GLYCOLYTIC SYSTEM

Summary

This screencast delves into the glycolytic system, the body's second energy system, which takes over after the ATP-PC system's 10-second burst. It explains how glycogen, stored as carbohydrates in muscles and liver, is broken down into glucose by glycogen phosphorylase, then into pyruvic acid by phosphofructokinase, yielding two ATP molecules. The absence of oxygen triggers lactate dehydrogenase, converting pyruvic acid into lactic acid, causing fatigue and decreased performance. The glycolytic system is crucial for high-intensity activities lasting up to 3 minutes, such as sprinting or recovery runs in team sports.

Takeaways

• 🔋 The glycolytic system is the second energy system that provides energy for high-intensity activities when ATP and PC stores are depleted.
• ⏱️ This system kicks in after about 10 seconds of high-intensity exercise, supplementing the ATP-PC system.
• 🍞 Glycogen, stored in muscles and liver, is the primary fuel source for the glycolytic system, which is broken down into glucose.
• 🔬 Glycogen phosphorylase (GPP) is the enzyme that initiates the breakdown of glycogen into glucose for energy production.
• 🏋️‍♂️ The glycolytic system is anaerobic, meaning it does not require oxygen to function, making it suitable for short, intense bursts of activity.
• 🚀 The key reaction in the glycolytic system is the breakdown of glucose into pyruvic acid by phosphofructokinase (PFK), yielding two ATP molecules.
• 🚫 In the absence of oxygen, pyruvic acid is converted into lactic acid by lactate dehydrogenase (LDH), a process that can lead to muscle fatigue.
• 🏃‍♂️ High-intensity activities like sprinting or recovery runs in team sports rely on the glycolytic system for the quick energy they need.
• ⏳ The glycolytic system can sustain energy production from 10 seconds up to about 3 minutes during intense physical activity.
• 📉 Lactic acid accumulation can lead to a decrease in blood pH, enzyme denaturation, and ultimately, muscle fatigue, limiting the duration of high-intensity exercise.

Q & A

What is the focus of today's screencast on the energy system?

Today's focus is on the second energy system, known as the glycolytic system, which provides energy for sporting activities.

What is the primary role of ATP in the body?

ATP serves as the energy currency of the body, being the only usable energy source for immediate energy needs.

How does the glycolytic system differ from the ATP-PC system?

The glycolytic system is the second anaerobic energy system that kicks in after the ATP-PC system, which provides energy for high-intensity activities up to 10 seconds, runs out.

What is the main fuel source for the glycolytic system?

The main fuel source for the glycolytic system is glycogen, which is stored in the muscles and liver and broken down into glucose.

What enzyme is responsible for breaking down glycogen into glucose in the glycolytic system?

Glycogen phosphorylase (GPP) is the enzyme that breaks down glycogen into glucose within the glycolytic system.

What is the role of phosphofructokinase (PFK) in the glycolytic system?

Phosphofructokinase (PFK) is the enzyme that breaks down glucose into pyruvic acid, which is a key step in the glycolytic system.

How many ATP molecules are produced during the breakdown of glucose by PFK in the glycolytic system?

The breakdown of glucose by PFK into pyruvic acid results in the production of two ATP molecules.

What happens to pyruvic acid in the absence of oxygen in the glycolytic system?

In the absence of oxygen, pyruvic acid is broken down by the enzyme lactate dehydrogenase (LDH) into lactic acid.

What is the impact of lactic acid accumulation on the body during exercise?

The accumulation of lactic acid leads to an increase in blood acidity, which decreases blood pH, denatures enzymes, and ultimately causes fatigue.

What is the time frame during which the glycolytic system provides energy?

The glycolytic system provides energy for activities lasting from 10 seconds up to approximately 3 minutes.

What are some examples of high-intensity sports that utilize the glycolytic system?

Examples include a 400-meter sprint in athletics and recovery runs in team sports like hockey, football, and basketball turnover runs.

