Lecture 29 Flashcards
What process drives gas exchange in the lungs?
diffusion; from high to low pressure (= concentration gradient)
What is partial pressure? If our atmosphere is ~20% oxygen, what is the partial pressure of oxygen?
the individual contributions to the overall gas pressure by the different gases in a mixture; if O2 is ~20% of our atmosphere then the partial pressure of O2 (= concentration) is 20% of atmospheric pressure (760mmHg).
What process transports gases in the circulation between the lungs and tissues?
bulk transport due to blood being circulated.
Why must we remove CO2 from our body?
To avoid acidosis
When the temperature is constant, volume changes, pressure will cause _____ ____ of air either in or out of our lungs as described by Boyles law equation.
bulk flow
A fixed mass of dry gas exerts increasing pressure with decreasing volume and increasing temperature (and visa versa), behaviors which can be summarized by what equation?
Gas Law: P1V1/T1 = P2V2/T2
What is Boyle’s Law equation if the temperature is constant?
Boyle’s Law equation: P1V1 = P2V2
Atmospheric pressure is due to the effect of _____ on the gases that form our atmosphere.
gravity
At sea level and standard temperature, the Earth’s atmosphere exerts a total pressure of ________.
760mmHg
What is the partial pressure of the gases of the atmosphere?
For N2 (Pn2) is therefore given by 78.6% of 760mmHg = 597mmHg For O2 (Po2) is therefore given by 20.8% of 760mmHg = 159mmHg For CO2 (Pco2) is therefore given by 0.04% of 760mmHg = 0.3mmHg
What is 1% of the atmosphere made of that is not N, O2, or CO2?
1% Argon which is a “noble” gas and totally inert
T or F? At ~ 20,000 feet atmospheric pressure is less than half normal which means the Po2 is less than half and will not saturate hemoglobin resulting in anoxia.
True
At normal pressures, what are the physiological effect of Nitrogen and Argon?
Nitrogen and Argon have no known physiological effect. However, if you breathe in pressurized air, you can force nitrogen into solution. (The Bends)
What is vital for gas diffusion/exchange and viability in our lungs?
Moist lungs.
What is the pressure exerted water vapors in our lungs?
47 mmHG (Saturated Water Vapor Pressure: SWVP)
T or F? Between breaths our alveolar pressure must equal the surrounding atmospheric pressure, (= 760mmHg)
True
How do you calculate the Po2 of our lungs?
(760 mmHg - 47 mmHg) x 20.8% = 148 mmHg
What is solubility coefficient of CO2 and O2?
CO2 = 0.57 O2 = 0.024
CO2 has only _____ of the partial pressure of equivalent amount of O2 in solution.
a. 1/5th
b. 1/10th
c. 1/20th
c. 1/20th
How is partial pressure calculated with solubility coefficient?
partial pressure = concentration of dissolved gas/solubility coefficient
By what process does oxygen transfers to the alveoli of the pulmonary capillaries?
Diffusion
T or F? Oxygen is permanently bound to hemoglobin.
False, they are reversibly bound to hemoglobin.
*What process drives gas exchange in the lungs?
Diffusion; from high to low pressure (= concentration gradient).
T or F? Diffusion in the alveoli is rapid, but most diffusion is actually in the water.
True
What are the components to consider when determining diffusion?
- Concentration/Partial pressure
- Solubility
- Area of diffusion
- Distance of diffusion
- Molecular weight of gas
- Temperature
If the temperature is constant, distance to capillaries maximized, area of exchange maximized, only the characteristics of the gases themselves to determine their relative rates of diffusion in water. What can be expected of the rate of diffusion of CO2 and O2?
CO2 is ~ x20 more soluble than O2 and this equates to a similar difference in relative rates of diffusion, (CO2 is x20 faster!)
Which has higher partial pressure differences?
a. CO2
b. O2
b. O2 partial pressure differences is higher.
What are the organs of respiratory system?
Nose Nasal cavities (including paranasal sinuses) Pharynx Larynx Trachea Bronchi Lungs
The “conduction zone” consists of all organs of respiratory except the alveoli. What does this zone do to the air?
Filters, warms, and humidifies the air before transferring to “respiratory zone”
Where in the lungs is the “respiratory zone” and what is its function?
