Exam 2 Review-Respiratory System Flashcards
Discuss the pathway taken by:
(a) inspired air to the alveoli
(b) expired air from the alveoli
Tip: “No People Like To Be At All”
a. Air flows from the atmosphere –> alveoli in lungs
b. Air flows from alveoli in lungs–> atmosphere
Tip: Nasal cavity
Pharynx
Larynx
Trachea
Bronchi
Abronchioles
Alveoli
Expiration Pathway (Expired air from alveoli) → Same path, reversed!
Explain this statement, “Swallowed substances have the right of way to air movement”
Analogy: “Traffic Merge at a Toll Booth”
This statement highlights how the body prioritizes the safe passage of food and liquids into the esophagus by momentarily closing off the airway, ensuring substances don’t interfere with air movement into the lungs.
Think of your pharynx as a highway with two lanes: one for air (trachea) and one for food (esophagus).
The epiglottis acts like a toll gate that closes the air lane when swallowing, making sure food goes down the esophagus and not the trachea.
Define Atmospheric pressure (Patm)
Atmospheric pressure exterted by atmospheric air
Define Intraalveolar pressure (Palv)
Pressure of air in alveoli (aka intrapulmonary pressure)
Define intrapleural pressure (Pip)
Pressure inside pleural sac
Define Transpulmonary pressure (Ptran)
Distending pressure across the lung wall
Is the Pip negative or positive during inspiration?
Pip is always negative
Is the Pip negative or positive during expiration?
Pip is always negative
What is pneumothorax?
Analogy: “Balloon with a Leak”
If the sealed pleural cavity is opened to the atmosphere, air flows in. The bond holding the lung to the chest wall is broken, and the lung collapses, creating a pneumothorax(air in the thorax)
If air enters (from injury or disease), Pip = Patm, and the lung collapses like a deflating balloon.
Describe in detail how
(a) normal/quiet inspiration occurs
(b) normal/quiet expiration occurs.
Inspiration: “D.I.E”
a. Quiet inspiration is the passive, automatic process of drawing air into the lungs during normal breathing. It primarily involves the contraction of the diaphragm and external intercostal muscles, leading to an increase in thoracic volume and a decrease in intrapulmonary pressure.
b. Quiet expiration is the passive process of expelling air from the lungs during normal breathing. Unlike inspiration, it does not require muscle contraction; instead, it relies on the elastic recoil of the lungs and relaxation of inspiratory muscles to decrease thoracic volume and increase pressure, pushing air out.
Normal Inspiration → “D.I.E.”
Diaphragm contracts
Intercostals (external) lift ribs
Expansion lowers pressure
Normal Expiration → Passive, just relax muscles
Name the accessory skeletal muscles employed in:
(a) deep inspiration
(b) forced expiration
Deep Inspiration: “Some Scared People Say”
Forced Expiration: “I.T. Abs”
a. Alongside the diaphragm and external intercostals, the sternocleidomastoid, scalenes, ectoralis minor
b. Forced expiration is an active process involving muscle
contractions: internal intercostal muscles, abdominal muscle, quadratus lumborum
Deep Inspiration:
Scalenes
Sternocleidomastoid
Pectoralis minor
Serratus anterior
Forced Expiration:
Internal intercostals
Transversus abdominis
Abs (Rectus and Obliques)
Discuss factors that affect pulmonary ventilation. Is compliance important during
expiration or inspiration? Explain your answer
Hint: “C.S.A.R”
Pulmonary ventilation is breathing and gas exchange between atmospheric air and alveolar air in the lungs.
In short, compliance is most crucial for inspiration because it affects how easily the lungs can fill with air.
C.S.A.R=Control System At Respiration
Compliance (Lung stretchability)
Surface tension (Surfactant reduces this)
Airway resistance (Affected by bronchodilation/constriction)
Respiratory muscle strength
How is spirometry used to differentiate between Obstructive pulmonary disease and Restrictive pulmonary disease?
