Respiratory System Flashcards
What gaseous exchange occurs in the lungs?
O2 entering the blood, and CO2 leaves it
How does respiratory system regulate pH?
by adjusting CO2 levels in the blood
What is Phonation?
production of sounds and speech from air movement over vocal cords
What are the 3 conducting airways?
- Trachea
- Bronchi
- Nonrespiratory bronchioles
How many divisions occur in the airway before the respiratory unit of the airways arises?
16 divisions
What are the 2 respiratory units of the airways?
- Respiratory bronchioles
2. Alveolar Ducts
What are Alveoli?
thin-walled polyhedral sacs organized into alveolar sacs
Where does gas exchange occur in the lungs?
across alveolar walls of alveoli, which form the air-blood barrier
What is the name of the mutual central opening of alveolar sacs?
alveolar ducts
What are the 2 types of alveolar cells?
- Type I Alveolar cells
2. Type II Alveolar cells
What is the total surface area that Type I alveolar cells occupy in lungs?
92%
What is the weakness/problem of Type I alveolar cells?
very susceptible to chemical injury; ex: smoking and pollution
What intracellular structure does Type II alveolar cells contain? What do they do?
Lamellar bodies (storage of pulmonary surfactat)
What is the function of pulmonary surfactant?
Coat type I alveolar cells and prevent their collapse
What cells in the lungs are susceptible to SARS-CoV-2 infection?
Type II alveolar cells
What is the most abundant and 2nd most abundant phospholipid in pulmonary surfactant?
1st - (75%) phosphatidylcholine
2nd - (10%) - phosphatidylglycerol
Why are the 2 things expressed in Type II alveolar cells that make them susceptible to SARS-CoV-2 infection?
- ACE2
2. TMPRSS2
What 4 things are a part of the lung parenchyma?
- Alveoli
- interstitium
- bronchi
- bronchioles
Why is the lung parenchyma, particularly the alveoli highly elastic? (even without pulmonary surfactant)
stretches in response to mechanical stress AND exhibits high passive recoil when stress is removed.
What are the 2 ways that the volume of the thoracic cavity can be altered?
- LENGTH of the cavity
2. WIDTH or anteroposterior diameter of the cavity
What is tidal volume?
amount of air that is moved in and out of lungs during rest
What is inspiratory reserve volume?
if you were to continue to breath in after a normal inspiration from rest
What is vital capacity?
The total amount of air that can be moved from forceful inspiration and expiration
What is the average total lung capacity?
Sum of all volumes : ~6L
What is dead space?
regions of the respiratory tract that occupy air that is breathed but does not undergo gas exchange
What are the 3 dead spaces? explain them
- Anatomical dead space (everywhere other than alveoli)
- alveolar dead space (non-functional alveoli from smoking or infection)
- total or physiological dead space (anatomical + alveolar
What Law is useful and related to pressure and volume in lungs?
Boyles Law: P1V1 = P2V2
Explain how boyles law determines how we draw air into our lungs?
As we increase volume in the lungs, we decrease the pressure in the lungs, which then causes air to rush in
What are the 4 factors that contribute to the expansion of the lungs?
- Surface tension holding the “visceral” and “parietal” pleura together
- Transpulmonary pressure differences
- surfactant film deposition on alveoli surfaces
- Interdependance of alveoli
What is the parietal and visceral layer attached to in respiratory system?
Parietal layer -> attached to inner surface of rib cage
Visceral Layer -> attached to outer surface of lungs
Where is the pleural cavity located?
between the visceral and parietal layer
What is Transpulmonary pressure (PL)
Is the difference between intrapulmonary pressure (Pa) and intrapleural pressure (Ppl).
PL = Pa - Ppl
How is the pleural pressure slightly more negative than the alveolar pressure (intrapulmonary pressure)?
Because the lymph system removes fluid from this space
What is surfactant, where is it deposited, and what does it do?
Is a lipoprotein film mixture deposited on alveoli surfaces, it reduces the high surface tension at air-water interface and allows alveoli to expand more easily
What does a lack of surfactant do to premature babies?
How do we treat?
produces respiratory distress syndrome
They must be ventilated
What role does surfactant play in small and large alveoli?
stabilizes inflation between different sized alveoli. Therefore transpulmonary pressure required for inflation of these different sized alveoli becomes similar
Explain how the interdependence of alveoli reduce tendancy for alveolar collapse?
most alveoli surround eachother and exert opposing traction. Also there are pores of Kohn and canals of Lambert which provide collateral ventilation of adjacent alveoli
What are the 2 main factors causing lungs to collapse? (allowing lungs to assume the smallest possible shape at any particular pressure)
- natural elastic properties of lungs
2. presence of a fluid film on alveoli
Weve talked about 1 law, but in total. What are all 3 fundamental gas laws in physics that determine the transport of gases in the lungs?
