Exam #1: Respiratory Flashcards
What mechanisms ensures that mucus moves in one-direction?
Cilia exhibit a forward (power) stroke followed by a backward (recovery) stroke. The power stroke beats the mucus toward the pharynx while the recovery stroke doesn’t touch the mucus, keeping the mucus moving toward the pharynx.
Why do we have different types of epithelium covering epithelium facing the oropharynx vs surface towards the trachea?
The epithelium facing the oropharynx is covered with non-keratinized stratified squamous epithelium because it’s an area that experiences a lot of wear and tear. The epithelium facing the trachea is made of TRE because this is an area where goblet cells produce mucus and the cilia can move the mucus down the pharynx.
What may be the function of trachealis muscle?
Allows the trachea to flatten out and allows expulsion of air when there’s forceful coughing.
How do we make a distinction between trachea, bronchi, and bronchioles.
Trachea -> TRE epithelial type. Has a cartilaginous ring sandwiched between the tracheal sub-mucosa and tunica adventitia, Also has a thin layer of smooth muscle toward one end of the trachea.
Bronchi -> TRE epithelial type. Has plates of hyaline cartilage and a layer of smooth muscle surrounding the bronchi. Goblet cells and sub-mucosal glands are present.
Bronchiole -> Has simple columnar to simple cuboidal epithelial type that’s ciliated and non-ciliated. Cartilage and sub-mucosal glands are absent. Goblet cells may or may not be present. Smooth muscle is present but is in circular fascicles.
What makes trachea prone for collapse?
If the cartilaginous rings lose strength or rigidity, the trachea will collapse during inspiration due to negative pressure.
Why do vocal cords and epiglottis differ?
The vocal fold region is an area that generally experiences wear and tear. The epithelia on the oral side of the epiglottis is made of the same epithelium as the vocal folds. The epithelium on the tracheal side is made of TRE because it experience less wear and tear and deals more with mucus build up.
Epithelium in the conducting portion? (nasopharynx and larynx)
TRE
What is the difference between nutritional blood and functional blood in the lungs?
Nutritional blood -> Supplies the pulmonary lymph nodes, bronchi, and bronchioles. Oxygenated blood is supplied by bronchial artery. Gas exchange occurs in the capillaries and the deoxygenated blood is transported to the left atrium via pulmonary vein.
Functional blood: The blood involved in gas exchange. Is transported from heart to lungs via pulmonary artery and transported from lungs to heart via pulmonary veins.
What is the reason for absence of erythrocytes within the lumen of lymphatic vessel when compared to artery or vein?
Because the lymph vessels do not carry blood. They carry lymph to the pulmonary veins.
Type II alveolar epithelial cells constitute about 5% of the total surface area of all the alveoli yet they are very important. Give 2 main reasons.
- They produce surfactant which increases the surface area of the alveoli.
- They can act as stem cells for type 1 alveolar cells.
Why does a patient with an underlying lung disease will experience difficulty in breathing when moved to higher elevation?
At higher elevations, the amount of total air decreases and the percent composition of individual gases remains the same. This means that the oxygen availability is limited.
Why does the resistance to airflow decrease in the deeper parts of the respiratory system?
Because the total surface area in the lungs increases due to the increase in branching of bronchioles
Can you use the results from the assessment of the lung volume and/or lung capacitities to diagnose a particular lung condition as restrictive vs obstructive?
Yes
Restrictive lung diseases: Characterized by fibrotic process in the lung parenchyma causes a decrease in VC, TLC, RV, and FRC.
Obstructive lung diseases: Characterized by inflammation of bronchioles and the smooth muscle contracts upon expiration resulting in difficulty expiring. Causes a decrease in VC but increase in TLC, RV, ERE, and FRC.
What keeps our alveoli open?
- The elastin and collagen recoil
2. Surface tension of alveolar fluid lining
Boyle’s Law
Air moving into and out of lungs governed by this law
P1V1=P2V2
Increase in pressure will lead to a decrease in volume
Increase in volume will lead to a decrease in pressure
Charle’s Law
V1/T1=V2/T2
Volume of a gas is directly proportionate to temperature at constant pressure
Ideal Gas Law
Pv=nRT
Pressure is directly proportionate to moles and temperature of gas
Pressure is inversely proportionate to volume of gas
In general, it is natural to have a thicker wall in the left ventricle of the heart when compared to the right ventricle. What does this indicate in pulmonary circulation?
That pulmonary circulation is a low pressure system and blood flow from the right ventricle to the lungs doesn’t require a high amount of pressure to pump blood through the lungs
What are the unique features of the pulmonary vessels?
- The veins carry oxygenated blood and the arteries carry deoxygenated blood
- Hypoxia induces vasoconstriction
- There’s a shit ton of pulmonary capillaries and some are just there to be recruited during times of extra blood flow (exercise)
- Also a shit ton of alveoli. Some are recruited and the used ones distend when we have increased blood flow through the lungs.
Why is it that when the lung is at FRC, blood flow through the lung is most favored?
Because the smaller alveolar vessels aren’t being crushed due to the expansion of the alveoli at TLC.
What is the pathophysiology behind the treatment of brisket edema?
At high elevations, ambient oxygen partial pressure falls resulting in hypoxic vasoconstriction and pulmonary arterial wall thickening. By reducing the elevation or implementing oxygen therapy, you are reversing the hypoxic vasoconstriction and it’s effects.
What is the pathophysiology behind the treatment of exercise induced pulmonary hemorrhage (EIPH)?
