Partial Pressures Flashcards
What is the po2 in alveolar air?
105
What is the po2 in venous blood?
40
What is the po2 in arterial blood?
105
What is the po2 in tissue cells?
40
What is the pco2 in atmospheric air?
0.3
What is the pco2 in alveolar air?
40
What is the pco2 in venous blood?
45
What is the pco2 in arterial blood?
40
What is the pco2 in tissue cells
45
What is the PN2 in atmospheric air?
597
What is the PN2 at all other air/blood?
569
What is the PO2 in atmospheric air?
160
What do partial pressures in alveoli depend on?
Air flow in and out of lungs
When is diffusion gradient reduced?
With impaired ventilation
What happens if the surface area of alveoli is reduced like on emphysema?
Exchange is impaired
What happens when membranes are thickened or swollen or air cells contain excess fluid?
Gaseous exchange is reduced
Where are chemo receptors found? 2
In the respiratory centre and in arterial walls
Where are peripheral chemoreceptors found?3
In arterial walls. Arch of the aorta and bifurcation of common carotids on each side
Where are central chemo receptors found?
In respiratory centre
What do central chemo receptors respond to? 3
Changes in partial pressure of co2 in blood and alterations in acidity and CSF
What inhibits the stimulation to ventilate? Hypoventilate
A drop in arterial pco2
What does an increase in pco2 hypercapnia stimulate?
Chemoreceptors
Where are stretch receptors found?
Bronchi and bronchioles
What does PH mean?
The power of hydrogen
What does the apneustic centre in the pond varolii do?
Cuts out breathing stimulation
What does the respiratory centre comprise of? 3
Medullary centre in medulla oblongata.
Pneumotaxic centre in pons varolii.
Apneustic centre in pons varolii.
What is hypoxic drive? 3
Co2 in blood is stimulus to breathe.
In COPD patients level of co2 in blood is high so it becomes insensitive to the level of co2.
The co2 drive to stimulate respiration is removed.
Respiratory centre in brain uses hypoxia as stimulus to breathe.