Outlines

00:00

🏋️‍♂️ Glycolytic System and Energy Production

The first paragraph introduces the glycolytic system, the second energy system discussed in the screencast. It follows the ATP-PC system, which provides energy for high-intensity activities up to 10 seconds. When the phosphocreatine (PC) stores are depleted, the glycolytic system kicks in. This system uses glycogen, stored in muscles and liver, as its primary fuel source. Glycogen is broken down into glucose by the enzyme glycogen phosphorylase (GPP). Glucose is then further broken down into pyruvic acid by phosphofructokinase (PFK), a critical step in anaerobic glycolysis, which releases two ATP molecules. This process is significant for activities lasting between 10 seconds and 3 minutes.

05:02

🚫 Lactic Acid and Its Impact on Performance

The second paragraph delves into the anaerobic nature of the glycolytic system and the production of lactic acid. When oxygen is scarce, pyruvic acid is converted into lactic acid by lactate dehydrogenase (LDH). Lactic acid accumulation leads to increased blood acidity, which in turn lowers blood pH and denatures enzymes necessary for energy production. This chain of events results in fatigue, halting or slowing down physical activity. The paragraph emphasizes the glycolytic system's limitations due to lactic acid production and its detrimental effects on performance during high-intensity, short-duration exercises.

10:03

⏱️ Applications and Limitations of the Glycolytic System

The third paragraph discusses the practical applications and limitations of the glycolytic system in sports and physical activities. It highlights that the system is suitable for high-intensity, anaerobic actions lasting from 10 seconds to 3 minutes, such as a 400-meter sprint or recovery runs in team sports. The paragraph also underscores the need for understanding the glycolytic system's key components, including the enzymes involved and the by-products produced, to effectively evaluate its role in energy metabolism during physical exertion.

Keywords

💡Glycolytic System

The glycolytic system is the second energy system discussed in the video, which is crucial for understanding how the body produces energy during high-intensity activities. It is an anaerobic process that breaks down glycogen into glucose, which is then converted into ATP. The video explains that this system becomes active after the ATP-PC system's energy stores are depleted, typically after about 10 seconds of intense exercise. It is highlighted as a key system for activities lasting from 10 seconds up to around 3 minutes.

💡ATP

ATP, or adenosine triphosphate, is described as the 'energy currency of the body' in the video. It is the immediate source of energy for cellular activities. The script discusses how ATP is broken down and then resynthesized through various energy systems, including the glycolytic system, to fuel high-intensity, short-duration activities.

💡Glycogen

Glycogen is a complex carbohydrate stored in the muscles and liver, primarily derived from dietary carbohydrates like pasta and bread. In the glycolytic system, glycogen is broken down into glucose by the enzyme glycogen phosphorylase (GPP). This process is essential for energy production during exercise, as it provides the substrate for ATP synthesis via anaerobic glycolysis.

💡Phosphofructokinase (PFK)

Phosphofructokinase, or PFK, is an enzyme that plays a central role in the glycolytic pathway. It catalyzes the conversion of glucose into pyruvic acid, a reaction that is critical for ATP production in the absence of oxygen. The video emphasizes that this is the most important reaction in the glycolytic system, as it directly leads to the generation of ATP.

💡Anaerobic Glycolysis

Anaerobic glycolysis is the process by which glucose is broken down into pyruvic acid without the presence of oxygen. This process is detailed in the video as a key mechanism for ATP production during high-intensity exercise when oxygen supply is insufficient. It results in the production of two ATP molecules per glucose molecule and is a critical part of the glycolytic system.

💡Lactic Acid

Lactic acid is a by-product of anaerobic glycolysis when oxygen is not available. The video explains that when pyruvic acid cannot be further broken down due to lack of oxygen, it is converted into lactic acid by the enzyme lactate dehydrogenase. This accumulation of lactic acid can lead to a decrease in blood pH, causing fatigue and ultimately stopping the exercise.

