Normal Respiratory Physiology Flashcards
T/F? The roles of the respiratory system are to exchange oxygen and carbon dioxide between
systemic venous blood in the pulmonary veins and alveolar air, and to contribute to the
maintenance of acidbase
balance.
False
T/F? The respiratory system exchanges oxygen and carbon dioxide at rates that depend on the
consumption of O2 and production of CO2
True
T/F? Normal values at rest in a young / middle aged adult are PaO2 9098
mmHg, PaCO2 3842
mmHg, arterial pH 7.387.42,
mixed venous PO2 about 40mmHg, mixed venous CO2 about 46
mmHg, mixed venous pH less than arterial pH, PAO2 about 100mmHg and PACO2 about
40mmHg.
True
T/F?The respiratory system can exchange oxygen and carbon dioxide at rates ranging from basal
metabolic rate of about 250 mls of O2 per minute and 200 mls of CO2 per minute, to about
double this with very heavy exertion.
False. More than doubles
T/F?Ventilation is a process that ensures that the concentrations of O2 and CO2 in alveolar air are
optimal for achieving the roles of the respiratory system
True
T/F? Ventilation is achieved by the inspiratory muscles generating a negative intrapleural pressure,
and this is an energy dependent process.
True
T/F? At rest, tidal volume is about 500 mls, minute ventilation 78
L/min, and exhalation is achieved
by relaxation of the inspiratory muscles and the elastic recoil of the lungs until FRC is reached
True
T/F? Much larger tidal volumes (about half VC), higher respiratory rates (3040
breaths per min) and
greater minute ventilation (> 100 L/min) can be achieved during exercise, and this requires the
use accessory inspiratory muscles and expiratory muscles in addition to the diaphragm
True
T/F?The total work of breathing involves overcoming the friction of air flowing through the airways
False
T/F? Transfer of gases across the alveolar capillary membrane occurs via intracellular transporters
False
T/F? An elevated PaCO2 implies inadequate alveolar ventilation, and the pH will be low until a
compensatory increase in bicarbonate occurs.
True
T/F?Central cyanosis implies inadequate supply of oxygen to tissues and organs.
False
T/F? Tissue oxygen supply depends on PaO2, Hb concentration, cardiac output, and local tissue
factors such as temperature, pH, tissue vascularity and tissue PO2.
True
T/F? Blood oxygen content is linearly related to Hb concentration and PaO2.
False. sigmoid curve
T/F? Haemoglobin carries both oxygen and carbon dioxide using the same binding sites.
False
T/F?Changes in PCO2 affect ventilation more than changes in PO2.
True
T/F? The peripheral and central chemoreceptors respond to the same stimuli.
False. Peripheral responds to O2, CO2, H+, central only H+.
T/F? The respiratory centre in the brainstem sends automatic stimuli to the respiratory muscles via the
phrenic nerves.
True
T/F? Transfer of CO2 across the alveolar capillary membrane is much less efficient than O2, and
hypercapnoea is common, even with mild lung diseases.
False
T/F?The structures of the bronchial tree and the pulmonary arterial circulation are fractal in design
and this contributes to relatively homogeneous ventilation and perfusion of most regions of the
lungs, and to relatively even V/Q matching.
True
T/F? Matching of ventilation and perfusion of individual alveolar capillary units is critical to efficient
gas exchange.
True
T/F? Under normal circumstances, transfer of oxygen across the alveolar capillary membrane is
limited by the diffusion characteristics of the alveolar capillary membrane.
False.
Q in respiratory physiology is?
perfusion
What limits O2 transport? perfusion or flow?
flow
