Tidal volume consists of:
Dead space volume
Air that remains in conducting zone and never reaches alveoli
About 150 ml
Air that actually reaches the respiratory zone
Usually about 350 ml
Inspiratory reserve volume (IRV)
Amount of air that can be taken in forcibly over the tidal volume
Usually between 2100 and 3200 ml
Expiratory reserve volume (ERV)
Amount of air that can be forcibly exhaled beyond tidal volume
Approximately 1200 ml
Residual volumeAir remaining in lung after expiration
About 1200 ml important in keeping alveoli inflated, allows continuous gas exchange, even during exhalation
Vital capacityThe total amount of exchangeable air
Vital capacity = TV + IRV + ERV
Respiratory capacities are measured with a spirometer
Body cells have used oxygen, and depleted blood is returned to the lungs. O2 in Air in Alveoli&gt;amt of O2 in blood.
Diffusion down its gradient. Passive process. Oxygen moves across respiratory membrane into blood, into RBC and binds to hemoglobin. Binding affinity dependent on pH.
Partial pressure of O2 is 160 mmHg, 21% in atmosphere at sea level.
BUT, since not all air is exchanged with each breath (only about 1/8 of total capacity),
the actual partial pressures in the alveoli are 104 mmHG O2 and 40 mmHg CO2.
Oxygen movement into the blood
alveoli (104 mmHg) always has more oxygen than blood entering lungs (40 mmHg)
Oxygen moves by diffusion towards the area of lower concentration
Pulmonary capillary blood gains oxygen, mostly bound to hemoglobin (100 mmHg)
Carbon dioxide movement out of the blood
Blood returning from tissues (46 mmHg) has higher concentrations of carbon dioxide than air in the alveoli (40mmHg)
Again, because not all air is exchanged, CO2 in atimosphere is only .04%, but much higher in alveoli.
Pulmonary capillary blood gives up carbon dioxide
Blood leaving the lungs is oxygen-rich and carbon dioxide-poor
Partial pressure of CO2 is almost neglible, as it is only .04% of atmospheric gases at sea level.
BUT, since not all air is exchanged with each breath (only about 1/8 of total capacity), the actual partial pressures in the alveoli are 104 mmHG O2 and 40 mmHg CO2.
Most = 70% of CO2 is bicarbonate. Write equation showing CO2 + H2O -(carbonic anhydrase) - H2CO3 --HCO3 + H+
This reaction is done inside the RBC, which contains an enzyme that helps push the reaction.
20% OF CO2 BINDS TO HEMOGLOBIN, specifically, the globin . O2 binds to the heme (iron containing portion)
So hemoglobin can carry both CO2 and Os at the same time.
10% of CO2 is directly dissolved in blood plasma. This is the first to diffuse out of the blood and into the alveoli in lungs. As this CO2 leaves, pulls equilibrium of HCO3 back to H2CO3 to CO2 and H2O, which diffuse out of blood, into alveoli.
CO2 moves into ca;illary, combines with H2O, forms H2CO3 inside RBCs (carbonic anhydrase enzyme)
HCO3 moves out of the RBCs into plasma. Some H+ remain, binding to hemoglobin and weakening its bond with O2.
Effect of this is to favor O2 binding to hemoglobin in the lungs and favor O2 release in tissues, where respiration has raised the CO2 level.
Allergens trigger immune system to produce lots of IgE, which triggers mast cells in lungs to secrete histamines, which cause inflammation response.
Albuterol adminstered via inhalers, gets droplets of medication directly to lungs, cells lining bronchioles. Dilators, corticosteroids to reduce inflammation.
90% of lung cancer victims are smokers. 10% are not. Can also be due to other chemicals, such as radon or asbestos
Prognosis not good: avg survival after diagnosis is 9 months. 5 yr survival is 7% of patients.
Why do people smoke? Social, emotional reasons. Nicotine is addicting. Extremely.
Damage caused by other chemicals in smoke, esp free radicals that cause mutations. Lung cells most heavily exposed, but these chemicals absorbed into blood, travel throughout body. Smoking also increases frequency of cancers in kidney, pancreas, bladder, and even cervical cancer.
Doom and gloom? YES.