Human Physiology Unit 4B:
Respiratory Pt. I
Supplemental Instruction
Iowa State University
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Leader:
Course:
Instructor:
Date:
Paige Stieneke
BIOL 256
Dr. Karri Haen
April 3, 2013
(Inspiration, Expiration) is where air flows into the lungs, and (Inspiration, Expiration) is
where air flows out of the lungs
(Internal, External) respiration is gas exchange between capillaries and tissues, while
(Internal, External) respiration is gas exchange between the lungs and blood
Lung Cavities: Review visceral, parietal, mediastinum and pulmonary!
Pressure in the Lungs
a. Alveolar Pressure (Palv): Aka
Intrapulmonary Pressure, pressure inside
the alveoli
i.
Negative Respiratory Pressure:
Palv less than Patm  pulls air in
ii.
Positive Repiratory Pressure:
Palv greater than Patm  pushes air
out
b. Atmospheric Pressure (Patm): Pressure outside the alveoli, exerted by air surrounding
the alveoli
c. Intrapleural Pressure (Pip): Pressure in the pleural cavity, always (less, greater) than
alveolar pressure and atmospheric pressure
d. Transpulmonary Pressure: Difference between Palv and Pip  keeps airways open due to
(low, high) Pip
Factors influencing Ventilation
1. Airway Resistance
a. Friction: Major source of resistance
2. Alveolar Surface Tension
a. Surface Tension: Attraction of liquid molecules to one another
i.
Wants to reduce alveoli to smallest possible size
b. Surfactant: Reduces surface tension to keep alveoli open
c. Which types of cells produce surfactant? Type II Alveolar Cells
3. Lung Compliance
a. Lung Compliance: Ease of lung expansion
b. Four main factors diminish lung compliance: Fibrosis, blockage, reduced surfactant,
decreased thoracic cage flexibility
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
Respiratory Volumes
1. What do we use to measure lung volumes? Spirometers
2. What two disorders can spirometers be used to distinguish?
a. Obstructive Pulmonary Disease: Increased air resistance (COPD, asthma)
b. Restrictive Disorders: Reduced compliance and decreased lung volume (lung
fibrosis, asbestos exposure)
Term
Tidal Volume (TV)
Inspiratory Reserve Volume (IRV)
Expiratory Reserve Volume (ERV)
Residual Volume (RV)
Inspiratory Capacity (IC)
Functional Residual Capacity (FRC)
Vital Capacity
Total Lung Capacity
Definition
Air moving in/out of the lungs with normal breathing
Amount of air that can be completely inspired past TV
Amount of air that can be completely expired past TV
Air left in lungs after strenuous expiration, cannot be
measured by spirometry
The total amount of air that can be inspired after a tidal
expiration
IC = IRV + TV
The total amount of air that is left after a tidal expiration
FRC = ERV + RV
The total amount of exchangeable air
VC = IRV + TV + ERV
Sum of all lung volumes
TLC = IRV + TV+ ERV + RV
What is an anatomical dead space? Volume of conducting respiratory passages such as
the mouth and trachea
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu