Biology: Human Respiration
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- 1. nasal cavities
- 2. pharynx
- 3. larynx
- 4. trachea
- 5. bronchi
- 6. bronchioles
- 7. alveolar sacs
Each alveolus is coated with a thin layer of liquid containing _______________, and is surrounded by an extensive network of capillaries.
_____________ lowers the surface tension of the alveoli and facilitates gas exchange across the membranes.
The lungs are surrounded by two membranes called ?
- Visceral pleura
- parietal pleura
The space between the two pleura is called the ______________.
The pressure differential between the ____________ and the _____________ prevents the lungs from collapsing.
Intrapleural space and lungs
- *diaphragm contracts and flattens
- *external intercostal muscles contract - pushing the rib cage and chest wall up and out
- *thoracic cavity increases in volume --- causes a decrease in intrapleural pressure -- causing the lungs to expand and fill with air
- * this is referred to as negative pressure breathing because air is drawn in by a vacuum.
- *passive process
- *thoracic volume decreases -- intrapleural pressure increases
- *internal intercostal muscles contract
- *surfactant reduces the high surface tension of the fluid lining the alveoli, preventing alveolar collapse during exhalation.
Ventilation is regulated by neurons located in the _____________, whose rhythmic discharges stimulate the intercostal muscles and/or the diaphragm to contract.
The neural signals can be modified by _________________, which respond to changes in the pH and the partial pressure of CO2 in the blood.
chemoreceptors - ie: in the aorta
When the partial pressure of the CO2 rises, the medulla oblongata stimulates an _____________ in the rate of ventilation.
Hyperventilation lowers the partial pressure of CO2 in the blood below normal
An instrument called a ____________ measures the amount of air normally present in the respiratory system and the rate at which ventilation occurs.
The maximum amount of air that can be forcibly inhaled and exhaled from the lungs is called the _______________.
The amount of air normally inhaled and exhaled from the lungs is called the _____________.
The ________________ is the air that always remains int he lungs, preventing the alveoli from collapsing.
The _________________ is the volume of air that can still be forcibly exhaled following a normal exhalation.
Espiratory reserve volume
__________________ = vital capacity + residual volume
total lung capacity
A dense network of minute blood vessels called the ______________ surrounds the alveoli.
Gases move from regions of lower partial pressure to regions of higher partial pressures.
High --> low
Blood enters the pulmonary capillaries in a ______________ state and thus has a lower partial pressure of O2 than does the inhaled air in the alveoli.
The partial pressure of CO2 in the capillaries is __________ than that of the inhaled alveolar air; thus CO2 diffuses from the capillaries into the alveoli.
At high altitudes the partial pressure of O2 in the atmosphere _____________, making it more difficult to get sufficient oxygen to diffuse into the capillaries.
- *The body compensates for these conditions by:
- hyperventilation - increasing the rate of ventiliation
- polycythemia - increasing the production of RBC to carry more oxygen
- *the affinity of hemoglobin for oxygen decreases to facilitate unloading of oxygen in tissues, and there is greater vascularization of the peripheral tissues.
All of the following facilitate gas exchange in the lungs EXCEPT:
a. thin alveolar surfaces
B. moist alveolar surfaces
c. differences in partial pressures of O2 and CO2
d. active transport
D. active transport
The lungs can collapse from
a. insufficient surfactant production
b. rupture of the parietal pleura
c. overproduction of the surfactant
d. both a and b
e. both b and c
D both a and b
Which of the following is generally a passive process?
c. gas exchange
d. both a and b
e. both b and c.
both b and c.
Most CO2 is transported as ____________ in the plasma.
dissolved bicarbonate ions (HCO3-)
The formation of HCO3- occurs in the _________________.
The formation of carbonic acid, H2CO3, is catalyzed by the enzyme _______________.
When a body is active, __________ production is increased.
Carbonic acid equation:
CO2 --> H2O --> H2CO3 --> H+ + HCO3-
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