Answer:
What sends oxygenated blood back to the heart from the lungs?
Oxygen-rich blood flows from the lungs back into the left atrium (LA), or the left upper chamber of the heart, through four pulmonary veins. Oxygen-rich blood then flows through the mitral valve (MV) into the left ventricle (LV), or the left lower chamber.
Explanation:
Answer:
The presynaptic membrane is formed by the part of the presynaptic axon terminal forming the synapse and that of the postsynaptic neuron is called the postsynaptic membrane. The space between the presynaptic and postsynaptic membrane is called the synaptic cleft. These three structures together form the synapse.
Explanation:
A fossils can’t form underwater because of how much oxygen can be found in the water.