Lung Structure and Function

Question 1

pulmonary disease

Answer 1

• COPD is 4th leading cause of death in the US

- pneumonia and flu 7th

Question 2

ventilation

Answer 2

• flow of air into and out of the lungs
• Vdot=f x TV
• f is frequency of breathing (breaths/min)
• TV is tidal volume (L/breath)
• delivers oxygen in from atm and tissues
• use oxygen to produce ATP
• need continuous supply

Question 3

spirometer

Answer 3

• measures ventilation
• typical is 7.5 L/min
• can rise over 15X to as much as 120 L/min
• collecting expired gas for 1 min or measuring tidal volume for 1 min
• spirometer has floating inverted drum and is attached to a pen
• measures volume and volume vs time gives flow

Question 4

ATPS

Answer 4

• ambient temp and pressure, saturated

- 25 C, 760 mm Hg, 24 mm Hg

Question 5

BTPS

Answer 5

• body temp and pressure, saturated

- 37 C, 760 mm Hg, 47 mm Hg

Question 6

STPD

Answer 6

• standard temp and pressure, dry
• 0 C, 760 mm Hg, 0 mmHg
• convert from ATPS to STPD for o2 consumption and Co2 production rates
• convert from ATPS to BTPS for lung volumes

Question 7

ideal gas law

Answer 7

PV= nRT

Question 8

boyle’s law

Answer 8

P= k/V

Question 9

charles’s law

Answer 9

V=kT

Question 10

gay-Lussac’s law

Answer 10

P=kT

Question 11

gas volume corrections

Answer 11

• ideal gas law is for dry gas
• PV=nRT
• PV/T=nR=constant
• so PLVL/TL= PspVsp/Tsp
• must correct pressures for water vapor pressure (24 for spirometer, 47 for lungs)
• can find ratio of volumes
• V in lungs is 1.07XVsp- 7% increase

Question 12

water vapor pressure

Answer 12

• function of temperature, constant at a given temo

- body at 37 is 47 mm Hg

Question 13

conductive zone of lungs

Answer 13

• first 16 branches (4 bifurcations)
• trachea
• bronchi
• bronchioles
• terminal bronchioles
• no gas exchange
• anatomic dead space (150 ml, 1 ml/lb of body weight)
• ciliated surface propels mucous secreted by goblet cells

Question 14

respiratory zone

Answer 14

• last 7 branches
• respiratory bronchioles
• alveolar ducts
• alveolar sacs
• 23 branches lead to 300 million alveoli, each of which is 250 microns in diameter and covered with about 1000 pulmonary caps

Question 15

structures and functions within the respiratory system

Answer 15

• ventilatory apparatus-conductive zone
• pulmonary gas exchanger-alveoli
• pulmonary circulatory system
• tissue gas exchanger

Question 16

respiratory zone 2

Answer 16

• gas exchange
• type I alveolar cells line alveoli
• type II secrete surfactant, lipoprotein containing DPPC

Question 17

surfactant

Answer 17

• from type II
• lipoprotein with DPPC
• coats alveoli
• lowers their surface tension, easier to inhale
• increases mechanical stability of lung

Question 18

alveolar cross sectional area

Answer 18

• trachea is 2 cm2
• alveoli is 70 m2
• area increases and velocity decreases, Q remains same
• diffusion rather than flow carries gas
• permits equilibrium of alveolar gas with blood

Question 19

movement of o2 from alveoli

Answer 19

• crosses surfactant covered alveolar epithelium
• alveolar interstitial space
• cap endo
• plasma
• RBC PM
• combines with hemoglobin

Question 20

composition of air

Answer 20

• 78% nitrogen
• 21% oxygen
• 0.03% carbon dioxide
• 1% argon

Question 21

gas fraction

Answer 21

• Fi=ni/nt
• Fn=nN/nt
• moles of nitrogen over total moles

Question 22

partial pressure

Answer 22

• from ideal gas law for dry gases
• Pt=nRT/V
• Pi=niRT/V
• Pt=sumPi
• Partial pressure for dry gas- FiPt (fraction times pressure- 0.21 fraction oxygen times total pressure)
• for wet gas
• Pi=F(Pt-PH2O) (Pwater is 47)

Question 23

solubility

Answer 23

• henry’s law
• [cg]=aPi
• dissolved gases don’t contribute to blood volume or blood pressure
• partial pressure of a gas in solution equals the partial pressure of the gas with which the solution has equilibrated (po2 in alveoli is 100, therefore it is 100 in blood)
• partial pressure of a gas in solution refers only to dissolved gas

Question 24

summaries

Answer 24

-see picture and draw out!