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
what triggers breathing?
build up of co2 triggers our next breath
define airway resistance
airway resistance changes with lung volumes
there can be LAMINAR flow which allows for normal breathing or TURBULENT flow which can lead to wheezing
TRANSITIONAL FLOW where there is slowing at junction ~ eddy flows
how could surface tension affect lung compliance?
surface tension can also promote collapse of the alveoli, reducing the surface area and draw out fluid increasing the diffusion pathway
> BUT work is required to overcome the surface tension
alveoli have elastic and collagen fibres in their walls which allow for expansion and lined with fluid allowing diffusion of gas into a liquid environment
what is the role of surfacant in the airways?
it acts as a detergent to MINIMISE surface tension
when can bronchioconstriction/dialtion happen and how does it affect airway resistance?
Constriction - increase the Raw due to irritants, changes in gas compostion or in ill health like asthma
BronchioDilation - decrease the Raw due to SNS stimulation and hormones (adrenaline) or sympathomimetic drugs e.g when treating asthma using B2 agonist
how do pathophysiological circumstances such as asthma affect airway resistance?
Brochiolconstric like asthma, COPD
inflamation narrows , mucus blocks the lumen
muscle action is unaffected but as airway resistance increases, it makes it harder to breathe as muscles need to OVERCOME the airway resistance
the diving reflex (holding our breathe) can be triggered by splash of cold water to face. what are its characgtersitics
vasoconstrict - blood goes to essential organs
reduced heart rate
lactate accumulates in muscle
» all to DELAY build up of C02 which triggers our next breath!!
why do centrochemoreceptors have a slow response time?
as C02 accumulates, it creates carbonic acid in the CSF increasing acidity
» this stimulates centrochemoreceptors but the C02 has to accumulate in the blood first before it reaches the CSF!
why is the control of breathing in the brain and not the lungs?
respiratory muscles have NO INTRINSIC RHYTHM so are dependent on the brainstem
