Flashcards in Overview Deck (31)
What is alveolar surface tension?
Attraction between water molecules at liquid air interface
What does this describe: a complex mix of lipids and proteins secreted by alveoli which lowers alveolar surface tension?
What type of alveoli secretes pulmonary surfactant?
Which forces keep alveoli open?
Transmuralpressure gradient, pulmonary surfactant, alveolar interdependence
Which factors promote alveolar collapse?
elasticity of stretched pulmonary connective tissue fibres, alveolar surface tension
What division of the ANS causes bronchoconstriction?
What happens to intrapleural pressure during inspiration?
What is pulmonary compliance?
measure of effort going into stretching/distending lungs
What factors decrease pulmonary compliance?
pulmonary fibrosis, oedema, lung collapse, pneumonia, absence of surfactant
What is alveolar dead space?
ventilated alveoli, not adequately perfused with blood
If 02 decreases, does vasoconstriction or vasodilation occur in pulmonary arterioles?
If 02 decreases, does vasoconstriction or vasodilation occur in systemic arterioles?
What encircle each alveolus?
What are alveolar walls made of?
single layer of flattened type 1 alveolar cells
How many Haem groups does a Hb molecule contain?
What is Sao2?
% haemoglobin saturated with 02
What can impair O2 delivery?
resp disease, heart failure, anaemia
What is cooperativity in Hb?
Binding of one 02 to Hb increasing the affinity of Hb for 02
What is myoglobin?
molecule present in skeletal and cardiac muscle which functions as short term storage in anaerobic conditions
How many haem groups does myoglobin have per molecule?
What does the presence of myoglobin indicate?
muscle damage is present
How can C02 be transported in the blood?
as solution, or as carbamino compounds, or as bicarbonate (most common)
In neural control of respiration, what group of neurons displays pacemaker activity, controls rhythm and where is it found?
Pre-Botzinger complex, found in upper end of medullar resp centre
When does active expiration occur and what controls this?
hyperventilation, controlled by ventral respiratory group neurones
Is active respiration normal?
What is apneusis?
Abnormal breathing, prolonged inspiratory gasps and brief expiration
What prevents apneusis?
What is hypercapnia?
too much C02
What do central chemoreceptors do?
respond to hydrogen ions in cerebrospinal flui