Choose one food that you ate today, where do you think digestion and absorption are taking place?

 Before the food you eat can be used it must be digested.  Your digestive system has 3 main functions- digestion, absorption, and elimination.

 The process by which the digestive system breaks down food into molecules that the body can use.  Mechanical digestion  Foods are physically broken apart into smaller pieces  Chemical digestion  Chemicals produced by your body break large molecules into smaller ones that your body uses.

 Mechanical digestion allows food to be digested faster and used sooner.  Most of the chemicals involved in digestion are enzymes, substances that speed up chemical reactions.

 Absorption is the process by which nutrients pass through the lining of your digestive system into your blood.  Blood transports the nutrients  Anything not used is eliminated

 Mouth  Pharynx  Esophagus  Stomach  Small Intestine  Large Intestine  Liver, gallbladder, and pancreas are slightly involved in the digestion process

 Mechanical digestion  Teeth tear, crush, and grind food  Tongue pushes the food around  Chemical digestion occurs with saliva  Saliva moistens food so it can be swallowed

 The junction between the digestive tract and the respiratory system.  Epiglottis opens and closes to allow air into the respiratory system and food into the digestive system.

 Muscular tube that connects the pharynx to the stomach.  Peristalsis occurs when muscle contractions push food through the esophagus, toward the stomach.

 Muscular pouch located in the abdomen  Able to contract and expand  Can hold about one gallon of food and liquid  Most mechanical digestion and some chemical digestion occurs here  Mechanical digestion occurs as 3 layers of muscle produce a churning motion  Mixes the food with fluids.

 Chemical digestion occurs as cells lining the stomach release gastric juice, which breaks down proteins.  Hydrochloric acid in gastric juice kills many bacteria that may be swallowed with food.  Mucus coats the lining of the stomach and gives it protection from the acidic gastric juice.