Lab #14 - Respiratory System Mechanics

Question 1

What does pulmonary ventilation consist of?

Answer 1

inspiration and expiration

Question 2

How is pulmonary ventilation achieved?

Answer 2

increasing/decreasing volumes of thorax and lungs

Question 3

Describe how volume and pressure are related to one another

Answer 3

inversely related

⬆vol = ⬇pressure
⬇vol = ⬆pressure

Question 4

Expiration is due to __________ __________ of alveolus

Answer 4

passive recoil

Question 5

Inspiration occurs mainly because diaphragm _______, ________ thoracic volume verticaly

Answer 5

contracts
increasing

Question 6

Which muscles contract during inspiration?

Answer 6

diaphragm
external intercostals (raise ribs)

(+ parasternal intercostal; raise ribs)

Question 7

What muscles contract during expiration?

Answer 7

internal intercostals

Question 8

Know the values for atmospheric, intrapulmonary, and intrapleural pressures when at rest, inspiration, and expiraiton

Answer 8

atmospheric: 760 mmHg (for all; constant)

intrapulmonary:
at rest: 760
inspiration: 757
expiration: 763

intrapleural:
at rest: 756
inspiraiton: 754
expiraiton: 757

Question 9

Pulmonary function is assessed by spirometry. What is spirometry?

Answer 9

a method that measures volume of air moved during inspiration and expiration

Question 10

What is anatomical dead space?

Answer 10

air in conducting zone where no gas exchange occurs

Question 11

What is tidal volume (TV)? What is the average amount?

Answer 11

amount of air inspired or expired per breath in quiet breathing

500mL

Question 12

What is vital capacity?

Answer 12

amount of air that can be forcefully exhaled after maximum inhalation
(note: cannot empty lungs completely)

Question 13

What is IRV?

Answer 13

amount that you can forefully inhale above TV

Question 14

What is ERV?

Answer 14

amount that you can forcefully exhale below TV

Question 15

What is RV?

Answer 15

amount that cannot be exhaled

(because lungs cannot be emptied completely)

Question 16

Know where to label TV, IRV, ERV, RV, and vital capacity on a graph

Answer 16

check slide #8 on slides

Question 17

automatic breathing is influenced by activity of _________ which are located in the ________ __________

Answer 17

chemoreceptors
medulla oblongata

Question 18

What do chemoreceptors monitor? What do they directly sense?

Answer 18

monitor PCO2, PO2, and pH

sense H+ concentration (changes)

Question 19

Chemoreceptors __________ ventilation to maintain normal _____, _______, and _______ levels

Answer 19

modify
CO2
O2
pH

Question 20

_____ is most crucial because of its effects on blood _____

Answer 20

PCO2
pH

Question 21

Ventilation is modified by chemoreceptors to maintain a constant…

Answer 21

PCO2 of 40 mmHg

Question 22

What type of control is breathing under?

Answer 22

autonomic and conscious control

Question 23

The rate and volume of breathing is homeostatically regulated by what? What are the functions?

Answer 23

hypothalamus: determines set point

pons
medulla oblongata
^ both keep breathing at setpoint via neg. feedback

Question 24

Under what condition was our lab partner able to hold their breath the longest? Why?

Answer 24

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

Question 25

Under what condition was it hardest for our lab partner to hold their breath? Why?

Answer 25

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