Spirometry helps doctors identify whether the issue is airway obstruction (obstructive disease) or reduced lung expansion (restrictive disease).
Will musculoskeletal deformities cause obstructive pulmonary disease and restrictive pulmonary disease? Explain
Analogy: “Blocked Pipe vs. Stiff Balloon”
Obstructive → “Pipe is clogged” → Airflow blocked (COPD, Asthma)
Restrictive → “Balloon is stiff” → Lungs can’t expand (Fibrosis, Scoliosis)
Will decrease in surfactant levels cause obstructive pulmonary disease and restrictive pulmonary disease? Explain
Musculoskeletal deformities can cause restrictive pulmonary disease by limiting lung expansion or chest wall movement.
They are unlikely to cause obstructive pulmonary disease, as this type of disease is caused by airway blockages, not issues with lung expansion or chest wall movement.
Describe the respiratory membrane. What is the function of the respiratory membrane?
Air-Blood Barrier
The respiratory membrane is extremely thin (about 0.2 to 0.5 micrometers) to allow efficient gas exchange. The large surface area of the alveoli (due to their many tiny sacs) and the thinness of the respiratory membrane optimize the exchange of gases between the air and blood.
Discuss the factors that affect external gas exchange.
Analogy: “Thin Fence vs. Thick Wall”
“S.A.T.”
Surface area (more = better exchange)
Alveolar size (too big = poor diffusion)
Thickness (thicker membrane = slower exchange)
A thin fence lets things move across easily (healthy lungs).
A thick brick wall (thickened alveolar walls) slows gas exchange (disease).
Explain how gas exchange is affected when alveolar size increases due to breakdown of alveolar walls.
when alveolar size increases due to the breakdown of alveolar walls, it reduces the surface area available for gas exchange, increases the distance gases must diffuse, and leads to ventilation-perfusion mismatches. These changes decrease the efficiency of oxygen and carbon dioxide exchange, resulting in lower oxygen levels in the blood and potentially higher carbon dioxide levels, which can lead to symptoms like shortness of breath, fatigue, and low oxygen saturation.
How is gas exchange affected when the thickness of the respiratory membrane increases?
When the thickness of the respiratory membrane increases, the rate of gas exchange decreases because the distance for gases to diffuse is longer. This leads to reduced oxygen absorption into the blood and less efficient carbon dioxide removal. As a result, individuals may experience hypoxemia (low blood oxygen levels) and an increased effort in breathing. Conditions such as pulmonary edema, fibrosis, and pneumonia can contribute to this thickening of the respiratory membrane.
Explain two factors that contribute to the lower PO2 in alveolar air (105 mmHg) than partial pressure of oxygen (PO2) in dry atmospheric air at sea level (159 mmHg).
Acronym: “WHR”
Humidification of inspired air reduces the partial pressure of oxygen in the alveoli.
The mixing of inspired air with the air already in the alveoli (which has already been partially depleted of oxygen) also lowers the PO₂ in the alveolar air. These two factors contribute to the lower PO₂ in alveolar air (105 mmHg) compared to dry atmospheric air (159 mmHg).
(Why It’s Lower)
Water vapor (humidification)
High CO2 (dilutes O2)
Rapid gas exchange
Define:
- Minute ventilation rate (MVR)
Volume of air inhaled or exhaled in a minute
Define: Alveolar ventilation rate (AVR)
Volume of fresh air reaching the alveoli in the lungs in a minute
Define: Dead space volume (DSV)
dead space volume is the air in the lungs that does not contribute to the exchange of gases between the lungs and the bloodstream.
What is hypoventilation? Explain how hypoventilation affects blood pH
Analogy: “Holding Breath vs. Panicking”
a. Hypoventilation is a condition where a person breathes at an abnormally slow rate or with insufficient depth, leading to inadequate ventilation of the lungs
b. hypoventilation leads to an accumulation of CO2, which increases the acidity of the blood and lowers its pH, causing respiratory acidosis.
Holding breath = CO2 buildup = Acidic (Hypoventilation)
