Module 3 Flashcards
What function do the lungs serve
they act as the location for gas exchange, and as the boundary between atmosphere and venous blood
What changes in ventilation during exercise? Why?
it increases to balance O2 consumption and CO2 production AKA maintains acid base balance
What are the alveoli
the point of gas exchange
how many alveoli are there
more than 500 million in the lungs. their surface area is 85m^2/4L, internal surface of 100m^2/L?
What are the zones of ventilation from top to bottom
trachea
primary bronchus
bronchus
bronchi
bronchioles
respiratory bronchioles
alveolar ducts
alveolar sacs
What is inspiration/expiration dependent on?
primary: the pressure differential (pressure diff between atmosphere and alveoli)
secondary: acid base balance
What is boyles law
when temp is constant, the product of pressure and volume remains constant.
what is the formula for boyles law
P1V1 = P2V2
How is CO2 formed?
by metabolism (of carb, fat etc?)
How is air moved in and out of the lungs
Diaphragm creates vacuum essentially
How do ATP demands affect breathing?
increased ATP demands = increased ventilation
Increased ATP levels = feedback inhibition to slow breathing
what occurs with increased ATP demand
increased oxygen demand
increased respiration (detected by chemoreceptors)
What occurs with increased ATP levels in the body
decreased oxygen demand
decreased respiration
define minute ventilation
the amount of air one breathes in a minute
what is the formula for VE
VE = fb x vt
fb = breathing frequency
vt = tidal volume
at rest, what is vt and fb
vt = 500mL
fb = 12 breaths/minute
What are the concentrations of atmospheric gas
O2 = 20.93%
CO2 = 0.03%
inert gases (N2) = 79.04%
what is dalton’s law
the total pressure of non-reactive gases is equal to the sum of the individual partial pressures
what equation represents dalton’s law
Partial pressure = concentration (%) x total pressure
what is 1 standard atmosphere equal to
760mmHg at sea level. at high altitude it is 220mmHg
What are the key gas change parameters
VO2, VCO2, Ve, RER
What is open circuit spirometry
using ambient air, measures O2 uptake and CO2 production
what is the formula for VO2
VO2 = diff in inhalation and exhalation
define hyperventilation
rapid and deep breathing
what physiological effects does hyperventilation have on the body?
it increases pulmonary ventilation, exceeds O2 consumption and CO2 elimination metabolism needs.
define dyspnea
shortness of breath, not getting enough air
describe what is meant by pressure differential
difference in pressure between two points
Describe the pathway of gas exchange in the lungs
O2 travels from high to low pressure (to alveolar membrane)
CO2 diffuses into lungs
Why does CO2 diffuse easily into the lungs
Because it has a higher pressure when returning in the veins compared to oxygen
How long does blood spend in the capillary?
0.75 seconds
What can impair gas transfer
- Buildup of pollutant layer in alveolar membrane
- reduction in alveolar surface area
How does impaired gas transfer directly affect performance
When exercising, the extra demand for gas exchange means less aeration, which limits performance. People with impaired lungs cannot get proper amounts of gas in their blood
What is the fick equation
VO2 = cardiac output x A-VO2 diff
= SV x HR x (arterial oxygen content - venous oxygen content)
what are the equations for venous and arterial oxygen content
venous = CvO2
arterial = CaO2
What are the functions of O2 in the body
- establishes PO2 of plasma/tissue fluids
- regulates breathing
- determines O2 loading/unloading
how much oxygen is in the blood at rest vs mod vs intense exercise
20ml per 100mL of blood
arterial: saturation may decrease due to higher utilization, cardiac output levels out the amount of O2 in the blood (arterial)
venous: oxygen content significantly decreases between rest and exercise due to higher utilization of oxygen
how is oxygen transported in blood
- physical solution
- hemoglobin
how much hemoglobin is in the blood
roughly 15g per 100mL (1.39mL oxygen binds to 1g hB)
define hemoglobin
iron-containing globular protein pigment
Is hemoglobin much better at carrying oxygen than physical solution
Yes! It carries 65-70 times more oxygen
How many oxygen molecules bind to one hemoglobin
- one for each iron containing protein
What dictates oxygenation of hemoglobin
partial pressure of O2. higher pressure = higher unloading
What are the hemoglobin differences between men and women
men = 15 g, women = 14 g
draw the oxyhemoglobin dissociation curve
What is the Bohr effect
bohr effect explains the affect of temperature and acidity on oxygen affinity
increased pH = increased affinity (less likely to let go of O)
increased temp = less affinity (more likely to let go of O)
What does an increase in acidity or temp mean for the oxyhemoglobin curve
it shifts down and right
decreased affinity, increased unloading
When do we see the Bohr effect most at work
During intense exercise. Exercise increases CO2 levels, O2 release, temperature and acidity from lactate
What is the partial pressure of venous oxygen at rest
40mmHg
What is the arteriovenous oxygen difference?
