Exercise Physiology Quiz

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Questions and Answers

What is the primary purpose of anabolism in the body?

To release energy from stored fats

To create new molecules from smaller ones (correct)

To digest food for ATP production

To break down large molecules for energy

Which of the following correctly describes catabolism?

It occurs exclusively during aerobic metabolism

It synthesizes ATP from glucose

It requires energy from the body

It breaks down larger molecules into smaller ones (correct)

What is the main substrate used in anaerobic glycolysis?

Oxygen

Muscle glycogen (correct)

Fatty acids

Amino acids

What is one of the byproducts of anaerobic metabolism?

Lactate Signup and view all the answers

Which energy system requires oxygen?

Aerobic metabolism Signup and view all the answers

How does the ATP-PC system affect the rate of ATP formation?

It allows for rapid ATP production due to few steps Signup and view all the answers

What characterizes the capacity for ATP production in aerobic metabolism compared to anaerobic metabolism?

Aerobic has a larger capacity Signup and view all the answers

What is the main function of ATP in muscle contraction?

To provide energy through breakdown Signup and view all the answers

What effect do changes in glycolytic enzymes have on performance?

They improve enzyme function and increase ATP availability. Signup and view all the answers

Which enzyme is known as the rate limiter in glycolysis?

Phosphofructokinase Signup and view all the answers

How does endurance training affect glycogen utilization?

It takes longer to run out of glycogen. Signup and view all the answers

What happens to buffering capabilities with endurance and sprint training?

They improve, aiding performance under muscle acidity. Signup and view all the answers

During a 30-second sprint, what is the primary energy source utilized?

45% glycolysis Signup and view all the answers

Which macronutrient is broken down into simple sugars like glucose?

Carbohydrates Signup and view all the answers

What is the primary energy production pathway during high-intensity exercise like sprinting?

Glycolysis Signup and view all the answers

Which of the following is a negative feature of the glycolytic pathway?

Leads to accumulation of lactic acid Signup and view all the answers

What is one of the main adaptations of energy systems that occurs with training?

Increased fat utilization Signup and view all the answers

What limits a sprinter's ability to maintain high intensity for long durations?

Inadequate carbohydrate stores Signup and view all the answers

What product is a result of anaerobic metabolism that can cause muscle fatigue?

Lactic acid Signup and view all the answers

Which metabolic substrate dominates during prolonged, low-intensity exercise?

Fat Signup and view all the answers

What is the primary role of the ATP-phosphocreatine system in energy production?

Immediate energy for short bursts of activity Signup and view all the answers

What must happen for muscles to continue contracting during exercise?

ATP must be replaced or resynthesized. Signup and view all the answers

Which form of carbohydrate is primarily used for energy in the brain?

Monosaccharides Signup and view all the answers

What is the storage form of glucose in mammals?

Glycogen Signup and view all the answers

What is the process called when two monosaccharides are joined by losing water?

Condensation Signup and view all the answers

Which of the following carbohydrates is not digestible by humans?

Cellulose Signup and view all the answers

What do fatty acids and triglycerides break down into during digestion?

Fatty acids and glycerol Signup and view all the answers

What is the biologically useful form of energy currency in cells?

Adenosine triphosphate (ATP) Signup and view all the answers

What is a key characteristic of carbohydrates as a fuel for exercise?

They are a rapid and readily available source of energy. Signup and view all the answers

What is the primary function of glycogenesis?

Forming glycogen from glucose. Signup and view all the answers

Which statement best describes glycogenolysis?

It is the breakdown of glycogen into glucose. Signup and view all the answers

What is one disadvantage of relying primarily on carbohydrates for energy during exercise?

They are quickly depleted after prolonged exercise. Signup and view all the answers

What describes the role of lipolysis?

It breaks down fatty acids for energy. Signup and view all the answers

Which of the following statements is true about fats as an energy source?

They are not depletable energy stores. Signup and view all the answers

Which of the following best characterizes proteins in terms of energy production?

A small amount can be used for energy. Signup and view all the answers

What term describes the building blocks of proteins?

Essential amino acids Signup and view all the answers

Which of the following enzymes breaks down fats?

Lipase Signup and view all the answers

What is the primary energy source for high-intensity activities lasting up to 15 seconds?

ATP-PC system Signup and view all the answers

Which process results in the breakdown of phosphocreatine to produce ATP?

PCr → Cr + P + energy Signup and view all the answers

What causes fatigue during high-intensity exercise related to ATP production?

Accumulation of H+ ions Signup and view all the answers

During recovery, how are phosphocreatine stores replenished?

