Why is a stimulus required for a muscle to contract?

When the intestine becomes infected with the food borne illness bacteria e. coli, the bacteria releases a enterotoxin that causes excessive loss of water and electrolytes in the intestines. necessary to return the osmolality of the intestines to normal?

Which geologic feature would most likely be represented by contour lines john far apart from one another? a cliff a hill a plain a valley

Ineed some everybody. the production of cells during mitosis into specialized function is called: recombination or differentiation