quotes from rosens notes... chapter 8

Question 1

partial pressure defines

Answer 1

• it defines the diffusion of gas

- it allows comparisons of gas activities in both LIQUID and GASEOUS states

Question 2

henry’s law is?

describes ?

Answer 2

• relationship between partial pressure and the amout of gas in solution
• Concentration = solubility * partial pressure

Question 3

daltons law describes?

Answer 3

how the partial presures of multiple gasses collide with a container and make a final total pressure

Question 4

daltons law equation is?

Answer 4

{partial pressure of gas x} = {total pressure} * {% of gas in air}

Question 5

what is the not so obvious thing about daltons law?

Answer 5

• in lungs, you have to take into account the partial pressure of water.
• it contributes to the total gas pressure and (in the lungs) is 47 mmHg
• so, if total pressure is 760, water makes up 47 of that… the other 713 is the other gasses)

Question 6

diffusion rate of gasses is proportional to

Answer 6

*** trick… its INVERSELY proportional to the square root of MW
==> overweight gasses take longer to move

Question 7

diffusion rate of gasses in SOLUTION is proportional to

Answer 7

• again INVERSELY proportional to the square root of MW

- then multiply by the solubility

Question 8

compare and contrast diffusion rate of CO2 and O2 in solution

Answer 8

in solution, CO2 is 20 times faster than O2 because it is WAAAY more soluble (even though CO2 is heavier)

Question 9

Fick’s law

Answer 9

Kylie and I call this Dicks law
stress = (penis * radius) / (condom wall thickness)
he gives it different names, but it describes how much something presses on a membrane wall

Question 10

disease of fick’s law

Answer 10

hyaline membrane disease…. premature babies. remember positive pressure ventilator?

Question 11

how do gases move across membranes

Answer 11

capillary exchange ( has two parts, each with its own resisitance)
1- membrane resistance
2- chemical reaction resistance

Question 12

relationship between diffusion, conductance, and resistance

Answer 12

• diffusion is considered analogous to conductance

- conductance is the inverse of resistance

Question 13

what affects membrane resistance

Answer 13

• 1 / (membrane diffusion rate)

- affected by anything that changes the alveolar capillary interface or the erythrocyte membrane

Question 14

what affects chemical reaction resistance

Answer 14

• 1 / [(oxygen’s binding rate) * (capillary blood volume)]

- anything that change the affinity of O2 for Hb

Question 15

total diffussive resistance =

Answer 15

membrane resistance + chemical reaction resistance

** look at the equation… it looks hard but it isn’t

Question 16

what value duration of depends on % saturation of Hb? result?

Answer 16

• theta
• when Hb is saturated, theta (oxygen affinity) gets small and chemical resistance is the major contributor to overall resistance

Question 17

Compare gas exchange of CO2 and O2 in lungs

Answer 17

• diffusion may be 20 times faster for CO2, but the reaction rate for CO2 release is much slower

Question 18

how long does it take to exhcnge gas?

Answer 18

• in a normal lung exchanging CO2 for O2 takes about 250 ms

- a RBC is in the pulmonary capillary about 750 ms

Question 19

when you exercise, what does your lung do?

Answer 19

it shortens the transit time of a RBC in the capillary, but thats ok in a normal person because it does not reduce the final PO2

Question 20

what type of lung would have a hard time with exercise?

Answer 20

• one with an abmormal thickening of the blood-gas barrier (increase in membrane resistance)

Question 21

what woudl altitude do to PO2

Answer 21

• depends… if you are at rest, its ok

- if you are exercising, you will have a reduced PO2

Question 22

Lung diffusion capcity equation

Answer 22

D(L) = rate of diffusion / ((alvolar press. - capillary press.)

Question 23

what affects the lung diffusion capacity?

Answer 23

body size (small person, small #)
exercise (demand = big #)
thickened alvolar/capillary membrane (lower #)
decreased alveolar surface area (lower #)

Question 24

if you want to decrease the lung’s surface area?

Answer 24

collapse a lung!!

Question 25

normal pH? normal PO2? normal CO2? normal bicarb?

Answer 25

7.35-7.45 80-100 35-45 22-26

Question 26

pressure gradients exist to move O2 from?

Answer 26

inspired air ==> alveoli ==> systemic arterial blood ==> tissues

Question 27

anatomical shunting =

Answer 27

some of the blood bypasses pulmonary capillaries and does not contribute to gas exchange (thebesian circulation)

Question 28

what is the effect of anatomical shunting?

