Lecture 6: Respiratory System pt. 2 Flashcards
What contributes to make up Barometric Pressure?
Partial pressure of oxygen, carbon dioxide, nitrogen
What do you treat the partial pressure as?
A concentration
PO2 is always ______% of barometric pressure
21%
Why is it 21%?
Because in naturally occurring air on earth, oxygen is ALWAYS 21% of the air.
In high elevation, why is there the same proportion of oxygen all around?
Because theres the same proportion of oxygen and barometric pressure is lower. ( same percentage of oxygen but it is 21% of a LOWER number of a “big easy”???)
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When we change barometric pressure, what does it change?
What the PO2, PCO2, Nitrogen is
The closer you are to the surface of the earth at sea level,….
the more stronger gravity can pull on it and the higher the pressure you have.
As altitude goes up, what happens?
Barometric Pressure goes down
For instance, if you were at a place where Barometric was 700, what would be the PO2 in that area?
The PO2 would 21% of 700. It would be 140.
For instance, if you were at a place where Barometric pressure was 300, what would the PO2 be in that area?
The PO2 would be 21% of 300. It will be 60
The bigger the concentration gradient is,
the more will move from point A (high) to point B ( low).
As the PO2 drops when going up in altitude,
the gradient gets smaller so less oxygen gets movin from the alveoli into the blood
What is a pulmonary capacity?
A pulmonary capacity is something we can measure. (two or more volumes added together)
What are the Pulmonary Volumes?
Tidal Volume, Expiratory Reserve Volume, Inspiratory Reserve Volume, Residual Volume
What is a Tidal Volume?
Volume of air in a normal expiration after a normal inspiration
What is the normal Tidal Volume?
About 500 ml of air
What is Expiratory Reserve Volume?
Amount of air you can breathe out AFTER you breathe out tidal volume
What is the normal ERV?
About 1.0 - 1.2 L of air
What is Inspiratory Reserve Volume?
The volume of air you can inspire forcibly after a normal inspiration.
What is the normal IRV?
About 3.3 L of air
What is Residual Volume?
The volume of air you cannot force out of your lungs
What is the normal RV?
About 1.2 L of air
Why is IRV bigger ERV?
It leaves us room at the top so if we need to have deeper breaths bc we’re exercising more, we have a lot of room above TV to do that.
What are pulmonary capacities calculated by?
By adding together pulmonary volumes
What is Total Lung Capacity?
The maximum amount of air you have in your lungs.
About 6 L of air.
What is the equation for Total Lung Capacity?
RV + ERV + TV + IRV
What is Vital Capacity?
The maximum amount of air you can move in and out of your lungs
How can you calculate Vital Capacity?
- Total lung capacity - Residual Volume
OR - IRV + TV + ERV
Why do we care about VC?
As residual volume goes up, VC goes down. The amount of air you move in and out of your lungs, decreases as RV goes up.
What can affect Vital Capacity?
The size of a person (smaller person has a lower VC than a taller person)
If there is more blood volume, what happens?
Less room for air
If you have excessive fluid in either abdominal cavity or pleural cavity, VC goes down. Why?
In the abdominal cavity, excessive fluid can keep diaphragm from moving down as much as it would like to and not so much of a pressure change.
If there is excessive fluid in the pleural cavity, the pleural fluid CAN’T BE COMPRESSED making the lungs be compressed.
What happens in Emphysema?
Alveoli gets stretches out and doesn’t have elastic recoil.
When someone with Emphysema breathes out, what happens?
less air leaves. RV is higher.
You can’t get more air out.
What are the hints to how somebody has emphysema?
Someone w/ emphysema has to work to breathe out. Very well developed neck muscles: to use to breathe out. Barrel chested: more air left in lungs after a normal respiration
What is Inspiratory Capacity?
The amount of air you can breathe in AFTER a normal expiration
What is the equation of IC?
TV + IRV
What is the normal IC?
3.5 - 3.8 L
What is Functional Residual Capacity?
The volume of air left in the lungs after a normal expiration
What is the equation for FRC?
ERV + RV
What is a normal FRC?
about 2.2-2.4 L
What is Alveolar Ventilation?
Volume of air inspired that takes part in gas exchange
How can Alveolar Ventilation be calculated?
Tidal Volume - Anatomical dead space
What is anatomical dead space?
Volume of air that is not involved in gas exchange and IS NOT SUPPOSED TO BE
-Normal
-All the small airways before gas exchange
What is physiological dead space?
Volume of air not involved in gas exchange BUT SHOULD BE
- NOT Normal
-ex: pneumonia (air in alveoli can’t have gas exchange bc gunk in alveoli)
What is Respiratory Minute Volume?
Amount of air moves in and out of the lung in a minute
What is Eupnea?
Normal quiet breathing
What is a normal range for Eupnea?
12-20 respirations / minute
What is Hyperpnea?
Increase in respiration because of an increase in O2 demand
When does Hyperpnea mostly occur in?
Exercise
What is Hyperventilation?
Increase in respiration w/o a change in O2 demand
What is an example of hyperpnea?
When you are running down the street and breathing heavily
What is an example of hyperventilation?
When you look down and see a spider and you breathe more.
