Block VI - Respiratory Flashcards
16. General respiratory function 17. Gas transport
What is the vital capacity?
The max volume that can be inspired after max expiration
In which form is most of the CO2 in arterial blood carried?
As bicarbonate in plasma
What is the normal arterial oxygen carrying capacity?
1.34 ml O2/gHB x gHb in 100 mL blood
If PaO2 is 100, hemo concentration is 12 g/100mL, and Saturation is 97%, what is concentration of O2 bound to hemo?
12x1.34x.97 = 15.6 ml o2 / 100 ml blood
PB is 523 torr, pt has hyperventilated in response to hypoxia, pao2 is 70 torr and R = 0.83. What is PaCO2? Water vapor pressure in airway is 47
- Alveolar air equation pao2 = pio2 - (paco2/r) where pio2 = 0.21(pb-47)
What happens to the oxygen binding on hemoglobin when blood temp increases?
Less oxygen carrying at the same po2 with temperature increase.
When the respiratory muscles are relaxed in a normal person with open airways, what is the volume of the lungs?
Function 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 is always more negative than alveolar
During normal quiet inspiration, what change will the intrapleural pressure be?
More negative
How are inspired gases mixed in alveolar space?
Simple diffusion
A subject with deadspace of 150 breathed 10 breaths per minute with tidal volume of 500. What is alveolar ventilation?
3.5 liters per minute
In general, what is the relationship between body weight and conducting deadspace?
1 mL per pound
What are the effects of acidity, DPG, and temp on oxyhemoglobin dissociation curve?
Increasing acidity, DPG, or temp of blood will shift curve to right
As mixed venous blood enters and travels through capillaries in well-ventilated areas of the lung, what happens to the blood pH?
pH increases
What is the effect on increase in arterial CO2 on ventilation?
It will stimulate both the peripheral and the central chemoreceptors and 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 give arterial PCO2)
What is the effect of H ion concentration on peripheral chemoreceptor activity?
Activity increases linearly with H concentration in ranges of 40-45 mEq/L
What is the vital capacity?
Max volume that can be inspired after max expiration
Is terminal bronchioles belong to the respiratory zone?
No. The respiratory zone consists 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 airway resistance?
Poiseuille states inverse to 4th power
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 the ratio of FEV1/FVC as % - the proportion of total volume of air that can be expired in the first second of expiration of normal individual?
80%
According to Fick’s first law, how do gases diffuse from alveoli to the cells that are related to the membrane thickness?
Flow is inversely proportional to membrane thickness
How does COPD differ from asthma?
Lung inflammation in asthma can be triggered. COPD is not this and does not respond well to anti-inflammatory. COPD presents evidence of permanent damage with plugging of airways
What change in the concentration of diphosphoglycerate DPG will shift an oxygen saturation curve to the left?
Decrease
Whicc is effect of CO on the oxygen saturation curve?
Shift curve to left
In which form the majority of O2 is transported in the blood?
Bound to hemoglobin
What is the critical enzyme used in CO2 transport?
Carbonic anhydrase. It catalyzes CO2 and H20 to bicarb in lung and peripheral tissues
What do Boyle’s Henry’s, Dalton’s, and Laplace laws refer to?
- Boyle: P1V1=P2V2
- Henry: partial pressure is same on both sides of liquid-air border
- Dalton: in the air, total pressure is sum or partials
- Laplace: smaller diameter produces higher pressure due to surface tension
What change in lung compliance under medical conditions?
Increase in emphysema, decrease in fibrosis, no change in asthma
What is tidal volume?
The lung volume change during a normal inspiration and expiration cycle
What forms of CO2 in blood?
10% CO2 in plasma, 30 HbCO2, 60 HCO3-
What is the major form of )2 in blood?
98.5% binds to hemoglobin
What is the effect of PO2 on oxygen saturation of hemoglobin?
O2 binding to hemoglobin increases with PO2 when it is less than 80, no significant increase beyond 80
What is the function of carbonic anhydrase in the alveolar capillaries and in the muscle capillaries, respectively?
In lungs, converts bicarb to CO2 and H20. in Periph, does the reverse.
