Lec 5 Flashcards
explain the movement of O2/CO2 in circulatory system, if 100mmhg of O2 enters lungs
100mmhg enters lungs, circulates to tissue (removes 40mmhg of O2, gains 46mmhg of CO2), CO2, dumped, oxygen cycles again
Explain Dalton’s law
-gases exert pressure proportional to their abundance, increased amount of an individual gas in mix = increased partial pressure
-sum of Pressures = 760mmHg
Explain Henry’s law
-movement of gas into/ out of fluid in the alveoli
-how much gas dissolves into a liquid (solubility) depends on partial pressure of the gas + temp.
-predicts how gases behave during as exchange based on the partial pressure gradient + solubility of O2 + CO2
-at a constant temp.: the conc. Of a gas dissolved in a liquid is directly proportional to the partial pressure of the gas in contact with the liquid
- increased pressure of gas = increased gas dissolved in liquid
what are the respiratory membrane pathway of O2 from alveolus to RBCs
-alveolus to RBC (O2 travels, and CO2 out)
1. alveolus
2. Alveolar fluid lining (surfactant)
3. Alveolar type 1 cells
4. Interstitial fluid
5. Capillary cells
6. Plasma
7. RBC membrane
8. Hb
what is Fick’s law + 3 factors its affected by
ficks law describes the diffusion of particles, it is affected by SA, thickness + pressure
increase in area = increase in diffusion
-SA is influenced by - Age, disease, pulmonary capillary recruitment, pulmonary alveolar recruitment
decrease in thickness = increase in diffusion
- thickness influenced by age + disease (e.g. pulmonary fibrosis)
increase in delta pressure (increases with exercise) = increase in diffusion
-refers to the rate of diffusion at the respiratory membrane
-total surface area of alveoli is huge (about 70m squared)
-each alveoli surrounded by network of capillaries
Explain amount of diffusion rate of CO2 vs O2
note: outward CO2 diffusion is 20 times inward diffusion of O2
define capillary transit time
-time tha of blood is exposed to the gas exchange surface for diffusion to occur
note: blood in the pulmonary capillaries is constantly moving
how much O2 and CO2 is dissolved in plasma (%)
-1.5% of O2 + 7% CO2
-the 1.5% of O2 is not enough to support the increase in body temp + increase in metabolic rate
-hemoglobin increases the amount of O2 blood can carry
what is Hb saturation (SaO2) + what affected by
% heme units containing bound O2
-is decreased by decrease in pH + increase in temp.
-the ability of blood to carry O2 is affected by RBC no. + hemoglobin in RBC
explain cooperativity + tense vs relaxed Hb
-hard to bind the 1st O2 to Hb, then gets easier until gets all 4
-Hb changes shape when O2 binds = cooperativity
-cooperativity means the relationship between PO2 + SO4 is NOT linear
-is tense (T) state when deoxygenated (low O2 affinity + favour CO2 = BOHR EFFECT)
-is relaxed (R) state when oxygenated (high O2 affinity + decrease CO2 BOHR EFFECT)
tense vs relaxed, plateau vs ave. resting values, + left/rigt shift
explain the Hb-O2 dissociation curve.
-is tense (T) state when deoxygenated (low O2 affinity)
-is relaxed (R) state when oxygenated (high O2 affinity)
CURVE IS OPPOSITE : RIGHT SHIFT MEANS GO LEFT, AND VICE VERSA
-plateau region (loading, at the top):
-PaO2 = 100mmHg
average resting PaO2 is 40mmhg - O2 binds to Hb = increase SaO2 (hemoglobin) -plateau maintains high SaO2 even if PaO2 (100-70mmHg) decreases -is the safety margin for O2 carrying capacity of blood -SaO2 maintained even if large decrease in PaO2
-steep region (unloading, going up-middle part)
-PtissuesO2 (40mmHg) at rest
-increase in delta P = O2 diffuses into cells
- PcapO2 decreases, pulls O2 off Hb) unloading). allows more diffusion.
-at P’vO2 = 40mmHg, saO2 about 75%
-decrease PcapO2 = increased unloading = decreased SaO2
-advantages= small decrease in PtissueO2 = large decrease in SaO2
-steep region greater for unloading O2 from Hb
-right shift = decrease SaO2 + increase in unloading
- left shift = increase SaO2 = increase loading
explain the Hb-O2 dissociation curve when temp increase
-right shift
-decrease in SaO2 = increase unloading
explain the Hb-O2 dissociation curve in regard to BPG
-is synthesized as a byproduct of TCA cycle
-increase BPG stabilizes T state = decrease O2 affinity
-BPG stabilizes T state = decrease O2 affinity
-BPG binds to electrostatic bonds between Hb beta chain
-increase BPG = right shift = decrease SaO2 = increased unloading
Why do exercising muscles favour a right shift
-an exercising muscle has decreased PO2, it needs O2 conditions in exercising muscle cause a right shift in the O2Hb dissociation curve to Favour unloading of O2 at the tissues
-similarities between exercising muscle + factors that favour a right shift- hot/increase in temp., acidic (lactic acid)/decrease in pH, has high PCO2/increasing PCO2, undergoing rapid glycolysis (lots of BPG)/increasing BPG
So right shift Favours unloading
3 CO2 diffusion methods + what helps it + what occurs in tissue/lungs
-is produced by cells diffuses into blood along it partial pressure gradient
-CO2 diffusion is helped by chloride shift-CO2 can be transported in 3 ways
-dissolved in plasma (5-10% depends on PCO2)
-bound to Hb (25-30%)
-bicarbonate ions (60-70%)
-in tissues: HCO3- out + Cl- in, helps maintain delta P for CO2 diffusion into RBC
-in lungs: HCO3 in + Cl- out, helps maintain delta P for CO2 diffusion out of RBC