What can cause hyperventilation?
-side effect of medications
-psychological issue
What is the difference between hyperpnea and hyperventilation?
hyperpnea is a RESPONSE to an increase in O2 demand and hyperventilation is NOT A RESPONSE to a need for O2.
What is Hypoventilation?
Decrease breathing that tends to lead to an elevated CO2 in the blood.
What are the medications that can cause hypoventilation?
Opioids and Morphine can suppress breathing
What is Dyspnea?
Patient is having trouble breathing and they’re aware that they’re having trouble breathing
What is an example of Dyspnea?
A kid having an asthma attack
They have trouble breathing and they’re freaking out because they understand they’re having trouble breathing
What is Orthopnea?
Describes the breathing of a person who has trouble breathing when they are laying down but can breathe more easily sitting up
For instance, a patient with heart failure can have orthopnea. How?
They can accumulate fluid in their lungs in the alveoli. When they lay down, fluid can spread across the whole bottom surface of the lung and mess up gas exchange. When you sit them up, the fluid can pool at the bottom of the lungs, which leaves you with more effective surface area for gas exchange.
What is Apnea?
A temporary cessation of breathing after a normal EXPIRATION.
Why is the “temporary” important?
Because if it is not temporary, you are dead!!
What is Apneusis?
A temporary cessation of breathing after an INSPIRATION.
When you swallow, you temporarily stop breathing. Why?
So you do not aspirate.
What is Respiratory Failure?
Failure to resume breathing after a period of apnea or apneusis
Why do we need partial pressures?
They work in air and liquid. Don’t have to change what we’re measuring when going from blood to air or vise versa.
What is the normal Arterial PO2?
100 mm Hg
What is the normal Venous PO2?
40 mm Hg
Why is Arterial PO2 > Venous PO2?
O2 left the capillaries and into the cells
What is normal Arterial PCO2 ?
40 mm Hg
What is normal Venous of PCO2?
46 mm Hg
When you look at a particular part of the body where there is a lot of metabolic activity, what happens?
it contributes MORE CO2 to the blood than an area that doesn’t do anything.
The only place that these blood gases can change is where?
At capillaries
Where we had the highest cross sectional area, what happens?
the blood moves the most slowly
What are one of the two places where it is critical?
Gas exchange at the lungs
How does gas exchange at the lungs occur?
The air in the alveolus with a PO2 of 100 mm Hg and a PCO2 of 40 mm Hg. As the blood starts to move past this alveolus, we have a gradient for oxygen to move from the alveolus into the blood and another gradient for CO2 to move from the blood into the alveolus.
When is O2 going to stop moving from the alveolus into the blood?
When there is no gradient.
When the blood is leaving the capillary and is heading for pulmonary venule, it looks exactly like air in the alveolus. Because the blood is moving so slowly in the capillary…
that blood spends enough time in that alveolus you actually hit equilibrium in a healthy person. Once you leave capillaries, gas exchange takes place next is systemic capillaries.
The size of the gradient determines what?
How much O2 moves from the alveolus into the blood or how much CO2 moves from blood into the alveolus.
What affects how much O2 can move from the alveolus and into the blood?
1.Anything that changes the gradient from the concentration of O2 in the alveolus and the concentration of O2 in the blood. (smaller gradient is, less O2 will move)
2. Total functional surface area for gas exchange ( anything that messes w/ surface area for gas exchange in the lungs)
3. Total Respiratory Minute Volume (breathe less; amount of air getting into your lungs -O2- are decreasing)
4.Alveolar Ventilation (If alveolar ventilation drops, the amount of O2 that can go from the alveolus and into the blood drops)
How do you drop alveolar ventilation?
If Tidal volume drops, smaller breathes, pneumonia
What are structural factors that affect the ease of O2 diffusion into the blood.
- Respiratory membrane is very thin : has a huge surface area
- Alveolar & Capillary surface areas are very large
- Lung capillaries have a high capacity
- Blood in capillaries distributed in such thin layer that each RBC comes close to alveolar air:
(RBC line up so that theyre single file in the pulmonary capillaries meaning every single RBC has the opportunity to have O2 diffuse in and bind to hemoglobin)
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How is oxygen carried in the blood?
-bound to hemoglobin inside RBC
-small amount of O2 that is dissolved in the plasma
The average hemoglobin molecule carries how many molecules of O2?
4
Where do we find hemoglobin?
in RBCs
CO2 can also be transported by hemoglobin. Where does the CO2 bind?
to the globin chains. So we don’t have O2 and CO2 competing for binding cites
Carbon Monoxide is..
-colorless & odorless gas
-binds to heme groups on hemoglobin
-binds more tightly than O2 (not a good thing)
Why is this not a good thing?
They are going to be competing for binding spots and the heme group. Carbon monoxide is going to win. When it binds to hemoglobin, Carbon monoxide binds ALMOST IRREVERSIBLY.
How do you overcome carbon monoxide binding?
Put a patient in a hyperbaric chamber. This is where we have control of what the barometric pressure is in that chamber. If we put O2 and the patient in there and raise the pressure up, we can make PO2 in the chamber so high that it can push the Carbon Monoxide off.
