BIOC3006 – Diets, Metabolism, Digestion & Absorption

A comprehensive set of vocabulary flashcards summarising key terms, pathways, nutrients, transporters, diseases and dietary concepts from the BIOC3006 lecture on metabolism, diets, and digestive/absorptive physiology.

Metabolism

Whole-of-organism chemical processes that convert nutrients into energy and cellular components.

Gluconeogenesis

Formation of glucose from non-carbohydrate precursors in liver (and kidney).

Glycogen

Branched polymer of glucose serving as the body’s short-term energy store.

β-Oxidation

Catabolic pathway that breaks down fatty acids to acetyl-CoA, generating NADH and FADH2.

Urea Cycle

Hepatic pathway that converts toxic ammonia to urea for renal excretion.

Gut Microbiome

Community of microorganisms in the gastrointestinal tract influencing metabolism and health.

Essential Nutrients

Dietary components (≈40) that the body cannot synthesise in adequate amounts.

Macronutrients

Energy-yielding nutrients: carbohydrates, fats, proteins (and alcohol), plus water.

Micronutrients

Non-energy-yielding vitamins and minerals required in small amounts.

Recommended Dietary Intake (RDI)

Level of nutrient intake estimated to meet the needs of 97.5 % of a population.

Body Mass Index (BMI)

Weight (kg) divided by height squared (m²); a crude index of fatness.

Metabolic Syndrome (MetS)

Cluster of visceral obesity, dyslipidaemia, hypertension and hyperglycaemia increasing CVD/T2D risk.

Energy Balance

Relationship between energy intake and energy expenditure; imbalance leads to weight change.

Positive Energy Balance

State in which energy intake exceeds expenditure, promoting weight gain.

High-Protein Diet

Eating pattern emphasising protein and restricting carbohydrates to promote weight loss.

Atkins Diet

Popular low-carbohydrate, high-protein, high-fat diet aimed at rapid weight loss.

Atherogenic Dyslipidaemia

Blood lipid profile characterised by high TG, low HDL-C, and small dense LDL particles.

Developmental Origins of Health and Disease (DOHaD)

Concept that prenatal and early-life environment shapes adult disease risk via developmental plasticity.

Epigenetic Modification

Heritable change in gene expression (e.g., DNA methylation) without altering DNA sequence.

Digestion

Enzymatic breakdown of macromolecules into absorbable units in the GIT.

Absorption

Transport of digested nutrients across intestinal epithelium into blood or lymph.

Gastrointestinal Tract (GIT)

Digestive tube from mouth to anus where food is processed and absorbed.

Salivary Amylase

Enzyme in saliva initiating starch digestion in the mouth.

Pepsin

Stomach protease activated from pepsinogen by HCl; begins protein digestion.

Pancreatic Lipase

Enzyme that hydrolyses dietary TAG to MAG and free fatty acids in the duodenum.

Bile Acids

Amphipathic cholesterol derivatives that emulsify lipids for digestion and absorption.

Micelle

Soluble aggregate of bile salts and lipids facilitating uptake of hydrophobic molecules.

Chylomicron

Enterocyte-derived lipoprotein rich in TAG that transports dietary fat via lymphatics.

Apolipoprotein B-48

Structural protein of chylomicrons synthesised in intestinal cells.

GLUT2

Facilitative glucose transporter in liver, pancreatic β-cells and enterocyte basolateral membrane.

SGLT1

Sodium-dependent glucose/galactose cotransporter on intestinal brush border.

GLUT5

Facilitative transporter specific for fructose on intestinal apical membrane.

Disaccharidases

Brush-border enzymes (sucrase, lactase, maltase, isomaltase) that split dietary disaccharides.

Isomaltase-Sucrase Complex

Dual-activity intestinal enzyme hydrolysing α-1,6 linkages and sucrose.

Peptidases

Enzymes that hydrolyse peptides to amino acids and small oligopeptides.

PepT1

H+-coupled transporter moving di- and tripeptides into enterocytes.

Amino Acid Transporters

Na+-dependent or independent carriers specific for classes of amino acids.

Enterohepatic Circulation

Recycling of bile acids from ileum to liver via portal blood.

Triacylglycerol (TAG)

Major dietary lipid consisting of glycerol esterified with three fatty acids.

Monoglyceride (MAG) Pathway

Enterocyte pathway resynthesising TAG from 2-MAG and acyl-CoA.

Short-Chain Fatty Acid

Fatty acid with ≤6 carbons; absorbed directly into portal blood.

Low-Density Lipoprotein (LDL)

Cholesterol-rich lipoprotein delivering cholesterol to peripheral tissues; contains ApoB-100.

High-Density Lipoprotein (HDL)

Lipoprotein that collects cholesterol from tissues for return to liver; rich in ApoA-I.

