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Exercise Physiology > Week 1: Bioenergetics & Physiology Revision > Flashcards

Week 1: Bioenergetics & Physiology Revision Flashcards

1
Q

Where is energy supplied from? What is broken down/converted to produce energy (ATP)?

A

Food supplies energy & the macronutrients are broken down to produce ATP.

Three stage process:
- Eat food –> broken down via catabolism
- Macronutrient oxidation
- Production of ATP

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2
Q

What macronutrient is broken down to produce glycogen? What happens to this molecule?

A

Carbohydrates are broken down into glycogen which is further broken down into glucose.

Glucose undergoes a series of chemical reactions within the muscle to form ATP.

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3
Q

What is ATP?

A

Energy that allows biological work to occur.

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4
Q

What happens to ATP to produce energy?

What does the energy produced by ATP allow to occur?

Is ATP a high or low energy compound for storing and conserving energy?

A

Phosphate bond is broken off. This energy allows actin/myosin coupling to occur.

ATP is a high energy compound for storing and conserving energy.

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5
Q

What is the chemical structure of ATP?

A

Three phosphate molecule and an adenosine molecule.

Note: adenosine = adenine & ribose).

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6
Q

What is oxidative metabolism?

ATP allows cross-bridging to occur with the actin-myosin - what happens in this process?

A
  • Carbohydrates, fats and amino acids undergo a series of biochemical reactions
  • Carbohydrates can undergo glycolysis to form ATP
  • ## Stored phosphocreatine within our muscle which allows to re-buffer ADP back to ATP to continually recycle ATP as well
    1. The myosin head is attached in the muscle when we get a nerve impulse into the muscle centrally from the brain we then release calcium from the sarcoplasmic reticulum that calcium then moves at the myosin binding site for ATP to occur
  1. When the ATP is broken down into ADP energy is provided and the actin-myosin head slide to produce movement
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7
Q

What enzyme facilitates phosphocreatine replenishing ADP to ATP?

A

Creatine Kinase

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8
Q

What energy source is used at rest?

A

Carbohydrates & fats

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9
Q

Predominant energy source for mid and intense exercise?

A

The body relies mostly on carbohydrate for fuel - its quicker to break down carbs (less chemical reactions required compared to fat). At lower intensity exercise we can contribute more fat to overall energy consumption because the demand for ATP supply is not as fast.

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10
Q

True or False? Protein provides little energy for cellular activity, but serves as building blocks for the body’s tissues

A

True

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11
Q

What are the sugars that form carbohydrate molecules?

A

Monosaccharides (glucose), oligosaccharides (sucrose, lactose & maltose) and polysaccharides (large chains)

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12
Q

What happens once carbohydrates are eaten?

A

Carbohydrates eaten –> blood glucose –> stored in muscles or liver as glycogen (glycogenesis)

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13
Q

What is the difference between glycogen being stored in the muscle or liver?

A

Muscles
* Glycogen broken down aerobically or anaerobically (glycolysis)

Liver:
* Glycogen –> glucose –> blood –> muscles (glycogenolysis)
* Longer process because it has to be broken down to glucose

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14
Q

What exercise does fat supply energy for?

A

Provides substantial energy during prolonged, low-intensity activity

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15
Q

Are body stores of fat larger or smaller than carbohydrate reserves?

A

Larger

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16
Q

What happens to fat when it is eaten?

A
  • Broken down to fatty free acids and glycerol
  • They can either be used immediately as energy or stored in the body as fat
  • Any excess energy is stored as fat (non-essential fat can be a problem for health and performance)
  • Free fatty acids and glycerol (lipolysis) –> that stored fat can then get broken down back into free fatty acids and glycerol via a process known as lipolysis.
17
Q

Fat has about …. the store of energy compared to carbohydrates

A

50x

18
Q

For a 65kg person who is ~12% body fat, they would have how many grams of glycogen in the liver, muscle glycogen, glucose in body fluids?

