Formative Flashcards
what is the max volume of air that can be voluntarily exhaled following a max inspiration?
vital capacity
air flows into the lungs during inspiration because…
the external intercostal and diaphragm muscles contract and thoracic volume increases
if a man has a resp. rate of 10 breaths per min and a tidal volume of 700ml. If his residual volume and his dead space volume measures 200ml what is Mr T’s alveolar ventilation?
5000 ml/min 700-200 = 500 500x10
what is the partial pressure of oxygen in mixed venous blood typically around
40 mmHg (5.3kPa)
Arterial partial pressure of oxygen will be reduced in which of the following conditions? - Anaemia resulting from iron deficiency - Anaemia resulting from vitamin B12 deficiency - Blood loss during child birth - Emphysema - Traumatic peripheral haemorrhage
Emphysema loss of elastic recoil so lungs can’t expand- oxygen concentration in solution (PaO2) will be reduced. The other conditions may result in significant decreases in total oxygen content (due to lack of oxygen binding to Hb or loss of Hb) but oxygen in solution in plasma will be unaffected. CO displaces O2 on binding sites so stops O2 binding
Which of the following statements is NOT true for individuals with chronic lung disease? A. Arterial PCO2 levels are elevated B. Nitrous oxide is a safe sedative to use C. They are said to be on hypoxic drive D. They have decreased sensitivity to PCO2 E. They rely on their peripheral chemoreceptors for stimulating ventilation
B- Nitrous oxide is not a safe sedative to use!! It blunts the peripheral chemoreceptor response to falling oxygen, and as these patients are on “hypoxic drive” this effectively leaves them with no intrinsic means of controlling their ventilation.
why is someone with chronic lung disease said to be on hypoxic drive?
because chronic elevation of PCO2 has blunted central response to CO2 so they rely on changes in O2
'’Shunt” is a term that would be used to describe what
When perfusion exceeds ventilation in L/min blood doesn’t get oxygenated
Which of the following is most likely to shift the haemoglobin oxygen binding curve to the right? A. Asthma attack B. Hypothermia C. Presence of foetal haemoglobin D. Respiratory alkalosis E. Voluntary hyperventilation
Asthma attack - poor ventilation would mean increased PCO2 in plasma, one of the factors that shifts the curve to the right, along with the associated acidosis
what happens to the haemoglobin oxygen binding curve in hypothermia
decrease in body temperature shifts curve to the left making it difficult to offload oxygen to peripheral tissues.
what happens to the haemoglobin oxygen binding curve in presence of foetal haemoglobin
higher affinity for oxygen than adult haemoglobin so curve would shift to the left.
what happens to the FEV, FVC and FEV1/FEV ratio in someone with pulmonary fibrosis
FEV decreases but FVC decreases more the FEV1/FEV ratio increases. FVC decreases the most as due to restriction during inhalation - full breath in is less
The articulation of the rib with the vertebrae allows for respiratory movements. At the costovertebral joints the head of the 9th rib articulates with which body of vertebrae?
T8 and T9
The lungs are dissimilar in their gross anatomical features. The left is characterised by
Upper and lower lobes separated by the oblique fissure - only 2 lobes in the left lung
A 45 year old man has been smoking 30 cigarettes a day for 20 years. Calculate his pack years.
30 years
Divide the number of cigarettes smoked per day by 20 (no. of cigarettes in a pack) and multiply this by the number of years smoked (30/20) x 20 = 30
