Lipids, Carbohydrates, and Proteins in Metabolism

Chylomicrons

Produced in the intestinal cells, transport dietary lipids through the lymphatic system to adipose tissue and other cells.

HDL

High-density lipoprotein scavenges cholesterol from the bloodstream and returns it to the liver for disposal.

Bile

Emulsifies fat in the small intestine.

Fatty acids

Influence the type of fat found in the body.

Triglycerides and phospholipids

Both contain fatty acids but differ in other components.

LDL (Low-Density Lipoprotein)

Transports cholesterol from the liver to tissues for storage.

Omega-3 Fatty Acids

Linolenic acid is an omega-3 fatty acid.

Saturated Fats

Solid at room temperature, no double bonds between carbons, and all carbons are fully hydrogenated.

Found in butter and cheese

Monosaccharides

Glucose, fructose, and galactose.

Polysaccharides

Examples include starch, amylopectin, and fiber.

Amylopectin

A starch, not fiber.

Fiber

Passes through the GI tract undigested or is fermented in the colon.

Insulin

Helps in glucose uptake by cells, regulating blood sugar levels.

Glycemic Index (GI)

Measures the blood sugar response after carbohydrate consumption (not insulin response).

Protein Structure

The amino acid sequence determines its three-dimensional structure.

Essential Amino Acids

9 essential amino acids (PVT TIM HiLL).

Peptide Bonds

Link amino acids to form proteins.

Conditionally Essential Amino Acids

Some amino acids become essential in certain conditions (e.g., phenylketonuria, PKU).

Positive Nitrogen Balance

Occurs during growth, tissue repair, or pregnancy (e.g., a woman in her second trimester).

Negative Nitrogen Balance

Occurs when the body is breaking down more protein than it is synthesizing, often due to illness or malnutrition.

Protein Requirements

0.8g per kg of body weight for healthy adults. A 220-pound male would require 80g of protein.

Lecithin

A phospholipid that helps with cell membrane structure but does not lower cholesterol.

Cholesterol

A sterol that serves as a precursor to certain hormones and is found in animal products.

Fat Storage

Fat has no limit for storage in the body, leading to weight gain when in excess.

Ketosis

Occurs when there is a lack of carbohydrate intake, leading to fat breakdown and the production of ketones.

Gluconeogenesis

The process where amino acids are converted into glucose during energy deprivation.

Recommended Fiber Intake

A 26-year-old woman should consume 25 grams of fiber daily.

Complementary Proteins

Lentils and rice provide all essential amino acids when combined.

Celiac Disease

Associated with gluten consumption.

Lactose Intolerance

Caused by an inability to break down lactose (not galactose).

Fluid Imbalance

Can cause edema (swelling due to excess fluid in tissues).

Protein Synthesis

Transcription: Information from DNA is transcribed into RNA. Translation: RNA is translated into protein.