Metabolism-Chapter 27

Question 1

What are the six major nutrients?

Answer 1

Carbohydrates, lipids, proteins, vitamins, minerals, water

Question 2

What are the functions of carbohydrates?

Answer 2

Glucose is broken down to generate energy; glycogen is stored in the liver and skeletal muscles

Question 3

What are the functions of lipids?

Answer 3

Triglycerides serve as a form of energy storage; phospholipids compose cell membranes

Question 4

What are the functions of proteins?

Answer 4

They are structural and functional components of the body

Question 5

What are the functions of minerals?

Answer 5

Serve as coenzymes in chemical reactions; participate in connective tissue synthesis, enhance calcium absorption

Question 6

What is the function of water?

Answer 6

Unique properties to support life including exhibinting cohesion, adhesion, surface tension, high specific heat, high heat of vaporization

Question 7

What is the difference between essential and nonessential amino acids?

Answer 7

Essential vitamins must be provided in the diet. If not, disease results. Nonessential vitamins are cofactors that the body is able to produce and recycle as needed.

Question 8

Distinguish between water-soluble and fat-soluble vitamins.

Answer 8

Water-soluble vitamins dissolve in water. They’re easily absorbed into the blood from the digestive tract. Some function as coenzymes to assist with normal enzyme function. Fat soluble vitamins dissolve in fat (not in water). They are absorbed from the gastrointestinal tract within the lipid of micelles and enter into the lymphatic capillaries. If dietary intake exceeds body requirements, the excess is stored in body fat and may reach toxic levels.

Question 9

What are the four stages of cellular respiration?

Answer 9

Glycolysis, Intermediate state; Citric Acid Cycle; and Electron Transport System.

Question 10

How do carbohydrates enter cellular respiration?

Answer 10

1)Monosaccharides are absorbed from small intestine in blood, enter hepatocytes. Fructose and galactose are converted to glucose. 2) Noncarbohydrates are converted to glucose by gluconeogenesis 3) Glucose molecules are bonded together to form glycogen by glycogenesis 4) Glucose molecules are released from glycogen by glycogenesis

Question 11

How do lipids enter cellular respiration?

Answer 11

1) Fatty acids joined with glycerol to for triglycerides (lipogenesis) 2) Fatt acids released from triglycerides (lipolysis) 3) Acetyl CoA changed to ketone bodies (water-soluble molecules); ketone bodies released into blood, transported to other cells, where they can be oxididized in cell respiration pathways

Question 12

How do proteins enter cellular respiration?

Answer 12

1) Deamination: Amino group removed from amino acids 2) Remaining components oxidized in cellular respiration to generate ATP from the liver

Question 13

Describe gluconeogenesis

Answer 13

Formation of glucose from a noncarbohydrate source

Question 14

Describe Describe glycogenesis?

Answer 14

Glucose molecules are bonded together to form glycogen.

Question 15

Describe Glycogenolysis

Answer 15

Glucose molecules are released from glycogen

Question 16

What happens to fructose and galactose?

Answer 16

They are converted to glucose

Question 17

Describe protein synthesis

Answer 17

Amino acids are used to form proteins, including plasma proteins

Question 18

Describe transamination

Answer 18

Amino acids are converted from one form to another

Question 19

Describe deamination

Answer 19

The amine group is removed from the amino acid in the hepatocytes of the liver

Question 20

What happens to the components of an amino acid after it has been deaminated?

Answer 20

The remaining portion of the amino acid enters the metabolic pathway of cellular respiration at different steps, depending upon the specific amino acid.

Question 21

Describe lipogenesis

Answer 21

Fatty acids are joined with glycerol to form triglycerides

Question 22

Describe lipolysis

Answer 22

Fatty acids are released from triglycerides

Question 23

Describe betaoxidation

Answer 23

Fatty acids are broken down into acetyl CoA

Question 24

What are some of the uses of acetyl CoA?

Answer 24

used in cholesterol synthesis; some use to form bile salts and released as a component of bile

Question 25

Describe lipid transport

Answer 25

1) Both triglycerides and cholesterol are transported within VLDL’s and LDL’s from the liver to the peripheral tissues 2) “Empty” HDL’s released to pick up lipids (e.g., cholesterol) from peripheral tissues and blood vessels; return as “full” HDL to the liver

Question 26

Describe cholymicrons

Answer 26

They are a lipoprotein (a lipid and protein “wrap”). Absorption of lipids from the small intestine requires the formation of cholymicrons within epithesial cells lining the sm. intestine. It is mostly composed of triglycerides and some cholesterol enveloped in protein. It is absorbed into a lacteal and transported w/in the lymph..

Question 27

Describe VLDLs (Very-low-Density lipoproteins)

Answer 27

contain various types of lipids packaged with proteins. Assembled within the liver then released into the blood. THey circulate in the blood to release triglycerides to all cells of peripheral tissues, but primarily adipose tissue.

Question 28

Dewscribe LDLs (Low-density lipoproteins)

Answer 28

They contain high amounts of cholesterol. THey deliver cholesterol to cells.

Question 29

Define HDLs (High-density lipoproteins)

Answer 29

They are associated with the transport of lipid from the peripheral tissues to the liver. They are produced in stages and have a function that opposes both VLDLs and LDLs. HDL molecules circulate throughout the blood and “fill” with lipids from peripheral tissue and the inner lining of arterial walls. They then transport these lipids to the liver.

Question 30

What is the function of lipoprotein lipase?

Answer 30

It is an enzyme that digests triglycerides

Question 31

Describe some of the other functions of the liver

Answer 31

1) Absorption of bilirubin; eliminated as a component of bile 2) Storage site for vitamins and minerals 3) Detoxification of drugs 4) Hormone breakdown

Question 32

Describe the regulation of blood levels of nutrients during the absorptive state and identify the primary regulatory hormone

Answer 32

The concentrations of glucose, triglycerides, and amino acids are increasing within the blood as they are absorbed from the GI tract. Insulin is the main regulatory hormone. 1) Insulin stimulates liver and muscle cells to form the polysaccharide glycogen from glucose by increasing glycogenesis 2) Causes adipose connective tissue to increase uptake of triglycerides from the blood and decreases the breakdown of triglycerides by stimulating lipogenesis and inhibiting lipolysis 3) Stimulates most cells to increase amino acid uptake that causes an accelerated rate in protein synthesis

Question 33

Describe the regulation of blood levels of nutrients during the post-absorptive state and identify the primary regulatory hormone

Answer 33

The challenge is to maintain hemeostatic levels of many nutrients as these substances are decreasing in the blood Glucagon is the main regulatory hormone. 1) Stimulates liver cells to engage in catabolism of glycogen to glucose by increasing glycogenolysis. Glucagon may also increase the formation of glucose from noncarbohydrate sources by stimulating gluconeogenesis 2) Causes adipose connective tissue to reak down triglycerides to glycerol and fatty acids by stimulating lypolysis

Question 34

Describe minerals and some of their functions in the body

Answer 34

Minerals are inorganic ions such as iron, calcium, sodium, potassium, etc. 1) Iron-present in hemoglobin and erythrocytes and binds oxygen-present in mitochondria in the electron transport system to bind electrons 2) calcium-required for formation and maintenance of the skeleton, for blood clotting 3) sodium and potassium function to maintain a resting membrane potential in excitable cells, and are required in the generation of an action potential 4) iodine is needed to produce thyroid hormone 5) zince has roles in both protein synthesis and wound healing