Gas transport and blood gases Flashcards
how are gases carried
dissolved in plasma
chemically combined with haemoglobin
covered into a different molecule
external respiration
occurs at the level of the lungs
alveoli
loading o2
o2 diffuses along its partial pressure gradient from alveolus to blood until equilibrium is reached
loading o2
o2 diffuses along its partial pressure gradient from alveolus to blood until equilibrium is reached
unloading co2
co2 diffuses along partial pressure gradient from the blood to the alveolus
factors influencing external respiration
- surface area and the structure of the respiratory membrane
- partial pressure gradients
- matching alveolar airflow to pulmonary blood capillary flow
internal respiration
o2 diffuses from systemic capillaries into cells
co2 cells to capillaries
factors influencing internal respiration
- available surface area
- partial pressure gradients
- rate of blood flow (metabolic rate of tissue)
internal respiration
at the level of the rest of the body
what is involved in internal respiration
myofibers
adipocytes
epithelial cells
immune cells
partial pressures of oxygen and carbon dioxide of arterial blood leaving the lung
they’re constant
what type of reaction is the binding of action to haemoglobin
reversible
label the image
iron atom
haem group
polypeptide chain
what occurs when 4 o2s are bound to haemoglobin
haemoglobin is full saturated
globin portion
4 polypeptide chains
4 iron pigments called haem groups
oxygen bound to haemoglobin
oxyhaemoglobin
affinity and saturation
affinity of haemoglobin for oxygen decreases as its saturation decreases
what occurs at high oxygen concentrations
oxyhaemoglobin forms
what occurs at lower oxygen concentrations
oxyhemoglobin dissociates to haemoglobin and oxygen
lungs at sea level
98% saturated
lungs at high elevations
95% saturated
Haemoglobin saturation at low partial pressure oxygen
Actively contracting muscle uses more oxygen
Lower partial pressure
35% saturated
As partial pressure decreases
Haemoglobin releases much more oxygen to tissues
Factors altering Haemoglobin saturation
Increase in affinity:
Shift left
Increased pH
Decreased partial pressure CO2 (Bohr shift)
Decreased BPG
O2 to the right
Increased:
H+
Partial pressure CO2
Temperature
2,3-diphosphoglycerate
Bohr effect cause
Action on H+ conc
Right shift
More unloading of O2 at given partial pressure O2 in tissue
Effect of decreased temperature
Shift left
Carbon Monoxide and O2 transport
Affinity of Haemoglobin for carbon monoxide is 240 times bigger than O2
CO competitively blocks combination of O2 with Haemoglobin
CO bound Hb= carboxyhaemoglobin
Shifts curve left
Leads to severe hypoxia
Transport of CO2 in blood
More readily than oxygen
20x more soluble in plasma
Arterial blood is 48%
Venous blood is 52%
CO2 transport
Physically dissolved 5%, arterial blood
Physically dissolved as bicarbonate ion, arterial blood
Combined Hb 23%
Where does carboxyhaemoglobin form
In regions of high partial pressures of CO2
Formation of carboaminohaemoglobin
Reversible
Lower pCO2 dissociâtes from CH
Oxygen saturation of Haemoglobin is affected by
Partial pressure oxygen
Ph
Temp
BPG
partial pressure carbon dioxide
Haldane effect
Oxygen loading facilitates Carbon dioxide unloading from Haemoglobin
