Introduction to Neurons, Nerve Conduction and Synaptic Transmission Flashcards
What do dendrites do?
- Receive input from other neurones
- Convey graded electrical signals to the soma
- Add surface area to the neurone
How are electrical signals conveyed to the soma?
Graded
PASSIVELY
What is the soma aka?
Perikaryon
What is the soma the centre of?
Synthesis and metabolism
What does the soma contain?
Nucleus
Ribosomes
Mitochondria
ER
What does the soma integrate?
Incoming signals that are conducted passively to the axon hillock
What occurs at the axon hillock?
Initiation of the ‘all or none’ action potential
What does the axon do?
Conducts output signals as action potentials to other cells/neurons
Mediate transport materials between the soma and the presynaptic terminal
What can viruses do to a neuron? Give examples of such viruses.
Affect retrograde transport
Herpes, Polio, Rabies
What direction does the axon transport materials in?
ANTEROGRADE
or
RETROGRADE
Dendrites can be either…..
Apical or Basal
Unipolar
1 neutrite
e.g PNS
Pseudounipolar
1 neutrite that bifurcates
Bipolar
2 neutrites
Multipolar
3/+ neutrites
e.g LMN
How many functional regions do most neurones have?
4
Name the 4 functional regions of a neurone.
Input
Integrative
Conductile
Output
What causes the upstroke of an AP in neurones?
The opening of voltage activated Na+ channels
What is ‘over-shoot’?
A brief period when polarity is reversed to inside positive
What causes the downstroke of an AP in neurones?
The opening of voltage activated K+ channels
and the closure of activated Na+ channels
Why does undershoot occur?
Because K+ channels don’t close immediately once membrane potential is reached
The nerve cell membrane is ‘leaky’. Explain this.
Not a perfect insulator
Passive signals don’t spread far from their site of origin due to current loss across the membrane
The amplitude of an AP is….
CONSTANT
Current leaks back to what across the membrane resistance (rm)?
Extracellular space
What does current leaking to the extracellular space generate?
Generates a potential change (Vm)
For a given current (I), Vm increases linearly with rm
TRUE