📌 Professor’s Notes: Quick Revision
High-yield revision notes for rapid review before university examinations.
- Nutrition provides energy and essential nutrients required for growth, tissue repair, immunity and normal organ function. Both undernutrition and overnutrition can impair health. A balanced diet should contain carbohydrates, proteins, fats, vitamins, minerals, fiber and water.
- Carbohydrates and fats are the main energy sources. Carbohydrates provide about 4 kilocalories/g, while fats provide about 9 kilocalories/g. Excess carbohydrate can be converted into fat and stored in adipose tissue.
- Important carbohydrates include glucose, fructose, galactose, sucrose, lactose, maltose and starch. Lactase deficiency causes lactose intolerance with bloating, abdominal discomfort, flatulence and osmotic diarrhea. Soluble fiber slows glucose absorption and helps lower cholesterol, whereas insoluble fiber increases stool bulk.
- Dietary fats include triglycerides, phospholipids and cholesterol. Essential fatty acids are linoleic acid and alpha-linolenic acid. Fats provide energy, form cell membranes, aid absorption of vitamins A, D, E and K, provide insulation and serve as precursors for eicosanoids.
- Lipids are transported as lipoproteins. Chylomicrons carry dietary triglycerides, very-low-density lipoproteins carry liver-derived triglycerides, low-density lipoproteins deliver cholesterol to tissues, and high-density lipoproteins transport excess cholesterol to the liver.
- Proteins are made of amino acids joined by peptide bonds. They are essential for tissue structure, enzymes, hormones, transport, immunity, coagulation and muscle contraction. Adult protein requirement is approximately 0.8–1.0 g/kg/day, with increased needs during growth, pregnancy, lactation and illness.
- Vitamins are organic micronutrients that do not provide energy but act mainly as cofactors or coenzymes. Fat-soluble vitamins are A, D, E and K, while water-soluble vitamins include vitamin C and the B-complex vitamins.
- Vitamin A is important for vision, epithelial integrity, immunity and growth. Its deficiency causes night blindness and xerophthalmia. Vitamin D regulates calcium and phosphate balance; deficiency causes rickets in children and osteomalacia in adults.
- Vitamin E acts mainly as an antioxidant, while vitamin K is essential for activation of coagulation factors II, VII, IX and X and proteins C and S. Vitamin C is required for collagen synthesis and iron absorption; its deficiency causes scurvy.
- Important B-vitamin deficiencies are high-yield. Thiamine deficiency causes beriberi and Wernicke–Korsakoff syndrome; riboflavin deficiency causes angular cheilitis and glossitis; niacin deficiency causes pellagra with dermatitis, diarrhea and dementia; vitamin B6 deficiency may cause sideroblastic anemia and neuropathy.
- Folate is essential for DNA synthesis and erythropoiesis; deficiency causes megaloblastic anemia and increases the risk of neural tube defects. Vitamin B12 requires intrinsic factor for absorption in the terminal ileum. Its deficiency causes megaloblastic anemia with neurological manifestations.
- Important minerals include calcium, phosphorus, iron, iodine, zinc and selenium. Iron is essential for hemoglobin and oxygen transport; deficiency causes microcytic hypochromic anemia. Iodine is required for thyroid hormone synthesis, while zinc supports growth, immunity and wound healing.
- A balanced diet should provide adequate energy and nutrients according to age, sex, activity and physiological state. Cereals and pulses can provide complementary amino acids.
- Kwashiorkor results mainly from severe protein deficiency and is characterized by edema, fatty liver, muscle wasting and growth retardation. Marasmus results from prolonged deficiency of calories and protein and produces severe wasting without edema.
- Obesity results from chronic positive energy balance. It increases the risk of diabetes, hypertension, coronary artery disease, fatty liver disease, sleep apnea and some cancers. The hypothalamus regulates feeding; the lateral hypothalamic area promotes feeding, whereas the ventromedial nucleus promotes satiety. Leptin suppresses appetite, while ghrelin stimulates hunger.
📝 Practice MCQs
🎙️ Frequently Asked Viva Questions
High-yield viva questions with concise answers for rapid university examination preparation.
Q1. Why is a balanced diet essential for normal body function?
Answer: A balanced diet supplies adequate energy and all essential nutrients needed for growth, tissue repair, metabolism, immune function, and maintenance of normal physiological processes.
Q2. Why are carbohydrates called the primary source of energy?
Answer: Carbohydrates provide the preferred fuel for most tissues, especially the brain and red blood cells, and yield about 4 kcal/g on complete oxidation.
Q3. Why does lactase deficiency produce osmotic diarrhea?
Answer: Undigested lactose remains in the intestinal lumen, increasing osmotic pressure and drawing water into the intestine, resulting in diarrhea.
Q4. What is the physiological role of dietary fiber?
Answer: Dietary fiber improves bowel function. Soluble fiber slows glucose absorption and lowers cholesterol, while insoluble fiber increases stool bulk and prevents constipation.
Q5. Why are essential fatty acids called “essential”?
Answer: They cannot be synthesized in sufficient amounts by the body and must be obtained from the diet for normal growth, cell membrane function, and neurological development.
Q6. What is the physiological role of HDL?
Answer: High-density lipoprotein removes excess cholesterol from tissues and transports it to the liver for metabolism and excretion, reducing cardiovascular risk.
Q7. Why are proteins considered the body’s building material?
Answer: Proteins are required for tissue growth, repair, enzymes, hormones, transport proteins, immunity, muscle contraction, and maintenance of plasma oncotic pressure.
Q8. Why is vitamin D essential for bone health?
Answer: Vitamin D increases intestinal absorption of calcium and phosphate, promoting normal bone mineralization and skeletal strength.
Q9. Why is vitamin C important in wound healing?
Answer: Vitamin C is required for collagen synthesis, which strengthens connective tissue and promotes normal wound healing.
Q10. Why does vitamin K deficiency cause prolonged bleeding?
Answer: Vitamin K is required for activation of coagulation factors II, VII, IX, and X. Deficiency impairs blood clotting and prolongs bleeding.
Q11. Why is intrinsic factor essential for vitamin B₁₂ absorption?
Answer: Vitamin B₁₂ binds intrinsic factor in the stomach, and the complex is absorbed in the terminal ileum. Without intrinsic factor, absorption fails.
Q12. Why does iron deficiency produce microcytic hypochromic anemia?
Answer: Iron deficiency reduces hemoglobin synthesis, producing smaller red blood cells with reduced hemoglobin content.
Q13. Differentiate kwashiorkor and marasmus.
Answer: Kwashiorkor results mainly from protein deficiency and presents with edema. Marasmus results from deficiency of both calories and protein and presents with severe wasting without edema.
Q14. What is the physiological role of leptin and ghrelin?
Answer: Leptin suppresses appetite by signaling adequate energy stores, whereas ghrelin stimulates hunger before meals.
Q15. Why is BMI commonly used to assess obesity?
Answer: BMI provides a simple estimate of body fat based on weight relative to height and is widely used to classify overweight and obesity.
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