Neuroscience A Flashcards
How is the PNS split up?
PNS splits into somatic and autonomic
Autonomic splits into sympathetic and parasympathetic
What are the 3 regions of the CNS?
Brain, brainstem, spinal cord
Define gyrification
Folding of the cortex
What is grey matter composed of?
Primarily neuronal cell bodies
What is white matter composed of?
Myelinated neurites projecting from neurons
How many pairs of cranial nerves are there?
12
How many pairs of spinal nerves are there?
31
Define neurites
In neurones, long filamentous extensions responsible for propagating action potentials
What is the role of interneurones?
Connecting neurons to each other, amplifying and attenuating activity of a neuronal circuit by integrating additional data
Describe the role of non-active astrocytes
Trophic support of neurons, synapse formation and maintenance, clearance of neurotransmitters
Describe the role of active astrocytes
Damage neurons, activate microglia, some phagocytic activity
What are the microglia in the brain?
Resident immune cell of the brain, surveying for pathogens and damaged
material
What are the morphological and functional changes of microglia when activated?
Increased motility,
Phagocytosis
Release of immune factors (cytokines)
Amoeboid shape
What sort of lipid makes up the myelinating layers?
Sphingolipids
What is the difference between Schwann cells and oligodendrocites?
Schwann cells myelinate a single axon, oligodendrocytes myelinate many at once
Name three types of excitable cells
Myocytes
Endocrine cells
Neuronal cells
At resting potential, what ions are neuronal membranes permeable to?
Na+, Cl-, K+
At resting potential, what molecules are neuronal membranes impermeable to?
Large anions
Organic acids
Phosphates
Sulphates
Amino acids
What does the sodium potassium pump do?
Exchanges sodium and potassium - 3 sodium go out, 2 potassium come in
What are the 4 main stages of an action potential?
Depolarisation
Repolarisation
Hyperpolarisation
Afterpolarisation
How many mV is the threshold stimulus (usually)?
-55mV
What is the standard resting potential?
-70mV
What is the absolute refractory period?
During the spike, a neuron cannot be stimulated
What is the relative refractory period?
During hyperpolarisation and afterpolarisation, a suprathreshold stimulus (ie larger) is required to trigger an action potential
What does the refractory period allow for?
Unidirectionality of action potentials
An upper limit on firing rate
What are the 2 key properties of voltage gated ion channels?
- Ion specific
- Voltage sensitive
What are the 2 kinds of synapse in the nervous system?
Electrical and chemical
How do electrical synapses transmit signals?
Via ion current through gap junctions; it’s instantaneous and bidirectional
Where are electrical synapses most commonly found?
In escape reflex circuits and inhibitory interneurons in the brain
What determines if a neurotransmitter is excitatory or inhibitory?
The type of receptor it binds to
What are the types of synaptic contacts?
Axodendritic, axosomatic, and axoaxonic
What is an axodendritic synapse?
A synapse formed between the axon of one neuron and the dendrite of another neuron
What is an axosomatic synapse?
A synapse, or connection, where the axon of one neuron connects to the cell body (soma) of another neuron
What is an axoaxonic synapse?
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
What 4 structures are found at synapses?
Synaptic vesicles, mitochondria, post-synaptic density, and glial processes
What is a post-synaptic density?
A region enriched in receptors and associated machinery
In 1 sentence, what triggers neurotransmitter release?
An action potential causing Ca²⁺ influx via voltage-gated channels
What proteins mediate vesicle docking and fusion?
SNARE proteins:
Synaptobrevin (v-SNARE),
Syntaxin & SNAP-25 (t-SNARE), Synaptotagmin (Ca²⁺ sensor)
How are vesicles recycled?
Via clathrin-mediated endocytosis and refilled using vesicular transporters (e.g., VGLUT, VGAT)
What does Botulinum do?
Cleaves SNAP25, preventing vesicle fusion—blocks ACh release
What does Tetanus toxin do?
Cleaves Synaptobrevin, inhibiting GABA release—causes muscle spasms
What receptors mediate fast synaptic transmission?
Ionotropic receptors (e.g., GABA 𝐴, AMPA, NMDA, Glycine)
What are EPSPs?
Excitatory Post-Synaptic Potentials
What are IPSPs?
Inhibitory Post-Synaptic Potentials
What do EPSPs do?
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
What do IPSPs do?
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
