ventilation of lungs

Question 1

What is movement of air dependent on?

Answer 1

pressure difference between atmospher and spaces inside lungs

Question 2

Intrapleural pressure

Answer 2

air pressure in the pleual cavity

Question 3

intrapulmonary pressure

Answer 3

air pressure within the alveoli

Question 4

What does Boyles law say about pressure and volume?

Answer 4

Boyles law states that pressure and volume are INVERSELY related

increase volume=decrease pressure
decrease volume=increase pressure

Question 5

Inspiration

*when does it occur
*whats happening with pressure

Answer 5

-occurs when diaphragm and external intercostals contract, which INCREASES volume of thoracic cavitiy (because wall is moving down)

-During inspiration, intrapleural pressure decreases which also drops the intrapulmonary pressure

-Atmospheric air pressure in higher than intrapleural and intrapulmonary pressure, which causes a vaccum inside the lungs which sucks air in

Question 6

Expiration

*when does it occur
*whats happening with pressure

Answer 6

-the elastic nature of lungs, relaxation of diaphragm, and possible contraction of interal intercostals decrease volume of thoracic cavity

-intrapleual and intrapulmonary pressure INCREASE

-atmospheric pressure is lower than intrapleual and intrapulmonary pressure and air gets forced out of lungs (bye bye CO2)

Question 7

inspired air make up

Answer 7

N2= 79%
O2=20.9%
CO2=0.03%
H20= whatever is left (.5%)

Question 8

expired air make up

Answer 8

N2= 75%
O2=15%
CO2=4%
H20= whatever is left (6%)

Question 9

inspired air pressure

Answer 9

PIO2= 150 mmhg
PICO2= 0 mmhg

Question 10

Alveolar blood pressure

Answer 10

PAO2=102 mmHg
PACO2= 40 mmHg

Question 11

Arterial blood pressure

Answer 11

PaO2=102 mmHg
PaCO2=40 mmHg

Question 12

Mixed venous blood pressure

Answer 12

PvO2= 40 mmHg
PvCO2=46mmHg