Macronutrients: Carbohydrates, Lipids, and Proteins

Study Notes

Macronutrients: Carbohydrates, Lipids, and Proteins

Carbohydrates (CHO): Primarily composed of carbon (C), hydrogen (H), and oxygen (O) atoms. Plants are the primary source. Animals store carbohydrates as glycogen in the liver and muscles, a chain of glucose molecules.
Lipids (Fats): Composed of carbon (C), hydrogen (H) and oxygen (O) atoms. Essential for cell membranes, energy storage, and hormone production. Include phospholipids (with a hydrophilic head and hydrophobic tails) and fatty acids.
Proteins: Composed of carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) atoms. Made up of amino acids. Essential for numerous bodily functions including muscle building and repair. Humans require both essential (9) and non-essential (11) amino acids.

Carbohydrate Structure and Function

Monosaccharides: Simple sugars like glucose.
Disaccharides: Two monosaccharides linked together, like maltose.
Complex Carbs/ Polysaccharides: Long chains of sugar molecules.
Glycogen: Storage form of glucose in animals, found in the liver and muscles. Vital for energy during exercise.
High Fructose Corn Syrup (HFCS): A common sweetener, comprising 8-9% of American caloric intake. The liver can quickly process it into glucose. A primary source of energy during intense workouts.
Glycogen Depletion/Replenishment: Glycogen stores allow for sustained (circa 2 hours) intense exercise. Consumption of carbs (around 30-60g/hour) is crucial for maintaining performance due to gut transport limitation. Post-exercise glycogen replenishment involves two phases, one stimulated by gut carriers Glut 4 in muscles .
Carbohydrate Intake and Performance: Sufficient dietary carbohydrate (CHO) intake is vital for maintaining appropriate performance levels before competitions and during training sessions. At least 7g/kg of daily protein intake is essential during pre-competition periods

Lipid Structure and Function

Fatty Acids (FAs): Chains of carbon and hydrogen atoms. Omega-3 and Omega-6 fatty acids are important, differring by the position of the first double bond and their corresponding inflammatory effects.
Essential Fatty Acids (EFAs): Omega-3 (anti-inflammatory)/Omega-6 (pro-inflammatory). Humans cannot produce Omega-6, therefore it is considered an essential fatty acid.
Phospholipids: Essential components of cell membranes. Constructed of a phosphate group, and two FAs (hydrophobic tail) and a hydrophilic head.
Saturated vs Unsaturated Fats: Saturated fats lack double bonds, forming a straight structure and are generally solid at room temperature, while unsaturated fats contain double bonds.
Fat Quality and Health: Certain fats contribute significantly to overall health. Consuming healthy fats from plant and animal sources can have positive effects on health.

Protein Structure and Function

Amino Acids: Building blocks of proteins.
Dipeptides: Two amino acids joined together.
Polypeptides: Three or more amino acids joined together.
Protein Synthesis: Ribosomes regulate the process.
Essential vs. Non-Essential Amino Acids: Humans need to consume nine essential amino acids, while our bodies synthesize the eleven nonessential ones.

Omega-3s and Omega-6s:

Omega-3s: Anti-inflammatory, important for immune function and found in fish.
Omega-6s: Pro-inflammatory, found in processed foods. High levels are linked to increased cancer risk, high blood pressure and inflammatory diseases like arthritis.
Balance is Key: The optimal ratio of omega-6 to omega-3 is roughly 4:1. This ratio is important for a balanced diet, but, an imbalance can have adverse effects.

Fueling and Oxidative Stress

Oxidative Stress: The production of free radicals from dietary fats, particularly polyunsaturated fats. Free radicals are unstable molecules.
Antioxidant Defence: The body requires dietary sources for antioxidant defense, to neutralise the effects of free radicals. Omega-3's help to manage free radical damage more effectively than omega-6s.

Lipid Bilayer

Cell Membrane Structure: Cell membranes are composed of two layers of phospholipids. The hydrophobic tails of the phospholipids face inwards
Fluidity: The cell membrane's fluidity, influenced by the type of fats (saturated vs unsaturated) in the diet, affects its permeability.

Description

This quiz covers the fundamental concepts of macronutrients, including carbohydrates, lipids, and proteins. It examines their composition, structure, and functions in the human body as well as their sources in nature. Test your understanding of these essential nutrients and their roles in health and nutrition.