NSC-419 Quiz 2 Review

What are carbohydrates?

Energy-yielding macronutrients made of carbon, hydrogen, and oxygen that serve as the primary energy source for the brain

What are the three main types of carbohydrates?

Monosaccharides, disaccharides, and polysaccharides

What are the most common monosaccharides?

Glucose, fructose, and galactose

What is the structure of a disaccharide?

Two monosaccharides joined by a glycosidic bond

What monosaccharides make up sucrose?

Glucose and fructose

What monosaccharides make up lactose?

Glucose and galactose

What monosaccharides make up maltose?

Glucose and glucose

What are oligosaccharides?

Carbohydrates composed of 3-10 monosaccharides that are often fermented in the colon

What are polysaccharides?

Long chains of monosaccharides such as starch, glycogen, and fiber

What is starch?

The storage form of carbohydrate in plants composed of amylose and amylopectin

What is glycogen?

The storage form of carbohydrate in animals stored in the liver and muscles

What is dietary fiber?

Indigestible carbohydrates found in plant foods

Where does carbohydrate digestion begin?

In the mouth

What enzyme begins carbohydrate digestion?

Salivary amylase

Why does carbohydrate digestion stop in the stomach?

The acidic environment inactivates amylase

Where does most carbohydrate digestion occur?

In the small intestine

What enzyme continues starch digestion in the small intestine?

Pancreatic amylase

What enzymes complete carbohydrate digestion at the brush border?

Maltase, lactase, sucrase, and isomaltase

How are glucose and galactose absorbed?

By active transport via SGLT1

How is fructose absorbed?

By facilitated diffusion via GLUT5

What transporter moves monosaccharides into the bloodstream?

GLUT2

What is euglycemia?

The maintenance of normal blood glucose levels

What is the normal fasting blood glucose range?

70-110 mg/100 mL

What hormone lowers blood glucose levels?

Insulin

What hormone raises blood glucose levels?

Glucagon

What hormone increases glucose availability during stress?

Epinephrine

What hormone promotes gluconeogenesis during fasting and stress?

Cortisol

What is glycolysis?

The breakdown of glucose into pyruvate to produce ATP

What is glycogenesis?

The conversion of glucose to glycogen for storage

What is glycogenolysis?

The breakdown of glycogen to release glucose

What is gluconeogenesis?

The formation of glucose from non-carbohydrate sources

What is the pentose phosphate pathway?

A pathway that produces NADPH and ribose-5-phosphate

What is the glycemic index (GI)?

A measure of how quickly a food raises blood glucose

What is glycemic load (GL)?

A measure that accounts for both carbohydrate quality and quantity

What are benefits of a low-GI diet?

Lower cholesterol, reduced risk of type 2 diabetes, improved blood glucose control

What is high-fructose corn syrup (HFCS)?

A liquid sweetener derived from corn used widely in processed foods

What is the composition of HFCS?

Approximately 55% fructose and 42% glucose

How does HFCS compare to sucrose?

They are nearly identical in composition and metabolism

What causes lactose intolerance?

A deficiency of the enzyme lactase

What is cow's milk allergy?

An immune reaction to milk proteins

What is soluble fiber?

Fiber that dissolves in water and slows digestion

What is insoluble fiber?

Fiber that increases stool bulk and promotes bowel regularity

What are examples of soluble fiber?

Pectins, gums, and mucilages

What are examples of insoluble fiber?

Cellulose, hemicellulose, and lignin

What are health benefits of dietary fiber?

Improved satiety, lower cholesterol, better glycemic control

What are health risks of low fiber intake?

Constipation, diverticulosis, and poor blood glucose control

What are lipids?

Energy-yielding macronutrients that provide 9 kcal per gram

What are the four main types of lipids?

Fatty acids, triglycerides, phospholipids, and sterols

What are the main functions of lipids?

Energy storage, insulation, cell membrane structure, and hormone production

What is a saturated fatty acid?

A fatty acid with no double bonds

What is a monounsaturated fatty acid?

A fatty acid with one double bond

What is a polyunsaturated fatty acid?

A fatty acid with two or more double bonds

What are essential fatty acids?

Fatty acids the body cannot synthesize and must obtain from the diet

What are the two essential fatty acids?

Linoleic acid (omega-6) and linolenic acid (omega-3)

What are the health roles of essential fatty acids?

Growth, inflammation regulation, and cardiovascular health

What is a triglyceride?

A lipid composed of a glycerol backbone and three fatty acids

What is the primary function of triglycerides?

Energy storage

What is a phospholipid?

A lipid with a glycerol backbone, two fatty acids, and a phosphate group

Why are phospholipids important?

They form cell membranes and act as emulsifiers

What is a sterol?

A lipid with a ring structure such as cholesterol

What is cholesterol used for in the body?

Hormone synthesis, bile acids, and vitamin D production

Where does lipid digestion mainly occur?

In the small intestine

What hormone stimulates bile release during fat digestion?

Cholecystokinin (CCK)

What is the function of bile?

Emulsifies fats to aid digestion

What are micelles?

Structures that transport lipid digestion products to intestinal cells

What are chylomicrons?

Lipoproteins that transport dietary fat through the lymph and blood

What is the building block of fatty acid synthesis?

Acetyl-CoA

What enzyme regulates fatty acid synthesis?

Acetyl-CoA carboxylase

What is the rate-limiting enzyme of cholesterol synthesis?

HMG-CoA reductase

What are lipoproteins?

Transport particles that carry lipids through the bloodstream

What is the function of VLDL?

Transports triglycerides made in the liver

Why is LDL called "bad cholesterol"?

It delivers cholesterol to cells and increases heart disease risk

Why is HDL called "good cholesterol"?

It removes cholesterol from cells and returns it to the liver