Final Exam: Lab 8 Respiratory Physiology Flashcards
What is another term for pulmonary ventilation?
breathing
Define pulmonary ventilation in simple terms.
The exchange of air between the atmosphere and the lungs
What causes pressure within a gas sample?
Pressure is caused by gas molecules striking the walls of a container
Define Boyle’s Law
The pressure of a gas is inversely proportional to the volume of its container.
Increase Vol = Decrease pressure
Decrease Vol = Increase pressure
How is the volume of the thoracic cavity changed?
. By muscle contraction and relaxation.
What happens to pressure when we increase the volume within the thoracic cavity and the
lungs?
Pressure decreases
What is the pressure within the lungs called?
- Intrapulmonary, or intra-alveolar, pressure
What is the value of intrapleural pressure compared to intrapulmonary (alveolar) pressure?
- Intrapleural pressure is always less than intrapulmonary (alveolar) pressure.
What three factors cause the intrapleural pressure to be less than intrapulmonary (alveolar)
pressure?
- (1) The surface tension of the alveolar fluid.
(2) The elasticity of the lungs.
(3) The elasticity of the
thoracic wall.
Why does a lung collapse if you cut into the pleural cavity?
- Because the pressure of the intrapleural cavity becomes equal to atmospheric pressure. There is no
longer less pressure in the intrapleural cavity compared to within the alveoli so the lung collapses.
a. What is the transpulmonary pressure? b. What is the function of the transpulmonary
pressure?
- a. The difference between the intrapleural and intrapulmonary pressures.
b. It creates the suction to
keep the lungs inflated.
If a pneumothorax occurs in one lung, why doesn’t it also occur in the other lung?
- Each lung has its own pleural cavity and pleural membranes so that changes in the intrapleural
pressure of one lung do not affect the other lung.
) Match the pressures to their definition:
• Intrapulmonary Pressure
• Transpulmonary Pressure
• Intrapleural Pressure
a. The pressure within the pleural cavity.
b. The pressure within the alveoli.
c. The difference between the pressure within the
pleural cavity and the pressure within the
alveoli
- a. Intrapleural Pressure b. Intrapulmonary Pressure c. Transpulmonary Pressure
Chose the proper words to explain what happens during inspiration.
The diaphragm and external intercostal muscles __________ (contract, relax).
↓
The volume of the thoracic cavity _________ (increases, decreases).
↓
Intrapleural pressure becomes ________ (more, less) negative.
↓
Lungs ________ (recoil, expand).
↓
Intrapulmonary pressure __________ (increases, decreases).
↓
Air flows _________ (into, out of) the lungs.
- contract, increases, more, expand, decreases, into
Chose the proper words to explain what happens during inspiration.
The diaphragm and external intercostal muscles __________ (contract, relax).
↓
The volume of the thoracic cavity _________ (increases, decreases).
↓
Intrapleural pressure becomes ________ (more, less) negative.
↓
Lungs ________ (recoil, expand).
↓
Intrapulmonary pressure __________ (increases, decreases).
↓
Air flows _________ (into, out of) the lungs.
Air flows _________ (into, out of) the lungs.
- relax, decreases, less, recoil, increases, out of
What two factors play roles in ventilation besides muscle contraction?
- (1) The resistance within the airways
(2) Lung compliance.
What is airway resistance due to?
- The gas molecules encountering resistance as they strike the walls of the airway.
***Diameter of airway
What happens to the airway resistance as the bronchiole constricts?
- As the diameter of the walls of the bronchiole decrease, the resistance increases
Does histamine constrict or dilate bronchioles?
constricts
- increase airway resistance –> decrease airflow
Does epinephrine constrict or dilate bronchioles?
dilates
- decrease resistance –> increase airflow
What two factors is lung compliance dependent upon?
- (1) The stretchability of the elastic fibers within the lungs. (2) The surface tension within the alveoli.
.
What happens to alveoli when there is not enough surfactant?
- Alveoli have high surface tension, and they tend to collapse
- Surfactant = decrease ST and increase lung complaince
Intrapulmonary pressure changes
pressure with in lungs
What causes intrapulmonary pressure changes
atmospheric pressure, inspiration, expiration
what are the results of the intrapulmonary pressure changes
- atmospheric pressure = 760mmHg
- inspiration = 1 mmHg below atmospheric pressure
- expiration = 1 mmHg above atmospheric pressure
*****Events during inspiration
Increase volume o thoracic cavity –> intrapulmonary pressure below atmospheric pressure = negative pressure Airflow into the lungs
End of inspiration -> when intrapulmonary pressure equals atmospheric pressure = airflow stops
** events during expiration
- decrease volume of thoracic cavity -> intrapulmonatry above atmospheric pressure
airflow out of the lungs -> end of expiration -> intrapulmonary equals atmospheric pressure
Other factors affecting ventilation
- resistance
the diameter of airway
(epi and hisptamine stuff)
airflow = (pressure/resistance)
how is resistance affected by changes in airway diameter
increase airflow -> decrease diameter -> increase resistance because more gas molecules encounters airway wall
how does increased resistance affect air flow
- (histamine constricts)
- increase airway resistance = decrease airflow
factors affecting airway resistance
histamine and epinephrine
lung compliancc
- ease with which the lungs expand
amount of elastic tissue
strethability of elastic fibers with in the lungs
surface tension
- intermolecular forces within fluid molecules that attract molecule to each other
Tidal volume
volume of air inhaled or exhaled in a single unforced breathe
inspiratory reserve volume
- difference between volume at end of normal inhalation and vital capacity
expiratory reserve volume
difference between volume at end of normal exhalation and vital capacity
vital capacity
maximum volume of air that can be moved into the lungs
residual volume
volume remaining in lungs after a maximum of expiration
total lung capacity
total amount of gas in lungs after a maximum inspiration
the spirogram shows relationship among various values..
total lung capacity =
vital capacity =
total lung capacity= vital capacity + Residual volume
vital capacity = Expiratory reserve volume + TV + IRV
spirometry in lab
spirometers in lab are instruments that can only measure exhaled volumes. only able to measure VC, TV, and ERV
IRV = VC - (TV + ERV)
Total minute volume
total volume of air moved in and out of the lungs in one minute. this value is the product of the ventilation rate (number of breaths per minute) and the tidal volume (ml of air per breathe)
When oxygen diffuses across the alveolar walls, most of the oxygen becomes bound to
hemoglobin
the percent exyhemoglobin saturation is
the percentage of hemoglobin molecules that have 4 oxygen molecules attached.
- this value indicates the effectiveness of gas exhange
gas exhange occurs by
diffusion, any abnormal conditionthat changes the rate of diffusion will change the percent oxyhemoglobin saturation
pulse oximeter
- an instrument that can measure percent oxyhemoglobin saturation continuously
would oxyhemoglobin saturation value change during exercise?
increase exercise -> (increase temp/decrease pH) -> increase 02 delivery to muscles because hb affinity for O2 decreases, therefore increases unloading of O2
