Digestion Honor

Science & Health

Requirements

Have the Nutrition Honor.
Answer: You should present to the instructor the duly signed card of the (basic) Nutrition Honor as a prerequisite to start Digestion, proving that basic concepts of nutrients, the food pyramid, diets, vitamins, minerals, and a balanced diet have already been studied previously, as required by the official program of Adventist Pathfinders currently in effect. — The Digestion Honor complements Nutrition: while Nutrition studies what to eat, Digestion studies how the body processes food. Without a nutritional foundation, it is difficult to understand the role of digestion in the absorption of nutrients. The card is the official document of the Adventist Pathfinder program that proves the prior completion of the prerequisite Honor.
Keep a record of what and how much you eat for one week. Now analyze it against the recommended portions according to the New Food Pyramid. Based on the result, what do you need to change in your diet?
Answer: A food diary is a standard tool used by nutritionists to identify patterns. The Brazilian New Pyramid (2014, Dietary Guidelines) prioritizes unprocessed foods and discourages ultra-processed ones. Comparing consumption with what is recommended reveals where to change — many people discover that they eat fewer vegetables and more sweets than they thought. Small, sustainable changes are more effective than radical diets for health.
What is digestion? What other name is given to the human digestive system?
Answer: You should present to the instructor that digestion is the process by which the body transforms the food ingested into smaller molecules (nutrients) that can be absorbed by the blood and used by the cells — it involves mechanical breakdown (chewing, movements of the stomach) and chemical breakdown (enzymes, acid). — Digestion begins in the mouth (saliva has amylase that breaks down starch) and ends with absorption by the small intestine. The stomach has a pH of 1-2 (extremely acidic) that kills bacteria and activates pepsin. The small intestine is 6-7 meters long and is where 90% of nutrients are absorbed. The digestive system is the most commonly used technical name in up-to-date Brazilian textbooks.
Where is saliva produced? What are its three main functions?
Answer: Saliva is produced by the salivary glands: parotid (in front of the ears), submandibular (under the jaw), and sublingual (under the tongue). Its three main functions are: 1) To lubricate and moisten food, making chewing and swallowing easier; 2) To begin the chemical digestion of carbohydrates, since it contains the enzyme salivary amylase (ptyalin), which begins to break down starch into smaller sugars; 3) To clean and protect the mouth and teeth, controlling bacteria (antibacterial action) and keeping the pH balanced. — Adults produce 1-1.5 liters of saliva per day. A lack of saliva (xerostomia) causes cavities and bad breath. The enzyme amylase already begins the digestion of bread in the mouth — hence the sweet taste that appears when you chew for a long time. The parotid glands are the largest and can become inflamed (mumps/parotitis). Saliva also contains a growth factor that helps heal small wounds.
Be able to identify the following parts of the tooth, describing each one: enamel, dentin, pulp, gum, cementum, and periodontal ligament. What is the role of the tooth in digestion?
Answer: You should present to the instructor: Enamel (the white outer layer, the hardest in the body, protects the tooth); Dentin (the yellowish layer beneath the enamel, provides support); Pulp (the central living tissue with vessels and nerves); Gum (the soft pink tissue that protects the base); Cementum (covers the root, anchoring it to the bone); Periodontal ligament (fibers that join the cementum to the alveolar bone). — There are 32 adult teeth: 8 incisors (cut), 4 canines (tear), 8 premolars, and 12 molars (crush and grind). Proper chewing with healthy teeth increases digestive efficiency — poorly chewed food overloads the stomach. That is why oral hygiene is so important: bad teeth compromise the entire digestive system of the individual from the very first stage.
Be able to identify, through pictures, the following organs that take part in the digestive process, describing each one: Mouth, salivary glands, esophagus, stomach, liver, pancreas, small intestine (duodenum, jejunum, and ileum), large intestine (cecum, ascending colon, transverse colon, descending colon, sigmoid colon, rectum), and anus.
Answer: Boca (mastigação e início da digestão do amido pela saliva); Glândulas salivares (produzem saliva com amilase); Esôfago (conduz o bolo ao estômago por peristaltismo); Estômago (digestão ácida com ácido clorídrico e pepsina, formando o quimo); Fígado (produz a bile que emulsifica gorduras); Pâncreas (suco pancreático com enzimas amilase, lipase e tripsina); Intestino delgado: Duodeno (recebe bile e suco pancreático), Jejuno (digestão e absorção), Íleo (absorção final de nutrientes); Intestino grosso: Ceco (porção inicial onde se liga o apêndice), Cólon ascendente, Cólon transverso, Cólon descendente, Cólon sigmoide (curva em S) — absorvem água e sais e formam as fezes; Reto (armazena as fezes); Ânus (eliminação das fezes). — The total digestive tract measures about 9 meters from start to finish. The small intestine is where 90% of nutrients are absorbed. The colon removes water from the fecal mass before expulsion. The liver and pancreas are accessory organs — food does not pass through them, but they secrete enzymes and bile that aid digestion. The cecum contains the vermiform appendix, vestigial in humans.
