Trachte: Respiratory System Under Stress Flashcards
How does exercise affect O2 consumption?
It can INCREASE to 3000-6000 ml/min from a baseline of 250 ml
How does exercise affect CO2 consumption?
It can increase to 3000 ml/min from a baseline of 200
What can lead to the dramatic increase in O2 and CO2 consumption during exercise?
VENTILATION
What happens to the respiratory quotient during exercise?
It can increase to one or higher
How can the respiratory quotient be higher than 1?
It is greater than one because the bicarb buffer is making up for acidosis at the VO2 max.
What happens to diffusion capacity during exercise?
HOw is this measured?
It increases 3 fold!
CO uptake per partial pressure gradient
What happens to cardiac output during exercise?
It increases 3-4 fold
Why does CO increase?
There is both increased HR and SV
How does increased HR and SV occur? What’s the efferent signal?
Sympathetic activation increases HR
SV- sympathetics> increased Venous return
What happens to systolic and diastolic pressure during exercise?
Systolic INCREASES
Diastolic DECREASES or is unchanged
What happens to resistance during exercise?
Since CO is dramatically increased, resistance falls during exercise
What happens to PO2 during exercise?
Unchanged or rises slightly
What happens to PCO2 during exercise?
decreased slightly
What happens to pH during exercise? Why?
Decreased
Lactic acid building up
What happens to atm pressure with altitude?
It DECLINES
How do you calculate inspired PO2?
Inspired PO2= (atm pressure-47) x .2093
47 is vapor pressure of water involved in humidification of inspired air
What is the most critical adaptation at high altitude?
HYPERVENTILATION
What drives hyperventilation?
Low O2*
What is polycythemia?
Besides hyperventilation, it is another critical adaptation at HIGH altitude.
RBC numbers in blood INCREASE in response to hypoxia
What does polycythemia do?
Increases the oxygen carrying capacity of blood
How does hypoxia lead to an increase in RBCs?
stimulates EPO
Shifts in the O2 dissociation curve
INCREASED VASCULARIZATION of tissues
increased oxidative enzymes
pulmonary VASOCONSTRICTION
Are all adaptive responses to….
High altitude
What causes acute mountain sickness?
respiratory alkalosis and hypoxia
Why can it be bad to breathe 100% oxygen?
It’s damaging to tissues!
It chronically decreases VITAL CAPACITY and can cause PULMONARY EDEMA
How does breathing 100% oxygen cause atelectasis (collapse of alveoli)?
It creates an ENORMOUS DIFFUSIONAL GRADIENT for air movement into the blood causing the alveoli to COLLAPSE
PO2: 668: 55
PCO2= 45:45
PH20 = 47:47
What happens to N at high and low pressures?
High- N equilibrates w/ tissues
Low- returned to blood
What happens if decompression occurs too quickly?
N escapes from blood as bubbles causing pain and neurological damage if bubbles form in the cranial circulation
How do you avoid hte bends?
replace N w/ helium
When is hyperbaric oxygen used?
CO poisoning
Why is hyperbaric oxygen used to treat CO poisoning?
Can increase O2 content of blood to 6 ml/dL by icnreasing pressure to 3 atm (.003 ml O2/dL/1 mmHg)
Describe the pathway for fetal oxygenation?
Umbilical a. picks up oxygen from placenta>
returns it to RA>
Most goes through the FORAMEN OVALE and oxygenates tissues
What is the PO2 of aortic blood in the fetus?
22-30 mmHg
What happens to most of the blood being pumped to the lung in fetal circulation?
Goes through the DA to get to systemic circulation
Why is the first breath of the fetus so important?
It requires ENORMOUS PRESSURE to overcome surface tension and lungs partially filled w/ fluid>
ENORMOUS drop in PULMONARY RESISTANCE
What causes hte drop in pulmonary resistance?
oxygenation of alveoli
What closes the foramen ovale at birth?
Increased pressure in the left atrium
What physiological variables does exercise increase?
O2 consumed CO2 produced H ion produced HR SV CO AV oxygen content Alveolar ventilation Systolic BP
What physiological variables does high altitude increase and decrease?
Increases ventilation and hematocrit (EPO)
Decreases PCO2 and PO2
**hypoxia is driving force
Why can pure O2 be harmful?
It can cause atelectasis
How does diving lead to the bends?
Diving causes compression or expansion of gas containing organs and can lead to the bends if N escapes from the blood to fast
How do you treat CO poisoning?
Hyperbaric oxygen
What is the state of oxygen tension and pulmonary artery resistance in the fetus?
Oxygen tension is LOW
Pulmonary artery resistance HIGH
