37

What does glutamate activate?

Postsynaptic, cation selective, ionotropic, glutaate receptors

38

What does glutamate generate?

Local graded excitatory (depolarising) response- the excitatory postsynaptic potential (epsp)

39

What transmitter is used most in inhibitory synpases in the CNS?

GABA, or glycine

40

What does GABA/glycine activate?

Postsynaptic, anion selective, ionotropic, GABAa or glycine receptors

41

What does GABA/Glycine generate?

Local graded, inhibitory (hyperpolarising) response- ipsp

42

What sequence is crucial to the computational capacity of the CNS?

Electrical-chemical-electrical

43

What is spatial summation?

Many inputs converge upon a neurone to determine its output

44

What is temporal summation?

A single input may modulate output by variation in ap frequency of that input

45

Where are amino acids and amines released from?

Synaptic vesicles

46

Where are peptides released from?

Secretory vesicles

47

What can glutamate, GABA, glycine, acetylcholine, and 5-HT activate?

Ionotropic ligand-gated ion channels (LGICs), and GPCR (excepet glycine)

48

What speed of neurotransmission do ionotropic ligand-gated ion channels (LGICs) mediate?

Fast

49

What speed of neurotransmission do metabotropic GPCRs mediate?

Slow

50

What are the stages of chemical neurotransmission?

1. Uptake of precursor
2. Synthesis of transmitter
3. Storage of transmitter
4. Depolarisation by ap
5. Ca2+ influx
6. Ca2+ induced release of transmitter (exocytosis)
7. Receptor activation
8. Enzyme mediated inactivation of transmitter
or
9. Reuptake of transmitter

51

What are secretory granules transported to the presynaptic terminal by?

Fast axoplasmic transport via microtubules