Answer:
You can't see the blood vessels themselves because vision depends on a process that makes it impossible to see things that are stationary with respect to the retina. Light receptors in the retina respond only to changes in light reaching them, not to a steady image.
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I think verterbrates have a back bone others do not. I only THINK so.
The property of all ionic compounds that makes chalk particularly useful for writing on a chalkboard is : Hardness and Brittleness
Those properties make chalk leaves residues on the board every time friction happen between the chalk and the board
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Answer:
Key points
Neurons communicate with one another at junctions called synapses. At a synapse, one neuron sends a message to a target neuron—another cell.
Most synapses are chemical; these synapses communicate using chemical messengers. Other synapses are electrical; in these synapses, ions flow directly between cells.
At a chemical synapse, an action potential triggers the presynaptic neuron to release neurotransmitters. These molecules bind to receptors on the postsynaptic cell and make it more or less likely to fire an action potential.
Explanation:
