Exercise physiology 1 Flashcards
Oxygen need increases X fold with exercise
10
What is limiting for glucose oxidation and aerobic performance?
Oxygen supply : adequate respiration is crucial
What is the process of oxygen being taken up from lungs to blood?
diffusion
O2 is transported in the blood bound to haemoglobin, because free oxygen..
Is hardly soluble in blood (plasma)
Synthesis of erythrocytes (RBC) occurs continuously in bone marrow, controlled by
EPO
EPO is produced in X, its secretion stimulated by X
liver, low arterial O2 pressure
What happens when you administer EPO (doping)?
increases max oxygen consumption and performance
Binding of haemoglobin to oxygen is dependent on..
Local O2/CO2 concentration
temperature
pH
What happens at low oxygen tension with haemoglobin?
Low oxygen tension: haemoglobin loses binding to oxygen -> released -> consumed
Affinity of haemoglobin with O2 depends on..
- Temperature: temp up, affinity down
- pH: H+ binds reversibly to HB -> competition with O2 (=bohr effect)
pH down, affinity down - PO2
CO2 binds reversibly to Hb -> competition with O2
PCO2 up, affinity down - 2,3-diphosphoglycerate (2,3-DPG)
Produced in RBC in response to low oxyhaemoglobin (oxHb)
OxHB down -> 2,3DPG down up, affinity down
What happens when affinity goes down of Hb and oxygen?
- When affinity goes down, oxygen is released to muscles if needed!
Why does the difference between blood oxygen content in arteries and veins becomes larger during exercise?
This difference = the amount of blood consumed by the muscles (oxygen in the blood – oxygen coming back from the tissues)
Why does the arterial O2 content stay roughly the same during exercise, whilst the venal O2 content diminishes?
Arterial O2 content stays roughly the same, bc the O2 concentration is 100% from the lungs.
During exercise, there is an increase/decrease in…
- A in PO2
- B in PCO2
- C in pH (more H+)
- D in 2,3-DPG (maximal exercise)
- E in Temp
A Decrease
B Increase
C Decrease
D Increase
E Increase
These intramuscular factors, result in…
- Causes A in affinity between Hb en O2
- Intramuscular release of oxygen B
- Venous O2 content C
- Arteriovenous O2 difference D
A decrease
B increases
C decreases
D increases
Muscle regulates its own consumption without increased blood flow: true/false
true
During exercise, there is an increased tidal volume (volume air/breath). What remains unchanged?
- Lung capacity + residual volume remains unchanged!
Is the vital capacity (part of lungs used for breathing) changed in endurance vs untrained subjects?
No
What does stimulate development of larger vital capacity?
Swimming/diving, because of the water pressure -> strengthen inspiratory muscles
Gas exchange only occurs in X, not in bronchi or bonchioles
alveoli
Resting: breathing under involuntary control of the chemoreceptors which detect..
PO2, PCO2/pH in the carotid artery
(=major blood vessels that provide your brain’s blood supply)
What chemical signal is most important during normal respiration?
PCO2
During exercise, chemoreceptors in the carotid artery do not seem to play a major role
(Arterial PO2 and PCO2 are relatively stable). What does play a major role?
Central command (motor cortex),
Peripheral input from joints, tendons and muscles (mechanoreceptors + chemoreceptors)
What is the Ventilatory threshold?
point where ventilation increases disproportional to VO2
What is the Lactate threshold?
point where lactate levels in the blood start to increase (>1mM)
What is the Onset of Blood Lactate Accumulation (OBLA)?
Point where blood lactate > 4.0 mM (anaerobic threshold)
Besides conversion of CO2, also intrafibrillar buffering of acid (lactate) occurs.
- Buffer capacity related to percentage X
- Histidine-containing peptides, such as X, seem to be involved
T2 fibers (more T2, more buffering)
- In sprinters and rowers, but not long-distance runners, buffer capacity is increased
Histidine-containing peptides, such as carnosine, seem to be involved
Higher carnosine = better performance
- Pulm. vent does not seem to be a limiting factor for oxygen delivery at max O2 consumption
True/false
True
Arterial PO2 is affected by exercise
True/false
False
What is an exeption in which extra oxygen supply with pulmonary ventilation does lead to improved performance?
High-intensity exercise may, in some cases, result in arterial desaturation (EIAH) = blood leaving the lungs is not completely saturated with oxygen. Can be prevented with extra oxygen supply -> improves performance.
Happens more in athletes than non-athletes.
Why is pulmonary ventilation not limiting to performance?
Usually, the blood has more than enough time when it passes the alveoli to be diffused with the same amount of oxygen as in the alveoli (equilibrium). However, during exercise, Blood flow increases, it is so fast that the time the blood passes the alveoli is too short. Gets too little oxygen.
If it is not the respiration that is limiting, perhaps role for the CVD?