What is the difference between the bolus and chyme?
Answer: You should present to the instructor that the bolus is the food chewed and moistened by saliva in the mouth, ready to be swallowed — still a solid, molded, and identifiable form; whereas chyme is the result of the action of the stomach on the bolus, after mixing with gastric juice (hydrochloric acid, pepsin) — it appears as a pasty, semi-liquid, acidic, and partially digested mass, which moves on to the small intestine to continue the digestive process. — After the stomach, chyme enters the duodenum and is mixed with bile and pancreatic juice, becoming 'chyle' (a more liquid, alkaline mass). Digestion is progressive: bolus → chyme → chyle. Each stage has a different pH and specific enzymes acting. The pyloric sphincter controls the release of chyme from the stomach into the duodenum in small amounts.
What is bile? Where is it produced? What is its function and where is it released?
Answer: You should present to the instructor that bile is a yellowish-green liquid produced continuously by the liver and stored in the gallbladder; it is released into the duodenum (the first part of the small intestine) through the common bile duct when there is fat in the food. Its main function is to emulsify fats (break them into smaller droplets) so that the pancreatic enzymes (lipases) can digest them efficiently. — Without bile, fats pass intact through the intestine — which is why people without a gallbladder avoid very fatty foods. Bile contains bile salts, cholesterol, and bilirubin (which gives feces their color). Gallstones (stones in the gallbladder) can block the duct and cause intense pain. The gallbladder is a storage organ — it can be removed without compromising digestion, although it requires a dietary adjustment.
What are villi? Why do they make food be absorbed more quickly? Do the following experiment: take a sheet of ordinary paper and a paper towel of similar size. Pour a tablespoon of water onto each one. Observe and make a comparison with the absorption by the villi.
Answer: Villi are small finger-shaped projections on the inner wall of the small intestine that, together with the microvilli (which cover them) and the intestinal folds, enormously increase the absorption surface (by up to about 600 times). They make food be absorbed more quickly because this enlarged surface places far more nutrients in contact with the absorptive cells and with the network of blood and lymphatic capillaries of each villus, speeding up the passage of nutrients into the blood. Experiment: pour a tablespoon of water onto an ordinary sheet of paper and onto a paper towel of similar size. The ordinary paper hardly absorbs anything (the water runs off/forms a puddle), while the paper towel absorbs quickly and abundantly, because it has a porous and irregular surface, with much more contact area. Comparison: the paper towel works like the villi — the larger the contact surface, the faster and more efficient the absorption of the liquid (or of nutrients, in the intestine). — Without villi, the small intestine would have to be 5 km long to absorb everything. With villi + microvilli, the absorptive area reaches 250 m² (the area of a tennis court). Celiac disease atrophies the villi, impairing absorption. The experiment of the paper towel vs. ordinary paper is instructive and clearly illustrates the principle of an increased surface for fast and efficient absorption.
What is dietary fiber? What is its importance for the digestive process? What happens if food remains longer inside the gastrointestinal tract?
Answer: You should present to the instructor that dietary fiber consists of plant parts that the body cannot digest (cellulose, hemicellulose, pectin, lignin), found in fruits, greens, vegetables, whole grains, and legumes. Importance: it speeds up intestinal transit, provides satiety, reduces cholesterol, controls blood sugar, and feeds the good bacteria. — WHO recommendation: 25-30g of fiber/day. Brazilians consume on average half of that. Soluble fibers (oats, fruits) reduce cholesterol; insoluble fibers (bran, greens) speed up transit. Chronic constipation is a risk factor for colorectal cancer — the second most common type of cancer in the world. Drinking water and exercising also help intestinal transit in addition to the dietary fiber consumed.
Demonstrate the digestion of starch into sugar, using the iodine test.
Answer: Iodine test experiment (to demonstrate the breakdown of starch): 1) Prepare two containers with a little starch dissolved in water (from corn or mashed bread); 2) In the first container, drop 2-3 drops of iodine (Lugol's) — it turns dark blue/violet, indicating the presence of starch (positive result); 3) In the second container, add saliva (which contains the enzyme amylase/ptyalin) and let it act for a few minutes, preferably warm; 4) Then drop 2-3 drops of iodine into the second container — the blue color does NOT appear (or is much weaker), because the amylase in the saliva broke the starch down into smaller sugars (maltose/glucose), which do not react with iodine. Conclusion: the comparison between the two containers demonstrates the digestion of starch into sugar by the action of saliva. — Iodine (Lugol's) reacts with starch to form a blue complex. Simple sugars (glucose, maltose) do not give this reaction. Salivary amylase breaks down starch into maltose and dextrins. The experiment is a classic in biology classes. It visually demonstrates the first stage of chemical digestion — proving that chewing well makes better use of the starch in the foods consumed.