By utilizing other energy systems Signup and view all the answers

Why can a sprinter maintain an all-out sprint for only a brief period?

Insufficient ATP production Signup and view all the answers

Which of the following adaptations to exercise related to the ATP-PC system is noted as inconsistent?

Variability in creatine kinase activity Signup and view all the answers

What happens to the levels of ATP and PC with specific types of training?

They may increase Signup and view all the answers

Which statement accurately describes the relationship between ATP breakdown and H+ ion accumulation?

H+ ions are necessary for ATP formation but excess leads to fatigue. Signup and view all the answers

Study Notes

Essentials of Bioenergetics and Anaerobic Metabolic Pathways

Students should be able to define three major metabolic substrates and how they are metabolized to produce energy.
Students should be able to determine which metabolic substrates predominate during rest and exercise.
Students should be able to describe energy production from the ATP-phosphocreatine system and glycolysis.
Students should be able to describe the positive and negative features of the phosphagen and glycolytic pathways.
Students should be able to explain the energy system adaptations that accompany training.

Metabolism: Applications

Sprinters can only sprint "all out" for a short time.
Marathon runners can sustain a race pace for over two hours.
Energy comes from the body's fuel sources (substrates)
Performance limitations are determined by several factors, and can be overcome.

Why do we need energy?

Muscle contraction
Digestion
Reproduction

Energy

It is the ability to do work
This is the capacity of work
Examples include various forms of energy:

How do we get energy?

We use food to make energy

Through Metabolism

Metabolism, also known as bioenergetics, refers to the total of all chemical reactions within cells.
Food provides energy.

Where does the energy come from?

The sun, through photosynthesis, plants convert sunlight to carbohydrates.
Humans and animals consume plants and animals to get carbs, protein, and fats.
The body then breaks down these substances into usable forms which helps in the production of energy

Energy Sources

Chemical energy from food is converted to produce mechanical energy
This results in muscle contractions and bodily movement.
Three essential chemical energy types that the body consumes are carbohydrates, fats, and proteins.
Carbohydrates are broken into simple sugars, (glucose, fructose, and galactose)
Fats are broken down into triglycerides and fatty acids
Proteins are converted into amino acids

Macronutrients

Carbohydrates, which are broken into simple sugars (glucose, fructose, and galactose).
Fats, which are broken down into triglycerides and fatty acids.
Proteins, which are converted into amino acids.
- These are broken down into usable forms to form high-energy compounds like ATP

Adenosine Triphosphate (ATP)

The energy currency for biological useful work/processes
Breaking phosphate bonds releases energy for other biological work.
ATP breaks down to release energy for muscle contraction.

When a Phosphate is Broken Off

ATP releases energy
This is called an exergonic reaction
ADP is formed
This reaction needs energy (endergonic)

What does a muscle need to contract and keep contracting?

A continuous supply of ATP to match demand

ATP Supply

ATP stored in limited amounts.
Enough for 1-2 seconds of all-out effort.
Nutrients are broken down to replace it.

Fuels (substrates) for Exercise

Carbohydrates (CHO)
Fats
Proteins
Creatine phosphate (CPR, PC, CP)

Carbohydrates

Rapid and readily available.
4 kcal/g
3 forms:
- Monosaccharides (single) like glucose, fructose, galactose
- Disaccharides (two sugars) like sucrose, lactose, maltose
- Polysaccharides (many sugars) like starch, glycogen
Blood sugar (monosaccharides), primary fuel for the brain, only source of energy for some cells

Polysaccharides

Many monosaccharides bonded together
- Starch: stored in plants (grains, legumes, and tubers)
- Glycogen: stored in animals (liver and muscles)
- Cellulose: insoluble fiber, plants

Glycogenesis

Formation of glycogen from glucose

Glycogenolysis

Breaking down glycogen into glucose

Glycogen Storage

When blood glucose drops, fatigue occurs.
Muscle glycogen provides energy for muscle
Liver glycogen helps to maintain stable blood sugar

Carbohydrates for Energy

Essential fuel during exercise, vital for the brain (CNS).
ATP quickly produced from them
Can be depleted after about 2 hours of extended exercise.
Influenced by dietary carbohydrate content.

Fats

Can be metabolized for energy.
Triglycerides: main form of fat storage (1 glycerol + 3 fatty acids).
Fat stores are large and not readily depleted.
Slower ATP production than carbohydrates. Used more at rest.
- Useful for long duration activity

Lipolysis

Breakdown of triglycerides to release energy in the form of fatty acids

Lipolysis (Continued)

Fats are broken down to produce ATP energy
ATP is slowly produced, important at rest, but not useful in intense exercise

Proteins

Used for energy in small amounts
Made from amino acids linked together.
Needed for various bodily functions, not primarily for energy.

