Respiratory System (GE) II Flashcards
Describe the respiratory membrane
3 layers - Very thin (0.2um)
High SA - GE by diffusion (solubility)
Affect by partial pressures and solubility of O2 and CO2
Define total pressure (Dalton’s law)
Sum of pressures of individual gases
Describe the correlation of partial pressures between gases and the atmosphere (O2/CO2)
Partial pressures of O2 is lower than that of the atmosphere
Partial pressures of CO2 is higher than that of the atmosphere
Which areas of the body has oxygenated blood?
Name them
Areas with greater O2 partial pressures
Alveolar air, Pulmonary veins, Systemic arteries
Which areas of the body has deoxygenated blood?
Name them
Areas with greater CO2 partial pressures
Systemic veins, Pulmonary arteries
Describe gas pressures in the air
Atmosphere: Po2 (160mmHg), Pco2 (0.23mmHg)
Alveolar air: Po2 (100mmHg), Pco2 (40mmHg)
What Factors are linked to alveolar air?
Gas exchange, dead space, water vapour
Describe gas pressures in the blood
Pulmonary and systemic veins: Po2 (100mmHg), Pco2 (40mmHg)
Cells: Po2 (<40mmHg), Pco2 (>46mmHg)
Pulmonary veins: Po2 (40mmHg), Pco2 (46mmHg)
Systemic veins: Depends on tissue activity
Describe how rapid gas exchange occurs
At a start point of 40, end point of 100 - Blood flows through 1/3 of capillary length completing gas exchange
What is the other 2/3 of the capillary for?
Used as a reserve in case part of the lung doesn’t work, oxygenated blood can be contributed to other areas where needed
Describe the efficiency of rapid gas exchange
Within 1/3 of capillary PPco2 decreases from 46>40 so efficiency is applied to both O2/CO2, completing both their gas exchange within 1/3 of the capillary
Describe the properties of gas exchange
Via diffusion, driven by pressure differenc, very thin respiratory membrane (0.2um), High SA, Rapid ~0.25sec, ⅓ of pulmonary caps, occurs in lungs and respiratory tissue
Describe the solubility of gases in terms of Henry’s Law
c = kP At equilibrium (btw gas/liquid) concentration of dissolved gas (c) is prop to PP (P) and solubility (k) of gas
Describe the link between solubility and partial pressure in terms of O2 and CO2
Different types of gas have different solubility
CO2 is more soluble than O2
Describe the effect having the same partial pressure has on the concentration of gases
With same partial pressure of CO2 and O2, theres a higher concentration of CO2 in the solution than O2
Describe the transport of O2 in the blood
Solubility of O2 very low (3ml/L of blood), Not meet demand (250ml/min)
What percentage of O2 is transported by haemoglobin?
98.5% (the rest is done by blood itself)
Briefly describe haemoglobin
4 subunits each with globin and Has a haem group, binds to O2 reversibly, Oxyhaemoglobin/deoxyhaemoglobin
Describe the structure of haemoglobin
2 alpha, 2 beta globins, 4 haem groups (Fe2+) for each O2
Describe the difference in haemoglobin in sickle cell anaemia patients
b-subunit shape altered not a-subunit
Describe the saturation of haemoglobin with O2
Arterial blood 98.5% saturated vs Venus blood 75% saturation reserve gained as 3 o2 bind to haem
Describe venus blood
Reserve gained as 3 O2 bind to haemoglobin
Describe the oxyhaemoglobin dissociation curve
% saturation inc as PO2 inc
S-shaped curve (sigmoidal), positive cooperativity (binding of one O2 inc affinity of next)
Systemic arteries - 100mmHg, 98.5% saturation
Systemic veins - 40mmHg, 75% saturation
Describe the temperature effect on O2 saturation
Higher temperature - Active tissues, shifts right, more O2 unloading in tissues, more O2 delivered to tissues