- Boyles Law
- Daltons Law
- Henrys law
Define External and Internal respiration
External respiration - gas exchange across respiratory membrane of lungs
Internal Respiration - Gas exchange across respiratory membrane of metabolizing tissue
With daltons law in mind explain how water vapor affects our breating?
With an increase in water vapor in the air we breath, the partial pressure of oxygen is reduced. So we need to breathe harder to get the same amount of oxygen.
What is Henrys Law?
States that gases will diffuse into or out of a liquid down its concentration gradient in proportion to its partial pressure
Rank CO2, O2, CO, and N2 in terms of solubility in plasma (from highest to lowest)
CO2>O2>CO>N2
What is Hyperbaric Air?
Hyperbaric air (supranormal pressure) generates a HIGH gradient for gas entry into the body
Explain how Hyperbaric Air is Good and Bad
Good: can treat carbon monoxide posioning, by using hyperbaric oxygen that is forced into blood to reverse (almost irreversible) carbon monoxide posioning.
Bad: At great depths, nitrogen will enter the blood stream (for scuba divers), if they arise to quickly, nitrogen will elave blood and produce bubbles in the blood, causing decompression sickness (the bends)
2 factors that govern gas exchange during external respiration?
- partial pressure gradients
2. solubility properties of the gas
Difference between ventilation and respiration?
ventilation just means the movement of air
respiration refers to the movement of the gases within air, particularly O2 and CO2
What is the partial pressure of CO2 in tissues and arterial blood? ish
45 mmHg in tissues and 40 mmHg in blood
What are the 4 subunits of hemoglobin (Hb)?
2 alpha chain, and 2 beta chains
Explain how sigmoidal shape is produced from oxygen binding to hemoglobin?
Binding of oxygen to hemoglobin is a cooperative, allosteric process. As oxygen begins to bind to hemoglobin, the efficiency at which hemoglobin binds the ramining oxygen increases (its affinity for oxygen increases)
What does a left shit and right shift to sigmoidal Hb-02 mean?
Left shift -> increase in oxygen affinity of Hb
Right Shift -> decrease in oxygen affinity of Hb
What are the 5 factors that affect Hb-02 binding affinity?
- partial pressure of oxygen
- partial pressure of CO2
- Blood pH (Bohr effect)
- Temperature
- 2,3– diphosphoglycerate (DPG)
How does DPG (2,3-diphosphoglycerate) affect O2 binding to Hb?
Where is DPG found in high concentrations in the body?
Increase in DPG decreases Hb affinity of oxygen (vise versa)
Near metabolically active tissues, increase Hb ability to drop off oxygen at these tissues
Where does DPG bind to on Hb?
Binds to beta sub units of deoxygenated Hb
Compare fetal hemoglobin to maternal Hb?
fetal Hb has a higher affinity to oxygen that maternal Hb
Explain how temperature, partial pressure of CO2, 2,3-DPG, and pH affect Hb affinity for Oxygen?
Decrease in termperature = increase Hb O affinity
decrease in partial pressure of CO2 = increase Hb O affinity
Decrease in 2,3-DPG = increase Hb O affinity
Increase in pH = increase Hb O affinity
What is hypoxia and what are the 3 subtypes?
hypoxia is below normal delivery of O2
anemic hypoxia - low RBC or Hb
stagnant hypoxia - impaired/blocked bloow flow
hypoxemic hypoxia - poor lung gas exchange
What form is most of CO2 transported in plasma?
60-70% bicarbonate ions
Where is HCO3- and CO2 formation favored in our body?
CO2 formation is favored at the lungs while HCO3- formation is favored at the tissues
What enzyme is responsible for the formation of carbonic acid from CO2?
Carbonic anhydrase in RBC’s: combines water with carbon dioxide to form carbonic acid
What is the Inspiratory capacity (IC)?
maximum volume of air that can be inhaled
What is the functional residual capacity (FRC)?
represents all non-tidal volume expiration
What is the vital capacity (VC)?
represents the total volume of air that can be moved
What is the Total lung capacity (TLC)?
represents the sum of all volumes (~6L)
