Chapter 24: Metabolism and Nutrition

fatty acid oxidation or beta (β)-oxidation

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.