Lecture 20 Flashcards
We bring in _________ from the _______ which goes into the _______ from the _________ and we need to extract ________ from the exercising lungs
O2 atmosphere blood lungs CO2
Which is the major fueling pathway for our exercising skeletal muscles?
oxidative phosphorylation
What are the three main goals of the respiratory system during exercise?
- ensure that the _______ _______ of O2 (________) in our _______ is well maintained to allow adequate ________ supply to our _________ muscles
- to ________ metabolic and ____________ CO2 to maintain the partial pressure of ________ (_______) in our _________
- to assist in the _______ of the metabolic ______ produced during ________ intensity exercise
- ensure that the partial pressures of O2 (PaO2) in our arteries is well maintained to allow adequate O2 supply to our exercising muscles
- to eliminate metabolic and non-metabolic CO2 to maintain the partial pressure of CO2 (PaCO2) in our arteries
- to assist in the buffering of the metabolic acids produced during high intensity exercise
At sea level, the PO2 in the air is about ________ mmHg by by the time it reaches the alveoli, it is about ________mmHg.
159
105
O2 diffuses into the lung _________ and then binds to ___________
capillaires
Hb
What fueling pathway is used in the lungs? Describe this in terms of the PO2.
Oxidative phosphorylation in the lungs which uses O2
The PO2 is decreased in the muscle (40mmHg)
How much O2 do muscles extract at rest and how does this change during exercise?
at rest: about 60mmHg
during exercise: we extract much more
If there is 20mL of O2 per 100mL of blood in the artery and 4-5mL diffuses into the muscles, how much is in 100mL of blood in the vein?
Is this at rest or during exercise?
15-16mL
this is at rest
If there is 20mL of O2 per 100mL of blood in the artery and 15mL diffuses into the muscles, how much is in 100mL of blood in the vein?
Is this at rest or during exercise?
5mL
this is during exercise
What are the two main CO2 sources?
metabolic and non-metabolic pathways
What are the two metabolic pathways where CO2 comes from?
Glucose + 6O2 → 30 ATP + 6CO2 +6H2O
Palmitate + 23O2 → 108 ATP + 16 CO2
What is the non-metabolic pathway that CO2 comes from?
H+ + HCO3 →H2CO3 → CO2 + H2O
After the blood has gone through the ________ beds, we have a decrease in _________ in the __________ system that needs to be replenished in the __________ system. We also need to expel _____. During exercise, there is an increase in ________
muscle PO2 venous pulmonary CO2 ventilation
What two things increase what we increase ventilation?
- tidal volume
- breathing frequency
By how many times does the tidal volume increase from rest to maximal exercise?
it is 8 times greater
By how many times does the breathing frequency increase from rest to maximal exercise?
is it 4 times greater
By how many times does the ventilation increase from rest to maximal exercise?
it is 32 times greater
What controls the increase in ventilation during exercise?
both neural and chemical pathways
How does the respiratory rate change in anticipation for exercise?
it starts to increase so it is greater than at rest but less than during exercise
Explain why exercise is hard at first and then it gets easier
it gets easier because the neural control settles down and the chemical control takes over
Fine turning of ventilation during steady exercise is by what? give examples
by blood borne substances such as CO2, pH/H+
What level does the chemical control occur?
at the level of the brainstem
What are the chemical stimulation for chemical control of ventilation?
H+ or CO2
Describe the order of energy use when exercising
- ATP stores
- ATP-CP system
- lactic acid system
- aerobic system
Describe the lactic acid system and how it acts on the central chemoreceptors
Lactate from glycolysis leads to activation of H+ levels which acidifies the blood. This is rapidly buffered by HCO3 which makes CO2. This diffuses into the CSFluid which gets converted back to H+. This acts on the central chemoreceptors to tell the lungs to increase ventilation rate as CO2 level in the blood is too high
We have to increase ventilation to get rid of what?
CO2
The predominant energy system to produce ATP at any one time depends on what three things?
