Flashcards in BIOL 0800 Reading- Chapter 13 Deck (113)
Every minute, approximately how much air and blood flows through the lungs/pulmonary capillaries?
4L air, 5L blood
What is the structure of the pulmonary system after the larynx?
Trachea, into two bronchi, into two bronchioles, into terminal bronchioles, into respiratory bronchioles, into alveolar ducts, into alveolar sacs: alveoli show up in respiratory bronchioles and increase in alveolar ducts and alveolar sacs
What is the conducting zone?
From the top of the trachea to the beginning of the respiratory bronchioles; contains to alveoli and no gas exchange
What is the respiratory zone?
From the respiratory bronchioles downwards; contains alveoli and gas exchange
What are type I alveolar cells?
One-cell thick, flat layer of epithelial cells lining the air-facing surfaces of alveolar walls
What are type II alveolar cells?
Interspersed between type I cells; thicker, specialized: produce surfactant
What is inside the alveolar wall?
Capillaries and a very small interstitial space: interstitial fluid and loose mesh of connective tissue
What are intercostal muscles?
Muscles that run between ribs
What is the pleural sac?
Completely closed sac that encloses each lung, made of thin sheet of cells called pleura
What is the difference between visceral and parietal pleura?
Internal surface touching the lung, and external surface touching the thoracic cavity interior
What is intrapleural fluid?
Fluid between the visceral and parietal pleura
What is the equation for bulk flow?
F = deltaP/R
In the equation for bulk flow, what is delta P?
Alveolar pressure (Palv) minus atmospheric pressure (Patm)
What happens when Palv is less than Patm?
Negative flow, or inspiration
What happens when Palv is greater than Patm?
Positive flow, or expiration
What is Boyle's law?
PV = PV
Lung volume depends on what two factors?
Transpulmonary pressure and lung stretchability
What is transpulmonary pressure?
The difference in pressure between the inside and outside of the lung; Palv minus Pip (intrapleural)
What are the formulas for transmural pressure on the lungs and on the chest cavity?
On the lungs is Palv - Pip, and on the chest cavity is Pip - Patm
How does transmural pressure affect inspiration/expiration?
Transmural pressure increases for inspiration (decreases Pip relative to Palv), and uses elastic recoil to drive passive expiration
When there is no airflow, why is Pip negative?
Because there is always a positive transmural pressure, so Palv > Pip, but Palv = 0
What forces cause intrapleural pressure to be zero when there is no airflow?
Elastic recoil of the lungs and the chest cavity causes the lungs to shrink and thoracic cavity to expand: pulls the pleural walls apart and decreases pressure
What is the crucial factor in keeping the lungs partially expanded between breaths?
The negative (subatmospheric) intrapleural pressure
What causes the diaphragm to contract?
Activation of the phrenic nerves
How does inspiration occur?
Thorax expands, Pip becomes subatmospheric, transpulmonary pressure increases, lungs expand, Palv becomes subatmospheric, air flows into alveoli
How does expiration occur?
Diaphragm and chest wall recoil inward; Pip returns to normal value, transpulmonary pressure decreases, elastic recoil overcomes transpulmonary pressure, and lungs passively recoil
What is lung compliance?
The magnitude of the change in lung volume produced by a given change in transpulmonary pressure
What is the formula for lung compliance?
Delta V/delta Ptp
What are two major determinants of lung compliance?
Stretchability of lung tissues, and surface tension on alveoli