BIO 102 Anatomy Chapter 24: Nutrition & Metabolism

BIO 102 Anatomy and Physiology - Chapter 24: Nutrition and Metabolism

• Learning Objectives:
  • Define and describe nutrient, macronutrient, micronutrient, essential nutrient, RDA, caloric balance, nitrogen balance, BMI, BMR, calorie, and metabolism (anabolism, catabolism)
  • Describe anabolic and catabolic processes of carbohydrate, lipid, and protein metabolism; explain processes related to absorptive (fed) and post-absorptive (fasted) states; identify major hormones associated with those states
  • Explain how neural and hormonal factors regulate food intake

Nutrients

• Nutrients are chemical substances from the environment needed for survival, growth, repair, and maintenance of the body
• Macronutrients: carbohydrates, proteins, fats
• Micronutrients: vitamins, minerals
• Essential nutrients: cannot be synthesized by human cells; include certain fatty acids, amino acids, and vitamins

Energy Values of Food

• Calorie (kilocalorie): amount of heat energy needed to raise the temperature of 1 kg of water by 1°C
• Carbohydrates: 4.1 calories per gram
• Proteins: 4.1 calories per gram
• Lipids: 9.5 calories per gram

Stages of Metabolism

• Stage 1: Digestion in the GI tract breaks down nutrients into absorbable units and transports them to tissues
• Stage 2: Tissue cells use the absorbed nutrients for anabolism (building macromolecules) or catabolism (breaking down nutrients)
• Stage 3: Mitochondria perform oxidative breakdown of nutrient products, releasing CO2, producing water, and forming ATP

Carbohydrate Utilization

• Disaccharides include sucrose, lactose, and maltose
• Monosaccharides include glucose, fructose, and galactose
• Glucose is the body's primary carbohydrate energy source
• Used for energy, producing certain molecules (ribose, deoxyribose), stored as glycogen in liver and muscles, and converted to fat and stored in adipose tissue

Carbohydrate Metabolism

• Glycolysis: converts glucose to pyruvic acid
• Glycogenesis: polymerizes glucose to form glycogen
• Glycogenolysis: hydrolyzes glycogen to glucose monomers
• Gluconeogenesis: forms glucose from non-carbohydrate precursors

Lipid Metabolism

• The liver synthesizes lipids from fatty acids
• Triglycerides are a major form of lipid storage
• Lipoproteins transport lipids in the blood
• Key types of lipoproteins include Chylomicrons, VLDLs, LDLs and HDLs
• Beta oxidation converts fatty acids to acetyl CoA
• Lipolysis breaks down lipids into fatty acids and glycerol
• Lipogenesis forms lipids from acetyl CoA and glycerol

Protein Metabolism

• Proteins are broken down into amino acids
• Amino acids can be used to make new proteins or to produce energy
• Essential amino acids cannot be synthesized by the body
• Transamination transfers an amine group from one amino acid to a keto acid, producing a different amino acid
• Oxidative deamination removes the amine group from glutamic acid, producing ammonia and a-ketoglutaric acid

Nitrogen Balance

• Homeostatic state where the rate of protein synthesis equals the rate of protein breakdown and loss
• Positive nitrogen balance: protein synthesis exceeds protein breakdown (normal in children and pregnant women)
• Negative nitrogen balance: protein breakdown exceeds protein synthesis (happens in times of stress, burns, infections, injuries, or poor nutrition)

Energy Requirements and Balance

• Basal metabolic rate (BMR): rate at which the body expends energy at rest
• Body Mass Index (BMI): measurement of body weight relative to height
• Energy balance: occurs when caloric intake equals caloric output, leads to weight gain or loss

Regulation of Appetite

• Short-term controls: vagal afferents, nutrient signals (glucose, amino acids, fatty acids) and gut hormones
• Long-term controls: signals from the hypothalamus, like insulin, leptin affecting appetite

###Dietary Guidelines

• Emphasize education
• Utilize resources like MyPlate
• Prioritize balanced food intake (fruits, vegetables, lean proteins, whole grains, low amounts of sugars)
• Follow healthy habits (exercise and reducing fast food)

Test your knowledge on nutrition and metabolism as covered in BIO 102 Anatomy and Physiology, Chapter 24. This quiz will explore key concepts such as nutrients, macronutrients, metabolic processes, and how the body regulates food intake. Understand the essential nutrients and their roles in the body.