Describe how cardiovascular drift takes place.

Identify the location and function of the pituitary gland.

Outline the chemical control of ventilation during exercise.

Explain physiological causes of peripheral fatigue in long distance running.

Explain excess post-exercise oxygen consumption (EPOC) during recovery.

Cardiovascular drift is an increase in heart rate during prolonged exercise <despite effort remaining the same>✔

during prolonged exercise there is an increase in core temperature ✔

the rise in core temperature causes redistribution of blood to the periphery in order to cool ✔

the blood volume redistribution causes the heart to work harder in order to maintain muscle blood flow / energy demands✔

blood flow to skin increases and water is lost via sweating ✔

prolonged cooling/sweating causes a decrease in blood volume / increase in viscosity✔

reduction in venous return/stroke volume causes the heart rate to increase to maintain cardiac output ✔

Location:
located «in the brain» below the hypothalamus ✔

Function:
main endocrine gland influencing other glands ✔

secretes hormones
OR
ADH/GH/TSH/ACTH/oxytocin secretion ✔

responsible for homeostasis
OR
regulates a wide range of bodily functions «growth», «water retention», «temperature» ✔

ventilation is «chemically» regulated by blood acidity levels/low pH ✔

blood acidity levels increase/pH drops due to an increase in carbon dioxide levels ✔

blood acidity levels are detected by chemoreceptors ✔

medulla oblongata/ANS/respiratory control centre receive information from receptors ✔

increased blood acidity «and information from the proprioceptors» increases the depth / rate of ventilation ✔

Accept appropriately labelled diagram.

depletion of muscle and liver glycogen reserves reduces energy source for ATP production ✔

reduction in Ca⁺⁺ release reduces muscle ability to perform muscle contraction ✔

depletion of acetylcholine decreases effectiveness of muscle contraction ✔

«muscles contain approximately 70% water» dehydration decreases effectiveness of waste product removal ✔

electrolyte loss causes decreased nerve function and can cause cramping ✔

overheating causes decreased muscle function as enzymes work best at normal body temperature conditions ✔

increased peripheral fatigue takes place with unusually high intensity/lower VO₂max ✔

Award [2 max] for a list.

Post-exercise oxygen consumption/EPOC/oxygen debt takes place because there is a need for:
breathing remains elevated until recovery is complete ✔

EPOC is paying back the oxygen deficit during the initial energy demands achieved by the anaerobic systems ✔

reformation of phosphocreatine ✔

replenishment of myoglobin stores ✔

removal of lactic acid ✔

replenishment of glycogen stores «up to 24 hours» ✔

a highly trained aerobic athlete returns to a steady state quicker than untrained
OR
a highly trained aerobic athlete has a smaller EPOC than untrained ✔

Most candidates struggled to define cardiovascular drift, but were able to describe the impact of blood volume on stroke volume and the effect on HR.

Location of the pituitary gland was answered well. Very few candidates were unable to provide two functions of the gland.

Candidates gave very varied responses to this question. Overall most were able to identify that blood acidity was the factor that caused an increase in ventilation. However, some candidates struggled to link the cause of blood acidity and how it was detected.

Many candidates listed the causes of peripheral fatigue but were unable to explain the causes. Some candidates focused on the effect of anaerobic exercise rather than long-distance running.

Few candidates were unable to define EPOC and therefore struggled to explain what it was and the reason it occurs. Candidates who were able to provide a diagram were generally more successful.