A

110g of glycogen
250g of muscle glycogen
15g of glucose in body fluids

(6500kJ of energy)

19
Q

For a 65kg person who is approximately 12% fat they would have how many grams of subcutaneous fat and intramuscular fat?

A

7800g of subcutaneous
161g intramuscular

(302,820kJ of energy)

You can see the store of energy of fat in the body is much greater than carbohydrates. The issue is accessing it during exercise which is difficult

20
Q

Energy content of fat vs carbohydrate (per gram)?

A

1g of carbohydrate = 17kJ (16.8)
1g of fat = 37kJ (37.8)

less energy in carbohydrate as there are less carbons

21
Q

How is protein used?

A

Can be used as energy but contributes very little. When we eat protein (beef, chicken etc) that will be broken down to amino acids. Used for growth and repair

22
Q

If protein is used for energy how must it be used?

A

When protein is used for energy production it must be converted to fat (lipogenesis) or glucose (gluconeogenesis) in the liver

Otherwise it is excreted as urea

23
Q

True or False - We can generate FFA’s in times of starvation through lipogenesis

A

True

24
Q

What are the three main energy systems?

A

ATP-PCr system (phosphagen system) : anaerobic

Glycolytic system: Anaerobic

Oxidative system: Aerobic

25
Q

ATP-PCr system

One molecule of ATP is produced per ….. of phosphocreatine

ATP-PCr provides an ….. source of energy during very ….. exercise

It depletes really quickly - T or F?

How long does it last?

We can maintain ATP levels for about …. seconds before they start to drop off

A
  1. One mole
  2. Immediate, intense
  3. True
  4. 3-20 seconds
  5. 10 secons
26
Q

Glycogen breakdown may be anaerobic or aerobic - T or F

A

True

27
Q

Glycogen breakdown & synthesis

Breakdown of glucose (…. ATP) or glycogen (…. ATP) in absence of oxygen to lactic acid

Occurs within the …..

Is relatively ….

When there is no oxygen present that glucose gets broken down to produce…..

The lactate itself becomes a fuel. Lactic acid produces …

That hydrogen is what drops the …. of the muscle and causes …..

That acidosis can inhibit the ….. enzymes or the enzymes that fuel …..

It can also inhibit actin-myosin coupling through blocking ….. binding sites in the muscle

A
  1. 2 ATP, 3 ATP
  2. Cytoplasm
  3. Fast
  4. Lactate and 2 hydrogen ions
  5. 2H+
  6. pH of the muscle, acidosis
  7. Glycolytic, glycolysis
  8. Calcium
28
Q

What is a rate limiting step of glycolysis?

A

Phosphofructokinase

29
Q

The glycolytic energy system

Requires ….. enzymatic reactions to breakdown glucose and glycogen into ATP

The pyruvic acid produced by anaerobic glycolysis becomes ….. (lactate + H)

One mole of glycogen produces …. mWole of ATP & one mole of glucose produces …. moles of ATP

Therefore more energy is produced from …… than from ……

But glycogenolysis and glycolysis have the negative effects as a result of ….. being created and then in the absence of oxygen lactic acid and that causes lactate and hydrogen ions (these consequences are discussed in the previous section)

A
  • 12
  • lactic acid
  • 3, 2
  • Glycogenolysis than from glycolysis
  • Pyruvic acid
30
Q

What are the three phases of glycolysis?

A

Phase 1: Sugar activation
* Glucose molecule is primed by using 2 ATP to prime that to form fructose-1,6 bisphosphate
* There are two phosphates at the end of that glucose molecule

Phase 2: Sugar cleavage
* In this phase that 6 carbon chain is broken into 2 carbon chains and that gets primed for the main oxidation and formation of ATP in the next phase of glycolysis

Phase 3: Sugar oxidation and formation of ATP
* The three carbon chain with a phosphate produces 4 ATP (previously 4 ADP) and two hydrogen ions which get picked up by NAD (a coenzyme) and takes them off to the electron transport chain
* The end result is 2 pyruvic acid molecules and when oxygen is present it is then sent via the Kreb cycle to the aerobic pathway
* When there is no oxygen present that pyruvic acid is converted into lactate acid (2 lactate & 2 hydrogen ions)

31
Q

What is involved in the oxidative production of ATP?

