Neurones, Nerve Conduction and Synaptic Transmission Flashcards Preview

Neurology Physiology > Neurones, Nerve Conduction and Synaptic Transmission > Flashcards

Flashcards in Neurones, Nerve Conduction and Synaptic Transmission Deck (54)
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1
Q

What in the neurone receive inputs from other neurones and convey graded electrical signals passively to the soma?

A

dendrites

2
Q

What is the synthetic and metabolic centre of the neurone?

A

soma (perikaryon)

3
Q

What is the site of initiation of the ‘all or none’ action potential?

A

Axon hillock and initial segment

4
Q

What contains the nucleus, ribosomes, mitochondria and endoplasmic reticulum (ER; rough ER is Nissl substance), and integrates incoming signals that are conducted passively to the axon hillock?

A

Soma (perikaryon)

5
Q

What is the point of chemical (usually) communication between neurones (or other cells)?

A

synapse

6
Q

What conducts output signals as action potentials to other neurones (or other cells), and mediates transport of materials between the soma and presynaptic terminal (anterograde direction) and vice versa (retrograde direction)?

A

Axon

7
Q

What may exploit retrograde transport to infect neurones (often with devastating effect)?

A

several viruses, eg polio, herpes and rabies

8
Q

Neurones can be defined by shape (how many processes (neutrites) come off of the main body (soma). What is a Peripheral autonomic
neurone shape?

A

unipolar

9
Q

What is a Dorsal Root Ganglion (DRG) neurone shape?

A

Pseudounipolar (one neurite, that bifurcates)

10
Q

What is the shape of a Retinal bipolar neurone?`

A

bipolar (two neurites)

11
Q

What is the shape of a Lower motor neurone (LMN)

(motoneurone)?

A

multipolar

12
Q

What allowed the visualisation of individual neurones?

A

Golgi’s staining method

13
Q

What type of neurone may come from ventral horn of spinal cord to skeletal muscle?

A

motor

14
Q

What neurone type may come from skin to dorsal horn of spinal cord?

A

sensory

15
Q

What neurone type may come from between neurones in CNS?

A

Local Interneurone

16
Q

Which neurone type has a Short axon: Golgi type II?

A

Local Interneurone

17
Q

Which neurone type has a Long axon: Golgi type I?

A

Projection Neurone

18
Q

What neurone type may come from dorsal horn of spinal cord to brain structures?

A

projection neurone

19
Q

Action potentials allow signals to travel long distances without decaying. Why is passive (non action potential signals) transmission leaky/ineffective for long distances?

A

The nerve cell membrane is ‘leaky’ (i.e. not a perfect insulator): passive signals do not spread far from their site of origin due to current loss across the membrane

20
Q

What happens to the membrane potential change in a passive neuronal process with distance?

A

decays exponentially with distance. λ= length constant

21
Q

The distance over which current spreads depends upon what?

A

membrane resistance (rm) and the axial resistance of the axoplasm (ri) (increasing the ratio rm/ri increases λ)

22
Q

If the length constant (λ) is longer, is the local current spread greater or smaller?

A

greater

23
Q

How can Rm be increased?

A

by adding an insulating material

24
Q

How can Ri be increased?

A

possible by increasing axon diameter

25
Q

What insulating materials can be added to increase Rm?

A

in PNS: myelin provided by Schwann cells

in CNS: oligodendrocytes

26
Q

Is conduction faster in myelinated or non myelinated cells?

A

MYELINATED

27
Q

True or false: one oligodendrocyte surrounds many axons

A

true

28
Q

What is “Saltatory Conduction in Myelinated Axons”

A

The action potential ‘jumps’ from one node of Ranvier to the next

29
Q

Demyelinating disorder in PNS?

A

multiple sclerosis

30
Q

Demyelinating disorder in CNS?

A

Guillian-Barre Syndrome

31
Q

Most common type of synapse?

A

Axodendritic

32
Q

What are the major amino acid neurotransmitters in the CNS?

A

Glutamate, GABA and glycine

33
Q

Synapses can be classified functionally as being what two things?

A

excititory or inhibitory

34
Q

In the CNS, what is the EXCITATORY transmitter most frequently?

A

glutamate

35
Q

In the CNS, what is the INHIBITORY transmitter most frequently?

A

GABA or glycine

36
Q

What does glutamate activate, generating what kind of response?

A

postsynaptic, cation selective, ionotropic, glutamate receptors
This generating a local, graded, excitatory (depolarizing) response: the excitatory postsynaptic potential (e.p.s.p.)

37
Q

What does GABA, or glycine, activate, generating what kind of response?

A

postsynaptic, anion selective, ionotropic, GABAA, or glycine, receptors generating a local, graded, inhibitory (hyperpolarizing) response: the inhibitory postsynaptic potential (i.p.s.p.)

38
Q

What separates pre and post synaptic membranes?

A

synaptic cleft

39
Q

What stores the neurotransmitter in the synapse?

A

vesicles

40
Q

Physiologically, spatial and temporal summation - are these isolated or complementary processes?

A

complementary

41
Q

Name the amine neurotransmitters.

A

ACh, Dopamine, Histamine, Noradrenaline, Serotonin

42
Q

Name the peptide neurotransmitters.

A

CCK, Somatostatin, Substance P, TRH, VIP, Neuropeptide Y, Enk, Dynorphin

43
Q

Amino acids and amines are released from where?

A

synaptic vesicles

44
Q

Peptides are released from where?

A

secretory vesicles

45
Q

What are LGICs and what can activate them?

A

Glutamate, GABA, glycine, acetylcholine, and 5-HT can activate ionotropic ligand-gated ion channels (LGICs). These mediate fast neurotransmission

46
Q

Which neurotransmitters can also activate metabotropic G protein-coupled receptors, which mediate relatively slow neurotransmission?

A

all except glycine

47
Q

In which cells do Glycine and glutamate occur?

A

all (not just neurones)

48
Q

Which neurotransmitters must be specifically synthesized by the neurones that release them, requiring specific enzymes?

A

GABA and amines

49
Q

How are Enzymes are synthesized in the cell body and are transported to the presynaptic terminal?

A

by axoplasmic transport along microtubules

50
Q

Where do enzymes mediate synthesis within the cytoplasm of neurotransmitter from precursor substances?

A

at the terminal

51
Q

What synthesises the precursor peptide?

A

ribosomes associated with the rough endoplasmic reticulum (ER)

52
Q

Where does Cleavage of precursor peptide occur?

A

Golgi apparatus

53
Q

What bud off from the Golgi apparatus?

A

secretory granules

54
Q

How are secretory granules are transported to the presynaptic terminal?

A

by fast axoplasmic transport via microtubules