The digestive tract has a nervous system of its own called the nervous system.

enteric

Control of the digestive system is also maintained by the enteric nervous system (ENS), which can be thought os as a digestive brain that helps to regulate motility, secreation, and growth. The enteric nervous system can act as fast, internal response to digestive stimuli. When this occurs, it is called a short reflex.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.

ionic bonds are two oppositely charged ions that attract. a sodium ion has a 1 positive charge; a chloride ion has a 1 negative charge. sodium and chloride have oppostive charged ions that attract which forms an ionic bond. a chemical bond formed when two atoms share electrons is called