Exam 1, Physiology of Exercise 2 II

Harding University, professor Bland

hypobaric

Low pressure

hypoxic

low oxygen

hypoxemia

low blood oxygen

barometric pressure

pressure that the atmosphere exerts on us - changes with altitude

partial pressure (Eg. pO2, pCO2)

pressure that one gas (O2N, etc) exerts in a mix

altitude near sea level

<500 m

low altitude

500-2000 m

moderate altitude

2000-3000 m

high altitude

3000-5500 m

extreme altitude

> 5500 m

As altitude increases, temperature…

decreases

As altitude increases, water vapor pressure…

decreases

Physiological changes at altitude

Pulmonary ventilation rate at altitude…

increases: hyperventilation to increase pO2

increased ventilation rate causes pCO2 in the blood to…

decrease; blood alkalizes; called respiratory alkalosis

What is the body’s response when pCO2 declines?

kidneys eliminate some bicarbonate buffer blood, try to rebalance blood pH

Oxyhemoglobin dissociation curve

Blood essentially moves up and down the hill, along the line as it moves from tissue to heart and back

Increase in pH (alkalizing) shifts the Oxyhemoglobin dissociation curve…

to the left; lower ability to unload O2 to muscle

Decrease in pH (acidizing) shifts the Oxyhemoglobin dissociation curve…

to the right; greater ability to unload O2 to muscle

What does altitude do to blood volume (BV)?

decrease; because low water vapor pressure, increased ventilation and urine output

What does decrease in BV at altitude mean for CO?

Decreased CO at altitude because decreased stroke volume (SV)

What does decreased CO at altitude mean for VO2?

VO2 max is automatically lower despite any maximal efforts. Training capacity is blunted at altitude.

What does altitude do to the nervous system?

Increases sympathetic response to increase HR to maintain CO;

What happens to appetite at altitude?

appetite decreases but basal metabolic rate (BMR) increases, both due to increased sympathetic stress response

What type of substrate is used more at rest at altitude?

CHO (carbohydrates)

Lactate paradox

Initial increase in blood lactate (LA) due to stress + using more CHO.

After training at altitude, huge decrease in maximal LA level, lower than training at sea level.

Paradox because this effect is counterintuitive.

Possibly due to expansion of mitochondria, that would give lactate more places to go to dissipate (decreases LA levels)

Nutritional needs at altitude

Need more fluids

Need more calories

Need more iron - aid RBC production

What amino acid stimulates mTORC (muscle protein synthesis) pathway?

Leucine

At altitude (above 1500m) VO2…

decreases

How long is needed for full acclimation to moderate altitude

3 weeks + 1 more for every 600m added

Increased EPO signals at altitude..

Occur within first few hours at altitude. Increase in RBC takes 2 weeks following.

Blood adaptations at altitude causes blood O2 carrying capacity to…

Increase; but never reaches sea level capacity

Altitude causes muscle mass to…

decrease; due to less mTORC stimulation and decreased appetite

how is mTORC pathway affected when hypoxia ..

inhibited/slowed

Mitochondiral and glycolytic enzyme activity at altitude is..

Decreased; less ability to produce ATP

Those living at altitude (acclimatized) have …

Right ventricular hypertrophy; heart increased blood flow (BF) and BP to lungs