By Nerea Campillo
Lung Physiology
Medical Physiology1: Chapters 39-42
These notes are not a complete summary of the chapter but a list of few noteworthy facts. See down
below for complete summaries.
Chapter 38: Pulmonary Ventilation
● External intercostal muscles: raise rib cage
Internal intercostal muscles + abdominal recti: lower rib cage
● Normal pleural pressures:
○ Begin inspiration: -5 cmH2O
○ End inspiration: -7.5 cmH2O
● Transpulmonary pressure = alveolar pressure - pleural pressure.
● Surfactant causes: decrease in alveolar surface tension → increase in
compliance → decrease in work of breathing.
● Tidal Volume (tV) = 500 mL
Inspiratory Reserve Volume = IRV = 3000 mL
Expiratory Reserve Volume = ERV = 1100 mL
Residual Volume = RV = 1200 mL
● Minute respiratory volume = Vt x respiratory rate = 6 L/min
● Normal dead space volume = 150 mL
Chapter 39: Pulmonary Circulation
● Bronchial blood supply empties into the pulmonary veins. It supplies the connective
tissue, septa and bronchi.
● Mean pulmonary arterial pressure (mean PAP) = 15 mmHg
● Blood distribution in the lungs: decreased O2 in alveoli → vasoconstriction
→ blood redirected to better ventilated areas
● During exercise:
○ Opening more lung capillaries
○ Distending lung capillaries
→ decrease in pulmonary vascular resistance + increased blood flow = no/
little increase in pulmonary arterial pressure.
● There is a continuous loss of fluid from the pulmonary capillaries into the pulmonary
interstitium. Mean filtration pressure = +1 mmHg
● Causes of pulmonary edema (fluid in alveoli):
○ Damming of blood in lungs
■ Left heart failure
■ Mitral stenosis
■ Mitral insufficiency
○ Damage to pulmonary capillary membrane
Chapter 40: Gas Exchange
● Vapor pressure of water at body temperature = 47 mmHg
● Increased diffusion capacity of O2 during exercise due to:
○ Increased surface area (opening up of capillaries)
○ Improved Va/Q
1
Textbook of Medical Physiology - Guyton & Hall, 13th edition
Lung Physiology
Medical Physiology1: Chapters 39-42
These notes are not a complete summary of the chapter but a list of few noteworthy facts. See down
below for complete summaries.
Chapter 38: Pulmonary Ventilation
● External intercostal muscles: raise rib cage
Internal intercostal muscles + abdominal recti: lower rib cage
● Normal pleural pressures:
○ Begin inspiration: -5 cmH2O
○ End inspiration: -7.5 cmH2O
● Transpulmonary pressure = alveolar pressure - pleural pressure.
● Surfactant causes: decrease in alveolar surface tension → increase in
compliance → decrease in work of breathing.
● Tidal Volume (tV) = 500 mL
Inspiratory Reserve Volume = IRV = 3000 mL
Expiratory Reserve Volume = ERV = 1100 mL
Residual Volume = RV = 1200 mL
● Minute respiratory volume = Vt x respiratory rate = 6 L/min
● Normal dead space volume = 150 mL
Chapter 39: Pulmonary Circulation
● Bronchial blood supply empties into the pulmonary veins. It supplies the connective
tissue, septa and bronchi.
● Mean pulmonary arterial pressure (mean PAP) = 15 mmHg
● Blood distribution in the lungs: decreased O2 in alveoli → vasoconstriction
→ blood redirected to better ventilated areas
● During exercise:
○ Opening more lung capillaries
○ Distending lung capillaries
→ decrease in pulmonary vascular resistance + increased blood flow = no/
little increase in pulmonary arterial pressure.
● There is a continuous loss of fluid from the pulmonary capillaries into the pulmonary
interstitium. Mean filtration pressure = +1 mmHg
● Causes of pulmonary edema (fluid in alveoli):
○ Damming of blood in lungs
■ Left heart failure
■ Mitral stenosis
■ Mitral insufficiency
○ Damage to pulmonary capillary membrane
Chapter 40: Gas Exchange
● Vapor pressure of water at body temperature = 47 mmHg
● Increased diffusion capacity of O2 during exercise due to:
○ Increased surface area (opening up of capillaries)
○ Improved Va/Q
1
Textbook of Medical Physiology - Guyton & Hall, 13th edition
