Answer the following question in as much detail as possible. As omnivores, our b
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Question
Answer the following question in as much detail as possible.
As omnivores, our bodies have evolved to efficiently digest carbohydrates, proteins, and lipids. However, in our culture we see an increase in the consumption of foods prepared or covered in lipids such as fats and dairy products, which lead to obesity and malnutrition. If you were to consume an empanada (corn flour pastry filled with meat and cheese), how would the digestive process of this pastry differ if the empanada is baked or fried? Explain the process of digestion (BOTH baked and fried) of the different compounds that make the empanada. (NOTE: describe organs, enzymes, accessory organs, and processes).
Explanation / Answer
Answer:
Digestion is the mechanical and chemical breakdown of food.
Digestive Processes in the Mouth:
1. mechanical digestion in mouth (chewing)
2. salivary amylase begins the breakdown of starch
3. mouth is at a neutral pH (great for amylase)
4. propulsion initiated for swallowing
5. The pharynx and esophagus serve as a passage way for food from the mouth to the stomach.
Saliva functions:
1. moisten
2. starch/fat digestion
3. clean teeth
4. inhibit bacteria
5. bind food together into bolus
Saliva is composed of:
1. Salivary amylase - begins the break down of starch
2. Lingual Lipase - digests fat activated by stomach acid
3. Mucus - aid in swallowing.
4. Lysozome - kills bacteria
5. Immunoglobulin a - inhibits bacteria
6. electrolytes- Na, K, Cl phosphate, bicarbonate
(pH of saliva is 6.8 to 7.0)
The stomach chemically breaks down proteins into fats, and food (bolus) turns into chyme.
Stomach Glands:
1. mucous neck cells- make mucus to protect stomach from acid environment
2. parietal cells- make HCl, ghrelin, and intrinsic factor
3. g cells- secrete gastrin and increase gastric/secretory mobility/activity.
4. chief cells - make pepsinogen and gastric lipase (pepsinogen activated to pepsin due to HCL in the stomach)
5. enterendocrine cells- make hormones that regulate digestion and gastric mobility
Stomach Acid Functions:
1. Activate enzymes pepsin and lingual lipase.
2. Breakdown plant connective tissues and cell walls.
3. Denatures proteins and converts minerals to a more bioavailable form.
4. Contributes to immunity by destroying ingested pathogens.
Small intestine is composed of three sections – Duodeum, jejunum, and ileum. Ileocecal valve (sphincter) connects the small intestine to the large intestine. Most digestion and absorption take place in the small intestine.
Baking:
Since the temperatures for baking are high, vitamins can be lost through baking, thiamine and vitamin C being the most unstable at heat. Baking can make protein in meat and eggs easier to digest, and in case of grain-based products, it can increase the amount of vitamin B, as this micronutrient can be synthesized as a result of yeast activity.
Frying:
The least healthy method of cooking is frying, which destroys more nutrients due to the higher temperatures. Frying requires you to cut and peel the foods before preparing them, so it exposes the products to oxidation and this causes significant nutrient loss.
Foods that are fried absorb fat and end up with a higher energy density, and they’re harder to digest than baked foods for example, so if you have to opt between frying and baking for your meat-based dishes, baking is always a better idea for keeping the meals lighter.
Digestion of fats in empanada:
Digestion of some fats can begin in the mouth where lingual lipase breaks down some short chain lipids into diglycerides. However fats are mainly digested in the small intestine.
Pancreatic lipase breaks down triglycerides into free fatty acids and monoglycerides. Pancreatic lipase works with the help of the salts from bile secreted by the liver and the gallbladder.
Bile salts attach to triglycerides and help to emulsify them; this aids access by pancreatic lipase because the lipase is water-soluble, but the fatty triglycerides are hydrophobic and tend to orient toward each other and away from the watery intestinal surroundings.
The bile salts act to hold the triglycerides in their watery surroundings until the lipase can break them into the smaller components that are able to enter the villi for absorption.
Digestion of carbohydrates in empanada:
Some carbohydrates are degraded into simple sugars, or monosaccharides (e.g., glucose, galactose) and are absorbed by the small intestine. Pancreatic amylase breaks down some carbohydrates (notably starch) into oligosaccharides. Other carbohydrates pass undigested into the large intestine, where they are digested by intestinal bacteria.
Brush border enzymes take over from there. The most important brush border enzymes are dextrinase and glucoamylase, which further break down oligosaccharides. Other brush border enzymes are maltase, sucrase, and lactase.
Digestion of proteins in empanada:
Proteins are degraded into small peptides and amino acids before absorption. Their chemical breakdown begins in the stomach and continues through the large intestine.
Proteolytic enzymes, including trypsin and chymotrypsin, are secreted by the pancreas and cleave proteins into smaller peptides. Carboxypeptidase, a pancreatic brush border enzyme, splits one amino acid at a time. Aminopeptidase and dipeptidase free the end amino acid products.