Respiratory System pt 2 Flashcards
describe the respiratory quotient
ratio of CO2 made to O2 used
briefly describe pulmonary circulation
- 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
describe the respiratory membrane
- surface where gas exchange occurs in lungs
- provides large surface area for diffusion
draw out gas exchange in the respiratory membrane with the flow of (de)oxygenated blood and main inner membrane structures
….
define dalton’s law
proportion of pressure of entire gas due to presence of individual gas (Ptot = P1+P2+P3+….)
what does partial pressure of gas depend on
fractional conc. of gas
partial pressure of gas mixture can be described with the eqn
%gas * Ptot
how is air composed
- ~4/5 nitrogen
- ~1/5 oxygen
- «< 1% CO2, helium, argon, etc
what happens to air as it moves thru conducting zone of respiratory system
humidifies to 100%
describe the diffusion of gases in respiring tissue i.e. what types of gradients
- gases: down the pressure gradient
- gas in gas mixtures: down its partial pressure gradient (presence of other gases are irrelevant)
how does oxygen transport thru blood
by hemoglobin due to insolubility in plasma
when hemoglobin is without oxygen it is referred to as
deoxyhemoglobin
when hemoglobin has oxygen it is referred to as
oxyhemoglobin
what does the binding/releasing of oxygen on hemoglobin depend on
PO2 in surrounding fluid
hemoglobin binds oxygen _______
reversibly
how many oxygen molecules can hemoglobin bind
- four (4 globular subunits)
- follows law of mass action (more O2 = more binding)
define saturation of hemoglobin
measurement of how much oxygen is bound to hemoglobin (x/4 binding sites have O2 bound)
compare hemoglobin saturation in arterial and venous blood
- 98.5% saturated
- 75% saturated
at which PO2 range does O2 affinity increase significantly
~20mmHg (db check)
when do hemoglobin molecules have low affinity to O2
PO2 < 15 mmHg
why does O2 affinity decrease at levels higher than 60 mmHg
at 60 mmHg, hemoglobin is quite saturated with O2 leading to dec affinity
what factors affect affinity of hemoglobin for oxygen
- 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
how does pH affect affinity of hemoglobin for oxygen
- active tissues make more acids which keeps it ↓ in tissues
- when H+ binds to hemoglobin, O2 affinity ↓
how does CO2 affect affinity of hemoglobin for oxygen
- 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
how does low oxyhemoglobin affect O2
high 2,3BPG which decreases affinity for O2 binding to hb and enhances O2 unloading
how does high oxyhemoglobin affect O2
leads to low 2,3BPG which has no affect on affinity
what does oxyhemoglobin inhibit
2,3BPG
when and where is 2,3 BPG made
- low O2 conditions
- RBCs
how does CO affect affinity of hemoglobin for oxygen
Hb has better affinity for CO than O2 so it prevents binding
