Last Resp - 11 Flashcards
Alveolus
-lined with simple squamous epithelium (type 1 alveolar cells)
-outer surface - network of capillaries (endothelium)
-resp. membrane = alveolar and capillary walls
Atmospsheric pressure
760mmhg (all pressures added such as o2, co2, n2, h2o ctc)
Dalton’s Law
the partial pressures of the individual gases will add up to the total pressure
Henry’s Law
-gasses will seperate down indivualc oncetnraon gradients
the amount of gas that is dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid when the temperature is kept constant
(scuba divers, opening can of pop)
Factors Affecting Pulmonary Gas Exchange
(external respiration)
- partial pressure gradients as gas solubilities
- matching alveolar ventilation and pulm. blood perfusion
- structural characteristics of the resp. membrane
Partial Pressure Gradients
-movement of gasses is passive
-O2 diffuses rapidly down its concentration
gradient into the pulmonary capillary blood
-CO2diffuses in the opposite direction down a gentler
concentration gradien
-co2 is 20x more liquid solulble than o2 so the exchange of gases equal even though the concentration gradients
slide 12 picture study and maybe rewatch lecture
Ventilation-perfusion coupling
ventilation = amount of gas reaching alveoli
perfusion = blood flow to pulm capillaries
-for sufficient exchange there needs to be a match (coupling) b/w ventilation and perfussion
-when Po2 is low, areteriols eonctrict and blood is redirected to areas where Po2 is high
Changes to Resp. Membrane
the greater the SA of resp. membrane, the more gass can diffuse across it (90m^2 in healthy adult male)
-pneumonia, tumors, emphysema, inflamation can impede SA and therefore gas exchange
rewatch lecture
lots of slides are not understood
Oxygen Transport in Blood
-little oxygen is dissolved into plasma, its mostly bound to hemoglobin to be carried around body
HbA = adult hemoglobin
HbF = fetal hemoglobin
HbS = sickle cell trait, autosomal recessive, RBCs are curved, spiky and fragile
Hemoglobin HbA
-composed of 2 alpha, 2 beta
-each alpha and beta contains a heme group that contains iron and can bind oxygen = oxyhemoglobin (red)
-each rbc containes 250million moelcules of hemoglobin - so each rbc can carry 1billion o2 molecles if Hb is full
Oxyhemoglobin
-hemoglobin has 4 o2 binding sites with positive cooperativity - when 1 o2 binds, hb changes shape so other o2 can bind easier
Hb and PO2
PO2 determines how much O2 binds to hemoglobin
Hb + O2 (reverse arrows for binding/dissasociating O2) Hb-O2 oxyhemoglobin
Oxygen-Hemoglobin Dissociation Curve
-the higher the Po2, the more combines with HB
-lower the Po2, hb does not hold aas much o2 (wants to jump off and move into tissue cell)
at rest, tissue cells with Po2 of 4ommhg = 75% Hb saturation
Other Factors Affecting Hb-O2 Binding
ph - lower ph = less O2 binding, and curve shifts right (and vice versa)
pco2 - co2 can also bind to Hb so more co2 = more acidic (and vice versa)
temperature - more heat = less binding of O2 to hb
ex. hypothermia means less o2 is needed, curve shifts left
BPG (formed in cells during glycolysis) high BPG = more hb binding - o2 binds less tightly to heme when bpg is present
