Chapter 24: Metabolism and Nutrition

**fatty acid oxidation** or **beta (β)-oxidation**

begins in the cytoplasm, where fatty acids are converted into fatty acyl CoA molecules.

**glucose-6-phosphate**

When glucose enters a cell, the enzyme hexokinase (or glucokinase, in the liver) rapidly adds a phosphate to convert it into ___

**tricarboxylic acid cycle (TCA)**

where additional energy is extracted and passed on.

**pyruvate**

The last step in glycolysis produces the product

**glycolysis**

Cells in the body take up the circulating glucose in response to insulin and, through a series of reactions

**cellular respiration**

Once the absorbed monosaccharides are transported to the tissues, the process of **__** begins.

**salivary amylase**

Carbohydrate digestion begins in the mouth with the action of __

 **polysaccharides**

are made of multiple **monosaccharide** molecules.

**oxidation**

releases a small amount of energy; both the electron and the energy are then passed to another molecule in the process of **reduction**, or the gaining of an electron.

**Radiation**

is the transfer of heat via infrared waves.

**Conduction**

is the transfer of heat by two objects that are in direct contact with one another.

**Convection**

is the transfer of heat to the air surrounding the skin.

**proteolysis**

Trypsin and chymotrypsin break down large proteins into smaller peptides, a process called

**ATP synthase**

Also embedded in the inner mitochondrial membrane is an amazing protein pore complex called

**oxidative phosphorylation**

The ETC couples the transfer of electrons between a donor (like NADH) and an electron acceptor (like O2) with the transfer of protons (H+ ions) across the inner mitochondrial membrane, enabling the process of

**electron transport chain (ETC)**

uses the NADH and FADH2 produced by the Krebs cycle to generate ATP.

**Krebs cycle**

The pyruvate molecules generated during glycolysis are transported across the mitochondrial membrane into the inner mitochondrial matrix, where they are metabolized by enzymes in a pathway called the

**Hexokinase**

is found in nearly every tissue in the body.

**Glucokinase**

on the other hand, is expressed in tissues that are active when blood glucose levels are high, such as the liver.

**Anabolic hormones**

are required for the synthesis of molecules and include growth hormone, insulin-like growth factor, insulin, testosterone, and estrogen.

**Catabolic hormones**

stimulate the breakdown of molecules and the production of energy.

**Catabolic reactions**

break down large organic molecules into smaller molecules, releasing the energy contained in the chemical bonds.

**Convection**

________ is the transfer of heat to the air surrounding the skin.

**Vitamins**

________ are organic compounds found in foods and are a necessary part of the biochemical reactions in the body.

**Beta**

________ (β)- hydroxybutyrate is oxidized to acetoacetate and NADH is released.

**complex sugars**

The ________ are also called polysaccharides and are made of multiple monosaccharide molecules.

**lipolysis**

To obtain energy from fat, triglycerides must first be broken down by hydrolysis into their two principal components, fatty acids and glycerol.

**chylomicrons**

Within the intestinal cells, these triglycerides are packaged along with cholesterol molecules in phospholipid vesicles called

**Lipid Metabolism**

begins in the intestine where ingested **triglycerides** are broken down into smaller chain fatty acids and subsequently into **monoglyceride molecules** by **pancreatic lipases,** enzymes that break down fats after they are emulsified by bile salts.

**Gluconeogenesis**

________ is the synthesis of new glucose molecules from pyruvate, lactate, glycerol, or the amino acids alanine or glutamine.

**Carbohydrate digestion**

________ begins in the mouth with the action of salivary amylase on starches and ends with monosaccharides being absorbed across the epithelium of the small intestine.

**Trypsin**

________ and chymotrypsin break down large proteins into smaller peptides, a process called proteolysis.

**small intestine**

The ________ also releases digestive hormones, including secretin and CCK, which stimulate digestive processes to break down the proteins further.

**Lipid metabolism**

________ begins in the intestine where ingested triglycerides are broken down into smaller chain fatty acids and subsequently into monoglyceride molecules by pancreatic lipases, enzymes that break down fats after they are emulsified by bile salts.

**Radiation**

________ is the transfer of heat via infrared waves.

**Metabolism**

________ is the sum of all of the chemical reactions that are involved in catabolism and anabolism.

**Ketones**

________ oxidize to produce energy for the brain.

**Hexokinase**

________ is found in nearly every tissue in the body.

**Metabolic processes**

________ are constantly taking place in the body.

**urea cycle**

The ________ is a set of biochemical reactions that produces urea from ammonium ions in order to prevent a toxic level of ammonium in the body.

**metabolic rate**

The ________ is the amount of energy consumed minus the amount of energy expended by the body.

**Evaporation**

________ is the transfer of heat by the evaporation of water.

**Anabolic reactions**

________ combine monosaccharides to form polysaccharides, fatty acids to form triglycerides, amino acids to form proteins, and nucleotides to form nucleic acids.

**Anabolic hormones**

________ are required for the synthesis of molecules and include growth hormone, insulin- like growth factor, insulin, testosterone, and estrogen.

**basal metabolic rate (BMR)**

describes the amount of daily energy expended by humans at rest, in a neutrally temperate environment, while in the postabsorptive state.

**oxidation-reduction reaction**

(also called a redox reaction)—when an electron is passed between molecules, the donor is oxidized and the recipient is reduced

**nicotinamide adenine dinucleotide (NAD)** and **flavin adenine dinucleotide (FAD).**

The two most common coenzymes of oxidation-reduction reactions

**ketone bodies**

If excessive acetyl CoA is created from the oxidation of fatty acids and the Krebs cycle is overloaded and cannot handle it, the acetyl CoA is diverted to create

**hydroxymethylglutaryl CoA (HMG CoA)**

In this ketone synthesis reaction, excess acetyl CoA is converted into

**beta (β)-hydroxybutyrate**

is oxidized to acetoacetate and NADH is released.

 **lipogenesis**

creates lipids (fat) from the acetyl CoA and takes place in the cytoplasm of adipocytes (fat cells) and hepatocytes (liver cells).

**pepsin**

When protein-rich foods enter the stomach, they are greeted by a mixture of the enzyme **_**

**sodium bicarbonate**

When the food-gastric juice mixture (chyme) enters the small intestine, the pancreas releases **__** to neutralize the HCl.

**secretin**

The small intestine also releases digestive hormones, including **_** and CCK, which stimulate digestive processes to break down the proteins further.

**elastase**

The pancreas releases most of the digestive enzymes, including the proteases trypsin, chymotrypsin, and **_,** which aid protein digestion.

**proteolysis**

Trypsin and chymotrypsin break down large proteins into smaller peptides, a process called **_**

**absorptive state**

or the fed state, occurs after a meal when your body is digesting the food and absorbing the nutrients (catabolism exceeds anabolism).

**postabsorptive state**

or the fasting state, occurs when the food has been digested, absorbed, and stored.During this state, the body must rely initially on stored **glycogen**.

**thermoregulation**

The body tightly regulates the body temperature through a process called

**thermoneutral**

when the body does not expend or release energy to maintain its core temperature.

**metabolic rate**

is the amount of energy consumed minus the amount of energy expended by the body.

**basal metabolic rate (BMR)**

describes the amount of daily energy expended by humans at rest, in a neutrally temperate environment, while in the postabsorptive state.

**Calorie (C)**

is the amount of heat it takes to raise 1 kg (1000 g) of water by 1 °C.

**Minerals**

in food are inorganic compounds that work with other nutrients to ensure the body functions properly.