Bio: Week 2: Nervous System
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- Created by: laurenlottie19
- Created on: 12-02-19 11:40
What is a neurone?
Specialised excitable cell that receives, integrates and passes on information.
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What is another name for the cell body of a nerve cell?
Soma or Perikaryon
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What is the role of the soma?
It contains the nucleus and is involved in protein synthesis and energy production.
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What is the membrane of a nerve cell made up of?
A bi-layer of lipid molecules
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What is cytosol?
watery liquid inside the neurone
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What are the supporting cells in the CNS?
Astrocytes, Oligodendrocytes, Microglia
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What are supporting cells in the PNS?
Schwann cells.
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What are the roles of the astrocytes?
1) Provide physical support by filling space between neurones, (2) Isolate neurones, (3) Clean up debris, (4) Regulate chemical composition of extracellular fluid, (5) Provide nourishment , (6) Form scar tissue
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What are the roles of oligodendrocytes?
1) Support axons , (2) Produce myelin sheath, (3) Provides electrical insulation increasing processing speed.
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What are the roles of the microglia?
1) Active immune defence, (2) Responsible for inflammatory reaction , (3) Act as phagocytes
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What is the resting potential of the neurone?
-70mV
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What is depolarisation?
Inside of the neurone becomes more positive than RP (-70mv)
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What is hyperpolarisation?
Inside of the neurone becomes more negative than RP (-70mV)
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What is the concentration of ions in the extracellular fluid?
High concentration: Cl- , Na+ : Lower concentration: K+
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What is the concentration of ions in the intracellular fluid?
High concentration: A- , K+. : Lower concentration: Cl- , Na+
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What are graded potentials?
Small (sub threshold) changes in membrane potential.
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What is the amplitude proportional to of the graded potential?
Their amplitude is proportional to the amplitude of the stimulation.
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What happens with the distance travelled by graded potentials?
They diminish in amplitude.
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What is the summation of a graded potential?
When they sum over time and space to become a supra threshold ( -55mV to generate an action potential).
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What is spatial summation?
The generation of electrical signals where an Input to different locations on dendrites, close together in time.
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What is temporal summation?
The generation of electrical signals where an input from a single neurone to a single input location in quick succession.
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What is the duration of an action potential?
1 - 2 msec
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What is the threshold potential of an action potential?
-55mV
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What re-establishes the resting potential?
Na+ / K+ pump
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What does the Na+ / K+ pump do?
Moves 3 Na+ ions out of the neurone and 2 K+ into the neurone
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How does the Na+ / K+ pump re-establish the resting potential?
It re-establishes a low Na+ concentration inside the neurone, thus allowing the cell to repolarise to -70 mV (RP).
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What happens in the AP conduction in unmyleinated axons?
There is an active and passive current flows, no decline in amplitude of AP and no backward propagation of AP.
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What happens in the AP condition in a myelinated axon?
The myelin improves passives flow of current and an AP travels alongs the nodes of ranvier to increase condition velocity.
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What is the role of Ca+ in synaptic transmission?
1) When an AP reaches axon terminal voltage-gated Ca2+ channels open, (2) Ca2+ moves into the neurone and causes vesicles to migrate and fuse with presynaptic membrane, (3) Vesicles opens into synaptic cleft and NT is released.
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What are excitatory postsynaptic potentials?
Leading to a depolarisation of postsynaptic neurone, increasing the probability of an AP.
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What are inhibitory postsynaptic potentials?
Leading to a hyperpolsation of the postsynaptic neurone, decreasing the probability of an AP.
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What are postsynaptic potentials?
Changes in membrane potential due to movement of ions in or out of the postsynaptic neurone.
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What synaptic activity influences the membrane potential?
1) Number of synapses active (i.e. strength) , (2) Balance of excitatory or inhibitory synapses
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What occurs if the synaptic integration is an excitatory input?
Depolarisation
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What occurs if the synaptic integration is an inhibitory input?
Hyperpolarisation
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When does stabilisation occur in synaptic integration?
If there is an equal excitatory and inhibitory input.
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Other cards in this set
Card 2
Front
What is another name for the cell body of a nerve cell?
Back
Soma or Perikaryon
Card 3
Front
What is the role of the soma?
Back
Card 4
Front
What is the membrane of a nerve cell made up of?
Back
Card 5
Front
What is cytosol?
Back
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