💡Lactate Dehydrogenase (LDH)

Lactate dehydrogenase, or LDH, is the enzyme responsible for converting pyruvic acid into lactic acid when oxygen is scarce. The video describes this enzyme as 'the enzyme you don't really want' because it signifies that the glycolytic system is under stress and cannot effectively produce ATP without oxygen.

💡Onset of Blood Lactate Accumulation (OBLA)

The onset of blood lactate accumulation (OBLA) is a term used to describe the point during exercise when lactic acid begins to accumulate in the blood, leading to a decrease in pH and the onset of fatigue. The video uses this term to illustrate the limitations of the glycolytic system and the need for oxygen to sustain high-intensity exercise.

💡Anaerobic

Anaerobic refers to metabolic processes that do not require oxygen. The video explains that both the ATP-PC system and the glycolytic system are anaerobic, making them suitable for short, high-intensity bursts of activity. The term is used to contrast these systems with aerobic processes that require oxygen.

💡Muscle Sarcoplasm

Muscle sarcoplasm is the cytoplasm within muscle cells where the glycolytic reactions take place. The video mentions that glycogen is stored in the muscle sarcoplasm and is broken down into glucose by the action of GPP, highlighting the importance of the muscle sarcoplasm as the site of anaerobic energy production.

💡High-Intensity Anaerobic Actions

High-intensity anaerobic actions are short-duration, high-intensity activities that rely on anaerobic energy systems. The video provides examples such as 400-meter sprints and recovery runs in team sports, illustrating how these activities are fueled by the glycolytic system when the ATP-PC system's energy reserves are depleted.

Highlights

Introduction to the glycolytic system as the second energy system for high-intensity activities.

Transition from the ATP-PC system to the glycolytic system after 10 seconds of high-intensity activity.

Glycogen as the primary fuel source for the glycolytic system, stored in muscles and liver.

Role of the enzyme glycogen phosphorylase (GPP) in breaking down glycogen into glucose.

Glucose is the key fuel that provides ATP through the glycolytic process.

Phosphofructokinase (PFK) as the enzyme responsible for breaking down glucose into pyruvic acid.

Anaerobic glycolysis is the process of glucose breakdown without oxygen, yielding two ATP molecules.

Formation of lactic acid due to the action of lactate dehydrogenase (LDH) when oxygen is absent.

Lactic acid accumulation leading to increased blood acidity and decreased blood pH.

Denaturation of enzymes due to decreased blood pH, affecting the body's ability to produce energy.

Onset of blood lactate accumulation (OBLA) as a term for the fatigue experienced during high-intensity exercise.

The glycolytic system's time frame of providing energy from 10 seconds up to 3 minutes.

The glycolytic system's low ATP yield compared to the ATP-PC system.

Lactic acid as a harmful by-product of the glycolytic system under anaerobic conditions.

Simplicity of the glycolytic system's reactions, occurring in the muscle sarcoplasm.

Examples of sports that utilize the glycolytic system, such as 400-meter sprints and recovery runs in team sports.

Summary of key points for understanding the glycolytic system, including fuel sources, enzymes, and by-products.

