96370
Description
Flashcards by alexlpeart, updated more than 1 year ago
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Created by alexlpeart
about 11 years ago
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| Question | Answer |
| Explain why we are more likely to experience heat stress when participating in endurance activities in warm countries compared to shorter events. | We see an intial decrease in blood flow upon the exercise onset, we then see vasodilation when we reach our thermal threshold so we can release more heat from the skin. When we undertake prolonged exercise we vasoconstrict skin in order to maintain central blood volume at the expense of poor heat control. |
| Describe the effects of dehydration when doing sport in hot conditions. | decreased sweating rate due to decreased plasma volume. Also leads to decreased SV so decreased CO so decreased VO2max. Also see decreased decreased muscle strength and increased use of glycogen/glucose. |
| What happens to us when we are exposed to hot conditions for a prolonged period of time? | Increase sweating rate, decreased threshold for sweating onset, decreased heart rate (back to normal), decreased core temp (back to normal), effective distribution of CO, decreased salt content of sweat (less electrolyte loss) less reliant on CHO metabolism |
| Give 6 factors affecting heat stress. | Acclimatization, fitness, clothing, environment (humidity/heat), wind, hydration |
| what is the effect of cold on performance? | Improve performance at low to moderate intensities but at high intensities decreases performance |
| Give normal core body temp | 36.5-37.5 |
| Where do we measure core temperature? | Hypothalamus |
| Give some methods of assessing core temperature. | Oral temp, rectal temp, tympanic temp, stomach temp |
| Give the 5 causes for change in temperature. Briefly explain what they each are. | Metabolic, heat byproduct of all reaction. Convection, between object and fluid e.g blood. Conduction, direct contact which travels down gradient. Radiation, electromagnetic waves. Evaporation, sweating. |
| Hows does the blood transfer heat round the body? | convection, then distributes heat. |
| When we are in high temperatures (above our core body temp) what method of cooling must we use and why. | Sweating, all other methods require heat to move down a concentration gradient so if the environment if hotter than us heat would be transferred into us. Sweating is the opposite whereby the hotter it become the quicker the rate of evaporation. |
| Where are thermoreceptors located? | Hypothalamus and the skin |
| Give the four things the hypothalamus controls on order to control core temperature. | Sweat glands, skin arterioles and the adrenal medulla, involuntary muscle contractions (shivering) |
| Central blood volume and stroke volume are ____ in heat. Why is this? | lower, more blood sent to the skin for thermoregulation. |
| Explain why we have an elevated heart rate in heat? | Lower central blood volume therefor heart rate needs to increase to compensate for the decreased SV. |
| The larger your initial the _____ the drop in CO we experience in heat. | larger |
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