transition - physiology Flashcards
where is resp rhythm generated
medulla
where are the peripheral chemoreceptors situated
carotid bodies, aortic bodies
what do the peripheral chemoreceptors sense
oxygen co2 and h+ in the BLOOD
where are central chemoreceptors situated
surface of medulla
what do central chemoreceptors respond to
H+ conc of the CSF (csf separated from blood by BBB)
what is hypoxic drive of respiration via
peripheral chemoreceptors
when is hypoxic drive important
in chronic co2 retention (COPD)
what is H+ drive of respiration via
peripheral chemoreceptors
what is the function of H+ drive of respiration
major role in adjusting acidosis by the addition of non-carbonic acid H+ to blood
Loss of transmural pressure gradient across the lungs?
pneumothorax
inspiratory muscles
diaphragm contraction and external intercostals to lift ribs and move out sternum
accessory muscles
sternocleidomastoid and scalenus
muscles of active inspiration
internal intercostals and abdominal muscles
what keeps alveoli open
transmural pressure gradient, pulmonary surfactant and alveolar interdependence
parasymp effect on lungs
bronchoconstriction
sympathetic effect on lungs
bronchodilation
is what condition is the v/q ratio high
PE = decrease perfusion, but normal ventilation
heart failure shifts frank-starling curve what way
right
what factors shift oxygen haemoglobin dissociation curve right - and what does that mean
inc pCO2
inc H+ (dec pH)
inc 2,3-DPG
inc temp
= decreased affinity for O2 to bind to haemoglobin
cardiac output calculation
CO = SV x HR
stroke vol calculation
SV = EDV - ESV
what determines preload
EDV
left sided HF features
pulmonary oedema and SOB
what is the pO2 value in anaemia
normal
maximum volume of air that can be inspired at the end of a normal quiet expiration
inspiratory capacity
what one is the green one
normal
what one is red
asthma
what one is blue
COPD
what is the COPD spirometry confirmed diagnosis
post bronchodilator FEV1/FVC<0.7
Question 1: functional residual capacity:
A usually increased in obese people
B measured by spirometry
C decreased in COPD
D normally 40% of total lung capacity
E approximately 20% vital capacity
= D
FRC: expiratory reserve + residual volume
FRC decreased in obese people due to diaphragm being pushed up by fat
Cannot measure FRC by spirometry because you cannot take residual volume out of lungs
COPD- in emphysema FCR is increased
Question 2: patient with pulmonary fibrosis, FEV1/FVC% is likely to be
A 45
B 50
C 60
D 65
E 85
Ans: 85
Question 3: 67 YEAR OLD, SMOKES SINCE TEENS AND BEEN DIAGNOSED WITH COPD. His FEV1/FVC is <70% and his airflow limitation is moderate. What is his post bronchodilator FEV1 (% predicted of normal) likely to be>?
A 20%
B 40%
C 60%
D 80%
E 90%
Ans: 60
Question 4: 23 y woman sees GP about intermittent breathlessness. Feels breathless when she’s in a crowded room. When she’s breathless she also notices numbness and tingling around mouth. FBC reveals Hb 10.5g/dl
A increased work of breathing due to reversible airways obstruction
B increased central and autonomic arousal
C reduced 02 carrying capacity of blood
D stimulation of peripheral chemoreceptors
E reduced SA for gas exchange
Ans: B
Tingling round mouth- co2 out from ventilation so blood ph increases ie respiratory alkalosis
Calcium decreased
Question 5: what is correct about normal lungs
A low po2 causes pulmonary vasoconstriction
B larger airways are supplied by pulmonary circulation
C beta 1 agonists cause bronchodilation
D parasympathetic stimulation causes bronchodilation
E SA for gas exchange remains constant in absence of disease
Ans: A
In lungs low po2 causes vasoconstriction, would rather perfuse more well ventilated areas
Large airways have their own blood supply via bronchiole arteries
B2 agonists cause bronchodilation
Parasympathetics cause bronchoconstriction
SA changes when you exercise, hyperventilate
Question 6: 72 y/o woman has had 2 MIs in the past and a recent echocardiogram has shown moderately impaired LV function. She has SOB worse at night
A increased alveolar surface tension
B increased work of breathing due to reversible airways obstruction
C reduced o2 carrying capacity of blood
D reduced pulmonary compliance and impaired gas diffusion
E stimulation of central chemoreceptors
Ans: D
Oedema affects pulmonary compliance and gas exchange
Question 7: in patient with COPD
A inspiration more difficult than expiration
B dynamic airway compression likely to occur during active expiration
C presence of emphysema will help alleviate dynamic airway compression
D o2 saturations should be maintained near 100% if patient is retaining co2
E dynamic airway compression likely to occur during inspiration
Ans: b
Question 8: which is correct about patient with emphysema
A gas exchange unaffected
B work of breathing decreased
C pulmonary compliance increased
D total lung volume decreased
E FEV1/FVC ratio increased
Ans: c
Work of breathing increases with emphysema
Question 9: for TPX:
A intra-pleural pressure becomes more negative
B trachea can deviate to same side
C patient likely to be hypotensive
D breath sounds increased
E chest pain not a symptom
Ans: c
INTRA-PLEURAL PRESSURE BECOMES MORE + IN EQUALIBRIUM WITH LUNG OR OUTSIDE PRESSURE
Question 10
Previous fit 22 year old has been unwell for 2 days, px with cough productive of green sputum, fever, SOB. Her PO2 is 8.2kPa. What are her saturations likely to be?
A 70
B 75
C 80
D 90
E 98
ANS: D
Function residual capacity- normally 40% of lung capacity
a - DKA
c
B
acute MI with pul oedema
nitrate infusion dilates peripheral veins and decreases preload
D
thyroid function tests
A
= a
Tingling around mouth and fingers = respiratory alkalosis
E
D
