Metabolism During Exercise

Question 1

What is the main feature of catabolism?

Answer 1

Oxidative

Generates = ATP, reducing power (NADH, FADH2, NADPH), building blocks

Exergonic

Question 2

What is the main features of anabolism?

Answer 2

Uses precursors to build macromolecules

Reductive

Endergonic

Question 3

Describe the major metabolic fuels and their sources in the normal individual

Answer 3

Glucose = preferred fuel source, stored as glycogen

FA = c be used by most cells except RBCs/brain/CNS as no mitochondria

AA = muscle protein can be broken down to supply - converted to glucose or ketone bodies

Ketone bodies = from FA when glucose is low

Lactate = anaerobic met in muscle

Question 4

What is the key regulator of glycolysis?

Answer 4

Phosphofructokinase

Regulation = allosteric and hormonal

Question 5

Briefly outline fatty acid oxidation

Answer 5

Activation of FA by + of CoA by fatty acyl CoA synthase

Carnitine to mitochondria

Beta-oxidation = removing C2, prod NADH and FADH2

Question 6

Describe how the blood glucose concentration is controlled

Answer 6

Insulin = uptake, promotes translocation of GLUT4

Glucagon = release

Question 7

Explain why control of [glucose] is necessary

Answer 7

CNS must receive adequate supply

rate of uptake it determined by [conc]

Question 8

Which hormones promote energy release from stores?

Answer 8

• Glucagon
• Adrenaline
• Cortisol
• Thyroid hormones

Question 9

Describe the metabolic responses to fasting

Answer 9

Low [glucose] = cortisol and glucagon

= gluconeogenesis breakdown of protein/fat

Ketone bodies

Once fat depletes, revert to protein

Question 10

What are the energy requirements of exercise?

Answer 10

ATP must be rapidly resynthesised

= creatine phosphate muscle stores

Or muscle glycogen

Question 11

Via the liver lactate is recycled via what cycle?

Answer 11

Cori Cycle

Question 12

Describe the metabolic responses to various types of exercise

Answer 12

100m =uses muscle glycogen then creates ATP anaerobically, lactate

Middle distance = starts using creatine phosphate + anaerobic met, then aerobically, finishing sprint anaerobic

Long distance = 95% aerobic

Question 13

Over a marathon how do hormone levels change?

Answer 13

Insulin = falls slowly (inhib by adrenaline)

Glucagon = levels rise

Adrenaline + GW = rise rapidly

Cortisol = rises slowly

Question 14

Explain the benefits of exercise

Answer 14

• Increase muscle, decrease adipose
• Increase glucose tolerance
• Decrease LDL
• BP falls
• Feeling of well-being