More Respiration Notes from Old Notes Flashcards
How is oxygen moved to exchange surface in lungs?
Bulk Flow
Ventilation
Movement of oxygen to exchange surface through air
How is oxygen uptaken across respiratory exchange surfaces in lungs?
Diffusion
How is oxygen transported to the cells?
Bulk flow
The movement of oxygen to cells through blood is called…
Blood Circulation
How is oxygen uptaken into the cells?
Diffusion
Name & Explain the 4 steps of the respiratory gas movement
- Ventilation - gas exchange between environment and lungs via bulk flow
- External Respiration - gas exchange between lungs and pulmonary circulation via diffusion
- Circulation - gas exchange between pulmonary capillary and other body capillaries via bulk flow of blood
- Internal Respiration - gas exchange between systemic capillaries and metabolizing tissues via diffusion
Flow Equation
Flow = Change in Pressure / Resistance
Common to both the respiratory tract and digestive tract
Pharynx
Runs between internal Nares and Glottis
The Food Tube
Esophagus
Refers to the opening on the Larynx
Glottis
Cartilaginous tissue over the Glottis
Epiglottis
Contains vocal chords
Larynx
Everything downstream from the Trachea is considered the
Lung
Sacs where gas exchange takes place, have very thin walls for diffusion
Alveoli
What is surfactant?
Surfactant is a phospholipid that reduces surface tension of water layer within alveolus
Inner membrane that adheres to the surface of the lung
Visceral pleurae
Outer membrane that adheres to the thoracic wall and diaphragm
Parietal pleurae
Between the two pleurae membranes
Intrapleural space; it contains a thin layer of fluid that keeps both membranes in contact with each other
Cleans the air in the alveoli
Alveolar Macrophage
The flow of air is approximately
Patmosphere - Palveolar
What happens to air pressure when we inhale/inspire
We decrease alveolar pressure (Palv) below atmosphere pressure (Patm)
What happens to air pressure when we exhale/expire
We increase alveolar pressure (Palv) above atmosphere pressure (Patm)
What happens to the thoracic cavity and rib cage during inspiration
Expand thoracic cavity/rib cage via external intercostal muscles & diaphragm lowers
Tidal Volume
ml of air moved in one breathe
Resting Tidal Volume
Minimum volume of air you would need to supply your body with oxygen while doing nothing
Inspiratory Reserve Volume
Maximum amount of air that can be inhaled above resting tidal volume
Expiratory Reserve Volume
Maximum amount of air that can be exhaled beyond resting tidal volume
Residual Volume
Minimum amount of air always in the lungs that cannot be moved
Total Lung Capacity
Total volume in lungs after maximum inspiration; sum of all 4
TLC = IRV + TVrest + ERV + RV
Vital Capacity
Maximum amount of air that can be expired after a maximum inspiration
Vital Capacity = IRV + TV + ERV
Inspiratory Capacity
Maximal amount of air remaining in lungs after a normal expiration
IC = IRV + TV
Functional Residual Capacity
Amount of air remaining in lungs after a normal expiration
FRC = ERV + RV
Minute Volume
ml air / min
The amount of air moved through the respiratory system per minute
Vm = Tidal Volume (ml air/breath) x #breaths per minute
Intrapulmonary Pressure
Pressure inside the alveoli
When you exhale the pressure is the same as the air outside at sea level, 1 atm
When you inhale the pressure drops to about -1 atm
Only slight pressure change needed to move large volume of air
Intrapleural pressure
Pressure inside pleural cavity
As you inhale you stretch out your cavity and the pressure falls
How do we prevent blood flow to poor alveoli
Constrict pulmonary arterioles serving poor alveoli
What happens to the bronchioles if we have poor ventilation?
Local Control; if we have poor ventilation we are not getting rid of carbon dioxide properly therefore the concentration of carbon dioxide will rise. If the concentration of CO2 rises you want the bronchioles leading to alveoli to dilate so more air can move in and out and so the alveoli will be better ventilated. Increase CO2 causes vasodilation of bronchioles.
What happens to the bronchioles if we have poor circulation?
The alveolus are not getting enough CO2. Therefore the CO2 concentration in the alveolus will be below normal. Decrease CO2 causes vasoconstriction of bronchioles
At the pulmonary arterioles; what happens when there’s high/low CO2 concentration
High CO2 causes vasoconstriction. If you have high CO2 in the interstitial fluid it means it is not leaving and entering alveolus. This means the particular alveolus has poor circulation and we want to reroute blood elsewhere.