Describe the six basic elements essential for life: carbohydrates, proteins, lipids, vitamins, minerals, and water, and where their digestion/absorption takes place.
Answer: 1) Carbohydrates (quick energy — digestion begins in the mouth, with salivary amylase, and is completed in the small intestine, with pancreatic amylase; absorption in the small intestine); 2) Proteins (building and repair of tissues — digestion begins in the stomach, with pepsin, and is completed in the small intestine, with pancreatic enzymes; absorption in the small intestine); 3) Lipids/Fats (energy reserve and hormones — digestion in the small intestine, with bile from the liver and pancreatic lipase; absorption in the small intestine); 4) Vitamins (regulators of the body — they do not need to be digested; they are absorbed directly in the small intestine); 5) Minerals (calcium, iron, etc., for bones, blood, and cellular functions — they are not digested; absorbed in the small intestine and partly in the large intestine); 6) Water (essential for life and transport — it is not digested; it is absorbed mainly in the large intestine and also in the small intestine). — Each nutrient has a specific site of digestion: carbohydrates begin in the mouth and end in the jejunum; proteins begin in the stomach; fats only in the small intestine. Most absorption takes place in the jejunum and ileum (small intestine). Water-soluble vitamins (B, C) are absorbed directly into the blood; fat-soluble ones (A, D, E, K) need fat to be absorbed by the enterocytes.
Know the difference between monosaccharides, oligosaccharides, and polysaccharides.
Answer: Monosaccharides: simple sugars formed by a single molecule (1 unit) — examples: glucose, fructose, and galactose. Oligosaccharides: formed by 2 to 10 linked units — examples: sucrose (glucose+fructose, table sugar), lactose (glucose+galactose, from milk), and maltose (2 glucoses, from malt). Polysaccharides: formed by many sugar units (hundreds to thousands) — examples: starch (the energy reserve of plants), glycogen (the energy reserve of animals), and cellulose (the fiber that forms the wall of plant cells). — The more units, the larger the molecule and the slower the digestion. That is why starch takes longer to turn into blood glucose than table sugar (an oligosaccharide) or fructose (a mono). Complex carbohydrates (polysaccharides) are preferable in healthy diets because of the slow rise in blood sugar. Cellulose (fiber) is not digestible by humans — it passes through the intestine without being absorbed.
What are amino acids? How many are there? What is the difference between essential and non-essential amino acids? What are the main sources of amino acids?
Answer: Amino acids are the small molecules that join together to form proteins. How many: there are 20 different amino acids that combine to assemble all the proteins of the body. Difference: 1) Essential amino acids (9: phenylalanine, valine, threonine, tryptophan, isoleucine, methionine, histidine, leucine, and lysine) — the body CANNOT produce them, so they must be obtained through diet; 2) Non-essential amino acids (the other 11) — the body itself can manufacture them from other substances, so they do not depend directly on the diet. Main sources: proteins of animal origin (meat, eggs, milk, and dairy products) and plant sources (legumes such as beans, lentils, chickpeas, and soybeans; oilseeds; whole grains). The combination of legumes with grains (e.g., rice and beans) provides the essential amino acids in a vegetarian diet. — The combination of beans + rice is a complete protein (together they have all the essential amino acids). Strict vegetarians need to vary their sources to ensure all the essential ones. Histidine is essential in children. A lack of tryptophan affects the production of serotonin (mood). Soy is one of the few complete plant proteins. Amino acids make up 20% of the human body, second only to water as the main component of tissues.
List 3 divine counsels regarding our diet.
Answer: 1) The original diet given by God was plant-based — Genesis 1:29 ('Behold, I have given you every herb bearing seed... and every tree, in the which is the fruit of a tree yielding seed; to you it shall be for meat'); 2) The distinction between clean and unclean foods — Leviticus 11 teaches which animals may or may not be eaten, a health principle maintained by God's people; 3) Everything we do, including eating and drinking, must be for the glory of God, with temperance — 1 Corinthians 10:31 ('Whether therefore ye eat, or drink... do all to the glory of God'). One may also cite the counsel to avoid alcoholic beverages and substances harmful to the body, which is the temple of the Holy Spirit (1 Corinthians 6:19-20). — The Adventist Church emphasizes healthy eating based on several texts. Ellen White wrote 'Counsels on Diet and Foods' detailing the ideal ovo-lacto-vegetarian diet. Current research (the Loma Linda Studies) shows that vegetarian Adventists live 7-10 years longer than the average American. Biblical principles about diet are part of Adventist identity around the world.