Biology Chapter: Nutrition and Digestion

Human Nutrition, Digestion, Malnutrition and Traditional Foods

• Nutrition can be classified as either autotrophic or heterotrophic.
• Autotrophs produce their own food, such as plants.
• Heterotrophs consume other organisms for food, such as animals.
• A balanced diet includes 5 daily portions of fruit and vegetables, fiber-rich starchy foods, dairy/alternatives, beans, pulses, fish, eggs, meat and other protein sources, and unsaturated oils.
• Portions of fruits and vegetables are 80g of fresh/canned/frozen, 30g of dried fruit, and 150ml glass of fruit juice.
• Healthy eating includes consuming food and drinks with adequate amounts of fats, salt, and sugar in moderation.

Food Tests

• Food tests identify specific nutrients in food samples.
• Starch is identified with the addition of iodine, which causes a color change from brown to blue/black.
• Glucose is detected using Benedict's solution, which turns from blue to red/brown when heated.
• Proteins are identified using the Biuret test, which reacts to form blue/purple to pink.
• Lipids are identified using Grease Spot tests.

Molecules for Life

• Organic compounds contain carbon and hydrogen, sometimes oxygen and nitrogen.
• Inorganic compounds are not primarily composed of carbon and hydrogen.
• Monomers (e.g., glucose) combine to form polymers (e.g., starch).
• Hydrolysis breaks down polymers using water, while condensation forms polymers by releasing water.

Carbohydrates

• Carbohydrates are made up of carbon, hydrogen, and oxygen.
• Monosaccharides are simple sugars (e.g., glucose, fructose, galactose).
• Disaccharides are formed from two monosaccharides (e.g., maltose, lactose, sucrose).
• Polysaccharides are complex carbohydrates (e.g., starch, cellulose, glycogen).

Proteins

• Proteins are made up of carbon, hydrogen, oxygen, and nitrogen.
• Proteins' monomers are amino acids.
• Enzymes are proteins that catalyze reactions.
• Proteins have specific functions and structures, influenced by temperature and pH.

Lipids

• Lipids include fats and oils, composed of carbon, hydrogen, and oxygen.
• Lipids are primarily made up of glycerol and fatty acids.
• Lipids are insoluble in water but soluble in alcohol.
• Saturated fats have the maximum number of hydrogens, while unsaturated fats have fewer.

Digestive System

• Ingestion is the intake of food.
• Digestion breaks down food into smaller molecules; Mechanical (physical) and Chemical (enzymatic)
• Absorption is the process of nutrients passing into the bloodstream.
• Assimilation is the use of absorbed nutrients by the body.
• Elimination is the removal of indigestible waste.

Digestive System Organs

• Mouth: Chewing and initial digestion.
• Oesophagus: Transport of food to the stomach.
• Stomach: Churns and partially digests food using mechanical movement and chemicals.
• Small Intestine: Digestion and absorption of nutrients occur here.
• Large Intestine: Absorption of water and minerals.
• Rectum: Storage of feces.
• Anus: Elimination of feces.

Accessory Digestive Organs

• Liver: Produces bile necessary for lipid digestion.
• Gall bladder: Stores bile produced by the liver.
• Pancreas: Produces enzymes to aid in the digestion of all nutrients.

Enzymes

• Enzymes are proteins that speed up chemical reactions in the body without being used up in the process.
• Enzymes have active sites where substrates bind.
• Optimal temperatures and pH levels are crucial for enzyme activity.
• Enzymes are specific to particular substrates.

Control of Sugar

• Glucose is a simple sugar.
• Glycogen is stored in the liver and muscles when glucose is high.
• Insulin lowers blood glucose levels.
• Glucagon raises blood glucose levels in the blood.
• Pancreas produces insulin and glucogon.

Diabetes

• Diabetes is a disease characterized by high blood sugar levels.
• Type 1 diabetes occurs when the body doesn't produce enough insulin.
• Type 2 diabetes develops when the body doesn't use insulin effectively.
• Treatment and management vary for each type of diabetes.