Nutrition, Metabolism, Catabolism, and Anabolism

• Nutrition is the process of absorbing nutrients from food to maintain homeostasis and prevent malnutrition.
• A balanced diet provides substrates for energy, essential amino acids, fatty acids, vitamins, minerals, and water.
• Malnutrition is an unhealthy state caused by inadequate nutrient, calorie, and/or vitamin intake.

Cellular Metabolism and Energy Production

• Metabolism maintains bodily function, provides energy, removes waste, and builds muscle.
• Mitochondria provide energy to cells.
• Metabolic turnover involves breaking down old cells and creating new ones.
• Cells grow by making more parts and then divide into two new cells for growth and repair.

Catabolism vs. Anabolism

• Catabolism breaks down food and molecules such as fatty acids and glucose, releasing energy for ATP production.
• Anabolism uses energy from ATP production to build structures like muscles or new body parts.
• ATP is the energy source cells use to perform work.

Homeostasis & Metabolic Regulation

• Homeostasis is the body’s way of maintaining balance.
• The function of the liver is to regulate blood sugar and store nutrients, also directs body on how to utilize food.
• Glycogen is the form of sugar stored in muscles as a backup energy source.
• Glucose is the sugar used by the brain for energy.
• Fat is stored in adipose tissue.
• A small amount of fat in the blood is carried by a protein as free fatty acids.
• Chylomicrons move fat from the intestines to the blood.
• VLDLs take fat from the liver to other body parts.
• LDLs carry cholesterol to the body and can cause heart problems if levels are too high.
• HDLs carry extra cholesterol back to the liver.
• Proteins are made from amino acids.
• Essential amino acids must be obtained from food, while nonessential amino acids can be synthesized by the body.
• Protein breakdown is not ideal for quick energy due to its slow process and waste product generation.

Absorptive vs. Postabsorptive States:

• During the absorptive state, which occurs right after eating, the body stores energy and uses food for fuel.
• In the postabsorptive state, between meals, the body uses stored energy like fat to sustain itself.
• Nitrogen, derived from proteins, is essential for building molecules like DNA.
• Positive nitrogen balance indicates more nitrogen intake than loss, which is good for growth.
• Negative nitrogen balance indicates more nitrogen loss than intake, potentially causing health issues.

Glycolysis & Mitochondrial Reactions

• Glycolysis breaks down glucose for quick energy without oxygen.
• The citric acid cycle and electron transport chain produce much ATP when oxygen is available.
• Glycolysis is quick but yields little ATP and creates lactic acid.
• Mitochondria are slower but produce more ATP with no harmful waste.
• Fat provides the most energy, followed by carbs and proteins.
• Metabolic rate is how fast the body uses energy.
• BMR is the energy used at rest.
• Consuming more energy than used results in fat storage, while burning more than consumed leads to fat loss.

Thermoregulation

• The body produces heat through metabolism.
• Heat loss occurs through sweating and breathing.

Heat control

• In hot conditions, the body sweats and skin turns red to cool down.
• In cold conditions, blood flow is directed away from the skin, and shivering occurs to retain heat.
• Larger individuals lose less heat.
• Babies struggle to maintain warmth but have special fat to assist.
• Fever occurs when body temperature rises to fight infection.