Communication Between Excitatory Cells Flashcards
What is a gap junction?
Pores between cells which allows current to pass from one cell to another.
What is a synapse?
A junction between two nerve cells (includes neuromuscular junction)
Name the 3 types of synapse.
Axo-dendritic - axon to dendrite
Axo-somatic - axon to soma(cell body)
Axo-axonic - axon to axon
Define a motor end plate.
A neuromuscular junction.
Where a neuron reaches muscle.
Described the six events that occur in synaptic transmission.
- Action potential travels down to presynaptic terminal.
- Voltage-gated calcium ion channels open. Calcium enters the pre-synaptic nob.
- Calcium triggers exocytosis of secretory vesicles containing neurotransmitter (acetylcholine at neuromuscular junctions)
- Neurotransmitter diffuses across synpase to neurotransmitter gated transport channels (proteins) on the post-synaptic membrane.
- Channels open to allow both K+ and Na+ into the post-synaptic cell.
- Triggers voltage-gated Na+ channels to open causing depolarisation of the cell membrane.
What happens in the knee jerk reflex?
- Compression of patella tendon
- Depolarisation of muscle spindle
- Excitatory post-synaptic potential passed onto an inhibitory interneuron and a motor neurone in the spinal cord.
What is the function of the inhibitory interneuron in the knee jerk reflex?
The interneuron secretes glycine which silences the flexor motor neurone as glycine allows Cl- into the neuron preventing depolarisation.
What are inhibitory post synaptic potentials and excitatory post synaptic potentials?
Subthreshold events which determine whether a neurone will reach threshold to fire an action potential or not.
What is temporal summation?
When a high frequency of pre-synpatic action potentials summate in the post synaptic response.
What is spatial summation?
When multiple neurons synapse to the same neuron, all the neurotransmitters add up to ensure depolarisation occurs.