Enzymes

Enzymes facilitate chemical reactions by speeding them up.
They have a unique shape that allows them to bind with substrates and catalyze reactions.
They end in '-ase' (e.g., protease, lipase).

ATP-PC System

Energy source for high-intensity activities requiring quick energy
Brief duration (3-15 seconds)
Examples include sprinting.
Phosphocreatine (PCr) is composed of creatine and phosphate.
PCr stores energy in the sarcoplasm for quick ATP production.

ATP-PC Mechanism

Energy from phosphocreatine breaks down to produce ATP.
This ATP is then broken down releasing the energy to fuel muscle contraction.
The rate of ATP formation in this system is high.

Glycolysis

Breakdown of glucose or glycogen into pyruvate.
A 10-step, anaerobic reaction that occurs in the absence of oxygen
A small amount of ATP is produced (but rapid). Used in high intensive, short duration activity
In the absence of oxygen, Pyruvate is converted to Lactate
In the presence of oxygen, Pyruvate is converted to Acetyl CoA (then into Krebs Cycle/Electron Transport Chain)

Glycolysis Overview

Anaerobic (fast): Does not utilize oxygen, used in short duration, high intensity activities
Aerobic (slow): Utilizes oxygen, used in low intensity, long duration activities

Glycolysis (Glucose to Pyruvate)

Occurs in 2 ways; Fast (anaerobic) & Slow (aerobic).
Fast when cells need quick energy.
Slow when cells do not need as much energy, but need it over a longer time.

Glycolysis: Substrate

ATP use to transform glucose into glucose-6-phosphate
Glycogen breakdown does not need ATP

Glycolysis: Key Points

Rapid ATP production
Limited capacity due to acidity
Dominant energy system in activities from 20-30 seconds to 2-3 minutes.

Glycolysis: Enzyme Adaptations

Changes in glycolytic enzymes may improve performance
Increase in ATP availability
Key studied enzymes:
- Glycogen phosphorylase
- Phosphofructokinase (rate-limiting enzyme)
- Lactate dehydrogenase

Glycolysis: Intramuscular Glycogen Adaptations

Endurance training increases muscle glycogen. More glycogen means it will take longer to run out of stored fuel.

Glycolysis: Buffering Adaptations

Endurance and sprint training increases buffering capabilities
Buffers H+ (which causes acidity) for better performance and recovery in activities that produce a lot of lactic acid
More ATP production before fatigue.

Interactions of Aerobic and Anaerobic Metabolism

Anaerobic system creates ATP rapidly for short, high-intensity activities
Aerobic system makes most ATP for long duration, low intensity activities

A 3-Second Sprint

A 3-second sprint is mostly powered by the ATP-PC system.
Other processes like glycolysis contribute to a lesser extent.

3-Second Sprint and Other Sprints

The ratio of contribution from ATP-PC, glycolysis, and aerobic metabolism changes depending on the length of the sprint.

Energy for Longer High-Intensity Efforts

If exercise goes beyond ATP-PC system capacity then other systems (like glycolysis) are involved

Lactate Response to Exercise

Lactate buildup occurs during exercise and plateaus after a while.
It increases then falls back to baseline

What's causing fatigue?

Accumulation of H+ (from lactic acid) increases acidity, causes fatigue
Breakdown of ATP that exceeds production will accumulate H+ which increases acidity

Replenishing PC Stores

Recovery process occurs when PC stores are depleted via other energy systems (Anaerobic and Aerobic)

Why can a sprinter only sprint "all out" for a brief period of time?

The ATP-PC system is quickly depleted because of the high energy demands needed for quick, intense movements
Hydrogen accumulation causes fatigue during sprinting

ATP-PC: Adaptations to Exercise

Mixed results in studies
Endurance training has no impact on creatine kinase activity
Increased content of intramuscular ATP and PC might not enhance short-term, high-intensity performance

Creatine: Mechanism of Action

Creatine combines with ATP to help produce more for muscle contraction

Common Adaptations

Improved enzyme function (enzyme activity)
Improved substrate availability means the enzymes can work at higher efficiency rates

Glycolysis: Enzymes Adaptations

Enzymes increase due to weight and sprint training, not just endurance training
Enzymes (like glycogen phosphorylase & Phosphofructokinase) change depending on type, volume, duration, intensity, and frequency of exercise. Muscle hypertrophy can also change PFK activity.