Transcripts

hello and welcome to energy system

screencast - today's focus is going to

be looking at the second energy system

which is called the glycolytic system

our last week or last screencast we had

a look at the role of ATP that energy

currency of the body are only usable

energy source and then we had a look at

the process of ATP breakdown and then we

had a look at how one ATP broke down how

we use PC in a coupled reaction to

resynthesizer ATP to give us what ATP

which would have then allow us to work

very high intensity for 0 to 10 seconds

that was our last sister we advanced

these disabilities of that so if we just

keep ourself there then if you think we

use this high intensity energy or ATP we

synthesis from the ATP PC sister that

gives us up to ten seconds now at that

point as we looked at when we evaluated

the ATP PC sister PC runs out okay at

ten seconds so at that point our energy

system or our system through synthesize

ATP switches to the glycolytic system so

pretend the screencast what I'm going to

look for you to be able to do is

objective one now so you're looking to

be able to explain how the glycolytic

system provides energy for sporting

activities and lesson content we'll have

a look at how you evaluate the

glycolytic system the advantages and

disadvantages so just tonight to keep us

where we are it in regard to our scheme

or sequence of work if you have a look

over here I've kind of just attempted to

put this here so if you look we look at

anaerobic physiology we've looked at

this anaerobic muscle fibers here we've

looked at the ATP PC system which

remember gives us the anaerobic a high

intensity energy for up to 10 seconds

now when 10 seconds finishes we then

switch to our glycolytic system so

glycolytic is our second anaerobic

energy system so so let them so I put it

up there just to remind you that it's

the anaerobic system of second anaerobic

energy system and so what we need to

have a look at now then is I think you

know if the ATP PC as a first topic

could be quite difficult at times but

now you look at it I think once we get

rid of that phosphor creatine store once

it's run out when we do an explosive

action what is the next fuel we use I

think it's quite helpful now because you

thinking this kind of energy systems

called the glycolytic system says good

start point to think that you know the

fuel that is the located or fuel that we

use is glycogen now to keep that to make

that a more simple if you just think

it's the fact that you know when you eat

pasta when you eat bread these are

examples of carbohydrates

now carbohydrates are stored in our

muscles and liver as glycogen okay of

this system takes first muster

sarcoplasm sorry it's stored as glycogen

in our muscles and livers now what

happens is a part of that is as we've

looked at with off your so far it's 80

people to PC as a fuel okay in order for

them to be broken down an enzyme has to

act to them in this case is the

glycolytic system glycogen off you'll

which is stored in a muscle it's broken

down by the enzyme GPP now this in its

kind of proper term is called glycogen

phosphorylase now you have to know GPP

but i think in the first instance as

always of an enzyme it's useful to just

write it down so you know where the GPP

comes from and it helps here because you

remember glycogen and then you've just

gotta remember ATP had a's then had

creatine kinase now we've got the the

enzyme that breaks down glycogen

glycogen phosphorylase always has an ace

as a suffix and then it's got the kind

of fuel usually at the start in most

case it's north as we'll see in a second

now as you can see glycogen and so i

kind of complex carbohydrate broken down

by the enzyme TPP to phosphorous into

glucose now glucose at this point i

glucose is actually the fuel that is

going to give us our ATP so when we get

down from glycogen into glucose okay

when we break it down into that glucose

then what happens is another enzyme will

break down glucose now this is the most

important reaction in the glycolytic

system okay so the process of glucose

being broken down starts by the enzyme

phosphofructokinase or pfk breaking it

down okay so it breaks down glucose

phosphofructokinase is the enzyme that

does it and then it breaks it down it's

something called pyruvic acid or

pyruvate now this process of glucose

being broken down by pfk into pyruvic

acid

actually called anaerobic glycolysis

okay it's the breakdown of glycogen and

glucose without oxygen present and when

this happens this process of glucose

into pyruvic acid this is where we've

recent the size to ATP now the good

thing on this is you don't need to know

the kind of exact process the kind of

resynthesis of this you need to know

that by glucose being broken down by pfk

into pyruvic acid there's two ATP

released now at this point when our two

ATP avium are synthesized we there's an

issue now what the issue is because this

is an anaerobic system when we get this

pyruvic acid broken down when the due to

the fact it's anaerobic and there's no

oxygen present this kind of stimulates

another enzyme and I suppose it is it's

the enzyme that you don't really want

and the enzyme is called lactate

dehydrogenase or out the H and out eh

