Lab #14 - Respiratory System Mechanics Flashcards
What does pulmonary ventilation consist of?
inspiration and expiration
How is pulmonary ventilation achieved?
increasing/decreasing volumes of thorax and lungs
Describe how volume and pressure are related to one another
inversely related
⬆vol = ⬇pressure
⬇vol = ⬆pressure
Expiration is due to __________ __________ of alveolus
passive recoil
Inspiration occurs mainly because diaphragm _______, ________ thoracic volume verticaly
contracts
increasing
Which muscles contract during inspiration?
diaphragm
external intercostals (raise ribs)
(+ parasternal intercostal; raise ribs)
What muscles contract during expiration?
internal intercostals
Know the values for atmospheric, intrapulmonary, and intrapleural pressures when at rest, inspiration, and expiraiton
atmospheric: 760 mmHg (for all; constant)
intrapulmonary:
at rest: 760
inspiration: 757
expiration: 763
intrapleural:
at rest: 756
inspiraiton: 754
expiraiton: 757
Pulmonary function is assessed by spirometry. What is spirometry?
a method that measures volume of air moved during inspiration and expiration
What is anatomical dead space?
air in conducting zone where no gas exchange occurs
What is tidal volume (TV)? What is the average amount?
amount of air inspired or expired per breath in quiet breathing
500mL
What is vital capacity?
amount of air that can be forcefully exhaled after maximum inhalation
(note: cannot empty lungs completely)
What is IRV?
amount that you can forefully inhale above TV
What is ERV?
amount that you can forcefully exhale below TV
What is RV?
amount that cannot be exhaled
(because lungs cannot be emptied completely)
Know where to label TV, IRV, ERV, RV, and vital capacity on a graph
check slide #8 on slides
automatic breathing is influenced by activity of _________ which are located in the ________ __________
chemoreceptors
medulla oblongata
What do chemoreceptors monitor? What do they directly sense?
monitor PCO2, PO2, and pH
sense H+ concentration (changes)
Chemoreceptors __________ ventilation to maintain normal _____, _______, and _______ levels
modify
CO2
O2
pH
_____ is most crucial because of its effects on blood _____
PCO2
pH
Ventilation is modified by chemoreceptors to maintain a constant…
PCO2 of 40 mmHg
What type of control is breathing under?
autonomic and conscious control
The rate and volume of breathing is homeostatically regulated by what? What are the functions?
hypothalamus: determines set point
pons
medulla oblongata
^ both keep breathing at setpoint via neg. feedback
Under what condition was our lab partner able to hold their breath the longest? Why?
after hyperventilation because they are expelling lots of CO2, which is gonna decrease PCO2 levels in the body, which decreases H+ ions. This means the person can hold their breath for a longer period of time because they have very low concentrations of H+. When holding their breath, it will take a longer time until H+ accumulates and chemoreceptors sense this and signal for pulmonary ventilation to begin
Under what condition was it hardest for our lab partner to hold their breath? Why?
after exercise (or after hypoventilation) because during exercise, your body is undergoing a lot of aerobic cellular respiration, creating a lot of CO2 as a waste product. This increases PCO2 levels in the body, which increases H+ ions. This means that the person will not be able to hold their breath long because they already have a high concentration of H+ ions, which will quickly stimulate chemoreceptors in the medulla oblongata to begin pulmonary ventilation
