Flashcards in PSL301: Respiratory 6 Deck (56):
what is considered high altitude?
> 1500 m
main problem at high altitudes?
What is the partial pressure of O2 in dry air?
253 x 0.21 = 53 mmHg
How does the peripheral chemoreflex respond to hypoxia?
- Will increase ventilation rate faster
- more dramatic increase
- begin responding at lower pCO2 levels
What happens to the hemoglobin saturation curve when hyperventilating?
- CO2 decreases
- H+ decreases
- pH increases (basic)
- more O saturation at tissues (does not release)
long term consequences of hypoxia
- release of erythropoietin
- synthesis of 2,3-DPG in RBC
What effect does 2,3-DPG have on the hemoglobin saturation curve?
- Hb has less affinity for O2
2,3-DPG is an intermediate of the ___ pathway
When does 2,3-DPG degrate?
When blood is stored
What conditions are related to high altitude? Which are very serious?
1. mountain sickness
2. high altitude pulmonary edema **
3. high altitude cerebral edema **
mountain sickness symptoms
symptoms of mountain sickness is caused by...
cerebral autoregulation of blood flow
symptoms of high altitude pulmonary edema
- swelling of lungs
- shortness of breath
- cough pink frothy fluid
high altitude pulmonary edema
hypertension in the lungs
high altitude cerebral edema
swelling of the brain
high altitude cerebral edema symptoms
- coma & death (due to capillary leakage)
- brain swelling
- herniation of brain through the tentorium
herniation of brain through the tentorium
brain is pushed out through a hole towards the cerebellum if swelling is severe
cannot control muscles
what happens during pulmonary edema?
Normally, lungs vasoconstrict blood vessels around aveoli that have low pO2 and pCO2 to increase efficiency. At high altitudes, all alveoli have low pO2 and pCO2 so all blood vessels become constricted.
- increased blood pressure
- pushes fluid out of vessels
- fluid surrounds alveoli, making it harder for gas exchange
prevention of hypoxia
what does acetazolamide do?
- stops CA enzyme
- diuretic: reduce fluid in body
- forces the kidneys to excrete bicarb: want less alkaline conditions
treatment for hypoxia
- go to lower altitude
- give O2
treatment for cerebral edema
treatment for pulmonary edema
Nifedipine: lower pulmonary artery pressure by blocking L-type Ca++ channels
what happens to oxygen levels during exercise?
increases (log graph), then plateaus high for duration of exercise
What happens to oxygen levels at the end of exercise?
Rapid decrease (hyperbola)
what is used to deliver more oxygen to muscles during exercise?
respiratory & cardiovascular systems
What is the limiting factor during exercise?
What components of the respiratory system is affected during exercise?
- breathing frequency
What components of the cardiovascular system is affected during exercise?
Regulation of blood flow during exercise
21% goes to skeletal muscles @ rest
88% goes to skeletal muscles @ exercise
CO: 6 L/min -> 30 L/min
How does the respiratory system know to increase ventilation during exercise?
1. motor system tells skeletal muscles to contract -> sends info to medulla, which tells breathing to increase
2. proprioceptors in muscles tell respiratory center to increase breathing
3. chemoreceptors can also cause increased breathing
Difference between aerobic -> anaerobic respiration
- arterial pH drops
- venous pO2 drops
- arterial pCO2 drops a little
- ventilation increases
what does not change between aerobic & anaerobic respiration?
arterial pCO2 (somewhat)
What causes the decrease in pH during anaerobic exercise
How can ventilation be increased in response to exercise signal? [rapid response]
1. mechanoreceptors & proprioceptors in exercising limbs send info to medulla
2. tells it to increase respiration
3. descending motor commands that go to muscles spill over to medulla
How can ventilation be increased in response to exercise signal? [slow response]
1. receptors in muscles & blood vessels send signals to medulla
2. central & peripheral chemoreceptors
define: cardio-respiratory fitness
- ability to perform large muscle, dynamic, moderate/high intensity exercise for prolonged periods
- ability to transport and use oxygen
cardio-respiratory fitness is measured as...
max oxygen consumed during intense whole body exercise (VO2 max)
higher VO2max means someone is ___ fit
max aerobic work that an individual can achieve
how to measure VO2max directly?
- make person work at max capacity
- measure O2 consumption
- units: L/min or mL/kg/min
How to normalize VO2 max values?
divide by weight
value: VO2 max for young males
3 - 3.5 L/min
value: VO2 max for young females
2 - 2.5 L/min
value: normalized VO2 max for young males
45 - 50 mL/kg/min
value: normalized VO2 max for young females
35 - 45 mL/kg/min
what is considered an excellent normalized VO2 max value for males?
what is considered an excellent normalized VO2 max value for females?
What test is used to estimate VO2 max?
Astrand Fitness Test
steps of the Astrand Fitness Test
1. exercise at known work rate for 5-6 min to reach steady state
2. measure heart rate using pulse in the last minute of exercise
3. use tables to look up VO2 max using HR, age, sex
assumptions of the Astrand Fitness Test
1. Aerobic work is proportional to oxygen uptake, independent of the type of work
2. oxygen uptake is proportional to CO, which is proportional to HR
3. max heart rate is the same for all individuals of the same age and sex
4. the slope of the HR vs. work is the same for all individuals
How to determine the fittest individual looking at the result of an Astrand Fitness Test?
- which has the lowest resting HR? (smaller y axis)
- which has the highest work rate? (bigger x axis)
Long-term benefits of aerobic exercise:
- higher oxidative capacity of skeletal muscle
- incr. CO
- decreased resting HR
- incr. max HR
- increase blood vlume
- decrease BP
- increase number of capillaries
- increase VO2 max
- maintain body weight
- improve psychological function
- decrease risk of chronic disease
- increase life span
what are some chronic diseases that are affected by exercise?
- heart disease
- Alzheimer's disease