basically is the enzyme when it notices

that there's no oxygen present and

pyruvic acid that's been formed it

breaks it down into and something called

lactic acid which I'm sure you'll all be

familiar with so what we have there

pyruvic acid when there's no oxygen

present it's broken down by the enzyme

LT h or lactate dehydrogenase okay to

give us lactic acid now lactic acid

causes as big big problems it can also

help us at times but when we do not have

oxygen okay

lactic acid can have a negative effect

it's what you will consider a harmful

by-product okay during exercise

so when lactic acid is reached or when

we start to have lactic acid there is a

cycle of events that will cause us

problems and cause us to stop and lead

us to have fatigue now at the moment

let's just make sure we kind of got this

before I start looking at those chain of

events that happens from here we're

looking here at thinking right takes

place in the muscle cytoplasm

glycogen is our main fuel okay so

glycogen is stored in our muscle cells a

bio carbohydrate and then it's broken up

by GPP into glucose glucose broken down

with pfk into pyruvic acid now once this

happens this releases two ATP and that

process for those no there are people

who will be interested in that it's the

process of anaerobic glycolysis to

breakdown of glycogen and glucose

without oxygen now when pyruvic acid

forms and there's no oxygen present

lactate dehydrogenase is the enzyme that

notices that and it's stimulated to

breakdown pyruvic acid into lactic acid

now that is where you get the majority

of your marks okay for this talking

about those breakdowns the enzymes of

course it to happen and the question

always people will ask is you know dude

what would you get from marks for an

example for God to n-side you get marks

with just the initials but again as I

said a repeat previous just make you

make a note of these to start with now

I'm sure you've all experienced lactic

acid lactic acid then we need to be able

to unlock a sequence of events and just

to explain why it is harmful when

there's no oxygen present so if we

looking at them these are the things

that happen so first thing lactic acid

and lactate basically accumulates in our

blood okay and this leads to an increase

in blood acidity now when there's an

increase in blood acidity this has a

knock-on effect okay and it decreases

the blood pH now when the blood pH is

decreased this then denatures enzymes

that can break down our fuels in order

to give us energy now the kind of the

net effect of this is that we have

fatigue or we experience fatigue and the

term associate when the fatigue stops us

from exercising okay is known as obler

okay or onset of blood lactate

accumulation at this point we will have

to stop slow down breathe in and get

oxygen so I'm sure you can start to see

the big disadvantage of the glycolytic

system is lactic acid and the reason why

lactic acid causes us to stop okay or

stops us from performing effectively

it's because of these knock-on effects

these really are the higher-order things

here your job for tomorrow is to make

sure that you feel confident breaking

down the glycolytic system it's what it

says on the tin glycolytic glycogen we

need to the enzyme product and I product

ATP and then enzyme product outta here

so next is a harmful by-product our job

is to make sure we can do that now just

and you know in terms of our summary

framework I'll put this up on the next

slide and things should be looking for

that as always you need to know the

following key things or hopefully you'll

start to pick some of these things out

or maybe what I didn't give specific

times I'll show you those now so the

fuel that the key fuel that they want to

be honest is glucose okay so glucose is

the key thing because the breakdown of

glucose that anaerobic glycolysis that

process where the ATP is produced that's

the key fuel but glycogen is also

accepted but it must be with glucose and

not at the expense of glucose so on top

of that is it aerobic or anaerobic

pretty straightforward it's an anaerobic

energy system okay always a good thing

because it doesn't require oxygen to

break down glycogen and glucose time I

hear the time that is given for this

energy system it picks up where the ATP

PCs left off so 10 seconds up to 3

minutes the energy yield as you saw

before it's the number of ATP so in this

case it gives us double the ATP PC

system but it's still a low ATP yield of

two byproducts okay at this time we have

an extremely harmful by-product that is

lactic acid complexity and the reactions

for this system are extremely simple

okay as you saw and site of reaction

muscle sarcoplasm sportin examples there

we're looking for these really high

intensity anaerobic actions that you

know would take place in that 10 second

to three minute period so I'll put a

sport an example from athletics a

400-meter sprint you might remember that

from when we looked at 2a fibers and

then if we had a look at recovery runs

in hockey football rugby if you look at

those sports basketball turnover runs

when you have to run for a longer than

10 seconds but still at really high

intensity okay so there's your

evaluation piece make good notes on this

thank you very much