These Chylomicrons are then secreted into the central lacteals and enter the lymphatic drainage for return of the blood via the thoracic duct. Dietary carbohydrates and proteins by contrast are digested by hydrolysis into simple sugars and amino acids that are absorbed through the intestinal epithelial cells without reassembly. These smaller molecules are then secreted directly into the blood of the hepatic portal vein and taken to the liver for processing or systemic distribution
Hydrolysis is the process of adding water to a molecule in order to break it down into subunits.
Following incubation, tubes 1 & 4 exercise "A" contained the most starch and tube 2 contained the most reducing sugar. Salivary amylase therefore, functions best at a neutral pH and is at least partially destroyed by boiling.
following incubation, the most digestion of egg albumin (protein) in exercise "B" occurred in tube 2. This shows that the enzyme pepsin had both a pH optimum (acidic) and a temperature optimum (37 C)
HCL stimulated the digestive action of pepsin, where as HCL inhibited the digestive action of similar amylase. This due to the difference in chemical composition and structure that determines the pH optima of these two enzymes. Pepsin is adapted to work best in the acidic environment of gastric juice, where as salivary amylase is adapted to work optimally at the nearly neutral pH of saliva
Following incubation in exercise "C" test tube 3 displayed the most rapid in pH. Thus tube contained not only the substrate molecules (fat or oil) but also contained emulsifying agents (bile salts ) and digestive enzymes (pancreatin) that together hydrolyzed the oil into fatty acid molecules. The increase in the number of fatty acid molecules lower the pH of the solution
The stomach doesnt normally digest itself because of the protective effects of an adherent layer of alkaline mucus, the tight junctions between adjacent epithelial cells, and the rapid rate of cell division that acts to replace damaged epithelial cells every three days. Gastric juice does not normally digest the duodenum because the acid gastric juice is deterred by the adherent layer of mucus, buffered by bicarbonate secreted by Brunner's glands in the submucosa which are unique to the duodenum, and rapidly neutralized by the arrival of alkaline juice from the pancreas; and to a lesser extent but the alkaline bile from the liver
Since fat is not soluble in water, dietary fat enters the duodenum in the form of large fat droplets which must be broken down into much smaller pieces before digestive enzymes can act upon them. There are two processes required for fat digestion:! Emulsification refers to the breakdown of large droplets into smaller droplets,(just as dishwashing detergents act on grease). Bile salts are responsible for this. Digestion of fat into monoglycerides and fatty acids (accomplished by lipases, such as pancreatic lipase, which you will use today). You can measure the digestion of fats by lipases because as the fatty acids are produced by enzymatic breakdown, the pH of the solution drops.
The digestive system breaks down food (complex polymers) into monomers through enzymatic digestion. Only very small molecules, such as monosaccharides or amino acids can be absorbed across the gut epithelia. This lab will examine the optima for 3 important digestive enzymes.
Lab Exercise 1: Digestion of Starch by Salivary Amylase
Pepsin is an enzyme that is secreted by the chief cells in the stomach which digests proteins. In this exercise, you will digest albumin, the major protein in egg whites. !
You will measure the activity of salivary amylase by measuring the amount of product formed using Benedict’s reagent, which consists of an alkaline solution of cupric ions (Cu++). Cupric ions will be reduced to cuprous ions (Cu+) in the presence of maltose, forming a visible yellow-colored precipitate of cuprous oxide (Cu2O).