- the intensity of the exercise
- duration of the exercise
- how fit you are
Explain how the intensity of the exercise affects the predominant energy system to produce ATP
The more intense the exercise, the more muscle glycogen and more creatine phosphate will be used and so we are relying on more anaerobic systems
Explain how the duration of the exercise affects the predominant energy system to produce ATP
If the exercise is two hours, we use aerobic system.
If we are going up a hill, we might switch back to anaerobic for that amount of time
Explain how fitness affects the predominant energy system to produce ATP
If you have a higher level of aerobic fitness, it will take an athlete longer to rely on their anaerobic system and so the faster you can go
As workload increases, so does what?
ventilation
it increase up until a certain point based on intensity
The harder you are working, the faster you are _________ and so the more _______ you require
breathing
tidal volume
At first, there is a ________ relationship between workload and ventilation and but then we reach a point and we get to an ___________ relationship and then we reach _________
linear
exponential
exhaustion
What is the point where the ventilation rate greatly increases? What causes it?
This is the anaerobic threshold and it is caused by an increase in CO2 level.
What does the anaerobic threshold show?
This is the start on non-sustainable exercise where your body can no longer rely on O2 systems to meet the ATP demands so you start to use anaerobic system
What is the modern term for the anaerobic threshold is what?
functional threshold power
Define the functional threshold power
This is the maximum intensity an athlete can hold without accumulation of lactate, or the fatigue that goes along with that phenomenon
Why did the term “anaerobic threshold” get changed to “functional threshold power”?
Because it became apparent from research that there is no point in time when the aerobic (with O2 systems) switch over to a level of intensity where O2 is simply not used (anaerobic) because at all times, all the systems are being used.
What four things increase at the anaerobic threshold?
- ventilation rate
- CO2
- O2
- blood lactic acid
There is an increase in the blood lactate concentration. It is too high that we can no longer buffer the H+ well enough so the CO2 starts to accumulate and you start to increase your ventilation rate
What two things is the functional threshold power dependent on?
- Aerobic system : how quickly lactate can be removed
* Anaerobic system: how much lactate is produced
We move to anaerobic system when what?
When we can’t get enough O2 to the skeletal muscle to sustain exercise aerobically
When the intensity gets even higher than the anaerobic threshold, we move to what threshold. Describe this
The lactate threshold
When the lactate starts to build up in our systems, we run out of glycogen and creatine phosphate stores very quickly and we have to slow down and our exercise stops. We have now used up all of our different creatine phosphate stores and our glycogen stores and we can’t use our anaerobic system anymore. We have to stop or slow right down to our aerobic systems are dominant.
What is the VO2 max?
This is the point at which we have to stop and we can’t sustain the exercise intensity level anymore
It is the point when the maximum amount of O2 is getting to our skeletal muscles. We are using aerobic systems but very much reliant on anaerobic systems. We are using all of our different fuel sources to try and sustain this huge work effort.
How does aerobic fitness affect how long you use each energy system for?
The more aerobic fitter you are, the further along the exercise intensity you can maintain relying on O2 systems before you switch over to needing the anaerobic systems.
How does the anaerobic fitness effect how long you use each energy system for?
You can get up to really intense workouts for about 2 minutes (as opposed to 1 minute in untrained people) before you use up the glycogen and creatine-phosphate stores are run out and anaerobic system has to take over and slow you down.
What can you do to improve your aerobic threshold?
endurance training
What can you do to improve you anaerobic fitness?
you can do interval training or heel-work to improve lactate threshold and therefore your anaerobic threshold
How do you measure VO2 max?
You put an athlete through that workload:
- at lower workload intensities, their aerobic system can maintain the pace
- as you increase the treadmill or resistance on the bike, the anaerobic system eventually takes over and then you keep increasing it until the athlete can no longer do it because all the creatine-phosphate and glycogen stores have been used up.
At this point, we measure the amount of O2 that the athlete is consuming in ml/kg/min.
The higher the VO2 max, the fitter the athlete
What is the range of VO2 max for a healthy 20 - 29 yr old female?
40-49
Which of the following sports is an anaerobic activity? • Baseball • Marathon running • Weightlifting • 1500m running
weightlifting
