The Respiratory System
Normal arterial PO2 is about...
100 mm Hg.
A dry mixture of gases has a total pressure of 600 mmHg and the oxygen comprises 20% of the gas mixture. The partial pressure of oxygen (P02) is therefore equal to _________.
120 mmHg
A decrease in volume leads to a(n) ________ pressure.
increase in
The pleura that surrounds the lungs consists of two layers, the ________.
visceral and parietal pleurae.
Acidosis is a state in which the blood and tissue fluid have an acidic pH.
FALSE
Even after exhaling as forcefully as possible, one still has air in the lungs.
TRUE
The enzyme ______ catalyzes the formation of H2CO3 from CO2 and water.
carbonic anhydrase
Gas exchange that occurs at the level of the tissues is called ________.
internal respiration
During inspiration,
intraalveolar pressure is less than atmospheric pressure.
Normal systemic venous PO2 is about
40 mm Hg.
The partial pressure of carbon dioxide is 45 mm Hg in the blood and 40 mm Hg in the alveoli. What happens to the carbon dioxide?
It diffuses into the alveoli.
An increase in temperature or decrease in pH will shift the oxygen dissociation curve to the...
RIGHT
Increasing the partial pressure of a gas increases the amount of that gas which will dissolve in a fluid.
TRUE
Carbon dioxide is carried in the blood in all of the following ways except as ___________.
a dissolved gas bicarbonate ion carbaminohemoglobin ***Carbon dioxide is carried in all those ways.***
The central chemoreceptors will increase their firing rate in direct response to increases in the level of ____________ in the CSF, resulting in _____________ ventilation.
acid; increased
The conducting zone of the respiratory system includes all of the following passages except ______________.
alveoli
The space __________ is referred to as a "potential space" because it is filled with pleural fluid, not air.
between the parietal and visceral pleurae
The rhythmicity center, a sort of pacemaker that sets the rhythm of automatic breathing, is located in the __________________.
brain stem
The pressure of dry atmospheric gas is primarily determined by all of the following gases except ____________, which makes a comparatively negligible contribution.
carbon dioxide
If a baby is born prematurely before type II cells produce sufficient pulmonary surfactant, which of the following might you expect?
difficulty inflating the lungs
External respiration refers to ________________.
gas exchange between the air and blood at the alveoli
Gas moves from an area of ________ partial pressure to an area of ________ partial pressure.
high; low
The amount of a given gas dissolved in the blood
increases as the partial pressure of the gas increases.
Forceful expiration requires the actions of the ________________.
internal intercostals and abdominal muscles
A chest wound can introduce air into the intrapleural space, a condition known as _______________.
pneumothorax
Which of the following processes does atmospheric pressure play a role in?
pulmonary ventilation
The volume of gas remaining in the lungs after a maximum expiration is the...
residual volume.
A deficiency of lung surfactant may result in ______________.
respiratory distress syndrome
Diffusion rate across the respiratory membrane is rapid because
there is a very large surface area in the lungs due to the alveoli. pulmonary ventilation maintains a relatively high PO2 and low PCO2 in the alveoli. the air-blood barrier is two thin cells thick. ***All of the choices are correct.***
The pressure difference across the lung wall is the ________________.
transpulmonary pressure
The amount of air that is inhaled or exhaled in one breath during unforced breathing is the _______________.
tidal volume
_________ states that the amount of pressure exerted by a gas in a mixture is proportional to the percentage of the gas in the mixture.
Dalton's law
The surface tension exerted by water in the alveoli prevent collapse of the alveoli during exhalation.
FALSE
The primary regulator of ventilation in normal circumstances is the _____________.
H+ concentration of the brain extracellular fluid monitored by central chemoreceptors
The conducting zone of the respiratory system does not ______________.
exchange gases with the blood
Which of the following prevents the alveoli from collapsing?
residual volume
During normal, relaxed respiration, about 500 ml of air enters and leaves the lungs with each respiratory cycle. This is called the __________________.
tidal volume
The pressure difference between the intra-alveolar and intrapleural pressures is called ________.
transpulmonary pressure
Lung surfactant is produced by ______________.
type II alveolar cells
