Pulmonary System (Test 2) Flashcards
What is the vital capacity?
The maximum volume that can be inspired after a maximal expiration
VC=ERC+TV+IRV
~4700mL
In which form most of the CO2 in arterial blood is carried?
As bicarbonate in plasma
CO2 + H2O H2CO3 HCO3- + H+
What is the normal arterial oxygen carrying capacity?
(amount of hemoglobin in 100 mL of blood)*(amount of oxygen 1 g of hemoglobin can store)
(X g Hb in 100 mL blood)*(1.34 mL O2/g Hb)
If PAO2 is 100 mmHg, hemoglobin concentration is 12 g/100 ml, and Saturation O2 is 97%, what is the concentration of oxygen bound to hemoglobin?
12.0 g Hb/100 ml blood × 1.34 ml O2/g Hb × .97 = 15.6 ml O2/100 ml blood
A student has climbed to an altitude where the barometric pressure PB is 523 torr. She has hyperventilated in response to the hypoxia so her PAO2 = 70 torr and R = .83. What is her PACO2? Water vapor pressure in the airways is 47 mm Hg.
25 torr. Use the Alveolar air equation: PAO2 = PIO2 - (PACO2/R) where PIO2 = .21 (PB-47). Rearrange: PACO2 = R (PIO2 - PAO2).
What happens to the oxygen binding on hemoglobin when blood temperature increases?
Less oxygen chemically bound to hemoglobin at the same PO2
When the respiratory muscles are relaxed in a normal person with open airways, what is the volume of the lungs?
Functional Residual Capacity (FRC)
Does muscle directly control lung movement?
No muscle directly attaches to the lungs. Lungs are wrapped by two layers of pleura membranes, the pressure in the space between the pleura membranes is always negative than alveolar pressure.
During normal quiet inspiration, what change will the intrapleural pressure be?
more negative
How are inspired gases mixed in the alveolar space?
Simple diffusion
A subject with a dead-space of 150 ml breathed 10 breaths per minute with a tidal volume of 500 ml. What is his alveolar ventilation VA?
3.5 liters/minute
In general, what is the relationship between body weight and conducting dead-space?
1 ml per pound
What are the effects of acidity, DPG or temperature on the oxyhemoglobin dissociation curve?
Increasing the acidity, DPG or temperature of the blood will shift the curve to the right.
As mixed venous blood enters and travels through capillaries in well- ventilated areas of the lung, what happens to the blood pH?
The pH increases
What is the effect of increase in arterial CO2 on ventilation?
It will stimulate both the peripheral and central chemoreceptors thus increase ventilation
What do you expect on the CO2 response curve with acclimation to altitude?
Shift to the left (that is, increase the respiratory response to a given arterial PCO2)
What is the effect of hydrogen ion concentration on peripheral chemoreceptor activity?
The activity increases linearly with hydrogen ion concentration in the range of 40-45 mEq/L
Do terminal bronchioles belong to the respiratory zone?
No. The respiratory zone consist of Respiratory bronchioles Alveolar ducts Alveolar sacs.
What type of flow is the movement of air into the airways?
bulk flow
How does the radius influence the airway resistance?
Poiseuille’s law states that airway resistance inversely proportional in the order of 4 to airway radius.
What are the alveolar pressures in the absence of surfactant two alveoli of different size sharing an alveolar duct?
Have different alveolar pressure (Psmall>Plarge).
What is value of the ratio of FEV1/FVC as % - the proportion of total volume of air that can be expired in the first second of expiration (% of predicted value) in a normal individual?
80%
According to Fick’s first law, how do gases diffuse from alveoli to the cells are related to the membrane thickness?
Flow is inversely proportional to membrane thickness.
How Does COPD Differ from Asthma?
The lung inflammation in asthma can be triggered by contact with substances that trigger allergies. However, in contrast to asthma, COPD the inflammation is not triggered by allergies and does not respond well to anti-inflammatory medication. In fact, the lungs of patients with COPD have evidence of permanent damage with destruction and plugging of the airways.
What change in the concentration of diphosphoglycerate (DPG) will shift the oxygen saturation curve to the left?
decrease
Which is effect of CO on the oxygen saturation curve?
Shift the curve to the left
In which form the majority of O2 is transported in the blood?
bound to hemoglobin
What is the critical enzyme used in CO2 transportation?
Carbonic anhydrase. It catalyzes CO2 + H2O H2CO3 in the lung and peripheral tissues.
What do Boyle’s law, Henry’s law, Dalton’s law and law of Laplace refer to?
Boyle’s law: P1V1 = P2V2
Henry’s Law: partial pressure is the same on both sides of the liquid-air border
Dalton’s law: in the air, total pressure is the sum of partial pressures.
Law of Laplace: smaller diameter produce higher pressure due to surface tension.
What change in lung compliance under different medical conditions?
Increase in Emphysema, decrease in fibrosis, no change or decrease in asthma
What is tidal volume?
The lung volume change during a normal (without forcing) inspiration and expiration cycle.
In what forms CO2 is present in the blood?
CO2 is carried in the blood in three forms:
10% : CO2 dissolved in the plasma
30% : HbCO2
60% : HCO3-
What is the major form of O2 in the blood?
98.5% of O2 binds to hemoglobin, 1.5% dissolved.
What is the effect of PO2 on oxygen saturation of hemoglobin?
O2 binding to hemoglobin increased with PO2 when it is less 80 mmHg, when PO2 is above 80 mmHg, no significant increase in O2 binding will occur.
What is the function of carbonic anhydrase in the alveolar capillaries and in the muscle capillaries (or other peripheral tissue), respectively?
In lungs, carbonic anhydrase converts H2CO3 to CO2 and H2O; in peripheral tissue, carbonic anhydrase converts CO2 and H2O to H2CO3.
What is and how do you calculate alveolar ventilation? (Va)
Amount of air entering alveoli per minute
Va=(Vt-Vd)*f where: Vt=tidal volume Vd=dead space (1 mL per pound) f=breaths/min
functions of conducting zone (5)
- Transmission-low resistance pathway
- Defends against microbes, toxins and foreign matter.
- Air Treatment - filtration
- warming
- humidifying
functions of respiratory zone
- Provides O2
- Eliminates CO2
- Regulates blood pH
- Forms speech sound
- Defends against microbes
- Traps and dissolves blood clots
Alveolar P_O2 calculation
pO2 ≈ F_O2 (Patm – P_H2O) – pCO2/RQ
F_O2=fraction of air that is O2=0.21
RQ=respiratory quotient=.8
