1. Respiratory Anatomy Respiratory Physiology Vital Capacity
Bio212
Laboratory 6
Respiratory Anatomy Respiratory Physiology Vital Capacity

2. Objectives for today’s lab
Define respiratory volumes and capacities and solve for an unknown volume or capacity
Describe how CO2 levels influence breathing rate and depth
Perform simple spirometry measurements and record/calculate your own respiratory parameters

3. Carbon dioxide can travel in several ways
CO2 and HCO3-
Carbon dioxide can travel in several ways
Dissolved in plasma (7%)
As carbaminohemoglobin (15-25%)
As HCO3- ion (70%)
Carbonic anhydrase in RBCs accelerates interconversion between CO2 and HCO3-
H+ combines with or dissociates from Hb
HCO3- diffuses into plasma or into RBCs
Cl- diffuses into RBC (chloride shift) as HCO3- exits
Diffusion of CO2 is related to PCO2 in alveoli and tissues

4. Control of Breathing
Rate of breathing is affected by several control centers
Central chemoreceptors in the medulla
Peripheral chemoreceptors in aortic and carotid bodies
Largely dependent upon [H+]
The most powerful respiratory stimulant is CO2
Normal, rhythmic breathing – dorsal respiratory group
The respiratory membrane
Simple squamous epithelium of the alveoli and capillaries
Basement membrane between them
Terms used to describe breathing (know these)

5. Hypoxia and Hyperventilation
Hypoxia is a low level of oxygen in the tissues
Hypoxic hypoxia (e.g., high altitude)
Histotoxic hypoxia (e.g., alcohol, CN-)
Stagnant (ischemic) hypoxia (e.g., cardiovascular problems)
Hypemic hypoxia (e.g., CO poisoning)
Hyperventilation is a rapid breathing that causes loss of excessive amounts of CO2 to be blown off (we will do this today…)

6. CO2 and Respiratory Demand
Note that with normal respiration, CO2 levels will stimulate breathing well before decreasing levels of O2 result in hypoxic effects
Compare this with stimulation of breathing after hyperventilation
(after holding breath)
Figure from: Martini & Welch, “A&P Applications Manual”, Benjamin Cummings, 2006

7. Respiratory Rates and Volumes
Number of breaths per minute
Resting adult: bpm
Resting child: bpm
Respiratory cycle = 1 inspiration followed by 1 expiration (part of ventilation)

8. Respiratory Volumes
Volumes of air moved in and out of the lungs. These are measured by spirometry using a spirometer.
tidal volume – volume moved in or out during a normal (eupneic) breath ( 500 ml)
inspiratory reserve volume – additional volume that can be inhaled following a normal inhalation ( 3.0 L/1.9L)
expiratory reserve volume – additional volume that can be exhaled following a normal exhalation ( 1.1 L/0.7 L)
residual volume – volume that remains in lungs at all times ( 1.2 L) ** Cannot be removed during life

9. Respiratory Volumes and Capacities
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

10. Respiratory Capacities
Note that capacities are derived (calculated) from volumes (which can be measured by spirometry)
inspiratory capacity = TV + IRV
functional residual capacity = ERV + RV
vital capacity = TV + IRV + ERV
total lung capacity = VC + RV
How would you express these capacities in words? (See you lab guide handout for some help…)
Know these for the lab exam

11. Respiratory Volumes and Capacities
IC = TV + IRV
FRC = ERV + RV
VC = TV + IRV + ERV
TLC = VC + RV
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

12. Tabular Method of Calculating Volumes/Capacities
Standard Lung Volumes and Capacities (See your Laboratory Guide, “Alveolar Ventilation” from Levitzky)
TLC = 6.0 L
IC = 3.0 L
IRV = 2.5 L
VC = 4.5 L
TV = 0.5 L
FRC = 3.0 L
ERV = 1.5L
RV = 1.5 L
IC = TV + IRV FRC = ERV + RV VC = TV + IRV + ERV TLC = VC + RV

13. Tabular Method of Calculating Volumes/Capacities
Example of how to use the Standard Lung Volume and Capacity Table to Solve for unknown lung volumes/capacities
Problem: Given the values in the table below, solve for the RV
TLC = 6.2L
IC = ?
IRV = ?
VC = 5.1L
TV = ?
FRC = ?
ERV = 1.7L
(Solve for this)
RV = ?

14. Sample problem using equations…
The vital capacity = 6000 ml, tidal volume = 500 ml, and expiratory reserve volume = 1000 ml. What is the inspiratory capacity (IC)?
Equations…
VC = TV + IRV + ERV IC = TV + IRV 6.0L 0.5L ? L ? L ?
Solution…
VC = TV IRV + ERV IRV = VC – TV – ERV .06L = 0.5L ? L ? L – 0.5L – 1.0L
IC = TV IRV ? = 0.5L L IC = 5.0L

15. Sample Problem Using Tabular Method
The vital capacity = 6000 ml, tidal volume = 500 ml, and expiratory reserve volume = 1000 ml. What is the inspiratory capacity (IC)?
TLC = ?
IC = ?
IRV = ?
VC = 6.0L
TV = 0.5L
FRC = ?
ERV = 1.0L
RV = ?

16. Minute and Alveolar Ventilation
minute ventilation (volume)
tidal volume (TV) multiplied by breathing rate
amount of air that is moved into/out of the respiratory passageways each minute
typically about 6 L/min
alveolar ventilation
major factor affecting concentrations of oxygen and carbon dioxide in the alveoli
volume of air that reaches alveoli – always less than minute ventilation
tidal volume minus anatomic dead space then multiplied by breathing rate
about 4.2 L/min
Alveolar ventilation = breaths/min x (TV – Dead space)

17. Review A respiratory cycle consists of 1 inspiration and 1 expiration
Spirometry is used to measure the different volumes of air in the lungs
Tidal Volume
Inspiratory Reserve Volume
Expiratory Reserve Volume
Residual Volume

18. Capacities are quantities derived from volumes
Review
Capacities are quantities derived from volumes
Vital capacity (what does this actually mean in words?)
Inspiratory capacity
Functional residual Capacity
Total lung capacity
Ventilation (quantity of air moved per minute)
Minute ventilation
Alveolar ventilation
Always less than minute ventilation
Takes anatomical dead space into account
Specific terms dealing with rates of breathing

19. Respiratory Lab Today
Record and analyze your own respiratory parameters; complete Laboratory Report 46 (p. 369)
Do Exercise 47 (use the instructions I handed out) and then complete Laboratory Report 47 (p. 375)
Hand in Laboratory Report 46 (with the Respiratory Parameters Table) and Laboratory Report 47
Look at the structures listed in your Laboratory Guide for the respiratory system and be able to recognize them