Answer 28

anatomical abnormalities will increase shunting, and in the end, it lowers PO2 in sysstemic arteries relative to the PO2 in the alveoli

Question 29

V/Q ratio

Answer 29

ratio of alveolar air flow to alvolar blood flow

Question 30

normal V/Q ratio

Answer 30

0.8

Question 31

what can change V/Q ratio

Answer 31

either an air or a blood obstruction blood obstruction increases the V/Q air obstruction decreases the V/Q This is useful in diagnosing pulmonary emboli

Question 32

base of lung gets ____ blood, ___ air

Answer 32

tooons of blood,and the greatest amount of air

Question 33

V/Q at base of lung compared to the apex of lumg?

Answer 33

when you are standing, the V/Q is lower at the base of the lung

Question 34

why is there a difference in ventilation of the lung?

Answer 34

"primarily due to the gradient of intrapleural pressure from apex to base of lungs" - at the base of the lung, alveoli are less expanded due tothe gravitational force, but have the best compliance because gravity pulls the surfactant down to the bottom of the lung

Question 35

perfusion is the greatest at the base of the lung because

Answer 35

- hydrostatic pressure decreases above the heart and icnreases below it - this distends the very flexible pulmonary vessels, decreasing their resistance and further increasing flow

Question 36

how does your body accomodate when V/Q is too high

Answer 36

- remember this means a blood obstruction - constrict broncioles to reduce V - vasodilate to increase Q

Question 37

how does your body accomodate when V/Q is too low

Answer 37

- remember this is an air obstruction - bronchiole dilation - vascular constrictuion

Question 38

partial pressure of CO2 and O2 determine

Answer 38

- amount of dissolved gas in solution | - rate of diffusion

Question 39

which gas is better at dissolving in plasma?

Answer 39

CO2 is still the better dissolver

Question 40

how much O2 can a hemoglobin hold?

Answer 40

one oxygen per heme subunit (4 of them)

Question 41

heme sandwich?

Answer 41

one role of Hb is to prevent the heme sandwich (when two hemes sandwich an oxygen between them)

Question 42

how is Hb different from Mb?

Answer 42

myoglobin is not cooperatve like hemoglobin

Question 43

how does pH affect oxygen binding

Answer 43

when the pH goes down (like with exercise) oxygen likes to jump off Hb this is the bohr effect

Question 44

what happens to oxygen binding when temperature rises

Answer 44

when the pH goes down (like with exercise) oxygen likes to jump off Hb

Question 45

BPG effect?

Answer 45

- present in fetal erythrocytes - increases the O2 affinity to a value greater than maternal Hb - i thought that fetal Hb expressed a different type of heme protein... but whatever

Question 46

Consequence of Hb chemistry for O2 transport

Answer 46

sigmoidal O2 dissociation curve | O2 delivered is unaffected by a moderate drop in alveolar PO2 unless you are anemic

Question 47

what things shift the O2 dissociation curve to the right

Answer 47

- increased H (decreased pH) - increased PCO2 - increased temp - increased 2,3 BPG

Question 48

How is CO2 transported?

Answer 48

carbamino compounds ==> produced by combination with plasma proteins, but really low transport bicarb ==> need RBC enzyme to turn into H2CO3

Question 49

RBC CO2 enzyme? how does RBC maintain electroneutrality?

Answer 49

carbonic anhydrase; each bicarb anion is exchanged for Cl- so there is also a net movement of water

Question 50

how is pulmonary circulation different from systemic? why?

Answer 50

- low pressure, lowe resistance, high compliance - wall thickness is about 1/3 of systemic - arterioles have little smooth muscle

Question 51

what is the same in pulmonary and systemic circulations

Answer 51

blood flow. duh

Question 52

increase in pulmonary artery pressure is associated with

Answer 52

- exercise - decrease in pulmonary vascular risistance because of distension and recruitment of unused or poorly perfused capillaries

Question 53

most of the total compliance is a result of ?

Answer 53

small vessels (smaller than 100 microns)

Question 54

how do vessels respond to alveolar inflation

Answer 54

less than 50 microns ==> decrease in diameter | small arteries and veins ==> increase in diameter because they are tethered to alveoli by CT

Question 55

why do people with COPD purse their lips?

Answer 55

they use Ficks law to increase the pressure in their lungs; it helps the O2 get across the membranes

Question 56

possible cause of pulmonary edema?

Answer 56

congestive heart failure; treat with IV diuretics