Body Systems L20 Flashcards
Describe what gases are transported from which systems / organs in the blood. (Major 2 paths)
• Transportation of Gas:
- O2 -> Alveoli to systemic tissues
- CO2 -> Systemic tissues to alveoli
Via Transportation -> Blood.
Describe the features required for efficient gas exchange in the blood
• Gas Transportation -> Blood: - Diffusion Surface area >> Large >> Moist Diffusion distance >> Short Conc. gradient / Diff. -> Partial pressure >> Alveolar air & blood Solubility of gases Coordination -> Blood & Air flow
What are the partial pressures of N2 in the lungs alveoli & pulmonary veins?
- Atmosphere N2 -> 78.6% -> 597mmHg - Alveoli N2 -> 75.4% -> 573mmHg - Pulmonary Veins N2 -> 12.5 ml/L
What are the partial pressures of O2 in the lungs alveoli & pulmonary veins?
- Atmosphere O2 -> 20.9% -> 159mmHg - Alveoli O2 -> 13.2% -> 100mmHg - Pulmonary Veins O2 -> 3 ml/L
What are the partial pressures of CO2 in the lungs alveoli & pulmonary veins?
- Atmosphere CO2 -> 0.04% -> 0.3mmHg - Alveoli CO2 -> 5.2% -> 40mmHg - Pulmonary Veins CO2 -> 26 ml/L
What is the partial pressures of water in the atmoshpere vs. the alveoli of the lungs?
Atmoshpere
H2O -> 0.46% -> 3.7mmHg
Alveoli
H2O -> 6.2% -> 47mmHg
What is Dalton’s Law?
• Dalton’s Law of Partial Pressure:
Total pressure exerted by mixture of gases = Sum of pressures exerted independently by each gas in mixture.
What is the partial pressure (Dalton’s Law)
Partial pressure
Pressure exerted by each gas
Directly proportional to % in total gas mixture
Eg. Partial pressure of O2 -> Sea Level
»_space; 20.9% of gases at sea level
»_space; Atmospheric pressure = 760mmHg
-» 20.9 x 760 = 159mmHg (Partial Pressure)
Describe the relationship between atmospheric pressure & altitude
• Atmospheric pressure decr. with incr. altitude above sea level.
What are the partial pressures found in the capillaries & alveoli in the pulmonary circuit?
- Pulmonary Circuit: >> External Respiration Capillary: P(O2) = 40 P(CO2) = 45 Alveolus: P(O2) = 100 P(CO2) = 40 Capillary : P(O2) = 100 P(CO2) = 40
What are the partial pressures found in the capillaries & alveoli in the systemic circuit?
- Systemic Circuit: >> Internal Respiration Capillary: P(O2) = 95 P(CO2) = 40 Tissues: P(O2) = 40 P(CO2) = 45 Capillary : P(O2) = 40 P(CO2) = 45
What is Henry’s Law?
• Henry’s Law:
- The amount of gas that dissolves in water determined by
Solubility in water
Partial pressure in air
Describe the conditions of equilibrium of Henry’s Law
- At equilibrium:
Vol. -> Dissolved gas in solution proportional to partial pressure of gas.
Eg. Incr. P(Gas) -> Incr. # gas molecules in solution
Incr. P(O2) -> Incr. amount of O2 in solution.
Outline the gas diffusion requirements of the human body
• Gas Diffusion Requirements: - At alveolar P(O2) -> (100mmHg) 1L plasma dissolves 3ml O2 Blood Flow -> Tissues = 5 L/min >> 15 ml/min O2 - Requires >200 ml/min (200-3000 ml/min) - 1 L blood -> 195ml O2
Describe the structure of Haemoglobin
• Haemoglobin: - 4 globular protein subunits >> 2 alpha >> 2 Beta - Each subunit >> Protein -> Globin >> Non-protein group -> Haem --> Fe2+ -> Porphyrin ring
State the reaction which occurs at haemoglobin & 2 properties of this reaction
Hb + O2 HbO2
Hb -> Deoxy-haemoglobin ; HbO2 -> Oxyhaemoglobin
»_space; Rapid & reversible
How many oxygen molecules does each Hb molecule bind with?
- Each haem portion -> Haemoglobin
Binds -> 4 molecules -> O2
Describe the different ways in which oxygen is transported in the blood & the proportions of oxygen transported by these methods.
• Transportation of O2:
- Approx. 97% O2 transported in Blood -> Using Hb
- Remaining 3% O2 transported in Blood -> Plasma
Describe the uptake of O2 by haemoglobin and what this causes.
Hb changes shape upon binding with O2
»_space; Enables further uptake of O2 -> Positive Feedback
»_space; Binding of O2 mol. to Hb cause change in shape of Hb
> Enables easier successive binding of O2 to Hb.
»_space; As max. limit of O2 binding approaches, affinity decreases.
What is Hb saturation?
Hb Saturation:
% of haem units per Hb mol containing bound O2
What is Hb saturation affected by?
Affected by: >> Partial pressure O2 - > P(O2) -> Blood >> Blood pH >> Temperature >> No. of O2 mol. already bound -> haem ---> O2 dissociation Curve