describes the difference between oxygen content at arteries vs veins
what is the average a-vo2
4-5ml O2/dL blood
Oxygen can release itself to tissues without needing __________
an increase in blood flow. Instead, we can see higher unloading through the bohr effect
How does the unloading of oxygen change in vigorous exercise compared to rest
increases by 3 times the resting level
The supply of what limits aerobic exercise
O2! We learned that O2 usage is not what limits it, but the supply of it
define myoglobin
iron containing protein in muscle fibres
Why is myoglobin important?
it acts as storage for intramuscular O2 storage
How are myoglobin and hemoglobin different?
Hemoglobin is in the blood, has 4 iron atoms
myoglobin is in the muscle, has 1 iron atom
Describe the curve for myoglobin. What does it mean for its affinity and unloading?
It means that it binds + retains O2 at low partial pressure of oxygen
when is myoglobin useful?
when exercise initially begins and during intense exercise (AKA when the pressure of oxygen declines dramatically)
when does myoglobin maintain a high oxygen saturation?
at rest and moderate exercise
At what level of partial pressure of oxygen does myoglobin do most of its unloading?
5mmHg
What conditions do not affect myoglobin affinity for oxygen?
acidity, CO2, and temperature
How is carbon dioxide transported in the blood?
- plasma (very small amount)
- hemoglobin
- plasma bicarbonate
How is CO2 transported via plasma bicarbonate
CO2 combines with water = carbonic acid
acid ionizes into H and bicarbonate
@ tissue: CO2 + water = H and carbonate
@lungs: H + bicarbonate = CO2 + water
how is pulmonary ventilation regulated
- neural circuits (brain)
- chemical state of blood
- gaseous state of blood
what factors affect medullary control of pulmonary ventilation
- peripheral chemoreceptors
- lung receptors
- proprioceptors
- core temp
- chemical state of blood
how do peripheral chemoreceptors and plasma PO2 relate to each other?
peripheral chemoreceptors measure PO2 to defend against hypoxia, and regulate ventilation at higher altitudes. (all to prevent hypoxia)
Why is the partial pressure of carbon dioxide so important?
it acts as a stimulus for respiratory changes! Small increases in PCO2 = large increases in Ve
Why is plasma acidity important for ventilation?
It has a big effect on ventilation
decreased pH = acidosis = CO2 retention = carbonic acid formation = decline in arterial pH = H accumulation = respiration increase to eliminate CO2 and carbonic acid levels
how long after holding your breath does the stimulus to breathe hit? Why does it hit?
40 seconds. Because of increased arterial PCO2 and H concentration! you hit your breaking point at 50mmHg
Why does hyperventilating before holding your breath help?
Because it lowers alveolar PCO2 (to about 15mmHg), meaning you have more time before you hit your breaking point again.
More CO2 leaves the blood @ hyperventilation, since you’re expelling it faster than it can be produced
Describe the process behind free diving blackout
You hit critically low oxygen levels before you hit CO2 threshold for breathing
Describe the chemical control of ventilation during PA
Primarily responds to PCO2 using arterial and central chemoreceptors to assess the chemical state of blood. It does not fully account for changes in ventilation during physical activity.
what happens to alveolar PO2 and PCO2 during exercise
nothing! they stay pretty level from resting levels
Do large increases in PCO2 change PO2 or PCO2?
No!
What are the major ventilation phases
- medulla increases ventilation (sensory feedback and cerebral cortex stimulate medulla)
- Plateau, then quick rise to steady state
- fine tuning of steady state rate ventilation (through sensory feedback)
How does minute ventilation change with VO2 and VCO2?
linearly!
