8-1 The Process of Nutrition
Nutrientsare substances that provide energy and materials for metabolic activities
Maintenance of cells
Nutrition = process by which organisms get food and break it down so it can be used for metabolism
Vitamins: coenzymes or converted into coenzymes
Minerals: from environment, chemical elements needed for normal functioning, Fe, Ca, P, I from soil, eat plants and animals
Organisms get food in two basic ways
Autotrophs organisms that can photosynthesize food
Phototrophs make their own food
Chemotrophs make food from chemical reactions
Heterotrophs - takes in food, ingest organic nutrients
Energy Content of Food
For any given quantity of food, the total energy released by cellular respiration is the same as would be released by burning the food.
Amount of heat given off
Joule - SI unit
Calorie commonly used unit
One calorie equals 4.2 joules. Also, defined the amount of heat that is needed to raise the temperature of 1 gram of water 1 degree Celsius.
Kilocalorie is 100 calories, or 1 Calorie
1 gram of carbohydrate or 1 gram of protein is about 4 Calories
1 gram of fat releases 9 Calories
Human Nutritional Needs
Energy from food
Daily calories needed affected by
Age, sex, lifestyle, weight, body condition
Younger more than old
Males more than females
Active people more than inactive
Gains weight = more calories than needed
Lose weight = less calories than needed
Figure 8-3, page 151
Need basic nutrients
Different kinds of food
Figure 8-4, page 152
Food Pyramid, figure 8-5, page 153
grains; vegetables; fruits; milk products; meat, poultry, fish, eggs, beans, nuts; fats, oils, sweets
Guidelines for a healthy plan
Variety of foods
Maintain a healthy weight
Low in fat and cholesterol, limit fried foods
Include vegetables, fruits, grain products in diet
Moderate sugar use, limit sweets and soft drinks
Moderate use of salt and sodium
Dont add salt to foods you eat
Linked to high blood pressure
8 - 1 Section Reviews
1. The way organisms obtain food and change it into forms usable for metabolism.
2. Proteins, carbohydrates, fats, vitamins, minerals, water.
3. Grain foods; vegetables; fruits; milk products; meat, poultry, fish, eggs, beans, and nuts; fats, oils, and sweets.
4. Humans are heterotrophs because they are classified as animals.
Adaptations for Nutrition and Digestion
Absorption in order for nutrients to be used by the cell it must pass through the cell membranes.
Digestion process by which food molecules are broken down.
Takes place in stages
Chemical breakdown into simpler compounds
Enzymes act on surface of food particles
Mechanical breakdown of food cut into small pieces
Exposes more food surface area to enzymes
The teeth of vertebrates are specialized to accommodate the type of food eaten.
Carnivores, eat-eaters, have pointed teeth but no flat grinding surfaces.
Herbivores, plan-eaters, have large and flat teeth.
Omnivores, such as humans, eat both plant and animal food and have both flat and sharp teeth.
Nutrition in Protists
Intracellular - happens inside the cell
Attracted to food by chemical stimuli
Crawl with false feet
Projections called " pseudopods "
Cytoplasm flow in and out
Membrane separates from other cell parts
Food vacuole forms
Moves about within cytoplasm
Fuses with lysosome, enzymes breakdown food into usable form
Diffusion across vacuole membrane into cytoplasm
Indigestible material is expelled from cell
Nutrition in the Earthworm
Inner tube digestive system
Mouth food enters
Food travels in one direction
Broken down mechanically and chemically
Anus waste leaves
Outer tube body wall
Nutrition in the grasshopper
Tubular digestive system
Mouthparts breakdown food mechanically
Chews leafy vegetation
Food mixes with saliva
Passes through esophagus into crop
Crop to gizzard
Ground into chitin
Passes to stomach
Chemical digestion and absorption occurs
Enzymes outside stomach act on food
Absorbs into blood stream through stomach walls
Transported to all cells
Undigested materials pass through the intestines
Stored in rectum where water is absorbed
Dried waste eliminated through anus
8 2 Section Review
1. In Food vacuoles within the cell
3. Increase the surface area of the intestine for absorption of nutrients
4. Mouth, esophagus, crop, gizzard, stomach, intestine, rectum, anus
5. Both are chemical breakdown of large molecules; extracellular digestion is outside cells, intracellular digestion is in cells
8 3 Human Digestive System
Parts of the Human Digestive System
Many adult humans cannot digest milk because they are deficient in lactase, the enzyme that hydrolyzes lactose, or milk sugar. A person who is lactose intolerant experiences abdominal bloating, cramps, flatulence, and diarrhea soon after ingesting milk or unfermented milk byproducts. Lactase deficiency is genetically determined.
The Mouth and Pharynx
The Small Intestines
The Large Intestines
8 3 Section Reviews
1. The salivary glands, liver, and pancreas aid digestion by secreting digestive fluids.
2. Wet food, cause it to form a bolus, break down starch into maltose.
4. Bile, pancreatic juice, intestinal juice.
5. Reabsorption of water, absorption of vitamins from bacteria, elimination.
6. Starch, maltose, proteins, fats, peptides.
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