L-7 Energy Balance and Metabolism II

Question 1

how is ATP generated?

Answer 1

by the combustion of:

• carbs
• fatty acids
• proteins

Question 2

what does ATP energize?

Answer 2

• synthesis of cellular components
• muscle contraction
• active transport across membranes
• glandular secretion
• nerve conduction

Question 3

what does phosphocreatine function as?

Answer 3

• an accessory storage depot for energy

- ATP buffer

Question 4

describe phosphocreatine

Answer 4

• has a high energy phosphate bond (13,000 cal)
• is 3-8 times more abundant than ATP
• cannot participate directly in energy transfer
• can transfer energy interchangeably with ATP

Question 5

what do non-essential amino acid formation depend on?

Answer 5

alpha-keto acid precursors

Question 6

what amino acid is present in the body in large quantities?

Answer 6

glutamine; serves as an amino radical storehouse

Question 7

what are aminotransferases derivatives of?

Answer 7

pyridoxine (vitamin B6)

Question 8

describe protein synthesis in regards to energy consumption

Answer 8

• one of the most energy expensive processes

- different peptide linkages require anywhere from 500 to 5000 calories per mole

Question 9

how many phosphate bonds are needed to form one peptide linkage?

Answer 9

4

- each peptide bond only stores 500-5000 calories

Question 10

what happens to excess amino acids in the body?

Answer 10

they are degraded and used for energy

Question 11

what is one of the end products of deamination?

Answer 11

ammonia

Question 12

what helps form urea? where?

Answer 12

in the liver; two molecules of ammonia + one molecule of CO2 are combined; this is the urea (ornithine) cycle

Question 13

where in the liver cells does the ornithine cycle occur?

Answer 13

in mitochondria and in cytoplasm

Question 14

describe process in mito

Answer 14

ammonia + CO2 –> carbamoyl phosphate

carbamoyl phosphate + ornithine –> citrulline

Question 15

describe process in cytoplasm

Answer 15

citrulline + aspartate –> argininosuccinate

argininosuccinate –> arginine + fumarate

arginine –> urea + ornithine

*fumarate can enter CAC

Question 16

what is the rate of the overall chemical reaction determined by?

Answer 16

• concentration of enzyme

- concentration of substrate

Question 17

in regards to reaction rate, what happens when substrate concentration is high

Answer 17

• reaction rate is determined almost entirely by concentration of enzyme

Question 18

give an example

Answer 18

diabetes mellitus and glucose:

• large quantities of glucose enter renal tubules
• glucose is in great excess in the tubules
• transport enzymes become saturated
• further incr in gluc concen in tubules have little effect on gluc reabsorption
• glucose reabs rate is limited by concen of transport enzymes

Question 19

what about when enzyme conc is high

Answer 19

• reaction rate becomes directly proportional to concentration of substrate enzyme

Question 20

give an example

Answer 20

absorption of substances from intestinal tract and renal tubules when concentrations of the substrate are low compared to transport enzymes

Question 21

EXAM: what is the major rate-limiting factor for almost all energy metabolism in the body?

Answer 21

ADP

Question 22

elaborate

Answer 22

• cellular concentrations of ADP are low
• chemical reactions that depend on ADP as one of the substrates are very slow
• ATP is converted to ADP during cellular activity; thus, ADP concen incr during cell activity
• incr ADP = incr reaction rates

Question 23

what are some examples of ADP substrate dependence

Answer 23

all oxidative metabolic pathways

other pathways for the release of energy

Question 24

how much of the energy in foods becomes heat during ATP formation and how much of it is used by functional systems?

Answer 24

35% and 27%

Question 25

what are factors that influence metabolic rate?

Answer 25

- arousal vs sleeping - skeletal muscle - age - thyroid activity - testosterone - growth hormone - fever - sleep - malnutrition

Question 26

what is the best known stimuli for increasing the rate of thyroid stimulating hormone?

Answer 26

the cold

Question 27

describe basal metabolic rate

Answer 27

95% of energy expended by body is dervied from oxidative phosphorylation involving different kinds of foods

Question 28

how can whole-body metabolic rate be calculated ?

Answer 28

from rate of oxygen utilization

Question 29

what do you metabolize 1 L of O2 with?

Answer 29

- glucose: 5.01 C - fat: 4.7 Cal - Protein: 4.6 Cal

Question 30

how many Cal are liberated per liter of oxygen with average diet?

Answer 30

averages to about 4.825 Cal = energy equivalent of oxygen

Question 31

give some averages and random numbers on basal metabolic rate

Answer 31

- avg 70kg man, inactive: 1650 Cal/day - 70kg man, inactive, reasonable diet: 1850 Cal/day - 70 man, sitting in chair, psychologically active, no exercise: 2000 Cal/day - walking upstairs requires 17x the energy as sleeping in bed all day

Question 32

what is the BMR average per hour?

Answer 32

65-70 Cal per hour

Question 33

How is BMR measured?

Answer 33

TEXT

Question 34

what are some factors affecting BMR?

Answer 34

- thyroxine and basal metabolic rate - malnutrition and basal metabolic rate - testosterone and basal metabolic rate

Question 35

describe the thyroxine and basal metabolic rate

Answer 35

- thyroxine incr rate of chem reactions in cells and incr metabolic rate - max secretion may incr metabolic rate 50 to 100 percent above average - loss of thyroid secretion decr met rate to 40-60% of normal

Question 36

describe malnutrition and basal metabolic rate

Answer 36

- malnutrition results in reduced food substances in the cells - this results in a marked reduction in metabolic rate - this process may accompany final stages of many disease conditions

Question 37

describe testosterone and basal metabolic rate

Answer 37

- T can incr met rate 10-15 % | - mainly related to anabolic effect of incr in skeletal muscle mass

Question 38

what is the minimal level of energy required for a person to just exist?

Answer 38

60% - basal metabolic rate

Question 39

what is much of the decline in BMR with increased age?

Answer 39

probably related to loss of muscle mass and replacement with adipose tissue with a lower rate of metabolism