Respiratory 5 Flashcards
What is the bronchial circulation?
Blood supplied via the bronchial arteries arising from systemic circulation to supply oxygenated blood to airway smooth muscle, nerves, lungs and tissues.
Describe the flow and pressure of the pulmonary circulation.
- high flow
- low pressure
What is systolic pressure?
The maximum arterial pressure during contraction of the left ventricle of the heart.
At what rate does blood circulate around both the body and the lungs?
5L/min
True or false:
Partial pressure gradients are not the same as concentration gradients.
True
What value is the partial pressure of alveolar oxygen in kPa?
13.3 kPa
What value is the partial pressure of alveolar carbon dioxide in kPa?
5.3 kPa
What value is the partial pressure of arterial oxygen in kPa?
13.3 kPa
What value is the partial pressure of arterial carbon dioxide in kPa?
5.3 kPa
What value is the partial pressure of venous oxygen in kPa?
5.3 kPa
What value is the partial pressure of venous carbon dioxide in kPa?
6.2 kPa
True or false:
The diffusion of gases between the alveoli and the blood does not obey the rules for simple diffusion.
False
From alveoli to arterial blood, which has the largest partial pressure gradient; oxygen or carbon dioxide?
Oxygen
Why is diffusion of oxygen slower than that of carbon dioxide?
Carbon dioxide is more soluble than oxygen.
Briefly define emphysema.
Emphysema is the destruction of alveoli, reducing surface area for gas exchange.
Briefly define fibrotic lung disease.
- thickened alveolar membrane which slows gas exchange.
- loss of lung compliance may decrease alveolar ventilation
Briefly define pulmonary oedema.
- fluid in interstitial space increases diffusion distance
Briefly define asthma.
- increased airway resistance decreases airway ventilation
- occurs as bronchioles are constricted
Where is the equilibrium point of blood flow and ventilation?
The third rib.
Define the term ‘shunt’.
Shunt is the term used to describe the passage of blood through areas of the lung that are poorly ventilated.
What happens when ventilation is less than blood flow?
- If ventilation decreases in a group of alveoli, the partial pressures of carbon dioxide increases and oxygen decreases.
- Blood flowing past those alveoli does not get oxygenated.
- This blood then dilutes the oxygenated blood from better ventilated areas.
How does the body combat shunting?
- vasoconstriction occurs, allowing less blood to the poor ventilated area and more blood the well ventilated area.
- the build up of carbon dioxide also triggers mild bronchodilation, allowing more oxygen to the poorly ventilated area.
What happens when ventilation is greater than blood flow?
This results in alveolar dead space
- through vasodilation and mild bronchial constriction
What is alveolar dead space?
- refers to alveoli that are ventilated but not perfused
