Physiology 2130 Lecture Notes - Lecture 52: Vo2 Max, Exercise Intensity, Circulatory System
1 May 2018
School
Department
Course
Professor
Lecture 052: Oxygen and CO2 transport
VO2
● Volume of oxygen that the body utilize (while breathing room air)
VO2 Max
● Maximum volume of oxygen that the body can utilize (while breathing room air)
● Best measure of aortic fitness
● Units: L/min or mL/kg/min
● Average person: 30-40 mL/kg/min
○ Higher for athletes
Functions Influencing VO2 Max
● Cardiovascular System
○ Gets the oxygen there
● Muscles
○ Oxygen utilization
● Respiration
○ Get the oxygen in the blood
● Cardiovascular system and the muscles are important for training to increase VO2Max
● Respiration is important for measuring VO2Max
Measuring VO2 Max
● VO2 = Amount of O2 inhaled - Amount of O2, exhaled
= (minute volume ) x ( % O2 of inhaled air - % O2 of exhaled air)
● Recall:
○ Minute volume = tidal
volume * respiratory rate
● To get the VO2 Max,
○ Have the person increase
in their exercise intensity
until the measurement of
VO2 does not increase
anymore
■ Ex. Stepwise
increases (linear) in
workload (on a
treadmill for
example).
○ This VO2,value is the VO2
Max value
Oxygen Transport
● As a dissolved gas (in the blood)
find more resources at oneclass.com
find more resources at oneclass.com
○ Minor component of O2 transport
○ Recall: Henry’s Law
■ The concentration of dissolved gas = pressure x solubility
● However, O2 is not very soluble in the blood
○ Thus only about 0.3 mL of O2, is dissolved and transported this way per 100 mL
of blood
■ NOT ADEQUATE TO MEET TISSUE DEMANDS
● 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
○ In blood there is approximately 15g Hb/100ml
■ 1 g of hemoglobin can hold a maximum of 1.34ml O2
○ LOTS OF O2
How much oxygen does the blood hold?
● Measure how much oxygen is bound to hemoglobin at different PO2
● Do an experiment to get the Hemoglobin-O2 Dissociation curve
Hemoglobin-O2 Dissociation curve
● In the lung, the partial pressure is
around 100 ml/Hg
○ At this pressure, hemoglobin
is completely saturated with
oxygen
○ Lots of oxygen is moved into
the blood at the lungs
● Even if the partial pressure drops to
around 60 ml/Hg in the lungs, the
saturation rate of hemoglobin is still
pretty high
○ Still can get a lot of oxygen
into the blood
● Lastly, at very low partial pressure of
oxygen, the oxygen dissociation from
hemoglobin very rapidly
○ This is what happens at peripheral tissue
● These 3 points of the sigmoidal shaped of the curve allows for:
○ Uploading of oxygen in the lung
○ Unloading of oxygen in the peripheral tissue
● The sigmoid shape of the hemoglobin-O2 dissociation curve is due to the binding
characteristic of O2,to hemoglobin
○ The first O2, takes the most energy to bind
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Volume of oxygen that the body utilize (while breathing room air) Maximum volume of oxygen that the body can utilize (while breathing room air) Cardiovascular system and the muscles are important for training to increase vo2max. Vo2 = amount of o2 inhaled - amount of o2, exhaled. = (minute volume ) x ( % o2 of inhaled air - % o2 of exhaled air) Minute volume = tidal volume * respiratory rate. Have the person increase in their exercise intensity until the measurement of. Stepwise increases (linear) in workload (on a treadmill for example). As a dissolved gas (in the blood) The concentration of dissolved gas = pressure x solubility. However, o2 is not very soluble in the blood. Thus only about 0. 3 ml of o2, is dissolved and transported this way per 100 ml of blood. Hemoglobin is a protein consisting of 4 subunits. Each subunit contains a heme moiety to which one o2 molecule can bind.
