Cardiovascular and Respiratory adaptation Flashcards
What are the respiratory adaptations to exercise?
-Partial pressure of Oxygen and Carbon Dioxide remain normal during mild and moderate exercise despite an increased ventilation
What are the partial pressures of Oxygen and Carbon Dioxide in the alveolus?
PCO2 - 5.3KPa
PO2 - 13.3KPa
What are the phases of ventilation during exercise?
Start of Exercise - anticipatory rise before exercise starts creating an increase in ventilation
Moderate exercise - Ventilation further increases until it reaches a plateau but partial presures remain normal
Strenuous exercise - Increase in hydrogen ions due to anaerobic metabolism forming lactic acid
Ventilation further increases to reduce oxygen debt
What causes the anticipatory rise?
Neural mechanism through detection by proprioceptors
What occurs during moderate exercise? And how is PP maintainned
Effective chemical control by central chemoreceptors to increase ventilation if an increased CO2 is present to keep the partial pressures the same throughout
What occurs during strenuous exercise?
- High body temperature and metabolic production of acid leads to increased ventilation
- Ventilation can increase from 5-6L/min to 120L/min in stenuous exercise
- Hyperventilation causes a decrease in Partial Pressure of Carbon Dioxide to ensure the acid base balance is maintained due to the increase in H+ ions
What are the cardiovascular adaptations to exercise?
- Activation of the sympathetic nervous system which can affect:
- Myocardial contractile force (Force of heart beat)
- Cardiac acceleration (Increased heart rate)
- Peripheral vasoconstriction (movement of blood to areas most needed such as heart lungs and brain which increases cardiac output)
- Cardiac blood flow to active muscles increases during exercise
What can occur the the respiratory and cardiovascular system during high altitude?
-Susceptible to hypoxia (inadequate delivery of oxygen to body tissues)
What further problems can occur from hypoxia occuring at high altitude?
Hypoxia is detected by peripheral chemoreceptors and they try to increase breathing. This causes PCO2 to fall and the cerebrospinal fluid becomes alkaline
So the system is trapped
Breathe more = die from alkalosis
Don’t breathe more = die from hypoxia
How does the body adapt to meet oxygen demands if mild hypoxia is occuring?
There is an increase in ventilation leading to an increase in alkalinity in the cerebrospinal fluid. However, choroid plexus cells export HCO3- from CSF to correct pH
- Hypoxic drive is then reinstated and ventilation increases
- After many hours, breathing is controlled around a lower PCO2 leading to increased ventilation from hypoxic drive
(Body eventually gets used to working in a more alkalinic environment as the body prioritises oxygen over an acid base imbalance)
Over a couple of days, the alkalinity of the blood is corrected by excretion of HCO3- in urine
Are there more adaptations to high altitude?
- Oxygen carrying capacity of the blood is increased due to polycythaemia
- On return to sea level, you can suffer from pain due to enlargement of the spleen as it breaks down excess RBC’s
- Cardiac output is increased
- Systemic acid base imbalance is corrected
-This is all only effective at approximately 5,500
What are the respiratory consequences of diving?
-Collapsed lung
to prevent this air is supplied at a very high pressure to keep the lungs inflated
What is Boyles Law?
Pressure is inversely proportional to volume at a constant temperature
B = P inversely 1/V
What happens during a descent underwater?
Increased Pressure
- Body and temperature occupy a smaller volumer
- Compress air in lungs, gut, sinuses and middle ear
- Equalise pressure
Respiratory consequences of diving?
Air = 70% N2 which is poorly soluble at sea presure
-Increased pressure in diving causes more N2 to dissolve in the body
Descent = Nitrogen Narcosis Ascent = Decompression sickness 'the bends'
