Neuroscience A

Question 1

How is the PNS split up?

Answer 1

PNS splits into somatic and autonomic
Autonomic splits into sympathetic and parasympathetic

Question 2

What are the 3 regions of the CNS?

Answer 2

Brain, brainstem, spinal cord

Question 3

Define gyrification

Answer 3

Folding of the cortex

Question 4

What is grey matter composed of?

Answer 4

Primarily neuronal cell bodies

Question 5

What is white matter composed of?

Answer 5

Myelinated neurites projecting from neurons

Question 6

How many pairs of cranial nerves are there?

Answer 6

12

Question 7

How many pairs of spinal nerves are there?

Answer 7

31

Question 8

Define neurites

Answer 8

In neurones, long filamentous extensions responsible for propagating action potentials

Question 9

What is the role of interneurones?

Answer 9

Connecting neurons to each other, amplifying and attenuating activity of a neuronal circuit by integrating additional data

Question 10

Describe the role of non-active astrocytes

Answer 10

Trophic support of neurons, synapse formation and maintenance, clearance of neurotransmitters

Question 11

Describe the role of active astrocytes

Answer 11

Damage neurons, activate microglia, some phagocytic activity

Question 12

What are the microglia in the brain?

Answer 12

Resident immune cell of the brain, surveying for pathogens and damaged
material

Question 13

What are the morphological and functional changes of microglia when activated?

Answer 13

Increased motility,
Phagocytosis
Release of immune factors (cytokines)
Amoeboid shape

Question 14

What sort of lipid makes up the myelinating layers?

Answer 14

Sphingolipids

Question 15

What is the difference between Schwann cells and oligodendrocites?

Answer 15

Schwann cells myelinate a single axon, oligodendrocytes myelinate many at once

Question 16

Name three types of excitable cells

Answer 16

Myocytes
Endocrine cells
Neuronal cells

Question 17

At resting potential, what ions are neuronal membranes permeable to?

Answer 17

Na+, Cl-, K+

Question 18

At resting potential, what molecules are neuronal membranes impermeable to?

Answer 18

Large anions
Organic acids
Phosphates
Sulphates
Amino acids

Question 19

What does the sodium potassium pump do?

Answer 19

Exchanges sodium and potassium - 3 sodium go out, 2 potassium come in

Question 20

What are the 4 main stages of an action potential?

Answer 20

Depolarisation
Repolarisation
Hyperpolarisation
Afterpolarisation

Question 21

How many mV is the threshold stimulus (usually)?

Answer 21

-55mV

Question 22

What is the standard resting potential?

Answer 22

-70mV

Question 23

What is the absolute refractory period?

Answer 23

During the spike, a neuron cannot be stimulated

Question 24

What is the relative refractory period?

Answer 24

During hyperpolarisation and afterpolarisation, a suprathreshold stimulus (ie larger) is required to trigger an action potential

Question 25

What does the refractory period allow for?

Answer 25

Unidirectionality of action potentials An upper limit on firing rate

Question 26

What are the 2 key properties of voltage gated ion channels?

Answer 26

1. Ion specific 2. Voltage sensitive

Question 27

What are the 2 kinds of synapse in the nervous system?

Answer 27

Electrical and chemical

Question 28

How do electrical synapses transmit signals?

Answer 28

Via ion current through gap junctions; it's instantaneous and bidirectional

Question 29

Where are electrical synapses most commonly found?

Answer 29

In escape reflex circuits and inhibitory interneurons in the brain

Question 30

What determines if a neurotransmitter is excitatory or inhibitory?

Answer 30

The type of receptor it binds to

Question 31

What are the types of synaptic contacts?

Answer 31

Axodendritic, axosomatic, and axoaxonic

Question 32

What is an axodendritic synapse?

Answer 32

A synapse formed between the axon of one neuron and the dendrite of another neuron

Question 33

What is an axosomatic synapse?

Answer 33

A synapse, or connection, where the axon of one neuron connects to the cell body (soma) of another neuron

Question 34

What is an axoaxonic synapse?

Answer 34

A specialized type of synapse where one neuron's axon terminal connects to another neuron's axon, rather than the more common connections to dendrites or cell bodies

Question 35

What 4 structures are found at synapses?

Answer 35

Synaptic vesicles, mitochondria, post-synaptic density, and glial processes

Question 36

What is a post-synaptic density?

Answer 36

A region enriched in receptors and associated machinery

Question 37

In 1 sentence, what triggers neurotransmitter release?

Answer 37

An action potential causing Ca²⁺ influx via voltage-gated channels

Question 38

What proteins mediate vesicle docking and fusion?

Answer 38

SNARE proteins: Synaptobrevin (v-SNARE), Syntaxin & SNAP-25 (t-SNARE), Synaptotagmin (Ca²⁺ sensor)

Question 39

How are vesicles recycled?

Answer 39

Via clathrin-mediated endocytosis and refilled using vesicular transporters (e.g., VGLUT, VGAT)

Question 40

What does Botulinum do?

Answer 40

Cleaves SNAP25, preventing vesicle fusion—blocks ACh release

Question 41

What does Tetanus toxin do?

Answer 41

Cleaves Synaptobrevin, inhibiting GABA release—causes muscle spasms

Question 42

What receptors mediate fast synaptic transmission?

Answer 42

Ionotropic receptors (e.g., GABA 𝐴, AMPA, NMDA, Glycine)

Question 43

What are EPSPs?

Answer 43

Excitatory Post-Synaptic Potentials

Question 44

What are IPSPs?

Answer 44

Inhibitory Post-Synaptic Potentials

Question 45

What do EPSPs do?

Answer 45

They open ion channels that let positive ions (Na⁺, Ca²⁺) into the cell. This makes the inside of the cell less negative (depolarization) and brings it closer to the threshold to fire an action potential. Multiple EPSPs need to summate within a short window (~10ms) to reach threshold - in short, they depolarise

Question 46

What do IPSPs do?

Answer 46

When neurotransmitters like GABA bind to their receptors (e.g., GABA 𝐴), they open channels that let Cl⁻ in (a negative ion). This makes the inside of the cell more negative (hyperpolarization), reducing the chance of an action potential. In short, they hyperpolarise