Physiology RESP Book Flashcards
What lung volumes cannot be measured by spirometry
FRC,RC
What is FRC
Volume left in lung after passive expiration
What is ERV
Volume that can be expired further after passive expiration
Define anatomical dead space
Air in conducting airways
Where is surfactant produced
Lamella of type 2 alveolar epithelial
Main constituent of surfactant
DPPC main
Remainder proteins, phospholipids
Causes of reduced surfactant production
Cigarette smoking
Cardiac surgery
Occlusion of main bronchus
Long term 100% O2
Elastance and compliance relationship
Reciprocal relationship
Compliance is the ability of a hollow organ (vessel) to distend and increase volume. It is the reciprocal of “elastance” which is a measure of the tendency of a hollow organ to recoil toward its original dimensions upon removal of a distending or compressing force.
When is compliance greatest in respiration
In expiration
Main transport of CO2
As bicarbonate
Physiological changes at higher altitude
Decreased PO2
Tachypneoic
Resp alkalosis
Increase in Hb due to EPO
Increased 2,3 DPG - decreased affinity- aiding unloading
Causes of pulmonary vasoconstriction
Hypoxia
Acidosis - increase in CO2I
Increase in pulmonary circulation in systole or diastole
Systole
Areas in the brain controlling respiration
Medulla- inspiratory and expiratory
Pons- apneustic and pneumotaxic - affect inspiration
Cerebral cortex- voluntary
Limbic- extreme states of emotion
Chemoreceptors affecting respiration
Central- close to medulla- sensitive to change in PCO2
- triggered by H+
Peripheral- carotids- respind to O2 when very low <8
What shifts the O2 curve to the right
Acidosis
High Temp
High DPG
Low CO
Chemoreceptors
Peripheral mainly sensitive to PO2
Central within BBB- sensitive to pH indirectly through CO2
What shift O2 curve to the left
Low temp
Low CO2
Low DPG
High pH
High CO
Cause of sigmoid curve
Binding of first O2 molecule increases affinity on next
What Oximetry measures and cannot measure
The saturation of Hb using red and infrared light- difference between oxygen and deoxy absorption
Doesn’t give good measure of ventilation - PCO2 better
If CO poisoning cannot differentiate
Composition of Haemoglobin molecule
4 haem- bind to 1 O2 molecule
4 globin- 2 a and 2 b
Causes of type 1 resp failure
Pulmonary oedema
Pneumonia
ARDS
PE
