Respiratory System Under Stress Flashcards
Describe how oxygen consumption changes with increasing work (exercise)
VO2 increases linearly until VO2 maximum is reached
Why do we see minute ventilation increase so sharply at the anaerobic threshold?
the subject has reached the point where oxygen cannot be delivered fast enough and lactic acid begins to form.
As the blood gets acidic, your body tries to blow off CO2
How does cardiac output change in comparison to ventilation in CPET (cardiopulmonary exercise testing)?
Cardiac output increases more slowly and to a lower maximum
What effect does exercise have on
- Alveolar and peripheral capillaries
- Pulmonary arterial & venous pressures
- Pulmonary vascular resistance
- Oxygen dissociation curve in muscles vs lungs
- Bp
- Peripheral vascular resistance
- Capillaries
- Alveolar - recruitment and distention
- Peripheral - open
- Pulmonary (arterial & venous) pressures increase
- Resistances
- Pulmonary vascular resistances (PVR) decreases
- Peripheral vascular resistance falls
- Oxygen dissociation curve shifts
- right in exercising muscles
- left in lungs
- Systolic BP increases
Physiologic changes that occur to acclimatize to high altitudes
- Ventilation increases to remove CO2 to increase alveolar pO2
- Maximum breathing capacity increases
- [Hemoglobin] increases, stimulated by Epo from the kidney
-
Alkalosis
- Initial alkalosis stimulates 2,3-BPG increases –> rightward shift of O2 dissociation curve
- Further alkalosis at higher altitudes causes a leftward shift in the curve to help load O2 in pulmonary capillaries
- Hypoxic pulmonary vasoconstriction
Acute vs chronic mountain sickness
Acute: headache, fatigue, dizziness, palpitations, insomnia, loss of appetite, and nausea
Chronic: polycythemia, fatigue, reduced exercise tolerance, severe hypoxemia
The concentration of oxygen is primarily dependent on ____ when partial is adequate to keep the at the plateau of the oxyehmoglobind issociation curve.
concentration of hemoglobin
In this diagram, why does the alveoli receiving pure oxygen have a venous O2 pressure of only 55 if pO2 in the alveoli is 668?
Hemoglobin has already been saturated - so no more oxygen is gonna enter.
What’s the problem with receiving too much oxygen?
Alveoli could collapse.
Gas will diffuse into the blood and the alveoli will collapse because there’s no large fraction of nitrogen to hold it up like there is in alveolus B.
e.g. after surgery when high O2 is given
Barometric pressure increases 1 atm for every __ of descent during diving
10m
The increased density of gas at depth increases the work o fbreathing
What happens to CO2 and N2 when diving?
Increased work of breathing –> more CO2 is produced & retained
N2 is forced into the body tissues, esp fat, bc of the increased atmoshperic pressure
the bends
Upon ascent, nitrogen that was forced into body fat during descent in diving is removed from tissues and forms bubbles
Why does helium-oxygen mixtures reduce decompression sickness (from ascent)?
Helium is less soluble in tissues and has lighter molecular weight
Rapture of the deep
Descent causes increased CNS nitrogen, which can produce narcosis
The fetal lung is inflated to ~__% of TLC with ___
Inflated to ~40% of TLC with amniotic fluid
Describe the path of fetal blood
- Comes into proximity with maternal blood in placenta –> HbF takes up the oxygen
- Goes from 22 mmHg to 30mmHg
- Mixes w fetal venous blood and enters the right atrium
- Foramen ovale –> crosses into left atrium –> left ventricle OR
- Right ventricle –> ductus arteriosus –> back to fetal system circulation
