Biology Unit 2 Macronutrients and Micronutrients PDF

Biology: Unit 2 ⋅˚₊‧ ୨୧ ‧₊˚ ⋅ Macronutrients 1. Carbohydrates → Source: Bread, rice, pasta → Function: Quick energy → Example: Glucose → ATP 2. Proteins → Source: Meat, beans, eggs → Function: Growth, repair, enzymes → Example: Amino acids → Muscle building 3. Fats → Sourc...

Biology: Unit 2 ⋅˚₊‧ ୨୧ ‧₊˚ ⋅ Macronutrients 1. Carbohydrates → Source: Bread, rice, pasta → Function: Quick energy → Example: Glucose → ATP 2. Proteins → Source: Meat, beans, eggs → Function: Growth, repair, enzymes → Example: Amino acids → Muscle building 3. Fats → Source: Butter, nuts, oils → Function: Long-term energy, insulation → Example: Fatty acids & Glycerol Micronutrients Vitamins → Vitamin C: Boosts immunity (Sources: Citrus fruits) → Vitamin D: Bone health (Sources: Sunlight, fish) Minerals → Iron: Red blood cells (Sources: Spinach) → Calcium: Bone strength (Sources: Milk, kale) Diet Comparisons Type About Pros Cons Vegan Made up of only Environmentally Risk of B12 plant-based foods. friendly, no animal deficiency, limited harm protein sources Vegetarian A diet that does not Balance of ethics & May lack protein contain meat and nutrition variety majorly plant-based Non-Vegetarian A diet that contains Complete protein, High cholesterol risk, both meat and rich in iron not sustainable plant-based foods Key Digestive Enzymes Amylase: Starch → Maltose (Saliva & Pancreas) Pepsin: Proteins → Peptides (Stomach) Lipase: Fats → Fatty acids & Glycerol (Pancreas) Enzyme Source Acts On End Product Salivary Amylase Salivary Glands Starch Maltose Pepsin Stomach Protein Peptides Pancreatic Amylase Pancreas Starch Maltose Tripsin Pancreas Protein Peptides Lipase Pancreas Fats Fatty acids + Glycerol Mouth → Teeth: Chew and grind food into smaller pieces (physical digestion). → Saliva: Secreted by salivary glands. Contains amylase, which starts breaking down starch into maltose (chemical digestion). Tongue: Helps mix food with saliva. Rolls food into a bolus for easier swallowing. → Taste buds: Detect flavors (sweet, salty, sour, bitter, umami). Incisors cut food, canines tear food, premolars crush it, and molars grind it into smaller pieces for swallowing. Oesophagus → Function: A muscular tube that connects the mouth to the stomach. Moves food through peristalsis (wave-like muscular contractions). Stomach → Function: Temporarily stores food and mixes it with gastric juices. Physical digestion: Churns food to break it down further. Chemical digestion: ○ Gastric juice contains: Hydrochloric acid (HCl): Kills harmful bacteria and provides an acidic environment for enzymes to work. Pepsin: Breaks down proteins into smaller peptides. ○ Mucus lining protects the stomach walls from acid. Liver Produces bile, which: ○ Emulsifies fats (breaks them into smaller droplets for easier digestion by enzymes). Stores and releases nutrients like glucose, vitamins, and minerals. Detoxifies harmful substances in the blood. Gallbladder Stores and concentrates bile produced by the liver. Releases bile into the small intestine via the bile duct when fats are present. Pancreas Produces digestive enzymes: ○ Amylase: Breaks down starch into maltose. ○ Lipase: Breaks down fats into fatty acids and glycerol. ○ Trypsin: Breaks down proteins into smaller peptides. Produces sodium bicarbonate to neutralize stomach acid in the small intestine. Small Intestine ➔ Divided into three parts: ◆ Duodenum: Receives bile and pancreatic juices to continue chemical digestion. ◆ Jejunum: Nutrients (sugars, amino acids, fatty acids) are absorbed into the bloodstream. ◆ Ileum: Absorbs vitamins (like B12) and leftover nutrients. ➔ Key Feature: Villi and microvilli increase surface area for maximum absorption. Large Intestine (Colon) ➔ Function: ◆ Absorbs water and salts from undigested food. ◆ Forms and stores solid waste (feces). ➔ Houses bacteria that: ◆ Help produce Vitamin K. ◆ Break down undigested carbohydrates (fiber). Rectum Function:  ○ Stores feces temporarily until defecation. Anus Function: ○ The opening through which waste exits the body. ○ Controlled by internal and external sphincter muscles. Digestive Process The digestive process begins in the mouth, where food is broken down physically by chewing and chemically by saliva. Saliva, produced by salivary glands, contains the enzyme amylase, which starts breaking down starch into maltose. The chewed food, now called a bolus, is pushed by the tongue into the oesophagus, where wave-like muscular contractions called peristalsis transport it to the stomach. In the stomach, food is mixed and churned with gastric juices containing hydrochloric acid (HCl) and pepsin, which initiate protein digestion. The acidic environment also kills harmful bacteria. From the stomach, the partially digested food, now called chyme, moves into the small intestine, specifically the duodenum, where digestion continues. The liver produces bile, stored in the gallbladder, which is released into the small intestine to emulsify fats, breaking them into smaller droplets. The pancreas secretes enzymes like lipase (fats → fatty acids and glycerol), amylase (starch → maltose), and trypsin (proteins → peptides), as well as bicarbonate to neutralize stomach acid. The small intestine is the primary site of nutrient absorption. Its inner surface is lined with villi and microvilli, which increase the surface area for efficient absorption of glucose, amino acids, fatty acids, vitamins, and minerals into the bloodstream. The undigested material then passes into the large intestine, where water and salts are reabsorbed, and helpful bacteria produce vitamins like Vitamin K. The remaining waste forms solid feces, stored temporarily in the rectum before being expelled through the anus during defecation. This coordinated system ensures food is broken down into usable components, absorbed for energy and growth, and efficiently disposes of waste, maintaining overall health.