Flashcards in Normal Respiratory Physiology Deck (54)
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
T/F? The respiratory system exchanges oxygen and carbon dioxide at rates that depend on the
consumption of O2 and production of CO2
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
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
T/F? Ventilation is achieved by the inspiratory muscles generating a negative intrapleural pressure,
and this is an energy dependent process.
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
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
T/F?The total work of breathing involves overcoming the friction of air flowing through the airways
T/F? Transfer of gases across the alveolar capillary membrane occurs via intracellular transporters
T/F? An elevated PaCO2 implies inadequate alveolar ventilation, and the pH will be low until a
compensatory increase in bicarbonate occurs.
T/F?Central cyanosis implies inadequate supply of oxygen to tissues and organs.
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.
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.
T/F?Changes in PCO2 affect ventilation more than changes in PO2.
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
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.
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.
T/F? Matching of ventilation and perfusion of individual alveolar capillary units is critical to efficient
T/F? Under normal circumstances, transfer of oxygen across the alveolar capillary membrane is
limited by the diffusion characteristics of the alveolar capillary membrane.
Q in respiratory physiology is?
What limits O2 transport? perfusion or flow?
How much C02 is transported in dissolved plasma?
How much C02 is transported in bicarbonate?
How much C02 is transported attached to proteins? (Hb)
What is the most important blood buffer?
CO2/HCO3 buffer system
Alveolar capillary membrane thickness?
What's the surface area of Alveolar capillary membrane?
What's the alveolar volume?
What's the capillary volume?
What is Ficks Law for?
Rate of diffusion of a gas
T/F? The diffusion of rate of C02 is 30x that of O2?
False. only 20x
What's the average time of O2/C02 diffusion/exchange?
How long is the RBC in contact with Alveolar capillary membrane?
Everyone is happy when V/Q is what?
V/Q = 1
In general, elevated PaC02 is due to what?
inadequate alveolar ventilation
How many generations of airways are there?
Which branchings contain the alveoli in the walls?
last 6 of 23 branchings
Bronchi are surrounded by?
External intercostals do what? where is the membrane part?
What does internal intercostals do?where is the membrane part?
T/F? contraction of external intercostals increases lateral diameter of thorax?
False. increase AP diameter of thorax
2 forces that inspiration has to overcome?
resistive: airflow through bronchi
elastic: expansion of lung/chest wall
Laminar flow happens where?
Turbulent flow happens where?
Where is the site of maximum airway resistance?
What does surfactant do?
reduce surface tension in alveoli
What is WOB? how is it calculated?
Work of breathing = elastic plus resistive
How do people with airflow obstruction breath?
deep slow breaths
How do people with stiff lungs breath?
rapid shallow breaths
Can you override your brainstem for breathing?
Of course. You can breath faster on command. aaaaaaaaaaand GO!