Respiratory Physiology Flashcards
What is dead space in the respiratory system?
Area where air travels but gas exchange does not occur
What are the two primary functions of the respiratory system?
- Pulmonary respiration or ventilation
- Transport of gases between the atmosphere and the tissues
What does respiration refer to?
All components of the interchange of gases between the atmosphere and the cell of the body
What does ventilation refer to?
The transport of air to and from the lungs
What does gas exchange refer to?
Transport of gases between the air in the lungs and the cells of the body
What must occur for air to move into the lungs?
An area of lower pressure must be created
How do you calculate the flow of air into the lungs?
F=Area of lower pressure/resistance
What is the approximate air pressure in alveoli at rest?
Atmospheric pressure - 760mmHg
How is an area of lower pressure created for ventilation?
The thoracic cavity expands causing a reduction in alveolar pressure
What is the tidal volume?
The volume of air flowing through the airways during inspiration and expiration
What is dead space volume made up of?
- Anatomical dead space
- Alveolar ventilation
What is anatomical dead space?
The volume of the upper airways that are not involved in gas exchange
What is alveolar ventilation?
The volume of air available for gas exchange in the alveoli per minute
What is alveolar dead space?
The volume of alveoli that are not being perfuse by blood so do not participate in gas exchange
How is alveolar ventilation calculated?
Alveolar ventilation = (tidal volume - anatomical dead space) x respiratory rate
What is the expiratory reserve volume?
The amount of air that can be forcefully exhaled from the lungs after a normal exhalation
What is the inspiratory reserve volume?
Maximum amount of air that can be inhaled after a normal breath
What is the residual volume?
The amount of air remaining in the lungs after a maximal exhalation a volume that cannot be expelled
What is the vital capacity?
Maximum amount of air a person can exhale from their lungs after a maximal inhalation
What is total lung capacity?
The maximum amount of air the lungs can hold after a maximal inhalation
What results in expiration?
The respiratory muscles relax and the lungs recoil and thoracic cage reduce thoracic volume
Why does the pO2 decrease in the alveoli?
The air is moistened by the respiratory tract so that the partial pressure of water increases which means pO2 must decrease
How does carbon dioxide move in between the alveoli and capillaries?
Moves from the capillaries to alveoli down concentration gradient
How does oxygen move in between the alveoli and capillaries?
Moves from the alveoli to capillaries down the concentration gradient
How much of air is exchanged with each breath in an alvieoli?
15%
What is meant by perfusion in the lungs?
Where blood goes in the lungs
What is the perfusion of the lungs?
Less blood flows to the highest part of the lungs due to gravity
Where does air usually go to in the lungs?
The more dependent parts (lower parts) of the lungs
What are the two ways oxygen can be transported in the body?
- Dissolved in the blood plasma
- Bound to haemoglobin in RBCs
How much O2 is in plasma?
3mL/L of blood
How much O2 is in blood with a haemoglobin concentration of 150mL/L?
200mL/L of blood
How many oxygen molecules can one haemoglobin molecule bind?
4 as it contains 4 heme groups
What is oxygen association in relation to haemoglobin?
The process of oxygen binding to haemoglobin in the lungs where the pO2 is high
What is oxygen dissociation from haemoglobin?
Is the release of oxygen from haemoglobin in the tissues where the pO2 of oxygen is low
Why is pO2 significant in oxygen transport?
pO2 determines how readily oxygen binds to or dissociates from haemoglobin
What is the oxyhaemoglobin dissociation curve?
Is a graph showing the relationship between haemoglobin saturation and pO2 indicating cooperative binding of oxygen
What is cooperative binding in haemoglobin?
The process where the binding of one oxygen molecule to haemoglobin increases its affinity for the next oxygen molecule
What causes the oxyhaemoglobin dissociation curve to shift to the right?
Conditions such as high CO2, low pH, increased temp and exercise making haemoglobin more likely to release oxygen
What is the Bohr effect on the oxyhaemoglobin dissociation curve?
Is the rightward shit of the cure in response to increased CO2 and decreased pH
What are the three ways carbon dioxide is transported in the blood from lowest to highest?
- Plasma
- Bound to Haemoglobin
- Bicarbonate ions
How does CO2 bind to haemoglobin?
Bind to the amino groups of the globin part of haemoglobin
What happens to CO2 when it enters red blood cells in tissues?
CO2 reacts with water to form carbonic acid, which then dissociates into hydrogen ions and bicarbonate ions
How does the pCO2 affect carbon dioxide transport?
High pCO₂ in tissues promotes CO₂ binding to haemoglobin, while low pCO₂ in the lungs promotes CO₂ release and exhalation
