Neurotransmission

Question 1

Describe the basic anatomy of a neuron.

Answer 1

Cell body/Soma (perikaryon and nucleus)
Dendrites and dendritic spines (80-90% of neuron surface area)
Axon (hillock, initial segment, collateral)
Telodendria

Question 2

Name the four types of neuronal circuits.

Answer 2

Diverging
- Motor neurons
Converging
 - Sensory neurons
Reverberating (impulses from later cells repeatedly stimulate early cells)
- Short-term memory, breathing
Parallel after discharge - single cell stimulates a group of cells that all stimulate a common postsynaptic cell)
- Maths problem

Question 3

Name the four structural classifications of neurons.

Answer 3

Anaxonic
Unipolar
Bipolar
Multipolar

Question 4

Anaxonic neurons

Answer 4

Small, multiple cell processes, cannot distinguish axons

Brain and sensory organs

Question 5

Unipolar neurons

Answer 5

Very long axons with cell body located off to the side

Sensory neurons of PNS

Question 6

Bipolar neurons

Answer 6

Small, two processes separated by cell body

Special sensory organs (sight, smell, hearing)

Question 7

Multipolar neurons

Answer 7

Very long axons, multiple dendrites, classical image of neuron
CNS, all skeletal muscle

Question 8

Where can synapses occur?

Answer 8

Dendrites - axodendritic
Soma - axosomatic
Axon terminal - axoaxonic

Question 9

What is a connexon?

Answer 9

Synaptic membrane channel allowing ions to pass in an electrical synapse

Question 10

Where are electrical synapses found?

Answer 10

Areas of brain
Eye
Ciliary ganglia

Question 11

Which is faster, chemical or electrical synapses?

Answer 11

Electrical

Question 12

Electrical synapses are bidirectional.

True or False?

Answer 12

True

Question 13

Where are chemical synapses found?

Answer 13

Most synapses between neurons

All synapses between neurons and other cells

Question 14

In a chemical synapse, what does the triggering of a postsynaptic action potential depend on?

Answer 14

Amount of neurotransmitter released

Excitability of postsynaptic cell

Question 15

Chemical synapses cannot become stronger.

True or false?

Answer 15

False

Question 16

What do excitatory neurotransmitters do?

Answer 16

Cause depolarisation

Promote AP generation

Question 17

What do inhibitory neurotransmitters do?

Answer 17

Cause hyperpolarisation

Suppress AP generation

Question 18

What two types of membrane receptors are found on postsynaptic cells?

Answer 18

Ionotropic (ligand-gated) receptors
- Open or close channel proteins
Metabotropic Receptors
- Linked to g-protein

Question 19

Name 6 common neurotransmitters.

Answer 19

Acetylcholine
Dopamine (monoamine)
GABA (amino acid)
Glutamate (amino acid)
Serotonin (monoamine)
Norepinephrine (monoamine)

Question 20

Describe ACh

Answer 20

Widely distributed
Muscle contraction
Hormone excretion

Question 21

Describe dopamine

Answer 21

Excitatory or inhibitory
CNS
Movement and posture

Question 22

Describe GABA

Answer 22

Inhibitory

Neurons of cortex

Question 23

Describe glutamate

Answer 23

Excitatory

Learning and memory

Question 24

Describe serotonin

Answer 24

CNS

Regulate body temperature, sleep, mood, appetite, pain

Question 25

Chemical synaptic potentials are graded potentials, so they can be depolarising or hyperpolarising. True or false?

Answer 25

True

Question 26

What happens at the neuromuscular junction when an AP arrives at the presynaptic terminal?

Answer 26

See notes

Question 27

How long is the synaptic delay?

Answer 27

0.2-0.5ms

Question 28

Why are chemical synapses one way?

Answer 28

Dendrites do not have neurotransmitter vesicles | Synaptic delay

Question 29

What is synaptic fatigue?

Answer 29

Neurotransmitter cannot recycle fast enough to meet demands

Question 30

What 4 factors classify a substance as a neurotransmitter?

Answer 30

- Synthesised in a neuron - Exist and released from pre-synaptic terminal in sufficient quantities - Can be applied externally to same effects - Has a mechanism for removal

Question 31

Describe norepinephrine

Answer 31

Excitatory Released by adrenergic synapses Brain and ANS

Question 32

What are neuromodulators?

Answer 32

``` Affect pre or postsynaptic membrane Have a long term effect Slow to appear Responses involve multiple intermediate steps e.g. neuropeptides, opioids ```

Question 33

What are opioids and what are their four classes?

Answer 33

``` Neuromodulators which bind to the same receptors as opium and morphine Relieve pain - Endorphins - Enkephalins - Endomorphins - Dynorphins ```

Question 34

What is curare?

Answer 34

Blocks nicotinic ACh receptor | Muscle relaxant

Question 35

How does ecstasy work?

Answer 35

Increases release of seratonin

Question 36

Which neurotransmitters effect G-proteins?

Answer 36

E, NE, dopamine, GABA

Question 37

Which neurotransmitters effect intracellular enzymes (adenylate cyclase)?

Answer 37

Lipid soluble gases NO, CO Brain cells

Question 38

What are adrenergic receptors?

Answer 38

Sympathetic system Norepinephrine or epinephrine alpha and beta receptors

Question 39

What are cholinergic receptors?

Answer 39

Parasympathetic system ACh Muscarinic and nicotinic