Alveoli, which is the site of gas exchange.
What are the function of the nose?
● Moistens and humidifies inhaled air, (plus “reclamation” of water on exhaling).
● Filters air using nose hairs.
● Resonating chamber for speech, (phonation).
● Houses olfactory receptors.
Nasal cavities are subdivided into 2 mucosas. What are they?
Olfactory (smelling)
Respiratory (breathing)
Which mucosa is composed of pseudostratified ciliated columnar epithelium containing many Goblet cells (“fly paper”)?
Respiratory mucosa (Lysozymes are secreted to digest pathogens)
The nares (nostrils) produce _______ to force particulate matter onto mucus-lined walls.
vortexes
T or F? The nasal cavities also warms, humidify air during inhalation.
True (during exhalation, they reclaim moisture)
Why are nose bleed common during cold weather?
Increase blood supply to the nose helps warms the inhaled air.
Cystic Fibrosis is due to defective ________ transporter./channel.
Cl-. This will inhibit salt secretion (sep. of charge) and therefore H2O (osmosis) so mucus too sticky for cilia.
What treatments are available for cystic fibrosis?
- Cystic fibrosis transmembrane conductance CFTC regulator/potentiator “helping” defective gene product
- generally helped by restoring fluidity, anti-inflammatories (NSAIDS), antibiotics (infections)
- double lung transplant in extreme cases
What are the 3 subdivision of the pharynx?
naso-, oro- and laryngopharynx. Composed of stratified squamous epithelium like the mouth.
T or F? The Larynx is common passageway for food and air; like mouth composed of stratified squamous epithelium (wet membrane/high traffic area)
False, Pharynx
Larynx is attached to what free floating bone?
The hyoid bone
What is the function of the Larynx?
Contains epiglottis (elastic cartilage covered by mucosa) which shuts off the trachea whenever food is swallowed. Contains vocal cords
What type of cells make up the larynx?
a. stratified squamous epithelium
b. ciliated pseudostratified columnar epithelium
c. both
d. none
C. Both. Superior is stratified squamous epithelium, inferior ciliated pseudostratified columnar epithelium with goblet cells.
T or F? Trachea contains the vocal cords.
False.
Which of the following is not true of the trachea?
a. Contains C-shaped incomplete rings of cartilage allows flexibility without collapsing
b. smooth muscle controlled by ANS can change diameter for coughing reflex/ decrease H2O loss
c. composed of pseudostratified and goblets
d. all of the above
e. none of the above
d. all of the above.
What is the final part of the conducting zone?
Bronchi
Which fact is not true about the Bronchioles
a. each primary bronchus divides ~x23 to give many bronchioles ~1mm diameter
b. contains incomplete rings of cartilage
c. smaller bronchioles have no cartilage and can collapse
d. lot of elastic tissue which contributes to lung compliance
e. smaller bronchioles composed of simple columnar: cleaning now by macrophages
f. smooth muscle controlled by ANS
b. bronchi/bronchioles are similar to the trachea but as the diameter of the airways decreases, the incomplete rings of cartilage are replaced by irregular plates of cartilage and by the time they become the smallest bronchioles there is no cartilage: elastic connective tissue is present throughout and this is very important as it contributes to the compliance of the lungs.
We have ~3 x 108 alveoli total giving ↑surface area, why is this important?
To maximize diffusion. Alveoli composed of simple squamous epithelium (Type 1 cells; optimized for diffusion)
T or F? Alveoli are totally covered with pulmonary capillaries: endothelium and alveolar epithelium basement membranes fused to minimize diffusion distance
True
Specialized cuboidal cells (Type 2) scattered throughout alveoli produce surface tension reducing detergent called ______
Surfactant
What would happen if no surfactant produced?
Decrease surface tension which would collapse the thin delicate alveoli
Why is it important that the aveoli are connected by poors?
To equalize pressure and gas access for obstructive conditions
What are 2 important functions of the pleurae?
- Pleural cavity and is filled with a lubricating fluid which allows near frictionless movement of the lungs as they inflate and deflate.
- Linking the lungs to the thoracic wall: this is vital as it prevents the alveoli from collapsing.
