Chapter 7: Energy Systems and Muscle Fibers

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Chapter 7: Energy Systems and Muscle Fibers

Myoglobin

Helps muscles sustain aerobic activity by providing oxygen when needed

Abundant in skeletal and cardiac muscle cells

Facilitates oxygen delivery to muscle tissues during periods of increased activity

Has a higher affinity for oxygen than hemoglobin, making it efficient at storing oxygen in muscles

Gives muscles their reddish color.

It has a globular structure, similar to hemoglobin

A protein that stores oxygen in muscle cells

Muscle Fibers

Type I (SO)

Generate energy slowly

Mainly depend on anaerobic processes

Slow-oxidative

Slow Twitch Muscle Fibers

Long-distance ideal

Maintain lower level of tension for longer duration

Generate and relax tension

Red or dark colour

Type IIb (FG)

Low fatigue resistance

High force production

Fast-glycolytic

Type IIa (FOG)

Low energy efficiency

Intermediate force production

Fast-oxidative glycolytic

Fast Twitch Muscle Fibres

Generate large amounts of tension with low endurance levels

Tense and relax quickly

Paler in colour

2-3x faster contractions than slow twitch fibres

Key Nutrients

Carbohydrates

Glucose & Glycogen

Found in foods like bread, rice, pasta, fruits, vegetables, and dairy products

Include sugars, starches, and fibers

Simple vs Complex carbohydrates

Complex Carbs: Starches and fibers found in foods like grains, vegetables, and legumes

Simple Carbs: Rapidly digested sugars found in foods like fruits, candies, and soft drinks

Composed of carbon, hydrogen, and oxygen atoms in a ratio of 1:2:1

Main source of energy for the body, especially for the brain and muscles

Dietary guidelines suggest consuming a majority of calories from carbohydrates, mainly from whole food sources

Proteins

No protein reserve

Found in foods like meat, fish, eggs, dairy, legumes, nuts, and seeds

Amino acids

Some amino acids are essential, meaning they must be obtained from the diet

20 different amino acids, each with a unique side chain

linked together by peptide bonds

Serve as building blocks for cells and tissues, and perform various functions in the body.

Essential for growth and repair

Fats

Found in foods like oils, butter, meat, nuts, and avocados

Contain large quantities of stored energy

Must be consumed with food

Found is muscle cells and adipose tissue

Saturated or un-saturated

Fats serve as a dense form of energy storage in the body.

Glycerol

Fatty acids

Energy sources

Creatine Phosphate

Creatine is synthesized in the liver and kidneys from amino acids

After use, creatine phosphate can be regenerated during rest periods when ATP demand is lower

Creatine supplementation is popular among athletes and bodybuilders to enhance short-term performance during high-intensity activities

Provides energy for activities like sprinting, weightlifting, and jumping, where the demand for ATP is immediate and intense

Stored primarily in skeletal muscle tissue, with higher concentrations in fast-twitch muscle fibers used for explosive movements

Creatine phosphate stores are quickly depleted during high-intensity activities and are not sustainable for prolonged endurance efforts

High-energy compound

Acts as a rapid and readily available energy reserve for muscle cells during short bursts of intense activity

Glycogen

Acts as a readily available energy reserve that can be quickly mobilized when needed

During prolonged exercise, muscle glycogen stores can become depleted, leading to fatigue

Glycogen stores are replenished through dietary carbohydrates, particularly after exercise or periods of fasting

Glycogen is broken down into glucose through glycogenolysis when the body requires energy

Stored form of glucose

It is a polysaccharide, meaning it consists of multiple glucose molecules linked together

Found in the liver and other muscles

Liver glycogen helps maintain blood glucose levels between meals and during fasting periods

Muscle glycogen provides energy for muscle contraction during exercise

Glucose

Excess glucose is stored in the liver and muscles as glycogen for later us

Metabolized through glycolysis, where it is broken down to produce ATP

Primary energy source of the human body

Belongs to the carbohydrate group, abundant in many foods like fruits, vegetables, and grains

During exercise, muscles rely on glucose for energy, especially during high-intensity activities

Essential for brain function, as neurons rely primarily on glucose for energy

Simple sugar, also known as a monosaccharide

ATP

Structure

Connected by high energy bonds

five carbon sugar molecule

Nitrogenous base

Stored in muscle and easily accessible

ATP is generated through cellular respiration in the mitochondria

Relies on the action of phosphocreatine

Carbs, fats, and proteins are all resynthesized into this molecule to become usable sources of energy.

Common Energy Molecule

"Free Energy"

Adenosine Triphosphate

Function

Provides energy for cell growth and division

Powers the contraction of muscles

Energy stored in high energy phosphate bonds

ATP is the primary energy carrier in all living organisms.

Cellular Respiration Pathways

Electron Transport Chain

Produces most of the cells ATP during respiration

Oxygen accepts electrons and forms water

Produces ATP

Inside the inner membrane of the mitochondria

Krebs Cycle

Produces a small amount of ATP directly

Produces CO2 as a waste product

Begins with acetyl-CoA

Provides high-energy electrons for the electron transport chain.

Occurs in the mitochondria

Glycolysis

Breaks down glucose to provide energy and intermediates for further cellular respiration steps

No oxygen required

Produces 2 pyruvate molecules

Produces a net gain of 2 ATP molecules

Begins with one glucose molecule

Occurs in the cytoplasm of the cell

Energy Systems

Aerobic

Aerobic (Cellular Respiration)

Energy source is glycogen, fats and proteins

2min and beyond duration

Fatigue resistant

Slow and complete breakdown of glucose

Long-distance swimming

Cross-country skiing

Marathon

Carbon dioxide and water are produced as waste products.

Produces 36 molecules of ATP

Consists of three main stages: glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation (electron transport chain)

Cells break down glucose and other organic molecules to produce ATP

Provides a highly efficient way to extract energy from glucose molecules, maximizing ATP production

Cellular respiration produces a large amount of ATP, with oxidative phosphorylation contributing the majority of ATP production

Location of activity is the mitochondria

O2 required

Anaerobic

Anerobic Lactic (Glycolysis)

Glucose as an energy source

15s-3min duration

Fast surge of power

HIIT circuit

Hockey shift

400m run

Lactic acid buildup causing a burning sensation in the muscles

Lactic acid is a byproduct

A net gain of 2 ATP molecules per glucose molecule.

Due to the accumulation of lactate and depletion of glycogen stores, the glycolytic system is not sustainable for prolonged periods of activity

Provides rapid but limited energy for short bursts of intense activity

Takes place in the cytoplasm of cells

Begins with the breakdown of glucose into pyruvate

Anerobic Alactic (ATP-PC)

10-15s duration

Fatigue quickly

Super quick surge of power

Shot put

Jump events

100m sprint

No by products

1-2 chemical reactions

1 molecule of ATP

Energy source is creatine phosphate

Takes place in the cytoplasm

02 not required