Humans need to intake about 2,000 1)____________________ of food energy per day to supply their needs for 2)_______________. The body needs the nutrients 3)_________________ (because our body is nearly 70% this substance), 4)__________________ as our source of energy, 5)_____________ so we can produce cell membranes, myelin sheaths, and hormones, 6) _______________ for growth and repair of skin and muscles, 7)________________ to help regulate body processes and work with enzymes, and 8)________________ such as calcium to build bones and teeth.
The function of the 9)_______________ ____________ is to first break food into ever smaller pieces to increase surface are for enzymes. This process is called 10)______________ ________________ because meat is still meat and potatoes are still potato pieces. 11)________________ _______________ occurs when enzymes break large molecules into smaller molecules such as 12)_________ _________ which are the monomers of proteins, 13)___________ which is a monomer of carbohydrates, and 13)_________ ______ and 14)_____________ which are the monomers of fats.
Mechanical digestion begins when food enters the digestive system through the 15)______________ and the food is chewed. Chemical digestion begins when the salivary glands secrete 16)___________ ___________ which begins breaking starch into sugars. When the food touches the uvula at the back of the throat, a muscular squeezing called 17)__________________ takes the food to the stomoch through a tube called the 18)__________________. Once in the stomach, an enzyme called 19)_______________ begins protein digestion. The stomach churns, squeezes, mixes, and sloshes the food and pepsin together with hydrochloric acid to activate the pepsin. When the chyme is ready, it is squirted into the 20)_____________ ____________ where the nutrients can be absorbed through tiny finger-like projections called 21)___________ into the blood for delivery to cells.
As food comes into the small intestine it is squirted with pancreatic secretions from the pancreatic duct. These include 22)______________ that breaks fats into fatty acid and glycerol, 23)________________ that break down polypeptides and proteins into smaller polypeptides, and 24)________________ ________________ that breaks down the starch that is left into glucose. The liver produces a greenish-brown substance called 25)___________ that mechanically digests fat into tiny fat droplets. The bile is stored in the 26)______ ___________. Final digestion of carbohydrates occurs in the villi cells where 27)_____________ breaks down sucrose into glucos and fructose and 28)_________________ breaks down lactose into glucose and galactose. If a person does not have adequate lactase, then they are 29)______________ intolerant and have painful digestive problems such as gas and diarrhea. Final digestion of proteins occurs when villi 30)_______________ break down polypeptides into amino acid monomers. Finally, all the materials that were not absorbed in the small intestine are dumped into the 31)__________ ___________ where water is absorbed and convenient 32)__________ are made to be removed from the body through the anus.