1. Describe the cardiovascular effects of catecholamines – why are these importa
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Question
1. Describe the cardiovascular effects of catecholamines – why are these important during exercise? What would likely happen to our maximal exercise capacity if our sympathetic nervous system was strongly suppressed? Why? (Broad question but think about cardio + metab effects)
2. How does sympathoadrenal activity change in response to an ABSOLUTE workload (i.e. 200W on the bike) after endurance training? How does the response change in response to a same RELATIVE workload? (i.e. 50% of pre-training VO2max vs 50% of post-training, greater VO2max).
3. What are some noninvasive markers of SNS activity that we can use instead of measuring catecholamines in the blood?
4. Why do cortisol levels rise later than catecholamine levels do, during prolonged exercise? Why does taking glucose steadily during the exercise bout prevent the rise in cortisol, but doesn’t suppress catecholamines as much?
5. Describe the direct and indirect effects of growth hormone.
6. Why does chronically high GH result in acromegaly?
7. How would you respond to someone in the gym telling you they’re starting to use growth hormone to enhance their gains in muscle hypertrophy and muscle strength?
1. Describe the cardiovascular effects of catecholamines- why are these important during exercise? What would likely happen to our maximal exercise capacity if our sympathetic nervous system was strongly suppressed? Why? (Broad question but think about cardio +metab effects) 2. How does sympathoadrenal activity change in response to an ABSOLUTE workload (i.e. 200W on the bike) after endurance training? How does the response change in response to a same RELATIVE workload? (ie, 50% of pre- training VO2max vs 50% of post-training, greater VO2max) 3. What are some noninvasive markers of SNS activity that we can use instead of measuring catecholamines in the blood? 4. Why do cortisol levels rise later than catecholamine levels do, during prolonged exercise? Why does taking glucose steadily during the exercise bout prevent the rise in cortisol, but doesn't suppress catecholamines as much? 5. Describe the direct and indirect effects of growth hormone 6. Why does chronically high G 7. How would you respond to someone in the gym telling you they're starting to use growth hormone to enhance their gains in muscle hypertrophy and muscle strength? H result in acromegaly?Explanation / Answer
1. Catecholamines (epinephrine and norepinephrine) increases heart rate, inotropic effect and overall increase in cardiac output.
- An exercise may lower blood glucose levels and may need more blood flow, calcium for the contraction of muscles and due to increased work load. This may lead to release of catecholamines which are called stress hormones to compensate the blood requirement of the muscles for contraction and causes increased heart rate and cardiac output.
- Maximum exercise capacity may decrease when sympathetic nervous system is suppressed because muscles may not be able to contract effectively and completely due to low blood glucose levels and inability to receive required blood circulation in the absence of catecholamines.
4. Catecholamins help the body and brain be alert, needing immediate response and regulating blood flow, muscle contractions within seconds, whereas Cortisol takes care of less important functions at the moment such as reproductive drive, immunity, digestion, etc. Moreover, Cortisol may take minutes to release from adrenal glands as the processing of exercise or stressful situation may have to go to amygdala first and then hypothalamus and it's release may follow only a release of Corticotropin Releasing Hormone from hypothalamus and then release of Adrenocorticotropic Hormone from pituitary gland.
- Taking glucose steadily during exercise bout prevent the rise in cortisol because cortisol acts mainly on non-crucial events at the moment of exercise such as reproductive drive, immunity, digestion and as glucose requirement by the body is met by intake, there is usually no need of cortisol to compensate the low blood glucose levels. Whereas catecholamines are important to maintain blood flow and meet the need of contracting muscles by increasing heart rate and cardiac output at the moment which doesn't depend on or relevant to glucose intake.
5. Growth Hormone promotes growth, stimulates skeletal muscle growth and elevates blood glucose levels which are a few of the indirect effects.
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