Nasal strips: Are placed around the nasoincisive notch to prevent it’s collapse due to increased negative pressure. By preventing it’s collapse, this reduces the negative pressure system of the respiratory system. This prevents the rupture of alveoli and leakage of RBC.
- Furosemide: Diuretic which reduces the total body fluid and pressure exerted by blood flow.
Why do shunts not respond to supplemental oxygen even when 100% Oxygen is administered?
Because no matter how high the oxygen concentration is, the amount of oxygen carried by hemoglobin is limited.
Why should ventilation and perfusion be matched?
Because the oxygen being moved into the body must match the ability of the hemoglobin to carry the oxygen to the rest of the body.
What happens when V is higher but Q is lower/vice versa?
- When V is higher than Q, there’s an increase in dead space, decreased alveolar compliance, and more negative intrapleural pressure.
When Q is higher than V, veins are distended because there’s an increase in the amount of deoxygenated blood, increased alveolar compliance, and less negative intrapleural pressure.
If you hold the gases like oxygen and carbon dioxide at -273 degrees Celsius, what happens to the blood-gas exchange process?
Movement of the gas molecules would cease because the kinetic motion of molecules drives the diffusion process At the Absolute Zero Temperature, this motion doesn’t occur.
Diffusion impairment due to increase in the thickness of the respiratory membrane (edema formation) could be overcome by increasing the partial pressure of inspired oxygen. Explain the principle involved.
When looking at Fick’s law of diffusion, you see that an increase in the partial pressure of oxygen increases P1 (the partial pressure of oxygen on the alveolar side). This increases the pressure gradient of oxygen which increases the binding of oxygen to hemoglobin.
Why is it possible to boil water at higher elevation with lower temperatures?
Because the partial pressure of oxygen (& overall atmospheric pressure) decreases at a higher elevation. The temperature the water must reach overcome the atmospheric pressure and vaporize decreases allowing water to boil at a lower temperature
Why do we need hemoglobin molecule? Discuss it’s importance in relation to oxygen transportation in the plasma and metabolic needs?
The oxygen carried via plasma diffusion is so low due to the solubility coefficient. It solely can’t keep up with the metabolic needs of the animal. Binding of oxygen to hemoglobin is a much more efficient way to transport oxygen throughout the body.
Why does the O2-Hb saturation assume a bell shape curve for someone breathing room air?
- Because there are multiple factors that will decrease the binding affinity of O2-Hb (decreased pH, increased PCO2, & increased 2,3 DPG) and increase the binding affinity (increased pH and CO).
- Once a hemoglobin molecule reaches 90% saturation, the binding affinity for O2 decreases, also causing a right shift in the Hb-O2 dissociation curve.
What is the impact of CO poisoning on O2 transportation and release?
It decreases O2 transportation and increases it’s release since CO has 250X more binding affinity to Hb than O2.
Why should clinicians use 5% CO2 to treat CO poisoning cases along with higher % of O2?
Higher percentage of O2 can cause hypoventilation. The 5% CO2 will stimulate peripheral chemoreceptors to increase drive for breathing. Also ensures CO is being expelled from body.
When compared to oxygen, CO2 diffusion can occur with a very small partial pressure gradient. Explain the reason/s.
Because CO2 has a higher diffusion rate than O2, so it doesn’t require as large of a pressure gradient for diffusion to occur when compared to oxygen.
Why is the formation of carbonic acid from the reaction between CO2 and water much faster in RBC when compared to plasma?
Because RBC’s carry carbonic anhydrase, an enzyme that drives the formation of carbonic acid in the hydration reaction.
When you compare the O2-Hb saturation curve with that of CO2 dissociation curve what do you learn/interpret?
- There is no plateau (no allosteric inhibition of CO2-Hb binding as the concentration of Hb- CO2 increases)
- Binding of 1 CO2 doesn’t help bind another CO2 bind to Hb
- CO2 graph is steeper
Do we make acid in the body? How do we eliminate the acid?
Yes. In cellular metabolism, one of the byproducts includes CO2. CO2 is considered a volatile acid since when it undergoes the hydration reaction, it produces carbonic acid (strong acid).
What are the 3 main buffer systems in the body? How do they differ in terms of their ability to buffer acid-base disturbances?
- Bicarbonate buffer system: When a weak acid is added to buffer a strong acid, a weak acid and salt are produced. When you add a weak base to buffer a strong acid, a weak base and water are produced.
- Phosphate buffer: Major intracellular buffer. Important in buffering fluid in the kidneys.
- Protein buffer: Hemoglobin is a better buffer of H+.
On an Anderson-Davenport nomogram, what are the 3 main parameters that are plotted?
- pH
- HCO3 values
- PCO2 line
How is the rhythmicity of breathing brought about? Can we voluntarily either increase rate and depth of breathing or stop breathing?
The dorsal and ventral respiratory groups located in the medulla generate the rhythm of respiration. The signal from DRG is sent via phrenic nerve to diaphragm. Signal from VRG sent via vagus nerve to abdominal muscles.
- The pulmonary stretch receptors in the lungs sense an increase in fluid accumulation which send a signal to DRG via vagus & glossopharyngeal to regulate breathing.
- The apneustic center can have a stimulatory effect on inspiratory neurons of DRG and VRG.
What is the main stimulus for central chemoreceptors?
Partial pressure of CO2
With respect to carotid bodies, describe their function and nerve supply?
Are located in the bifurcation between the internal and external carotid artery.
- Sense a decrease in PO2, decreased pH, and increase in PaCO2.
- Respond by increasing ventilation.
- Innervated by glossopharyngeal nerve
What mechanism prevents overstretching of lungs?
Pulmonary stretch receptors located in our lungs.
