respiratory challenges and research Flashcards
Which of the following conditions is most likely to be associated with an increased ventilation:perfusion (V:Q) ratio?
A Acute asthma attack
B Occlusion (blockage) of the primary bronchus
C Chronic Obstructive Pulmonary Disorder
D Pulmonary emboli
Option D - only pulmoniary embol
So emboli is a thrombus, so it will block the blood flow/decrease perfusion
The other obtions will block the Airways so will reduce the ventilation
more ventilation than blood flow
How are the blood gases of a free-diver likely to be altered by hyperventilating just prior to the dive? A PO2 increased AND PCO2 increased B PO2 increased AND PCO2 reduced C PO2 reduced AND PCO2 increased D PO2 reduced AND PCO2 reduced
OPTION B
hyperventilation, breathe in more than breathe out
so more oxygen than co2
Risk of respiratory alkalosis
which factors affect rate of diffusion?
FICKS LAW
temperature p,p gradient length of diffusion pathway size of molecule s.a. of gas exchange surface its solubility in liquid
what is important about s.a:V
as organism gets larger its SA:V ratio gets smaller so it cannot rely on simple diffussion anymore
> so require specialised gas exchange surfaces
what values can you get from a spirometer?
tidal volume
vital capacity
inspiritory capacity
resdiual volume - prevent complete collapse of lung
compare tidal breathing with unidirectional flow
flow is more efficient as incoming air NEVER mixes with the expired air so all air can be used for gas exchange.
It is optimised to MINIMISE the ‘dead space’
All gas movement is…
active
passive
osmosis
passive process governed by diffusion
what DOESN'T make the Bohr shift occur? (shift right) A increase of Co2 B decrease [H+] - more acidic C increase [H+] - more alkali D increase temperature E increase 2-3 BPG
OPTION C - INCREASING PH/ALKALO
> high carbon increases acidity, high temp and 2-3 bpg all contribute to Bohr
> 2-3 BPG changes Hb from a high affinity to low affinity oxygen state so will release oxygen at metabolizing tissues
23 BOG released by redblood cells in hypoxic environment
surfacant is produced from which type of alveolar cell?
type 1 pneumocyte
type 2 pneumocyte
type 3 pneomocyt
type 2 pneumocytes secrete surfacant which reduces surface tension of the alveoli!
How do resistive forces affect airflow?
They oppose inspiration and assist expiration.
how does gravity affect pattern of ventilation and perfusion (blood flow)?
blood flow is more affected by gravity. at the top of the lungs we have the least volume of blood and ventilation.
when ventilation mathces perfusion we get the optimum gas exchange
how can ventilation be modified to reach optimum gas exchange?
you can vasoconstrict and divert blood away from poorly ventilated areas (e.g. low ppO2/ hypoxia)
how can we we hold our breath in?
we can temporarily override the medulla and VOLUNTARY breathe via the cortex
where are centro chemoreceptors found and where are peripheral chemorecepotes found
near the venolatieral surface of medulla
near the cartoid bodies and aortic bodies - areas of high blood flow
what is the relationship between hypercapnia (high co2) and hpoxia (low oxygen)
they have a synergistic effect together to increase minute ventilation
> to meet metabolic demands of body
> much greater effect together than alone
