Lecture 18

Question 1

Energy is defined as

Answer 1

the capacity to do work

Question 2

Adenosine Triphosphate (ATP)

Answer 2

Energy Currency of the Cell, medium of energy exchange

Question 3

what do glucose and fatty acid metabolism generate?

Answer 3

most of the ATP … relatively little
from amino acids (but still some)

Question 4

Some ATP is generated by

Answer 4

glycolysis and Kreb’s cycle

Question 5

Glycolysis, beta oxidation and Kreb’s cycle produce

Answer 5

reducing equivalents …
NADH and FADH2

Question 6

NADH and FADH2 supply

Answer 6

protons (H+) and electrons (e-) to the electron transport chain. THIS is where most of the ATP is
made.

Question 7

ATP can also be generated WITHOUT O2 by:

Answer 7

Phosphocreatine (PCr) degradation, about 9-10 seconds worth
ATP → ADP + Pi
PCr + ADP + H+ → ATP + Cr
ATP is rebuilt by adding a phosphate to ADP

Question 8

end products in anaerobic
conditions

Answer 8

lactate, E.g sprints

Question 9

most energy is stored as

Answer 9

triglycerides (a form of fat)
in our adipocytes

Question 10

Carbohydrate stored as

Answer 10

• Glycogen in liver (~150 g); most concentrated as liver is only ~2 kg
• Glycogen in muscle (~350 g); ~40% body mass is muscle (varies highly based on genetics and body type)
• Only ~ 30 g of glucose is found in the blood – not much (body rids blood of glucose quickly)

Question 11

Protein also represents

Answer 11

a large potential energy source (~40% body mass is muscle)

This is obviously protected, but will be used in starvation or
caloric restriction

Question 12

potential energy source means..

Answer 12

not the first source of energy, not broken down first. Stored for emergency - starvation or muscle breakdown

Question 13

Carbohydrate, aerobically

Answer 13

can generate ATP slightly
faster than from fat

Question 14

Carbohydrate, anaerobically

Answer 14

Can also generate ATP, 3x
faster than aerobic

Question 15

carbs hold

Answer 15

a lot of water i.e. “heavier”;
less energy dense than fat

Question 16

Fat doesn’t hold

Answer 16

water, more than twice
as energy dense as carbohydrate

Question 17

fat represents

Answer 17

our most abundant
energy reserve

Question 18

fat cannot

Answer 18

provide energy
anaerobically (must have oxygen!

Question 19

Absorptive State:

Answer 19

First 3-4 hours after a meal
Energy (macronutrients) are stored (anabolism)

Question 20

Excess nutrients taken up will be stored i.e. anabolic state in

Answer 20

• Glycogen (carbohydrate) stored in liver and muscle
• Triglycerides (fat) stored in adipose tissue, liver and muscle

Question 21

Excess calories in the form of glucose or amino acids can get converted into

Answer 21

fat

Question 22

during Postabsorptive State / Fasting…

Answer 22

Stored macronutrients are mobilized for energy (catabolism); Glucose is spared for nervous system

Question 23

Gluconeogenesis

Answer 23

making glucose from non-
carbohydrate precursors (occurs in the liver -primarily – but also kidneys)

Question 24

Glycogenolysis

Answer 24

breakdown of glycogen, a stored form of glucose, into glucose molecules (fasted state)

Question 25

Normal fasting blood glucose is

Answer 25

~ 4 – 5.5 mmol/L (very narrow range!)

Question 26

free fatty
acids

Answer 26

the other major circulating fuel, vary from 0.2 - 2 mmol/L

Question 27

Fasting hyperglycemia:

Answer 27

Glucose > 7 mmol/L

Question 28

Fasting hypoglycemia:

Answer 28

Glucose ~ < 3.5 mmol/L

Question 29

Why is blood glucose maintained so tightly?

Answer 29

• Many cells require glucose e.g. neural tissue, kidney
• Maintain osmotic balance (optimal concentrations of electrolytes and
  non-electrolytes are maintained)
• Hyperglycemia can cause glycosylation of amino acids in kidneys,
  peripheral nerves, lens of the eye, causing damage

Question 30

glucose regulation via insulin happens when

Answer 30

blood glucose is elevated, after a meal / post absorptive state

or

when blood glucose is low
This could be induced by fasting

Question 31

glucagon is decreased during

Answer 31

post absorptive state, insulin to glucagon ratio
increases

Question 32

why don’t we want glucogenolysis process to occur after eating a meal

Answer 32

process in which liver makes glucose, don’t need this, blood sugar is already high

Question 33

insulin is decreased during

Answer 33

fasted state, glucagon to insulin ratio increases

Question 34

reciprocal changes in______ and _____ are more important than the change in one of these hormones

Answer 34

insulin and glucagon

Question 35

what is used for energy during prolonged low intensity exercise? (Cycling, jogging, swimming)

Answer 35

plasma-derived substrates mostly fatty acids, some blood glucose

Question 36

as exercise intensity increases what is used for energy? (heavy weight lifting + sprinting)

Answer 36

increased need to mobilize energy stores (substrates) within the muscle itself, muscle glycogen (mostly) + triglycerides used