15.5 Structure And Function Of Synapse Flashcards
Synapse definition
Point between 2 neurones or neurone and effector
What is the synaptic cleft?
Gap that separates neurones
Neurotransmitters
Chemicals that transmit information from one neurone to another
Presynaptic neurone definition
Neurone that releases the neurotransmitter
Synaptic knob definition
Swollen portion of the neurone end
Where is the neurotransmitter stored?
Synaptic vesicles
How will the postsynaptic neurone receive the neurotransmitter?
Possesses specific receptor proteins on its membrane
Draw the structure of a synapse
Page 360
Which way does the neurotransmitter pass?
From the presynaptic neurone to the postsynaptic neurone
Spatial summation definition
Number of DIFFERENT presynaptic neurones together release enough neurotransmitter to exceed the threshold level of the postsynaptic neurone
Temporal summation definition
A SINGLE presynaptic neurone releases neurotransmitter many times over in a short period to exceed the threshold value of the postsynaptic neurone
What are inhibitory synapses?
Synapses that make it less likely a new action potential will be created on the post synaptic neurone
How do inhibitory synapses work?
- presynaptic neurone releases neurotransmitter
- neurotransmitter binds to Cl- channels on postsynaptic neurone
- Cl- channels open
- Cl- move into postsynaptic neurone by facilitated diffusion
- k+ channels open on postsynaptic neurone
- K+ move out of post synaptic neurone by facilitated diffusion
- causes hyperpolarisation
Hyperpolarisation definition
Potential is much more negative than its resting potential
What happens when hyperpolarisation occurs?
Less likely a new action potential will occur because a larger influx of Na+ is needed to produce one (larger generator potential needed)
A single impulse along one neurone can do what at a synapse?
Initiate new impulses in a number of different neurones
What is the advantage of having a single impulse along a neurone initiating new impulses to an number of other neurones at synapses?
Single stimulus can create a number of simultaneous responses
What can happen to lots impulses at a single synapse?
Can be combined
What does combining nerve impulses at a synapse allow?
Allow nerve impulses from receptors reacting to different stimuli to contribute to a single response
What happens to the vesicles when an action potential reaches the synaptic knob
Vesicles fuse with the presynaptic membrane to release the neurotransmitter
Where are the protein receptors complementary to the neurotransmitter found?
Only on the postsynaptic neurone
Excitatory synapses definition
Synapses that produce new action potentials
