PHYSIOLOGY

Question 1

What are the muscles of inspiration?

Answer 1

diphragm, external intercostals

Question 2

what are the muscles of inspiration?

Answer 2

normally passive, but can also include abdominal muscles (compress abd. cavity) and internal intercostals

Question 3

define compliance

Answer 3

changes in lung volume for a change in lung pressure

Question 4

what is elastance?

Answer 4

the greater the amount of elastic tissue, the greater the tendency to snap back with elastic recoil force, and lower the compliance

Question 5

what is hysteresis?

Answer 5

when there is a difference in the slopes of inspiration and expiration on a pressure-volume loop. (explains why there is a difference in compliance for inspir. vs. expir.)

Question 6

how do surfactants work

Answer 6

they reduce the surface tension by reducing the collapsing pressure of an alveoli for a given radius (keeps small alveoli open)
-also increases lung compliance

Question 7

what is atelectasis

Answer 7

collapse of alveoli

Question 8

what is the most important constituent of surfactant?

Answer 8

DPPC (dipalmitoyl phosphatidylcholine)

Question 9

why is there constantly a negative intrapleural pressure?

Answer 9

the lung wants to collapse and the chest wall is trying to expand

Question 10

what is one test you can do to determine the difference between obstructive and restrictive disease?

Answer 10

peak flow, the peak flow for obstructive diseases is reduced (problem in getting air out), and the peak flow for restrictive diseases should be normal flow but with less volume

Question 11

what is interdependence

Answer 11

Individual alveoli are prevented from collapsing by the structure of other alveoli holding them open

Question 12

what 2 things determine lung compliance?

Answer 12

1. tissue properties

2. surface forces

Question 13

what is the name of the organelles in type 2 pneumonocytes that store surfactant?

Answer 13

lamellar bodies

Question 14

what is the respiratory quotient and what is the normal value?

Answer 14

production of CO2/O2 consumed

normally 0.8

Question 15

Dalton’s law

Answer 15

in a mixture of gases the pressure exerted by each gas in independent of the pressure exerted by the other gases

Question 16

henry’s law

Answer 16

relates the concentration of gas in solution to partial pressure (amount dissolved= partial pressure x solubility)

Question 17

fick’s law

Answer 17

volume flux = SA x (1/thickness) x diffusion constant x concentration difference

Question 18

If CO2 production is constant then PACO2 is determined by _______________

Answer 18

alveolar ventilation

Question 19

define hypoxemia

Answer 19

lower than normal PO2

Question 20

define A-a gradient

Answer 20

difference b/w PAO2 and PaO2, measure of whether O2 has equilibrated b/w alveolar gas and pulmonary capillary blood

Question 21

define hypoxia

Answer 21

decrease O2 delivery to or utilization by the tissues

Question 22

define hypercapnia

Answer 22

higher than normal arterial PCO2 (most often due to low alveolar ventilation

Question 23

why does the Oxygen-HGB dissociation curve have a sigmoid shape?

Answer 23

because of the positive cooperativity

Question 24

what is the P50

Answer 24

the pressure of oxygen at which HGB is 50% saturated

Question 25

what 4 things cause a right shift for hemoglobin?

Answer 25

decrease pH
increase in PCO2
increase in temperature
increase 2,3-BPG

Question 26

what 5 things can cause a left shift of HGB?

Answer 26

increase pH
decreased CO2
decreased temperature
decreased 2,3-BPG
HbF

Question 27

Bohr effect

Answer 27

explains how increase in CO2 and decrease pH cause right shift on Oxygen dissociation curve

Question 28

what is Hamburger’s phenomenon?

Answer 28

when bicarbonate diffuses into plasma, leaves a decrease in net negative charge compensated by Cl- movement into cell causing the cell to swell

Question 29

what is the name of the protein that drives the chloride shift?

Answer 29

band 3 protein

Question 30

what has a bigger role in CO2 excretion the lungs or the kidneys, and why?

Answer 30

the lungs, they excrete 10,000 mEq/day compared to kidney 100 mEq/day

Question 31

Lung arteries and arterioles constrict in response to what?

Answer 31

1. hypoxia

2. hypercapnia and acidosis