Acute metabolic responses

Question 1

Where is energy stored in ATP?

Answer 1

Phosphoanhydride linkages

Question 2

How much ATP is stored in muscle?

Answer 2

5.6 mmol/kg

Question 3

How much ATP is used whilst sprinting per second? Approx. how long does it last for?

Answer 3

3.7 mmol/kg/s
< 2 seconds

Question 4

How much ATP is used in sub-maximal exercise per second? Approx. how long does it last?

Answer 4

0.4 mmol/kg/s
< 15 seconds

Question 5

Name the two types of phosphorylation that resynthesis ATP in skeletal muscle.

Answer 5

Substrate-level phosphorylation - PCr and glycolysis
Oxidative phosphorylation

Question 6

What are the two enzymes involved in the resynthesis of ATP in PCr system and their function?

Answer 6

Creatine kinase - removes Pi from Cr
Adenylate kinase - phosphorylates ADP

Question 7

Where does glycolysis occur?

Answer 7

Cytosol

Question 8

Sources for glycolysis and its products?

Answer 8

Circulating glucose
Stored glycogen in skeletal muscle, liver
2 x pyruvate
Or, 2 x lactate

Question 9

What enzyme is responsible for converting glucose into glucose-6-phosphate?

Answer 9

Hexokinase

Question 10

What metabolite is oxidised in glycolysis and why is it important?

Answer 10

NAD+ - must be oxidised for pyruvate to enter krebs cycle

Question 11

What enzymes are responsible for the conversion of pyruvate (2)?

Answer 11

Pyruvate dehydrogenase - to acetylcoA
Lactate dehydrogenase - lactate

Question 12

What is the importance of the citric cycle?

Answer 12

Oxidation of electron carriers which can be used in oxidative phosphorylation

Question 13

What happens to the metabolites in oxidative phosphorylation?

Answer 13

H+ move across mitochondrial membrane to create electrochemical gradient to activate ATP synthase

Question 14

What is the final product of oxidative phosphorylation?

Answer 14

H20

Question 15

What type of oxidation does fat undergo to enter Krebs cycle?

Answer 15

beta oxidation

Question 16

What are the main 2 factors affecting exercise?

Answer 16

Exercise intensity and exercise duration

Question 17

What is the importance of recovery in between exercise bouts?

Answer 17

Allows for the replenishment of ATP

Question 18

What is the preferred source of fuel in endurance exercise?

Answer 18

CHO

Question 19

Respiratory exchange ratio equation

Answer 19

VCO2 / VO2

Question 20

What is fatigue?

Answer 20

Exercise induced decrease in ability to produce force

Question 21

Factors influencing fatigue?

Answer 21

Reduced ATP
Reduced PC
Increased Pi
Increased H+

Question 22

What is metabolic acidosis?

Answer 22

Increased presence of H+ decreases pH
Therefore, affecting rate of enzyme function

Question 23

Possible mechanisms of fatigue (4)

Answer 23

Reduced calcium reuptake
Reduced calcium release
Calcium insensitivity
Transport of potassium

Question 24

Causes of fatigue during endurance exercise? (4)

Answer 24

Reduced CHO stores
Impaired handling of calcium
Reduced propagation of sarcolemma
Greater reliance of fat

Question 25

What enzyme is responsible for the breakdown of glycogen stores?

Answer 25

Glycogen phosphorylase

Question 26

Why is lactate produced?

Answer 26

The system cannot keep up with the demand of pyruvate conversion to acetyl-coA

Question 27

Regulation of glycogen phosphorylase

Answer 27

Increased epinephrine and IC calcium activates phosphorylase kinase Phosphorylase kinase activates glycogen phosphorylase Via a process called covalent regulation

Question 28

What is an allosteric regulator?

Answer 28

Direct interaction with another molecule to change its function, e.g. ADP and AMP

Question 29

What stimulates phosphofructokinase?

Answer 29

Products of ATP - ADP and AMP Fructose-6-phosphate

Question 30

What reducing equivalent is important in the conversion of pyruvate to lactate?

Answer 30

NADH to NAD+

Question 31

What are the key regulators during intense exercise? (2)

Answer 31

Phosphorylase Phosphofructokinase

Question 32

What activates release of CHO from the liver?

Answer 32

Increased epinephrine Increased glucagon to insulin ratio Increased glucose output

Question 33

How does circulating glucose enter skeletal muscle?

Answer 33

GLUT4 transporter - further detail in block 3 cards

Question 34

Regulation of PDH enzyme during exercise.

Answer 34

Regulated via covalent regulation of PDH phosphotase Increased IC calcium activated PDH phosphotase PDH activated by the removal of Pi

Question 35

What stimulates isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase in the TCA cycle?

Answer 35

Increased intracellular calcium

Question 36

What is the breakdown of fat in adipose tissue called? And what enzymes are involved?

Answer 36

Lipolysis TG lipase and hormone sensitive lipase

Question 37

What does FFA bind to in the blood

Answer 37

Albumin

Question 38

What stimulates breakdown of fats?

Answer 38

Increased epinephrine And increased IC calcium in muscle stores

Question 39

What molecule transports fat into the mitochondria and what process occurs?

Answer 39

Carnitine Beta oxidation

Question 40

Why isn't fat recruited at higher intensities? (4)

Answer 40

CHO regenerates ATP at a faster rate Decreased adipose tissue blood flow Inhibition of HSL Decreased transportation of fat via carnitine

Question 41

What regulates rate of beta oxidation?

Answer 41

Beta-HAD

Question 42

What 3 structure uses the most ATP in the body during exercise, and what do they allow?

Answer 42

Myoisin ATPase Calcium ATPase Na+ and K+ ATPase

Question 43

Where do the two steps of substrate phosphorylation take place in the glycolysis?

Answer 43

Formation of glucose-6-phosphate Fructose-1,6-bisphosphate

Question 44

How many molecules of glucose produce ATP?

Answer 44

2 x ATP from circulating glucose 3 x ATP from stored glucose