A&P - Chapter 37 Flashcards
What does pulmonary gas exchange refer to?
The exchange of gases in the lungs which takes place between the alveolar air and the blood flowing through the lung capillaries
What can the amount of O2 that diffuses into the blood be affect by? (4)
- The oxygen pressure gradient between alveolar air and blood
- The total functional surface area of the respiratory membrane
- The respiratory minute volume
- ml of air moved per minute - Alveolar ventilation (volume of inspired air that reaches the alveoli) and alveolar function
What do the walls of the alveoli and capillaries form?
A very thin barrier for gases to cross
What is the size of the alveolar and capillary surfaces?
Large
How is the blood distributed through the alveoli and capillaries?
In a thin layer so that each red blood cell comes close to alveolar air
How does pulmonary gas exchange occur?
Through passive diffusion due to the pressure gradient of O2 & CO2 between blood and lung capillaries surrounding alveoli
What does O2 follow in pulmonary gas exchange?
Its concentration gradient from an area of high to an area of low
What does CO2 do in pulmonary gas exchange?
It will diffuse in the opposite direction
Where does O2 move in exchanges of gases in the lungs?
From the alveoli into the lung capillaries
Oxyhemoglobin
Hemoglobin combined with O2
Carbaminohemoglobin
CO2 and hemoglobin
What does CO2 do during exchanges of gases in the lungs?
Moves out of lung capillary blood into alveolar air and out of body in expired air
How does exchange of gases in the tissues occur?
Due to the pressure gradient of O2 and CO2 between the tissue capillaries and the tissue cells
Internal respiration
Exchange of gases between blood in tissue capillaries and the body cells
How are O2 and CO2 transported in the blood? (2)
- In a dissolved state
2. Combined with other chemicals
What does dissolved O2 and CO2 rapidly form?
A chemical union with some other molecule (e.g. hemoglobin) because fluids (such as blood) can only hold small amounts of gas in solution
What happens once O2 and CO2 are bound to another molecule?
Their plasma concentration (partial pressure – PO2 or PCO2) decreases and more gas can diffuse into the plasma allowing comparatively large volumes of these gases to be transported
What is the majority of O2 transported by?
Blood is in the form of oxyhemoglobin
How much O2 is dissolved in the blood?
1.5%
Hemoglobin molecules
Large proteins containing 4 iron-containing heme components
- each capable of combining with an O2 molecule
What does hemoglobin combined with very rapidly?
O2
How much hemoglobin is combined with O2?
97%
- oxygenated blood
How much deoxygenated’ blood is found in the systemic veins and pulmonary arteries?
75%
- saturated with O2
What does the difference in O2 saturation result in?
The release of O2 from oxyhemoglobin to supply the body cells with O2
- the chemical ‘bond’ between O2 and hemoglobin is reversible
What are the 2 forms of O2 in the blood?
- Dissolved O2
- Ooxyhemoglobin
- vast majority
What is a by-product of cellular metabolism?
CO2
What does CO2 contribute to?
The pH of body fluids
What happens if you have excess CO2?
It can be toxic and is eliminated from the body
- enters alveoli and is expelled during expiration
In order to expel CO2 via expiration it must be transported in
the blood to the lungs by what? (3)
- Dissolved CO2
- Carbaminohemoglobin
- Bicarbonate ions
What percent of total CO2 is transported in the blood for dissolved CO2?
10%
What does dissolved CO2 produce?
PCO2 of blood plasma
What percent of total CO2 is transported in the blood for carbaminohemoglobi?
20%
What is the formation of Carbaminohemoglobin accelerated by?
An increase in PCO2 and slowed down by a decrease in PCO2
What percent of total CO2 is transported in the blood for bicarbonate ions?
70%
