FN20170 Exam 2 Complete Study Guide: Lipids, Protein, and Energy

Comprehensive vocabulary flashcards covering nutritional biochemistry concepts from FN20170 Exam 2, including lipid classes and transport, protein synthesis, digestion and malnutrition, energy balance, and metabolic regulation.

Triglycerides

Lipids composed of $1$ glycerol backbone attached to $3$ fatty acid tails; their dense hydrocarbon chains pack efficiently in adipose tissue as a concentrated, lightweight energy storage form.

Phospholipids

Amphipathic lipids composed of $1$ glycerol, $2$ fatty acids, and a phosphate group; the hydrophilic phosphate head and hydrophobic tails allow them to form cell membrane lipid bilayers and act as emulsifiers in digestion.

Sterols (Cholesterol)

Lipids featuring a multi-ring carbon structure that insert into cell membranes to maintain fluidity and serve as structural precursors for steroid hormones, vitamin D, and bile acids.

Saturated Fatty Acids

Fatty acids containing no carbon-carbon double bonds ($0$ double bonds), yielding straight hydrocarbon chains that pack tightly together and remain solid at room temperature (e.g., butter).

Monounsaturated Fatty Acids (MUFA)

Fatty acids containing exactly $1$ double bond, creating a single bend or kink in the hydrocarbon chain.

Polyunsaturated Fatty Acids (PUFA)

Fatty acids containing $2$ or more double bonds; the resulting multiple kinks introduce bends and rigidity, lowering the melting point and increasing cell membrane fluidity.

Cholecystokinin (CCK)

A gut hormone released by the small intestine into the bloodstream upon the arrival of dietary fat; it signals the gallbladder to contract and secrete bile, while also acting as a short-term satiety signal.

Bile

An emulsifier released by the gallbladder that mechanically disperses large fat globules into tiny droplets to increase surface area for enzymatic attack, without cleaving chemical bonds.

Pancreatic Lipase

A digestive enzyme that chemically hydrolyzes triglycerides by cutting ester bonds, breaking them down into monoglycerides and free fatty acids.

Micelles

Water-soluble aggregations of free fatty acids, monoglycerides, and bile salts that transport lipid digestion products across the aqueous mucosal layer of intestinal villi to reach enterocytes for absorption.

Chylomicrons

Lipoproteins that originate in intestinal enterocytes to transport dietary lipids (principally triglycerides) through the lymphatic system into the bloodstream, delivering lipids to muscle and adipose tissue via lipoprotein lipase.

Low-Density Lipoprotein (LDL)

A lipoprotein formed in circulation from VLDL remnants that transports cholesterol and delivers it to peripheral cells and tissues.

High-Density Lipoprotein (HDL)

A lipoprotein originating in the liver and small intestine that scavenges excess cholesterol from peripheral cells and transports it back to the liver for excretion or bile acid synthesis (reverse cholesterol transport).

Peptide Medicines

Therapeutic agents consisting of amino acids linked by peptide bonds (such as insulin or GLP-1 agonists); they must usually be injected because oral ingestion exposes them to degradation by stomach acid and digestive proteases into free amino acids.

Protein Denaturation

The uncoiling and disruption of a protein's secondary and tertiary structure caused by external stressors like heat or acid breaking non-covalent bonds, leaving the primary sequence and covalent peptide bonds intact.

Amino Acid Quality

The nutritional value of a dietary protein determined by its completeness in essential amino acids and its physiological digestibility (measured using indices such as PDCAAS or DIAAS).

Marasmus

A form of severe protein-energy malnutrition caused by starvation and marked deficiency in both energy and protein, clinically characterized by extreme wasting and loss of body fat and skeletal muscle.

Kwashiorkor

A form of severe protein-energy malnutrition classically caused by inadequate protein intake despite adequate or near-adequate caloric intake; characterized by edema and a swollen abdomen resulting from insufficient albumin to maintain vascular fluid balance.

Protein-Energy Malnutrition (PEM)

A broad spectrum of nutritional disorders encompassing extreme somatic wasting (marasmus) as well as impaired protein synthesis and fluid retention (kwashiorkor).

Deamination

The enzymatic removal of the nitrogen-containing amine group ($-\text{NH}_2$) from an amino acid, allowing the carbon skeleton to be utilized for energy while converting the nitrogen into urea for renal excretion.

Gluconeogenesis

The metabolic pathway by which glucose is synthesized from non-carbohydrate carbon substrates (such as glucogenic amino acids) during states of low carbohydrate availability or fasting.

Total Daily Energy Expenditure (TDEE)

The total amount of energy expended by an individual across a 24-hour day, calculated as $\text{TDEE} = \text{BMR} + \text{TEF} + \text{NEAT} + \text{EAT}$.

Basal Metabolic Rate (BMR)

The foundational energy expended to maintain involuntary, resting vital physiological functions, driven primarily by total body mass and lean muscle tissue.

Thermic Effect of Food (TEF)

The component of daily energy expenditure required for the ingestion, digestion, absorption, and metabolic processing of food nutrients.

Non-Exercise Activity Thermogenesis (NEAT)

The energy expended through spontaneous, non-deliberate daily activities such as standing, pacing, walking, taking the stairs, and fidgeting throughout the day.

Exercise Activity Thermogenesis (EAT)

The energy expended through intentional, planned physical exercise workouts.

Catabolism

The metabolic breakdown of larger, complex molecules into simpler compounds to release energy (e.g., lipolysis, glycolysis).

Anabolism

The energy-requiring metabolic synthesis of complex cellular structures and molecules from simpler precursor units (e.g., protein synthesis, glycogen storage).

Hunger

The internal, physiological biological drive to eat initiated by physical homeostatic cues such as low blood glucose, elevated ghrelin, and empty stomach wall stretch.

Appetite

The psychological desire to consume food triggered by external environmental cues, sensory experiences, emotions, or habit, occurring even without physiological energy deficits.

Lipoprotein Lipase (LPL)

An enzyme located on vascular endothelial capillary surfaces activated by postprandial insulin that promotes the uptake and clearance of circulating fatty acids for storage within adipose tissue.

Hormone-Sensitive Lipase (HSL)

An intracellular enzyme in adipocytes stimulated by lower insulin and elevated catecholamines (such as epinephrine) that hydrolyzes stored triglycerides into free fatty acids to be mobilized for fuel.

Ghrelin

An orexigenic peptide hormone secreted by the stomach that stimulates hunger and drives food intake between meals or during prolonged caloric deficit.

Leptin

A long-term satiety hormone produced by adipose tissue that communicates stored energy availability to the brain; its circulating levels decline during sustained caloric restriction and fat loss.

GLP-1 Medication

A class of pharmaceutical agents that mimics glucagon-like peptide-1 to delay gastric emptying and act on central nervous system receptors to enhance satiety and suppress appetite.

Gastric Bypass

A bariatric surgical intervention that physically restricts stomach volume and reroutes the small intestine, promoting weight loss through both mechanical restriction and induced nutrient malabsorption.

Metabolic Adaptation

A disproportionate reduction in basal metabolic rate below what is predicted by mass loss alone, alongside persistent elevations in ghrelin and suppression of leptin, observed after massive rapid weight loss.

Diet Culture

A societal belief system that equates thinness with moral virtue and health while promoting restrictive, rigid dietary behaviors.

Weight Stigma

The negative social stereotyping, prejudice, and discriminatory practices directed at individuals based entirely on their physical body size and weight.