Lipoprotein Lipase (LPL)

Endothelial enzyme hydrolysing TAG in chylomicrons and VLDL to release fatty acids.

Water-Soluble Vitamins

Vitamin group (B-complex, C, choline) absorbed mostly in jejunum, not stored extensively.

Fat-Soluble Vitamins

Vitamins A, D, E, K absorbed with dietary fat and stored in tissues.

Intrinsic Factor

Gastric glycoprotein required for vitamin B12 absorption in ileum.

Cobalamin (Vitamin B12)

Water-soluble vitamin acting as coenzyme in nucleic acid metabolism; absorbed via IF-cubulin complex.

Folate (Vitamin B9)

Coenzyme in one-carbon transfer reactions critical for DNA synthesis.

Thiamine (Vitamin B1)

Coenzyme (TPP) in carbohydrate metabolism; absorbed via pH-dependent transporter.

Coeliac Disease

Autoimmune intolerance to gluten causing villus atrophy and malabsorption; treated by gluten-free diet.

Exocrine Pancreatic Insufficiency

Deficiency of digestive enzymes leading to maldigestion and nutrient malabsorption.

Lactose Intolerance

Reduced lactase activity resulting in osmotic diarrhoea and gas upon lactose ingestion.

Malabsorption

Defective nutrient uptake due to reduced surface area, rapid transit or enzyme/bile deficiency.

Basal Metabolic Rate (BMR)

Energy expended at rest to maintain vital body functions.

Thermic Effect of Food (TEF)

Energy required for digestion, absorption and metabolism of nutrients.

Physical Activity Energy Expenditure

Calories burned through movement and exercise.

Coronary Heart Disease (CHD)

Atherosclerotic disease of coronary arteries; risk increased by obesity and dyslipidaemia.

Type 2 Diabetes Mellitus (T2D)

Metabolic disorder of insulin resistance and relative insulin deficiency.

Hypertension

Chronic elevation of arterial blood pressure; component of MetS.

Visceral Obesity

Excess adipose tissue around internal organs; strongly associated with MetS.

Insulin Resistance

Reduced responsiveness of cells to insulin, impairing glucose uptake.

Atherogenic

Promoting the formation of fatty plaques in arteries.

Dyslipidaemia

Abnormal blood lipid levels, especially high TG and LDL, low HDL.

Overweight

BMI 25–29.9 kg m⁻² indicating excess body weight for height.

Obesity

BMI ≥30 kg m⁻² associated with increased health risks.

Morbid Obesity

BMI ≥40 kg m⁻² or ≥35 with comorbidities; high mortality risk.

Dynamic System

Concept that human body composition and metabolism continually adapt over multiple time scales.

Heterotroph

Organism obtaining organic nutrients from other organisms; all animals are heterotrophs.

Dietary Reference Values (NRVs)

Australian framework incorporating RDI, EAR, UL and AI for nutrient intake.

Energy Density

Amount of energy (kJ or kcal) per gram of food.

High-Saturated-Fat Intake

Dietary pattern raising LDL-C and CVD risk.

Micronutrient Deficiency

Insufficient vitamin or mineral intake leading to specific disorders.

Transamination

Enzymatic transfer of an amino group between amino acids and keto acids.

Alanine

Amino acid transaminated from pyruvate; transports nitrogen from muscle to liver.

Gluconeogenic Substrate

Non-carbohydrate molecule (e.g., lactate, alanine, glycerol) that can be converted to glucose.

Ketone Bodies

Acetoacetate, β-hydroxybutyrate, acetone produced from fatty acids during fasting.

Very-Low-Density Lipoprotein (VLDL)

Liver-derived TAG-rich lipoprotein delivering endogenous fat to tissues.

Cholesterol Ester

Esterified form of cholesterol stored in lipoprotein cores.

Lecithin-Cholesterol Acyl Transferase (LCAT)

Plasma enzyme that esterifies cholesterol on HDL, promoting reverse cholesterol transport.

Disability-Adjusted Life Year (DALY)

Measure of overall disease burden combining years lived with disability and years of life lost.

Non-Alcoholic Fatty Liver Disease (NAFLD)

Hepatic fat accumulation often linked to obesity and insulin resistance.

Hyperglycaemia

Abnormally high blood glucose level, hallmark of diabetes.

Hypercortisolaemia

Elevated cortisol levels which can alter metabolism and promote central obesity.

Therapeutic Diet

Evidence-based dietary pattern aimed at treating a medical condition.

Placebo Effect in Dieting

Perceived health benefit arising from belief in a diet rather than its biochemical impact.

Dietary Fibre

Indigestible plant polysaccharides promoting bowel health and reducing CVD risk.

Phytochemicals

Bioactive plant compounds (e.g., polyphenols) with antioxidant or health-modulating effects.

Sarcopenic Obesity

Concurrent low muscle mass and high fat mass, especially in older adults.