Chapter 22 Notes - Dr. Meshagae Hunte-Brown PDF

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Dr. Meshagae Hunte-Brown...

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Chapter 22- Nutrition and Digestion 22.1-22.3: Food provides the raw materials for growth and the fuel to make it happen. 22.1- Why do organisms need food? Living organisms need raw materials and fuel to function. 1. Growth and activity 2. Raw materials required for life Digestion= The process that physically and chemically breaks down the food we eat into its fundamental macromolecular components. Our body quickly breaks down food and separates it into the usable and unusable. Nutrients= The usable materials: carbohydrates, lipids, proteins, vitamins, minerals, and water. These substances are used for energy, raw materials, and maintenance of the body’s systems. 22.2- What’s on the menu? Animals have a variety of diets. Carnivores= Predatory animals that consume only other animals. Ex. Spiders, snakes, mammals: wolves, seals, bats, cats, hawks, owls Herbivores= An organism that consumes only plants. Omnivores= Eat plants and animals and can digest both efficiently. Ex. Humans, cockroaches, bears, raccoons, chickens, flies, wasps 22.3- Calories count: organisms need sufficient energy. Calories= The energetic value of food is measured in very small amounts of energy. A single calorie is defined as the energy required to raise the temperature of 1 gram of water by 1° C. Kilocalorie (kcal)= “Calorie” in human consumption actually refers to this, which is 1,000 calories. Ex. Cookie box says “100 calories” actually “100 kilocalories” or “100,000 calories” Basal Metabolic Rate (BMR)= Refers to the amount of energy expended at rest, with no food in the digestive tract, in a neutral-temperature environment. 22.4-22.7: Nutrients are grouped into six categories. 22.4- Water is an essential nutrient.  Water transports nutrients and waste materials throughout the body.

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It takes part in chemical reactions. It serves as a solvent for many vitamins and minerals, amino acids, and sugars. It lubricates many joints, the spinal cord, and the eyes. It helps regulate body temperature.

22.5- Proteins in food are broken down to build proteins in the body. 3 Sources for Calories: 1. Proteins 2. Carbohydrates 3. Fats Proteins: Raw Material for Growth  Building material  Broken down into individual amino acids Are all proteins the same, or do they vary in important ways?  All animals require 20 different amino acids Essential Amino Acids= The 8 amino acids we must consume in food Ex. Milk, Eggs, Meat, Poultry, Cheese, and Fish “Complete Proteins” Non-Essential Amino Acids= The remaining 12. Ex. Plants “Non-Complete” 22.6- Carbohydrates and lipids provide bodies with energy and more. Carbohydrates: Fuel for Living Machines Carbohydrates= Primary fuel on which animal bodies run. Stored in our body mostly as glycogen in liver and muscle cells.  Ex. Fruits, vegetables, and grains Animals consume carbohydrates in form of: 1. Simple Sugars (Monosaccharides)= Glucose and Fructose 2. Disaccharides & Digestible Complex Sugars= Multiple simple sugars bonded together  Disaccharides= 2 simple sugars joined together o Ex. Sucrose (Table Sugar)  Complex Sugars= Hundreds of glucose densely connected o Ex. Starch and Glycogen 3. Fiber (Indigestible Complex Sugars)= Complex carbohydrate  Ex. Cellulose

Fats= Dense source of energy that can be efficiently stored in the body. The caloric content of a gram of fat is more than double that of a gram of protein or carbohydrate. o Saturated Fats  Fatty acids have straight tails and can be packed together tightly  Tend to be solid at room temperature  More likely to be stored as fat in the body  Fewer double bonds o Unsaturated Fats  Fatty acids have kinked tails and cannot be packed together tightly  Tend to be liquid at room temperature  Less likely to be stored as fat in the body 22.7- Vitamins and minerals are necessary for good health. Vitamins= Organic compounds that are essential nutrients required by the body in small amounts for normal growth and health. Minerals= The chemical elements, other than those commonly found in organic molecules- carbon, hydrogen, oxygen, and nitrogen- some of which are required in the diet in small amounts. 3 features common to all vitamins and minerals: 1. Don’t yield any usable energy- catalyze a wide range of other chemical reactions around the body. 2. Need to be consumed in smaller amounts than proteins, carbohydrates, and fats. Serve as reaction catalysts- so they can be used again and again. 3. If we have a healthy diet, we consume sufficient quantities of vitamins and minerals in our food. 22.8-22.13: We extract energy and nutrients from food. 22.8- We convert food into nutrients in four steps. 1. Ingestion  Food is taken into the body. 2. Digestion  Food is dismantled by physically and chemically breaking it down into absorbable molecules. 3. Absorption  Energy-rich food molecules are taken into the cells of the body, where they are used for energy and building materials. 4. Elimination

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The remaining parts of the consumed food (indigestible materials) are discarded as waste products, and much water reabsorption occurs.

