A&P II: Chapter 24

Nutrients

Substances in food used for growth, maintenance, and energy.

Macronutrients

Nutrients required in large amounts (carbohydrates, lipids, proteins).

Micronutrients

Nutrients required in small amounts (vitamins, minerals).

Essential Nutrients

Nutrients the body cannot make fast enough and must obtain from diet.

Kilocalorie (kcal)

The energy value of food; amount of heat needed to raise 1 kg of water by 1°C.

Carbohydrates

Sugars and starches used primarily for energy.

Glucose

Body’s preferred cellular fuel.

Complex Carbohydrates

Starches found in grains and vegetables.

Simple Carbohydrates

Sugars found in fruits, honey, and milk.

Glycogen

Storage form of glucose in liver and muscles.

Soluble Fiber

Fiber that reduces blood cholesterol levels.

Insoluble Fiber

Fiber that increases stool bulk and speeds movement through the colon.

Lipids

Fats used for energy storage, membrane structure, and hormone production.

Triglycerides

Most abundant dietary lipid; composed of glycerol + 3 fatty acids.

Saturated Fats

Mostly animal fats; solid at room temperature.

Unsaturated Fats

Plant oils; liquid at room temperature.

Trans Fats

Hydrogenated oils associated with increased heart disease risk.

Cholesterol

Steroid found in animal products; used for membranes and hormone synthesis.

Essential Fatty Acids

Linoleic and linolenic acids; needed for prostaglandins and membrane synthesis.

HDL (High-Density Lipoprotein)

“Good cholesterol” that transports excess cholesterol to liver.

LDL (Low-Density Lipoprotein)

“Bad cholesterol” delivering cholesterol to tissues.

Proteins

Chains of amino acids used for structure, enzymes, and muscle.

Amino Acids

Building blocks of proteins.

Essential Amino Acids

Cannot be made by body; must be in diet.

Complete Proteins

Provide all essential amino acids (meat, eggs, dairy).

Incomplete Proteins

Lacking some essential amino acids (legumes, nuts, grains).

Nitrogen Balance

Balance between protein breakdown and synthesis.

Positive Nitrogen Balance

When synthesis exceeds breakdown (growth, pregnancy).

Negative Nitrogen Balance

When breakdown exceeds synthesis (illness, starvation).

Vitamins

Organic compounds needed in small amounts for metabolism.

Fat-Soluble Vitamins

Vitamins A, D, E, K stored in body fat.

Water-Soluble Vitamins

B-complex and vitamin C; not stored in large amounts.

Vitamin Deficiency

Lack of vitamins causing metabolic problems.

Minerals

Inorganic elements needed for body function (e.g., Ca, P, K, Na, Fe).

Major Minerals

Required in significant amounts (e.g., Ca, P, Mg).

Trace Minerals

Needed in small amounts (iodine, iron, zinc).

Calcium

Mineral important for bones, teeth, blood clotting, muscle function.

Sodium

Major extracellular ion important for fluid balance.

Potassium

Major intracellular ion required for nerve and muscle function.

Iron

Essential for hemoglobin production.

Iodine

Required for thyroid hormone synthesis.

Metabolism

Total sum of all biochemical reactions in the body.

Catabolism

Breakdown of larger molecules into smaller ones.

Anabolism

Building of large molecules from smaller ones.

ATP (Adenosine Triphosphate)

Main energy currency of the cell.

Phosphorylation

Adding a phosphate to a molecule to activate it.

Oxidation

Loss of electrons or hydrogen.

Reduction

Gain of electrons or hydrogen.

Oxidation–Reduction (Redox) Reaction

Coupled reaction where one molecule is oxidized and another is reduced.

NAD+

Electron carrier used in redox reactions.

FAD

Electron carrier used in ATP production.

Cellular Respiration

Catabolism of glucose to produce ATP.

Glycolysis

Breakdown of glucose into pyruvic acid in cytosol.

Krebs Cycle (Citric Acid Cycle)

Metabolic cycle producing NADH, FADH2, and ATP.

Electron Transport Chain

Mitochondrial pathway generating most ATP.

Chemiosmosis

Process using hydrogen gradient to make ATP.

Oxidative Phosphorylation

ATP formation driven by electron transport.

Substrate-Level Phosphorylation

ATP formation directly from chemical reactions.

Glycogenesis

Formation of glycogen from glucose.

Glycogenolysis

Breakdown of glycogen to release glucose.

Gluconeogenesis

Formation of glucose from noncarbohydrate sources (e.g., amino acids).

Lipolysis

Breakdown of stored fat into fatty acids and glycerol.

Lipogenesis

Conversion of excess glucose into fat stores.

Beta-Oxidation

Breakdown of fatty acids into acetyl-CoA.

Ketone Bodies

Acidic compounds formed during fat metabolism.

Ketosis

Accumulation of ketone bodies in blood.

Ketoacidosis

Dangerous drop in pH due to excessive ketones.

Amino Acid Deamination

Removal of amino group allowing amino acids to enter metabolism.

Urea

Waste product from amino acid breakdown excreted by kidneys.

Protein Synthesis

Formation of proteins from amino acids.

Essential Amino Acid Use

Must be present for proper protein synthesis.

Insulin

Hormone promoting glucose uptake and storage.

Glucagon

Hormone promoting energy release during fasting.

Fed (Absorptive) State

Period after eating when nutrients are being absorbed.

Postabsorptive (Fasting) State

Period when GI tract is empty; body uses stored energy.

Glycogen Reserves

Stored glucose in liver and muscles.

Fat Reserves

Body’s largest stored energy form.

Protein Reserves

Last-resort energy during severe starvation.

Hormonal Control of Fed State

Insulin dominates.

Hormonal Control of Fasting State

Glucagon, epinephrine, growth hormone dominate.

Role of the Liver

Processes nutrients, detoxifies, stores vitamins, and produces bile.

Hepatocytes

Liver cells performing metabolic functions.

Energy Intake

Energy from food consumed.

Energy Output

Energy lost as heat, used for work, or stored.

Basal Metabolic Rate (BMR)

Energy needed for vital functions at rest.

Thyroxine

The major hormone controlling BMR.

Factors Increasing BMR

Stress, fever, exercise, thyroxine.

Factors Decreasing BMR

Age, fasting, low thyroid hormone.

Hunger

Desire to eat triggered by physical need.

Appetite

Desire for food influenced by emotional/psychological factors.

Satiety

Feeling of fullness controlled by hypothalamus.

Short-Term Food Intake Regulation

Gut hormones, blood glucose, vagus nerve signals.

Long-Term Food Intake Regulation

Leptin and insulin levels.

Leptin

Hormone from fat cells that suppresses appetite.

Obesity

Excessive adipose tissue due to chronic energy imbalance.

Body Mass Index (BMI)

Weight-to-height ratio used to classify obesity.

Temperature Regulation

Controlled by hypothalamic “thermostat”.

Heat Production

By metabolism and muscle activity.

Heat Loss

Through radiation, evaporation, conduction, convection.

Fever

Controlled increase in body temperature due to pyrogens.