Lecture 3 - Neuronal Structure And Function Flashcards
(29 cards)
Whats common properties of the neurone with other cells?
- cell membrane
- nucleas
- ## organelles and machinery for translating genetic code into proteins
Whats the neuronal specialisation?
Excitability of the membrane:
The nerve cell’s outer layer can react and send electrical signals.
Dendrites:
Branch-like parts coming from the cell body that receive messages from other neurons.
Synapse:
The tiny gap where two neurons connect and pass signals.
Axon:
A long fiber that carries messages away from the cell body to other cells, often over long distances.
Myelination:
A fatty coating around the axon that helps messages travel faster and more efficiently
Explain the membrane potential?
The neuronal cell membrane lets some substances (like certain ions) pass through, but not all — this is called selective (or differential) permeability.
Because of this, ions like sodium (Na⁺) and potassium (K⁺) are not evenly spread inside and outside the neuron.
This creates a difference in electrical charge across the membrane.
That difference is called the membrane potential.
In a resting neuron, this is about –70 millivolts (mV) — meaning the inside is more negative than the outside.
Whats the resting potential of membrane potential?
-70mV
What does the dendrites do?
Receiving incoming signals
What does the axon do?
Rapid transmissions of signals over long distance
Whats the connection between two neurons called?
The synapse
Who won the noble prize in physiology or medicine in 1963?
John Eccles
Alan Hodgkin
Andrew Huxley
What happens permeability increases?
Increasing the permeability to sodium (Na+) causes the membrane potential to
become less negative (depolarisation)
Whats hyperpolairsation in membrane potential?
Increasing the permeability to chloride (Cl-) causes the membrane potential to
become more negative (hyperpolarisation)
Describe the changes in charge in the dendrites?
Relatively slow
Decay over distance
Whats signal integration ?
Signal integration is how a neuron adds up all the incoming signals (both excitatory and inhibitory) to decide whether to fire an action potential (send a signal) or not.
What’s spatial summation?
Spatial summation is when a neuron adds up signals from multiple different places on its surface at the same time
Whats temporal summation?
After an EPSP or IPSP, it takes a short time for the membrane to return to
resting potential (around 5-10 msec).
• Another polarising event (EPSP or IPSP) occurring during this period will
cause an additional change in the membrane potential
• Therefore polarising events occurring close together in time will add
together (temporal summation)
Whats the action potential?
An electrical spike cause by reversal of membrane polarity
- mediated by rapid changes in membrane permeability to sodium and potassium
Whats the all of non phenomenon
an action potential is always the
same size
Does not decay over distance
• an action potential is the same size
when it reaches the terminal as it
was when it left the axon hillock
What’s the comparison fo diff classes of primary afferent axon?
A - alpha fibre
A - beta fibre
A- delta fibre
C fibre
Thick - thin
What does increasing the permeability to sodium cause?
Depolarisation
An EPSP - Excitatory Post-Synaptic Potential)
What it is: A small electrical change that makes the neuron more likely to fire.
How: Caused by positive ions (like Na⁺) entering the cell → inside becomes less negative (depolarization).
🟢 EPSP = Encourages firing
What does increasing the permeability to chloride cause?
Hyperpolarisation
An IPSP - (Inhibitory Post-Synaptic Potential)
What it is: A small electrical change that makes the neuron less likely to fire.
How: Caused by negative ions (like Cl⁻) entering or positive ions (like K⁺) leaving the cell → inside becomes more negative (hyperpolarization).
🔴 IPSP = Prevents firing
What released through the synaptic cleft?
Neurotransmitters and receptors
Explain neurotransmitters?
• Synthesised in the neurones, close to the site of release
• Stored on the terminal until required for release
• Released into synaptic cleft in response to an action potential
• Binds to receptors in post-synaptic membrane
• Causes changes in membrane potentia
What does excitatory receptors cause?
Depolarisation
What does inhibitory receptors cause?
Hyperpolarisatio
Examples of neurotransmitters?
Amino acids
Acetylcholine
Dopamine
