Applied Respiratory physiology Flashcards
How does the body deal with increased O2 comsumption?
- vasoconstriction of non essential organs to inc blood flow to exercising skeletal muscle
- Inc CO
- Inc resp rate and depth
- Production heat,
- production CO2, = dec HB affinity to oxygen
- inc production acid (due to CO2 and metabolism of tissue itself)
- Inc Red blood cell count
- inc diffusion gradient for O2 at tissues
- Myoglobin O2 store in muscles
How do we get inc resp rate and depth?
- peripheral chemoreceptors (carotid and aortic arteries) detect [H+], PaCO2, PaO2
- central chemoreceptors detect Pa CO2 = by CO2 diffusing into spinal fluid, into bicarbonate and H+
Other than inc resp rate and depth what else helps facilitate inc O2 exchange at lungs when exercising?
- venous pressure of O2 reduced blood returning to lungs = less O2 in it so bigger diffusion gradient of O2
- pulmonary perfusion inc: CO inc: blood flow to lung inc
- Alveolar ventilation increased- more A has ideal V: perfusion ratio
What causes inc offloading of O2 at tissues when exercising?
- larger O2 gradient: more offloading which due to cooperative binding, reduced affinity of Hb to O2 attached!
- Production CO2 :. H
- H+ from increased cell metabolism
- all of which dec pH = reduced affinity of Hb for O2
- inc temp muscle = reduce affinity for O2
What decreases affinity of O2 for Haemoglobin? and where does the curve shift?
- shifts RHS
- inc CO2
- Inc products cell metabolism
- dec pH
overall gives off more O2
When the cell pH drops what happens to myoglobin?
O2 stores released
What does increased cardiac output result in
- Increases skeletal muscle perfusion
2. Increased pulmonary perfusion
What does increased pulmonary perfusion result in?
- Increases blood flow in vessels = NO (nitric Oxide) production from endothelium cells = dilation of blood vessels
- in improved O2 uptake
- Increased pulmonary arterial pressure
- Increased left atrial pressure PRELOAD
- pulmonary capillary pressure increases
If pulmonary perfusion results in super high pressure in pulmonary capillaries what could occur?
- exercise induced pulmonary haemorrhage
2. cause bleeding into airway and lung! can be extreme (racehorses)
Why do you get an increased RBCC when increase exercise short term:
- Acute = spenic contraction due to sympathetic nervous system (stitch) = releasing stored blood with a higher RBCC
What do inc RBCC long term
Over time increased erythropoietin production
Why do you need a balance in the RBCC?
- inc RBCC = inc blood viscosity = inc cardiac workload as inc resistance
If at altitude what happens to O2 level in air.
equation
- Decreaseds
- Because atmospheric pressure drops
- O2 level is 21% of the gas mixture you breath = still 21% oxygen just of less as lower atmospheric pressure: PiO2 = Patmospheric X 0.21
What happens over time when alveolar pressure of O2
- increased erythropoiesis = production RBC = get more O2 of what is there
- Vasoconstriction of pulmonary vasculature - helps body cope with not well ventilated alveoli = maintaisn V:perfusion ratio
What with hypoxic pulmonary vasoconstriction what deos it depend on
- generalised vasoconstriction of pulmonary
- severity depends on species according to how much smooth muscle is in pulmonary arterioles: Cattle> pigs> horses> sheep> dogs
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