Physiology 3120 Lecture Notes - Lecture 4: Protein Folding, Metabolic Alkalosis, Respiratory Alkalosis
9 May 2018
School
Department
Course
Professor
Physiology 3120
Dr. Veldhuizen
Oxygen and CO2 Transport
VO2 and VO2 Max
- VO2: volume of oxygen that the body utilizes (while breathing room air)
- VO2max: Maximum volume of oxygen that the body can utilize (while breathing room air)
- Units: Liters/min or ml/kg/min
- Average person: 30-40ml/kg/min
- Good (the best) measure of aerobic fitness
Factors influencing Vmax:
- If you want to train to increase your VO2, its mostly about getting O2 to your muscles and
getting your CV system to get the O2 there
- The respiratory is good at getting oxygen in the blood and taking CO2 out – its not usually a
limiting factor
- So usually people who want to increase their VO2max focus on their CV system and muscles
How VO2max can be measured:
- Recall: Minute volume = tidal volume * respiratory rate
Measurement of max:
- You have a person doing exercise and the intensity increases in a
stepwise fashion and you are measuring the VO2
- Stepwise increases in workload (for ex: on a treadmill)
- it increases linearly until you reach a point where even if you increase
your intensity, your VO2 consumption does not change this is your
VO2max
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Oxygen Transport:
1. dissolved gas
2. bound to hemoglobin
Oxygen Transport: as a dissolved gas
- Minor component of O2 transport
- Henry’s Law: concentration of dissolved gas = pressure*solubility
o O2 not very soluble in blood
- Only approx. 0.3 ml of O2 per 100ml blood is transported this way
- Not adequate to meet tissue demands
Oxygen Transport: Bound to Hemoglobin
- Major component of O2 transport
- Hemoglobin is a protein consisting of 4 subunits
- Each subunit contains a heme moiety to which one O2 molecule can bind
- 1g of hemoglobin can hold a maximum of 1.34ml O2
- In blood there is approximately 15g Hb/100ml
How much oxygen does blood hold?
Do an experiment:
- Divide the blood into different containers and expose them to different partial pressures of O2
- After equilibrium is reached, you can measure how much O2 is in the blood, how much is
dissolved and how much is bound to hemoglobin
- The result you get is called an oxygen-hemoglobin dissociation curve
Oxygen-hemoglobin dissociation curve
- Vertical axis:
o Hb saturation – how much of the Hb is bound to O2
o O2 content
- Horizontal axis:
o Partial pressure of O2
- The solid line is the amount of O2 bound to Hb
- The dashed line at the bottom is the dissolved Hb
- The dashed line at the top is the total O2 (dissolved O2 + O2 bound
to Hb)
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- In the lung PO2=100mmHg Hb sat 97.5%
o Partial pressure in the lung is about 100mmHg
o At 100 mmHg, most of the Hb has O2 bound to it (its almost completely saturated)
o There is also about 20ml per 100 ml of oxygen in total
- If PO2 in the lung drops still high saturation
o We can go down to almost 60 but the saturation and the amount of O2 we have is still
very high
- If peripheral tissue PO2 is low allows dissociation of O2 into the tissues
- The three points about the curve above leads to the conclusion that the sigmoidal shape of
hemoglobin-O2 dissociation curve allows for:
o uploading of O2 in the lung and
o unloading in the peripheral tissue
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Vo2: volume of oxygen that the body utilizes (while breathing room air) Vo2max: maximum volume of oxygen that the body can utilize (while breathing room air) Good (the best) measure of aerobic fitness. If you want to train to increase your vo2, its mostly about getting o2 to your muscles and getting your cv system to get the o2 there. The respiratory is good at getting oxygen in the blood and taking co2 out its not usually a limiting factor. So usually people who want to increase their vo2max focus on their cv system and muscles. Recall: minute volume = tidal volume * respiratory rate. You have a person doing exercise and the intensity increases in a stepwise fashion and you are measuring the vo2. Stepwise increases in workload (for ex: on a treadmill) it increases linearly until you reach a point where even if you increase your intensity, your vo2 consumption does not change this is your.