22.9- Ingestion is the first step in the breakdown of food. Ingestion= The intake of food into your body. 1. Mouth 2. Teeth 3. Tongue 4. Esophagus  Salivary Glands- Secretes mucus that lubricates the food to help it pass into your stomach &…  Alpha-Amylase- Initiates the process of digestion  Breaks bonds and releases glucose that can be used for energy Teeth- Break down food  Tongue- Pushes food to back of back and down throat where it opens to 2 passageways:  Trachea= The windpipe, connects to the lungs.  Esophagus= Connects to the stomach.  Peristalsis= Waves of smooth muscle contractions that propel the food down the esophagus and into the stomach, where digestion continues. 22.10- Digestion dismantles food into usable parts. Stomach= A muscular J-shaped organ with thick, elastic walls that can expand greatly in size to accommodate a large meal. Sphincter= A ring of muscle at the point where the esophagus connects to the stomach. It seals off the stomach once the food has entered, preventing regurgitation of the stomach’s acidic contents into the esophagus. 3 functions of the stomach: 1. Breaks down and mixes food. 2. Secretes acid to further break down food chemically and to kill bacteria. 3. Begins some chemical digestion of proteins. Pepsin= A precursor molecule quickly converted to the protein-dismantling enzyme. Chyme= End result of the food: creamy, very acidic liquid. Small Intestine= Most chemical digestion occurs here- A long thin tube connected to the stomach. Pancreas= Nestled at the point where the stomach connects to the small intestine, plays a central role in digestion by secreting pancreatic juice through a duct into the very beginning portion of the small intestine.

Liver= Assists the small intestine with digestion. Bile= Produced by the liver and stored in the gall bladder- A juice that aids in the breakdown of fats. 22.11- Absorption moves nutrients from your gut to your cells. Absorption= The process by which the energy-rich food particles are taken from the digestive tract into the bloodstream and then into cells throughout the body, where they can be used for energy and building materials. 1. Nutrients are transported into the cells lining the walls. 2. Nutrients diffuse out of the cells and into the interstitial fluid bathing the cells. 3. Nutrients are picked up by the capillaries and move into the bloodstream, where they can be delivered to the organs tissues that need them. Small Intestine: 20 feet long with many folds. Villi: Finger-like projections that line the small intestine. Microvilli: Thread-like projections that line cells in the villi 22.12- Elimination removes unusable materials from your body. Elimination= Last phase in the breakdown of food- takes place as what’s left of the chyme (indigestible materials)- leaves the small intestine and enters the large intestine (colon) Large Intestine (Colon)= Serves to absorb water, salts, and some vitamins. The last part is the rectum, which serves as a storage compartment for the remaining parts of consumed food, the feces, which can then be defecated. Vitamin-synthesizing symbiotic bacteria found in the mammalian digestive system are found primarily here. 22.13- Animals have some alternative means for processing their food. Ruminant= Cows, bison, deer, goats, and sheep have complex 4-part stomachs in which they can digest plant matter that humans cannot. Coprophagy= Eating some of their feces allows them to significantly increase their nutritional intake from their cellulose-laden diet. 22.14-22.18: What we eat profoundly affects our health. 22.14- What constitutes a healthy diet?

1. Water 2. Proteins 3. Carbohydrates 4. Lipids 5. Vitamins 6. Mineral 2. Energy but no surplus calories 1. Grains 2. Vegetables 3. Fruits 4. Dairy 5. Meats and Beans 6. Oils 22.15- Obesity can result from too much of a good thing. Body Mass Index (BMI)= Equals body weight in kilograms divided by height in meters squared. 22.16- Weight-loss diets are a losing proposition. “Eat less. Move around more.” Problems with weight-loss diets: 1. Nutritional deficiencies 2. Metabolic rate reduction 3. Loss of muscle mass and body fluids rather than body fat 4. Increased lipoprotein lipase activity 22.17- Diabetes is caused by the body’s inability to regulate blood sugar effectively. Glycemic Index= Higher  considered less desirable in the diet. Diabetes= Problems with insulin-response systems 22.18- Food and infection: spicy foods may act as natural antibiotics....