Chapter 7.2 Flashcards
What controls the air pressure inside the lungs?
The diaphragm and the rib muscles
What is the diaphragm?
A dome shaped layer of muscle the separates the region of the lungs from the region of the stomach and liver
What is another name for the rib muscles?
The intercostal muscles
Where are the rib muscles found?
Between the ribs along the ventral (inside) surface of the ribs and extend down to the diaphragm
How does inhalation begin?
The external rib muscles and the diaphragm contract. This expands the rib cage upward and outward and the floor of the chest cavity downward increasing volume
What happens when the volume of the thoracic cavity increases?
The same amount of air is contained in a larger space so molecules of gas are farther apart and they exert less outward pressure. As a result air pressure in the thoracic cavity decreases
What happens to the lungs as air pressure decreases?
The walls of the lungs are drawn outward and the lungs expand
What happens when the lungs expand?
Air pressure within the lungs is lower than air pressure in the external environment. So air moves into the lungs
How does exhalation begin?
The diaphragm and the rib muscles relax reducing volume in the thoracic cavity
What happens when volume in the thoracic cavity decreases?
The volume of lungs decrease and the air pressure within the lungs increase and air moves from the lund to the lower pressure environment outside the body
What is tidal volume?
The volume of air that is inhaled and exhaled in a normal breathing movement when the body is at rest
What is inspiratory volume?
The additional volume of air that can be taken into the lungs beyond a regular/tidal inhalation
What is expiratory reserve volume?
The additional volume of air that can be forced out of the lungs beyond regular/tidal inhalation
What is vital capacity?
AKA total lung volume capacity. The total volume of gas that can be moved into or out of the lungs.
How is vital capacity calculated?
Tidal Volume + Inspiratory Reserve + Expiratory Reserve
What is residual volume?
The amount of gas that remains in the lungs and the passageways of the respiratory system after a full exhalation
Which gas never leaves the respiratory system?
Residual volume gas
What would happen if the residual volume gas left the respiratory system?
The lungs and respiratory passage would collapse
Why does residual volume have little value for gas exchange?
Because it is not exchanged with air from the external environment
What are the 2 separate processes in respiration?
External respiration and internal respiration
Where does external respiration take place?
In the lungs
What happens between external respiration?
Gasses are exchanged between the alveoli and the blood in the capillaries
What is the concentration of oxygen in air that enters the alveoli after inhalation?
It has a higher concentration of oxygen than the blood in the capillaries
What happens because of the difference in concentration of oxygen and CO2 in alveoli and capillaries?
Oxygen diffuses out of the alveoli and into the blood of capillaries
Since diffusion is not enough to exchange all gasses what happens?
Approx. 30% of oxygen transfer happens by facilitated diffusion
What happens during the facilitated diffusion of oxygen from the alveoli to the capillaries?
Protein based molecules in the walls of the alveoli help with diffusion by by carrying oxygen across cell membranes. This doesn’t require extra energy because it is still moving with the concentration gradient
What is the concentration of CO2 from the capillaries vs the alveoli?
They have a higher concentration of CO2 because it is returning from body tissues
What happens after oxygen and carbon dioxide have been exchanged between the capillaries and the alveoli?
The blood in the capillaries begin their journey back to the heart and then to the tissue cells
What kind of respiration happens in the tissue cells?
Internal respiration
What is 99% of oxygen transported by to reach cells?
An oxygen transporting molecule called hemoglobin
Where is hemoglobin found?
Only in red blood cells
How carbon dioxide is carried in the blood by hemoglobin?
23%
What is most CO2 carried in the blood by?
70% is dissolved and carried in the blood a bicarbonate ion (HCO3-)
How does carbonic acid form?
When carbon dioxide molecule reacts with the water molecule to form H2CO3. Then the carbonic acid breaks down into an H+ ion and bicarbonate ion (HCO3-)
Where does the reaction of the CO2 and Water occur?
In the red blood cells
What happens to the free H+ ion?
It combines with hemoglobin and bicarbonate ions diffuse out of red blood cells into plasma which carries it too the lungs
What happens when the plasma reaches the lungs?
The whole bicarbonate ion reaction reversed to reform CO2 and water
