Exam 2 - Human Nutrient Use and Metabolism

Question 1

What are the characteristics of carbohydrates?

Answer 1

• digested into small pieces, glucose or other sugar, that is absorbed into blood cells
• can only be stored in limited quantities so body is eager to use them
• excess stored in the liver as glucose or glycogen
• also stored in muscle and nervous tissues

Question 2

What are the characteristics of fats?

Answer 2

• broken down into fatty acids which can travel in the blood freely or associated with protein
• stored as triglycerides in fat cells
• typically provide more than half of the body’s energy needs
• excess carbs also stored as fatty acids

Question 3

What are the characteristics of proteins?

Answer 3

• broken down into amino acids that are then used to build new proteins
• can yield energy when there is a shortage of fats or carbs

Question 4

If all three nutrients are abundant in the diet…

Answer 4

• carbs and fats will be used primarily for energy

- proteins from food are broken down to provide AAs for proteins

Question 5

What is anabolism?

Answer 5

-synthesizing large molecules from small ones

Question 6

What is catabolism?

Answer 6

-breaking down complex molecules to simpler ones

Question 7

What is gluconeogenesis?

Answer 7

synthesis of glucose from a non-carbohydrate precursor

Question 8

What is glycogenesis?

Answer 8

synthesis of glycogen from glucose

Question 9

What is glycogenolysis?

Answer 9

breakdown of glycogen to form glucose

Question 10

What is lipogenesis?

Answer 10

excess glucose is converted to fat

Question 11

What is lipolysis?

Answer 11

breakdown of stored fats into glycerol and fatty acids

Question 12

What is ketogenesis?

Answer 12

production of ketone bodies from breakdown of fatty acids

Question 13

What is the catabolic-anabolic steady state?

Answer 13

dynamic state in which organic molecules (except DNA) are continuously broken down and rebuilt

Question 14

What are the characteristics of nutrient pools?

Answer 14

• available for immediate use
• stores of amino acids, carbohydrates, and fats
• inter-convertible

Question 15

What are the characteristics of the amino acid pool?

Answer 15

• body’s total supply of FREE amino acids
• source for resynthesizing body proteins, forming amino acid derivatives, and gluconeogenesis
• not stored as proteins
• must be converted to a citric acid cycle keto acid to be used for energy

Question 16

What are the characteristics of carbohydrate and fat pools?

Answer 16

• easily interconverted
• oxidized directly to produce energy in mitochondria
• can be stored as carbohydrates and fats

Question 17

What is the absorptive state?

Answer 17

period right after eating a meal; everything needed for energy production is used and the rest is stored

Question 18

What is the post-absorptive state?

Answer 18

in between meals; use what is stored to provide energy

Question 19

What are the characteristics of the absorptive state?

Answer 19

• lasts about 4 hours after eating
• anabolism exceeds catabolism
• excess nutrients stored mainly as fats, as well as carbs

Question 20

What are the characteristics of the sympathetic nervous system?

Answer 20

• arouses body for “fight or flight” response

- neurotransmitter is norepinephrine

Question 21

What are the characteristics of the parasympathetic nervous system?

Answer 21

• predominates during relaxation, “rest and digest”

- neurotransmitter is acetylcholine

Question 22

What is the role of the endocrine system?

Answer 22

• hormones involved in blood glucose regulation are insulin and glucagon
• both produced by the pancreas

Question 23

What stimulated insulin secretion from pancreatic beta cells?

Answer 23

elevated blood levels of glucose and amino acids

Question 24

What is the role of insulin?

Answer 24

to bind membrane receptors and facilitate the diffusion of glucose into muscle and adipose cells

Question 25

Which organs do not require insulin in order to take up glucose?

Answer 25

• brain

- liver

Question 26

What are the characteristics of the post-absorptive state?

Answer 26

• energy sources supplied by body’s reserves
• catabolism exceeds anabolism
• goal is to maintain blood glucose between meals

Question 27

What are the sources of blood glucose during the post-absorptive state?

Answer 27

• glycogenolysis in the liver
• glyogenolysis in the skeletal muscle
• lipolysis in adipose tissues and liver
• catabolism of cellular protein

Question 28

What is glucose sparing?

Answer 28

the body’s use of non-carbohydrate energy sources during long periods of fasting in order to conserve glucose

Question 29

What stimulates the release of glucagon from the pancreas?

Answer 29

• declining blood glucose levels

- rising amino acid levels

Question 30

What are the two types of diabetes mellitus?

Answer 30

• Type 1: inadequate insulin production

- Type 2: abnormal insulin receptors

Question 31

What does diabetes result in?

Answer 31

• unavailability of glucose to most body cells
• excessively high blood glucose levels
• glucose loss in urine
• metabolic acidosis, protein wasting, and weight loss
• coma and death