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Chapter 28

Absorption of Nutrients

Carbohydrates are a fundamental part of the human diet, primarily acquired from milk and edible plant sources. The primary sugars  — …
Proteins are essential macronutrients for the human body. They serve as vital structural materials, such as keratin and collagen, and functional proteins, …
Dietary lipids, or fats, primarily comprising triglycerides, are essential to human nutrition. Saturated fats predominantly come from meat, dairy, and …
Dietary vitamins are essential as they facilitate the utilization of various other nutrients. They predominantly act as coenzymes, assisting different …
During digestion, polysaccharides are broken down into simple sugars. After their absorption in the GI tract, glucose is transported into other cells …
During digestion, proteins are broken down into smaller peptides and amino acids, which are absorbed. The amino acids are not stored for later use. …
Lipid metabolism includes lipolysis and lipogenesis. In lipolysis, dietary triglycerides are converted into fatty acids and glycerol, producing ATPs …
The liver synthesizes most cholesterol from acetyl CoA and transports it to the blood through lipoproteins. These lipoproteins are of three types. VLDLs …
Digestion of carbohydrates, such as dietary starch, begins in the mouth with chewing and the action of the salivary amylase. After being partially …
Proteins in the gastrointestinal tract primarily come from food but can also originate from disintegrated cells or secreted enzymes. In the stomach, these …
In the duodenum, dietary triglycerides in chyme are mixed with bile salts. This process breaks down large fat droplets into smaller ones. Once emulsified, …
Essential elements, including iron, calcium, sodium, chloride, and bicarbonate, are primarily consumed as dietary minerals or ions. While most …
The absorptive state is a well-fed period lasting approximately four hours after a meal when the body absorbs nutrients from the gastrointestinal tract. …
The postabsorptive state typically begins about four hours after a meal and lasts until the next meal is consumed. During this period, the digestive …
During the initial hours of fasting, the body depletes its glycogen stores for energy. As glycogen stores diminish, the body begins the breakdown of …
Energy is released when the chemical bonds in organic compounds, such as carbohydrates, proteins, and fats, are broken down. Food energy is measured in …
The body's metabolic rate refers to the overall rate at which metabolic reactions consume energy. It can be measured as the total metabolic rate or …
The average body temperature is 98.6 degrees Fahrenheit. At rest, metabolically active organs like the liver, heart, brain, and endocrine organs are vital …
Heat is transferred between the body and its surroundings in four ways. Conduction is the heat transfer between molecules of two materials in direct …
The body regulates core temperature through negative feedback mechanisms. When the core temperature drops, thermoreceptors send signals to the …
Hyperthermia is an umbrella term for elevated body temperature that occurs when heat production exceeds the body's ability to dissipate it. …
The hypothalamus releases peptides influencing feeding behavior. Two hypothalamic neuronal groups participate in this process. Neuropeptide Y (NPY) and …
Obesity is a clinical condition marked by excessive body fat, with a BMI of 30 or higher, while a BMI of 18.5 to 24.9 is considered healthy. Excess …
Genetic anomalies that disrupt metabolic processes cause inborn errors of metabolism. Phenylketonuria is an autosomal recessive protein metabolism …
Minerals are elements that work with other nutrients to ensure healthy body function. The human body primarily requires seven minerals — calcium, …
Natural killer (NK) cells are a subset of the cytotoxic lymphocyte population of the innate immune system and participate as a first line of defense by …
Glycogen is synthesized as a storage form of glucose by a wide array of organisms, ranging from bacteria to animals. The molecule comprises linear chains …
Fatty acid synthesis is a complex and highly energy demanding metabolic pathway with important functional roles in the control of whole-body metabolic …