What is the average ventilation for each L of oxygen consumed
20-25 L
How does minute ventilation increase with growing intensities? What comes first?
- Tidal volume will be responsible for big changes early on
- increasing intensity means increasing breathing frequency
what is ventilatory equivalent
the ratio of minute ventilation to oxygen consumption (how much we need to breathe to get a certain amount of oxygen)
= Ve / VO2
what is the formula for ventilatory equivalent
Ve/VO2
What is ventilatory equivalent during submax exercise
25L, up to 55% of VO2 (max?)
What is ventilatory threshold
the point at which ventilation increases significantly (at a faster rate than oxygen uptake, or VO2)
define buffering
chemical and physiological mechanisms to minimize changes in H concentration
what are the mechanisms for balancing pH
- Chemical buffer: weak acid + salt of acid
- when H is high = weak acid
- when H is low = release of H
- 3 types of buffers
- pulmonary ventilation
- renal function
what are the types of chemical buffers?
- bicarbonate = carbonic acid and sodium bicarbonate
- increase in H/CO2 = elimination of CO2, carbonic acid
- decrease in H/CO2 = retention of CO2, bicarbonate
- protein
- physiological buffer (ventilation)
- increase in H = increase ventilation
- decrease in H = decrease ventilation
What are some possible factors that contribute to lactate threshold?
- inadequate O2 delivery
- anaerobic metabolism
- buffering
- minute ventilation
What are the three zones of exercise intensity
- lactate accumulation not begun 50%
- lactate out of control (max oxygen consumption) 75%
- working towards VO2 max 100%
What is polarized training?
describes the training of zones 1 and 3, but not so much zone 2
What is meant by energy cost of breathing
The amount of oxygen/ATP that is required to actually breathe! increases with intensity, too
how does energy cost of breathing change with PA
it increases! Demands go up with intensity. oxygen, ATP, ventilation demands all increase, and with increasing minute ventilation comes more energy requirements of larger tidal volume
what is the energy cost of hyperpnea
hyperpnea=15% VO2
light intensity = 3-5%
mod = 8-11%
high intensity = ?
As we work harder, what happens to our energy cost of breathing
it increases. We are going to give a larger percentage of the oxygen that our body is bringing in to the muscles that need it
what is the relationship between Ve and energy cost of berathing?
non linear. increasing
What is work and displacement equal to in the respiratory system
pressure and change in volume
Where do we see most of the adaptation on aerobic endurance?
not so much ventilation/pulmonary structure adaptations. more so cardiovascular and neuromuscular
Why do we hyperventilate at higher intensities? what does it do to the body?
Because the body experiences inreased oxygen demands, and a higher need to expel CO2. Hyperventilation acheives both
what does the body’s oxygen supply depend upon?
gas concentration
gas pressure
what happens to PO2 and PCO2 with exercise
rest in muscle cell: PO2=40mmHg PCO2=46mmHg
exercise in muscle cell: PO2=0mmHg PCO2 = 90mmHg
why is it important to have a background level of carbon dioxide
because it allows for stimulation of the medulla and respiratory centres. without it, they wouldn’t be stimulated, and wouldn’t be able to modulate respiratory activity
What factors of Bohr’s effect lead to an increase in oxygen release
- increased heat
- increased CO2
- increased acidity
How do arterial and venous PO2 and PCO2 levels differ?
PO2 decreases (100 to 40mmHg)
PCO2 increases (40 to 46mmHg)
How does hemoglobin saturation of oxygen change with exercise
hemoglobin release increases with exercise
exercise = increased temp and acidity = more unloading
hemoglobin saturation might decrease slightly but compensation occurs (increasing cardiac output or breathing)
How does EPOC change with exercise intensities
light = small EPOC
mod = mod EPOC
heavy = large EPOC
How does EPOC change with people of different training levels
trained people will have smaller EPOC, since their body is more accustomed to activity
untrained will have larger EPOC
in what scenarios might a trained person have a larger EPOC than untrained?
When the exercise intensity or duration is longer! Trained individuals are more able to push themselves physically, leading to a larger EPOC
How does venous partial pressure of oxygen change across exercise intensities?
Rest: 40mmHg
mod: 30mmHg
intense: 20mmHg
