Neurones, Nerve Conduction and Synaptic Transmission

Question 1

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

Answer 1

dendrites

Question 2

What is the synthetic and metabolic centre of the neurone?

Answer 2

soma (perikaryon)

Question 3

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

Answer 3

Axon hillock and initial segment

Question 4

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?

Answer 4

Soma (perikaryon)

Question 5

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

Answer 5

synapse

Question 6

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)?

Answer 6

Axon

Question 7

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

Answer 7

several viruses, eg polio, herpes and rabies

Question 8

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

Answer 8

unipolar

Question 9

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

Answer 9

Pseudounipolar (one neurite, that bifurcates)

Question 10

What is the shape of a Retinal bipolar neurone?`

Answer 10

bipolar (two neurites)

Question 11

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

(motoneurone)?

Answer 11

multipolar

Question 12

What allowed the visualisation of individual neurones?

Answer 12

Golgi’s staining method

Question 13

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

Answer 13

motor

Question 14

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

Answer 14

sensory

Question 15

What neurone type may come from between neurones in CNS?

Answer 15

Local Interneurone

Question 16

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

Answer 16

Local Interneurone

Question 17

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

Answer 17

Projection Neurone

Question 18

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

Answer 18

projection neurone

Question 19

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

Answer 19

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

Question 20

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

Answer 20

decays exponentially with distance. λ= length constant

Question 21

The distance over which current spreads depends upon what?

Answer 21

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

Question 22

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

Answer 22

greater

Question 23

How can Rm be increased?

Answer 23

by adding an insulating material

Question 24

How can Ri be increased?

Answer 24

possible by increasing axon diameter

Question 25

What insulating materials can be added to increase Rm?

Answer 25

in PNS: myelin provided by Schwann cells | in CNS: oligodendrocytes

Question 26

Is conduction faster in myelinated or non myelinated cells?

Answer 26

MYELINATED

Question 27

True or false: one oligodendrocyte surrounds many axons

Answer 27

true

Question 28

What is "Saltatory Conduction in Myelinated Axons"

Answer 28

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

Question 29

Demyelinating disorder in PNS?

Answer 29

multiple sclerosis

Question 30

Demyelinating disorder in CNS?

Answer 30

Guillian-Barre Syndrome

Question 31

Most common type of synapse?

Answer 31

Axodendritic

Question 32

What are the major amino acid neurotransmitters in the CNS?

Answer 32

Glutamate, GABA and glycine

Question 33

Synapses can be classified functionally as being what two things?

Answer 33

excititory or inhibitory

Question 34

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

Answer 34

glutamate

Question 35

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

Answer 35

GABA or glycine

Question 36

What does glutamate activate, generating what kind of response?

Answer 36

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

Question 37

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

Answer 37

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

Question 38

What separates pre and post synaptic membranes?

Answer 38

synaptic cleft

Question 39

What stores the neurotransmitter in the synapse?

Answer 39

vesicles

Question 40

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

Answer 40

complementary

Question 41

Name the amine neurotransmitters.

Answer 41

ACh, Dopamine, Histamine, Noradrenaline, Serotonin

Question 42

Name the peptide neurotransmitters.

Answer 42

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

Question 43

Amino acids and amines are released from where?

Answer 43

synaptic vesicles

Question 44

Peptides are released from where?

Answer 44

secretory vesicles

Question 45

What are LGICs and what can activate them?

Answer 45

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

Question 46

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

Answer 46

all except glycine

Question 47

In which cells do Glycine and glutamate occur?

Answer 47

all (not just neurones)

Question 48

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

Answer 48

GABA and amines

Question 49

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

Answer 49

by axoplasmic transport along microtubules

Question 50

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

Answer 50

at the terminal

Question 51

What synthesises the precursor peptide?

Answer 51

ribosomes associated with the rough endoplasmic reticulum (ER)

Question 52

Where does Cleavage of precursor peptide occur?

Answer 52

Golgi apparatus

Question 53

What bud off from the Golgi apparatus?

Answer 53

secretory granules

Question 54

How are secretory granules are transported to the presynaptic terminal?

Answer 54

by fast axoplasmic transport via microtubules