L17 - Respiration 4 Flashcards
What is the hemoglobin saturation at a partial pressure of 100 mm Hg in the lungs?
around 98% saturation
What is the hemoglobin saturation at a partial pressure of 40 mm Hg in the lungs?
around 75% saturation
How much lower is hemoglobin saturation in peripheral tissues during exercise? Why is hemoglobin saturation lower?
significantly lower
around 40-50% saturation
because more oxygen is being utilised by the tissues resulting in a lower pO2
What are common factors that change hemoglobin’s affinity for O2?
pH, temperature and partial pressure of CO2
How does pH affect hemoglobin affinity?
increase in pH results in curve shifting to the left = tighter O2 binding and vice versa
How does temperature affect hemoglobin affinity?
increase in temperature results in curve shifting to the right = weaker O2 binding and vice versa
How does partial pressure of CO2 affect hemoglobin affinity?
increase in partial pressure of CO2 results in curve shifting to the right = weaker O2 binding and vice versa
Why does hemoglobin dissociation curve shift back to original position in the lungs?
homeostasis is maintained in the lungs and all values for pH, pCO2 and temp should be at their normal physiological levels
How is 2,3-DPG made?
intermediate of the glycolysis pathway (anaerobic metabolism)
What happens when there is low O2?
increase in 2,3-DPG
What are the three main ways in which CO2 is transported in the body?
dissolved CO2 in blood = 7%
bound to Hb = 23%
HCO3- in plasma = 70%
Under normal resting conditions at sea level, which of the following would control ventilation? (plasma O2 levels / plasma CO2 levels / plasma O2 + CO2 levels)
plasma CO2 levels
How is plasma pCO2 regulated?
increase in plasma CO2 in CSF and arteries -> stimulation of central and peripheral chemoreceptors which trigger an increase in ventilation = decrease in plasma CO2 -> negative feedback
What do central chemoreceptors do? Where are they located?
monitor CO2 in CSF
in the medulla
What do peripheral chemoreceptors do? Where are they located?
sense changes in pO2, pH and pCO2
located in carotid and aortic arteries
Are peripheral chemoreceptors as sensitive as central chemoreceptors?
no
How does altitude affect atmospheric pressure and proportion of gas molecules?
atmospheric pressure decreases
proportion of gas molecules remains the same
At high altitude what will happen to plasma pO2 levels, plasma CO2 levels and ventilation rate?
plasma pO2 levels would decrease, plasma CO2 levels would decrease and ventilation would increase
At high altitude, plasma pH woud (increase / decrease / not change)
increase
Why does plasma pO2 decrease at high altitude?
due to increase in pO2 in air and alveoli
hypoxia at tissues
Why does ventilation increase at high altitude?
due to decrease in plasma pO2 to below 60 mm Hg
Why does pCO2 decrease at high altitude?
due to increase in ventilation
Why does plasma pH increase at high altitude?
due to decrease in pCO2
What are factors that contribute to acclimatization to high altitude?
red blood cell production increases
number of capillaries within tissues increases
nitric oxide increases
cells use O2 more efficiently via an increase in mitochondrial enzymes
What are factors which limit exercise?
muscles need to obtain and use large amount of oxygen
cardiovascular system may reach its maximum
pulmonary system not limiting (unless highly trained)
Why do muscles which need to obtain and use large amount of oxygen limit exercise?
may be limited by oxygen availability via local blood flow and number of mitochondria