A
  • Involves three processes:
  • Glycolysis (oxidative) –> glucose/glycogen is broken down into pyruvate. When 02 is present that pyruvic acid enters mitochondria and is converted to acetyl-COA.
  • Krebs cycle –> three carbon chain of pyruvate is converted into 2 acetyl-CoA molecules and they enter the kreb cycle where they are used to produce hydrogen ions which are sent to the electron transport chain via NAD & FAD.

The H+ combine with two carriers:
- 1) Nicotinamide adenine nucleotide (NAD)
- 2) Flavin adenine nucleotide (FAD)

  • Electron transport chain
32
Q

Where is oxidative capacity produced? It it slow and what quantity is produced in terms of energy yield?

A

The mitochondria

Slow rate but high energy yield

33
Q

Process of oxidation of carbohydrate?

A
  • Pyruvic acid from glycolysis is converted to acetyl coenzyme A (acetyl CoA)
  • Acetyl CoA enters the Krebs cycle and forms 2 ATP, C02 and H+
  • H+ in the cell combines with two coenzymes (NAD & FAD) that carry it to the electron transport chain
  • Electron transport chain recombines H+ to produce ATP and water
  • One molecule of glycogen can generate up to 39 molecules of ATP
34
Q

Total of ATP produced in aerobic glycolysis & ETC?

A

Glycolysis: 3 ATP, 2 ATP through kreb cycle, 34 ATP through electron transport chain = 39 ATP molecules from 1 mole of carbohydrate glycogen.

35
Q

Oxidation of fat

A
  • Triglycerides stored in muscle and fat cells
  • These triglycerides are broken down by lipases to 1 glycerol and 3 free fatty acids which attach to plasma albumin and can diffuse into muscle.
  • Beta oxidation is the process of breaking down FFA to acetyl CoA
  • Acetyl CoA enters the Krebs cycle and the electron transport chain
  • Oxidation of fat within the Krebs cycle requires carbon chains from carbohydrate since one of the substrates that acetyl CoA combines with oxaloacetic acid and is derived from pyruvic acid (CHO source only)

Beta oxidation is fundamentally breaking down big long carbon chains into smaller carbon chains and ultimately into acetyl-CoA which is two carbon fragments and they enter the kreb cycle.

  • Fat needs more oxygen per gram than CHO since FFA contain more carbons and hydrogens
  • Palmetic acid: C16H3202 –> this has 16 carbons and 32 hydrogen
  • Glucose: C6H1206
  • ATP production for each gram of:
  • Fat (~9kcal or ~37.8kj)
  • CHO (~4kcal or ~16.8kJ)
  • Per molecule of oxygen
  • Fat gives 5.6 ATP
  • CHO gives 6.3 ATP (more energy for same 02 compared to a fat)
36
Q

What percentage of protein is used during rest and exercise?

A

Less than 5-10%

37
Q

What is the alanine glucose cycle (cahill cycle)?

A

The Alanine-Glucose cycle or the Cahill cycle - the process which involves muslce protein being degraded to provide more glucose and it generates more ATP for muscle contraction. A series of biochemical reactions whereby Alanine is converted to muslce glucose in the liver. During prolonged exercise the branch chain of amino acids are released from the muscles and they are carbon back bones they are used as an energy source while the nitrogen component to the amino acid is made to produce alanine. The alanine is then converted to glucose in the liver helping the body maintain its glucose levels.

38
Q

Why is protein oxidation complex?

A

Because amino acids contain nitrogen which cannot be oxidised

Amino acids:
* Gluconeogenesis in liver
* Enters Kreb Cycle as pyruvate
* Enters as acetyl CoA
* Some also broken down to ammonia and excreted as urea

39
Q

What percentage of the energy expended by the human body is degraded to heart; the rest is used for cellular and muscular activity

A

60-70%

Exercise Physiology (12 decks)

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