Low CO2 causes vasodilation
How do we eliminate particles that settle on the walls of respiratory tree?
Mucous layer moves upward to pharynx via cilia and is swallowed
Sneeze = expelled by blast of air
How do we eliminate particles that settle in alveoli?
They are engulfed by lymphocytes or
Remain permanently encapsulated on alveolar surface
What is air composition?
21% Oxygen
78% Nitrogen
1% Argon
0.03% Carbon Dioxide
How do we calculate the partial pressures?
PP of o2 can be calculated by the fact that 21% of air is O2 so 21% of 760 mm Hg = 159 mm Hg
PP of co2 is 0.03% of air so 0.03% of 760 mm Hg = 0.228 mm Hg
T/F: In order to get new fresh air you have to take breathes that are smaller than your dead space volume
Falso
In order to get new fresh air you have to take breathes that are larger than your dead space volume
Describe Hemoglobin’s structure
4 proteins (globins) - each has a heme in center
Oxygen binds reversibly with iron
Each hemoglobin can bind to 4 Oxygen due to 4 irons & hemes
Causes of anemia
Too few RBC
Too little Hb/RBC
Not enough iron
Too little blood (not a major worry)
Erythropoietin
Secreted by kidney
Acts on bone marrow to increase RBC production
Myoglobin
Allows for the storage of O2 within muscle fiber. Increases O2 diffusion rate, does not have to wait for increase in blood supply for oxygen. Aids in the diffusion of blood to the muscle. Especially important in heart because blood flow to muscle is 0 during systole. During systole = no blood flow to cells thus this oxygen store is necessary
What is important about fetal hemoglobin
You have a different type of Hb when you are a fetus – different globins that do NOT react with 2,3 DPG therefore higher affinity so it can draw oxygen across from placenta more easily. When ready to be born, it shifts to a form that does react with 2,3 DPG
Which is more soluble in blood, Carbon Dioxide or Oxygen?
Carbon dioxide is more soluble than oxygen in blood
What is carbonic anhydrase?
It is an enzyme that catalyzes the reaction that allow CO2 to dissolve in plasma as bicarbonate
Describe CO2 Transport
- CO2 is dissolved in solution in the plasma (and blood cell cytosol)
- Most of the dissolved CO2 combines with water to form carbonic acid.
○ Rate is slow in the plasma
○ Rate is fast in RBC due to presence of enzyme carbonic anhydrase - Carbonic acid will dissociate to H+ and HCO3-
○ Bulk of CO2 is transported as bicarbonate ions - Hemoglobin will buffer the H+ and reduce hemoglobin’s affinity for O2
○ H+ binds to the globin of hemoglobin 5. Bicarbonate diffuses out of RBC down concentration gradient allowing Cl- to move in (Chloride Shift)
○ Concentration of bicarbonate exceeds that in the plasma because there is more enzyme in RBC hence faster dissolving of CO2 leading to unequal concentrations.
○ As bicarbonate diffuses out, negative charge is lost which is what draws chloride into the cell to balance the charge - CO2 is lost at alveoli
○ Reaction reverses
○ Affinity of hemoglobin for O2 increases at the lungs - CO2 also binds to globin part of hemoglobin to form caraminohemoglobin
• This does not cause competition with oxygen to bind to hemoglobin because CO2 only binds at the globin portion
• Binding to hemoglobin increases the carrying capacity in blood
What is a molecule that is in competition with oxygen for hemoglobin?
Carbon Monoxide
CO binds to the heme of hemoglobin
The heme’s affinity for carbon monoxide is much greater than its affinity for oxygen
When CO binds to heme, oxygen cannot replace it
CO therefore stays bound, the partial pressure of O2 would need to increase severalfold in order to allow O2 to compete with CO for the binding sites
What is normal rhythmic breathing rate regulated by?
In the medulla
Higher centers in Pons
T/F: Increase H+ stimulates increased breathing rate?
T
What happens when you expel CO2 too rapidly/hyperventilate?
The concentration of CO2 in the blood falls too low and apnea (no breathing) occurs
For example: when a person is hyperventilating, he is blowing off CO2 faster than normal. You stop breathing after the episode is over to allow CO2 to build up in the blood to restore normal levels
We can measure metabolic rate via
Heat given off
Volume oxygen consumed (ml O2 / min)
Carbon Dioxide expelled
How can we measure oxygen at an organismal or cellular level?
VO2 =(CO)([O2]a-[O2]v)
ml O2 / min) = (ml blood / min) (ml O2 / ml blood
