17. Nutrients and Metabolism

Vocabulary practice cards covering organic compounds, essential nutrients, vitamins, minerals, liver anatomy and function, and the stages of cellular metabolism.

Nutrient

Any substance that is ingested and utilized in the body for growth, energy synthesis, and survival.

Six Categories of Nutrients

The essential nutrient groups required for animal metabolism: water, carbohydrates, lipids, proteins, vitamins, and minerals.

Essential Nutrient

A nutrient that an animal's body cannot synthesize on its own in sufficient amounts and must obtain from an external dietary source.

Taurine

An essential amino acid in felines that must be present in their diet because their bodies cannot synthesize it.

Simple Carbohydrates

Easily digestible sugars, such as glucose, that serve as immediate substrates for energy production.

Complex Carbohydrates

Polysaccharide starches and dietary fibers, such as cellulose, that provide energy storage and structural components.

Erythrocyte Metabolism

Red blood cells lack mitochondria and cannot utilize oxygen, requiring them to depend exclusively on glucose via anaerobic respiration to generate ATP.

Neutral Fats (Triglycerides)

Lipids that store energy (yielding twice as much energy as carbohydrates), store fat-soluble vitamins (A, D, E, K), and insulate and cushion internal organs.

Phospholipids

Lipids composed of glycerol, fatty acids, and a phosphate group that form the lipid bilayer of cellular membranes.

Cholesterol

The most important steroid in the body, serving as the essential precursor molecule for synthesizing other physiological steroids.

Essential Fatty Acids

Fatty acid monomers that must be consumed in the diet; the three clinically significant ones for dogs and cats are linoleic acid (omega-6), linolenic acid (omega-3), and arachidonic acid (omega-6).

Linoleic Acid

An omega-6 fatty acid that animals require in higher amounts than any other essential fatty acid.

All-or-Nothing Rule

The biological principle stating that if a cell is to synthesize a particular protein, all required amino acids must be present; otherwise, the anabolic process will not begin.

Water-Soluble Vitamins

Vitamins B and C, which dissolve quickly in blood, take effect rapidly, but leave the body quickly through metabolism.

Lipid-Soluble Vitamins

Vitamins A, D, E, and K, which take longer to break down, readily cross cell membranes, and are stored within tissues for long periods.

Vitamin K

A fat-soluble vitamin used extensively in the clotting cascade, often administered therapeutically to animals with severe coagulopathies.

Vitamin D

A fat-soluble vitamin (calciferols) required for bone growth and maintenance; animals require sunlight access because they cannot synthesize sufficient amounts independently.

Minerals

Inorganic chemical elements derived from external sources that are consumed in small quantities but are essential for organ function and systemic health.

Calcium

A vital mineral required for bone mineralization, muscle contraction, and transmission of nerve impulses.

Potassium

An essential mineral electrolyte required for nerve impulse transmission and healthy cardiac muscle contractions.

Iron

A mineral component of hemoglobin that reversibly binds oxygen for transport through the cardiovascular system.

Iodine

A trace mineral necessary for the biochemical synthesis of thyroid hormones by the thyroid gland.

Albumin

A major plasma protein produced by hepatocytes that maintains intravascular osmotic pressure, directly regulating blood volume and blood pressure.

Fibrinogen

A circulating liver protein that is converted to fibrin during coagulation, creating the meshwork that binds platelets together into a clot.

Bile

An alkaline emulsifier produced by hepatocytes and delivered through the biliary tree to facilitate the breakdown and digestion of lipids.

Hepatic Ammonia Detoxification

The metabolic process whereby hepatocytes convert toxic ammonia (generated from intestinal protein catabolism) into blood urea nitrogen (BUN) for safe renal excretion.

Catabolism

The metabolic breakdown of complex organic molecules into simpler components via decomposition reactions, releasing stored energy.

Anabolism

The metabolic synthesis of larger, more complex cellular molecules from simpler components via synthesis reactions, requiring energy input.

Absorptive State

The metabolic period occurring when nutrients are actively present in the gastrointestinal tract and undergoing absorption and utilization.

Post-Absorptive State

The metabolic phase during periods of fasting when the digestive tract is empty, forcing the body to break down stored reserves for energy.

Glycolysis

The initial cytosol stage of cellular respiration that cleaves glucose anaerobically into pyruvate and acetyl-CoA while generating ATP without free oxygen.

Aerobic Respiration

The oxygen-dependent mitochondrial stage of cellular respiration where acetyl-CoA is oxidized into $CO_2$ and NADH, driving the electron transport chain to produce large amounts of ATP.

Artifactual Hypoglycemia

A false laboratory finding caused by leaving whole blood unseparated at room temperature, allowing metabolically active erythrocytes to consume the serum glucose via anaerobic glycolysis.