Respiratory System pt 2

Question 1

describe the respiratory quotient

Answer 1

ratio of CO2 made to O2 used

Question 2

briefly describe pulmonary circulation

Answer 2

• O2 enters alveoli and CO2 leaves alveoli by bulk flow of air during ventilation
• O2 and CO2 bw alveolar air and blood thru diffusion, down conc. gradients

Question 3

describe the respiratory membrane

Answer 3

• surface where gas exchange occurs in lungs
• provides large surface area for diffusion

Question 4

draw out gas exchange in the respiratory membrane with the flow of (de)oxygenated blood and main inner membrane structures

Answer 4

….

Question 5

define dalton’s law

Answer 5

proportion of pressure of entire gas due to presence of individual gas (Ptot = P1+P2+P3+….)

Question 6

what does partial pressure of gas depend on

Answer 6

fractional conc. of gas

Question 7

partial pressure of gas mixture can be described with the eqn

Answer 7

%gas * Ptot

Question 8

how is air composed

Answer 8

• ~4/5 nitrogen
• ~1/5 oxygen
• «< 1% CO2, helium, argon, etc

Question 9

what happens to air as it moves thru conducting zone of respiratory system

Answer 9

humidifies to 100%

Question 10

describe the diffusion of gases in respiring tissue i.e. what types of gradients

Answer 10

• gases: down the pressure gradient
• gas in gas mixtures: down its partial pressure gradient (presence of other gases are irrelevant)

Question 11

how does oxygen transport thru blood

Answer 11

by hemoglobin due to insolubility in plasma

Question 12

when hemoglobin is without oxygen it is referred to as

Answer 12

deoxyhemoglobin

Question 13

when hemoglobin has oxygen it is referred to as

Answer 13

oxyhemoglobin

Question 14

what does the binding/releasing of oxygen on hemoglobin depend on

Answer 14

PO2 in surrounding fluid

Question 15

hemoglobin binds oxygen _______

Answer 15

reversibly

Question 16

how many oxygen molecules can hemoglobin bind

Answer 16

• four (4 globular subunits)
• follows law of mass action (more O2 = more binding)

Question 17

define saturation of hemoglobin

Answer 17

measurement of how much oxygen is bound to hemoglobin (x/4 binding sites have O2 bound)

Question 18

compare hemoglobin saturation in arterial and venous blood

Answer 18

• 98.5% saturated
• 75% saturated

Question 19

at which PO2 range does O2 affinity increase significantly

Answer 19

~20mmHg (db check)

Question 20

when do hemoglobin molecules have low affinity to O2

Answer 20

PO2 < 15 mmHg

Question 21

why does O2 affinity decrease at levels higher than 60 mmHg

Answer 21

at 60 mmHg, hemoglobin is quite saturated with O2 leading to dec affinity

Question 22

what factors affect affinity of hemoglobin for oxygen

Answer 22

• shifts right (decreased affinity) or left (increase affinity) on hemoglobin-oxygen dissociation curve
• temperature (↑ temp = more O2 delivery and unloading)
• pH
• effects of CO2; 2,3BPG; carbon mono

Question 23

how does pH affect affinity of hemoglobin for oxygen

Answer 23

• active tissues make more acids which keeps it ↓ in tissues
• when H+ binds to hemoglobin, O2 affinity ↓

Question 24

how does CO2 affect affinity of hemoglobin for oxygen

Answer 24

• CO2 reacts with hemoglobin to make carbamino-hemoglobin
• this structure has even lower affinity for O2
• ↑ in metabolic activity ↑ O2
• ↑ O2 unloading in active tissue

Question 25

how does low oxyhemoglobin affect O2

Answer 25

high 2,3BPG which decreases affinity for O2 binding to hb and enhances O2 unloading

Question 26

how does high oxyhemoglobin affect O2

Answer 26

leads to low 2,3BPG which has no affect on affinity

Question 27

what does oxyhemoglobin inhibit

Answer 27

2,3BPG

Question 28

when and where is 2,3 BPG made

Answer 28

• low O2 conditions
• RBCs

Question 29

how does CO affect affinity of hemoglobin for oxygen

Answer 29

Hb has better affinity for CO than O2 so it prevents binding