Respiratory system Flashcards
What are the two functional zones of the respiratory system?
- Conducting
- Respiratory
This functional zone consists of where air flows from the mouth/nose through the terminal bronchioles
conducting
this functional zone consists of respiratory bronchioles and alveoli
respiratory
The purpose of this region of the respiratory system is to warm and humidify the air
upper airways
What are 3 defenses of the upper airways?
- air turbulence
- mucus
- ciliary cells
What prevents the collapse of the airways on in breaths (where pressure is negative)?
airway cartilage
at what point does airway cartilage cease?
transition to 1 mm bronchioles
what prevents airway collapse at the bronchiole level?
elasticity of surrounding tissues
Alveolar gas exchange works the best under what conditions?
37C and 100% humidity
what portions of the respiratory tract are NOT lined with ciliated mucosa?
pharynx and alveoli
about how many highly vascularized alveoli are in the lungs?
300 million
The destruction of alveoli; ends up reducing SA for gas exchange
Emphysema
With the loss of alveoli in emphysema, fewer alveoli are present to put pressure on the bronchioles causing what?
collapse during expiration
lung pressure is lower than atmospheric pressure during what phase of respiration?
inspiration
lung pressure is greater than atmospheric pressure during what phase of respiration
expiration
This law states that the smaller the sphere, the greater the surface tension and higher the pressure
LaPlace’s Law
This combats LaPlace’s Law in the alveoli by diminishing surface tension and reducing the tendency for alveoli to collapse
surfactant
The lack of surfactant in preemie babies leads to what?
IRDS
in adults, low levels of surfactant leads to what?
ARDS and atelectasis
What can cause low surfactant levels in adults?
trauma, sepsis, aspiration, or other conditions
What is the total surface area of alveoli?
~760 ft^2
What is the pressure of water in 100% humidified air?
47 mmHg
What is the pressure of air?
760 mmHg
Nitrogen makes up what percentage of the atmosphere?
78%
Oxygen gas makes up what percentage of the atmosphere?
21%
Carbon dioxide makes up what percentage of the atmosphere?
<1%
What law refers to the idea that partial pressures add up to equal the total pressure of an environment
Dalton’s Law
What gas concentration gradients provide the foundation for gas exchange?
Po2 and Pco2
What are the partial pressures of O2 and CO2 in the blood entering pulmonary capillaries?
Po2 = 40; Pco2 = 46
the primary O2 carying capacity limitation is what?
hemoglobin concentration
This blood protein increases the plasma’s capacity to hold onto excess dissolved oxygen
hemoglobin
What is the %saturation of hemoglobin leaving the lungs?
97%
At rest, what percentage of oxygen saturation is lost as hgb travels to systemic tissues?
~25%
what is the %saturation of hemoglobin when returning to the lungs?
75%
With exercise, how much oxygen is lost to the tissues?
~65%
With exercise, plasma po2 drops to what?
~20 mmHg
what is the primary effect on oxyhemoglobin saturation?
arterial po2
What are the 3 factors that influence oxygen dissociation?
- pH
- temperature
- working muscle environment
In an acidic environment, how easily will O2 dissociate from hgb? why?
dissociates more quickly; H+ has a higher affinity for hgb
Higher temperatures do what to O2 dissociation from hgb?
increase rate of dissociation
what conditions in a working muscle environment encourage quick O2 dissociation from hgb?
- high acidity (via lactic acid)
- increased temperatures
This blood protein is found more readily in muscle tissues and has a much higher O2 affinity than hgb
myoglobin
What is the optimal arterial blood pH?
7.40
what is the optimal venous blood pH?
7.36
Where do the acids in the blood come from?
- cellular respiration
- food metabolism
What are two buffer methods for maintaining pH consistency?
- chemical buffers
- physiologic buffers
What are 3 examples of chemical buffers?
- proteins
- bicarbonate
- phosphate
What are 2 physiologic buffers?
- respiratory
- renal
what percentage of CO2 is dissolved in plasma?
10%
what percentage of CO2 is bound to hemoglobin?
20%
What percentage of CO2 reacts with water to form H+ and bicarbonate?
70%
What is the key thing to regulate in order to prevent acidosis?
CO2
This type of breathing results in alkaline blood
hyperventilation
this type of breathing results in acidic blood
hypoventilation
why does hyperventilation increase blood pH?
increased CO2 elimination which removes H+ from blood
