How does the cardiovascular system and respiratory system provide oxygen to cells ?

The respiratory system works directly with the circulatory system to provide oxygen to the body. Oxygen taken in from the respiratory system moves into blood vessels that then circulate oxygen-rich blood to tissues and cells.

"a scientist studying a whale and its surroundings would need to understand the structure of atoms in case something was negatively affecting the whale or its surroundings."

explanation:

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the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.