Chapter 5: Carbohydrates

Vocabulary flashcards covering carbohydrate types, digestive enzymes, regulatory hormones, and metabolic pathways from Chapter 5 of Wardlaw's Perspectives in Nutrition.

Carbohydrates

One of the body's main sources of energy, composed of carbon, hydrogen, and oxygen, providing $4\,\text{calories per gram}$.

Monosaccharides

The simplest carbohydrates, consisting of a single sugar unit.

Glucose

A monosaccharide that serves as the main sugar circulating in the blood and a vital energy source for cells, including the brain under normal conditions.

Fructose

A monosaccharide found naturally in fruit and honey.

Galactose

A monosaccharide that functions as a component of lactose, the sugar found in milk.

Disaccharides

Carbohydrates composed of two linked sugar units.

Sucrose

A disaccharide composed of glucose and fructose, commonly known as table sugar.

Lactose

A disaccharide composed of glucose and galactose, commonly known as milk sugar.

Maltose

A disaccharide composed of glucose and glucose, formed during the digestion of starch.

Polysaccharides

Complex carbohydrates made up of long chains of sugar units, including starch, glycogen, and fiber.

Starch

A polysaccharide that functions as the storage form of carbohydrate in plants.

Glycogen

A polysaccharide that functions as the storage form of glucose in humans and other animals.

Fiber

Carbohydrate that human digestive enzymes cannot fully break down.

Soluble fiber

Fiber that dissolves in water or forms a gel; it can slow glucose absorption, help lower LDL cholesterol, and be fermented by large intestine bacteria.

Insoluble fiber

Fiber that does not dissolve readily in water, adding bulk to stool and supporting regular bowel movements.

Amylase

An enzyme produced in the salivary glands and pancreas that breaks down starch into smaller carbohydrate chains and sugars.

Lactase

An enzyme located on the intestinal surface that breaks down lactose into glucose and galactose.

Sucrase

An enzyme that breaks down sucrose into glucose and fructose.

Maltase

An enzyme that breaks down maltose into two glucose molecules.

Lactose intolerance

A digestive condition caused by insufficient lactase production, resulting in undigested lactose entering the large intestine where it ferments, draws water, and causes gas, bloating, and diarrhea.

Insulin

A hormone produced by pancreatic beta cells that lowers blood glucose after meals by promoting glucose uptake, glycogen formation, energy storage, and suppressing hepatic glucose production.

Glucagon

A hormone produced by pancreatic alpha cells released during fasting to raise blood glucose by signaling the liver to break down glycogen and stimulating gluconeogenesis.

Glycogenesis

The metabolic process of making glycogen from glucose for storage.

Glycogenolysis

The metabolic process of breaking down glycogen.

Glycolysis

The metabolic pathway that breaks down glucose to release energy.

Gluconeogenesis

The metabolic process of making new glucose from non-carbohydrate sources, such as certain amino acids, glycerol, and lactate.

Liver glycogen

The storage form of glucose in the liver that is broken down to maintain circulating blood glucose levels between meals.

Muscle glycogen

The storage form of glucose in muscle tissue that exclusively supplies energy to the muscles themselves, lacking the enzyme required to release free glucose into the blood.

De novo lipogenesis

The metabolic conversion of excess carbohydrates into fatty acids when energy intake exceeds expenditure.

Glycemic index (GI)

A ranking system for carbohydrate-containing foods based on how much they raise blood glucose compared with a reference food under standardized conditions.

Glycemic load (GL)

A measure that evaluates the blood glucose impact of a food by accounting for both its glycemic index and the total amount of carbohydrate in a serving.

Glycemic response

The actual change in blood glucose concentration that occurs after consuming food.