Exam 2

Exercise Physiology: Metabolic Calculations and Endocrine System Study Guide

I. Quiz (Short Answer)

Answer each question in 2-3 sentences.

1. What is the significance of knowing the conversions for miles per hour to meters per minute and pounds to kilograms when performing metabolic calculations?

2. Explain the difference between gross and net VO2, and why is understanding this distinction important?

3. What does the term "work rate" refer to when using the leg or arm ergometer formulas, and why is it a common area for student errors?

4. What is the role of the hypothalamus in the endocrine system, and what is its approximate size?

5. What are the key differences between the anterior and posterior pituitary glands concerning their function?

6. How do the hormones secreted by the thyroid and parathyroid glands interact to maintain calcium homeostasis?

7. What is the function of aldosterone, and how does it contribute to fluid balance during exercise?

8. How do leptin and adiponectin influence metabolism, and what happens to their levels with increased fat mass?

9. What are myokines, and how do they affect skeletal muscle function and overall metabolism?

10. Describe how epinephrine and norepinephrine affect fuel utilization during exercise, noting differences in secretion rates based on activity type.

Quiz Answer Key

1. Knowing these conversions is crucial because the metabolic formulas require speeds to be in meters per minute and body weight to be in kilograms. Failing to convert properly will result in inaccurate VO2 calculations and incorrect estimations of caloric expenditure.

2. Gross VO2 refers to the total oxygen consumption, including the resting component, while net VO2 is the oxygen consumption specifically due to the exercise, excluding the resting component. This distinction is important for accurately assessing the caloric cost of exercise beyond basal metabolic needs.

3. Work rate, for leg and arm ergometer formulas, refers to the product of resistance, speed (RPM), and distance (flywheel). Students often make mistakes by omitting a component of the calculation or using incorrect units, thus resulting in an inaccurate VO2.

4. The hypothalamus controls secretions from the pituitary gland, linking the nervous and endocrine systems to maintain homeostasis. It’s about the size of an almond.

5. The anterior pituitary gland secretes hormones that control several bodily functions and other glands, including adrenocorticotropic hormone, follicle-stimulating hormone, luteinizing hormone, melanocyte-stimulating hormone, thyroid-stimulating hormone, prolactin, and growth hormone. The posterior pituitary gland releases oxytocin and antidiuretic hormone.

6. Calcitonin, secreted by the thyroid gland, lowers blood calcium levels by inhibiting calcium release from bones and stimulating kidney excretion, while parathyroid hormone increases blood calcium by stimulating calcium release from bones and reabsorption by the kidneys. These hormones work antagonistically to maintain blood calcium levels.

7. Aldosterone controls sodium reabsorption and potassium secretion by the kidneys, which influences water retention and blood volume. During exercise, it helps maintain plasma sodium and potassium levels, thus supporting fluid balance and preventing dehydration.

8. Leptin influences appetite, enhances insulin sensitivity, and promotes fatty acid oxidation, while adiponectin increases insulin sensitivity and fatty acid oxidation while also lowering the risk for type 2 diabetes and cardiovascular disease. With increased fat mass, leptin levels increase, while adiponectin levels decrease.

9. Myokines are proteins produced and released by skeletal muscles. As hormones, myokines regulate metabolism within muscle cells, control the switching and usage of different muscle types, and stimulate glucose uptake and fatty acid oxidation.

10. Epinephrine and norepinephrine increase glycogen breakdown (glycogenolysis) and free fatty acid mobilization and also interfere with glucose uptake during exercise. As exercise intensity increases, there is a greater rise in epinephrine. During prolonged activity, there is a greater increase in norepinephrine.

II. Essay Questions

1. Discuss the importance of understanding metabolic calculations in exercise physiology. How do these calculations assist in prescribing exercise, estimating energy expenditure, and monitoring training adaptations? Provide specific examples to illustrate your points.

2. Explain the role of the endocrine system in regulating metabolism and maintaining homeostasis during exercise. Focus on the interaction between slow-acting and fast-acting hormones and their impact on fuel utilization.

3. Compare and contrast the effects of training on hormone secretion rates and substrate utilization during exercise. What adaptations occur in trained individuals compared to untrained individuals, and how do these adaptations contribute to improved performance?

4. Discuss the potential health risks associated with the misuse of anabolic steroids. Explain how these substances impact hormone production, cardiovascular health, liver function, and mental well-being, providing specific examples to support your answer.

5. Explain the concept of the "fight or flight" response and the role of the adrenal medulla in mediating this response. Discuss the physiological changes that occur during the "fight or flight" response and how they prepare the body for immediate action.

III. Glossary of Key Terms

• VO2: Volume of oxygen consumed; a measure of cardiorespiratory fitness.

• Relative VO2: Volume of oxygen consumed relative to body weight (mL/kg/min).

• Absolute VO2: Volume of oxygen consumed expressed in liters per minute (L/min) or milliliters per minute (mL/min).

• Metabolic Equivalent (MET): A unit used to estimate the amount of oxygen used by the body during physical activity; 1 MET is equal to 3.5 mL/kg/min.

• Gross VO2: The total oxygen consumption, including resting oxygen consumption.

• Net VO2: Oxygen consumption due solely to exercise, excluding resting oxygen consumption.

• Work Rate: Measure of the rate of work performed, especially on a cycle ergometer, usually expressed in watts or kg·m/min.

• Hormone: Chemical messenger secreted by endocrine glands that exerts a specific effect on target cells.

• Endocrine System: A collection of glands that produce hormones regulating metabolism, growth, reproduction, and other bodily functions.

• Hypothalamus: A region of the brain that controls the pituitary gland and regulates various bodily functions.

• Pituitary Gland: An endocrine gland located at the base of the brain that secretes various hormones regulating growth, metabolism, and reproduction.

• Thyroid Gland: An endocrine gland located in the neck that secretes hormones regulating metabolism.

• Parathyroid Gland: An endocrine gland located near the thyroid gland that secretes parathyroid hormone, which regulates calcium levels in the blood.

• Adrenal Glands: Endocrine glands located above the kidneys that secrete hormones involved in stress response, metabolism, and electrolyte balance.

• Pancreas: An organ located near the stomach that secretes insulin and glucagon, regulating blood glucose levels, and digestive enzymes.

• Ovaries: Female reproductive organs that produce estrogen and progesterone, regulating the menstrual cycle and reproduction.

• Testes: Male reproductive organs that produce testosterone, regulating male sexual development and function.

• Leptin: A hormone secreted by adipose tissue that influences appetite and metabolism.

• Adiponectin: A hormone secreted by adipose tissue that increases insulin sensitivity and promotes fatty acid oxidation.

• Myokines: Cytokines and other peptides produced and released by skeletal muscle during contraction.

• Gluconeogenesis: The synthesis of glucose from non-carbohydrate precursors, such as amino acids and glycerol.

• Glycogenolysis: The breakdown of glycogen into glucose.

• Lipolysis: The breakdown of triglycerides into fatty acids.

• Fast-Acting Hormones: Hormones that elicit a rapid response, such as epinephrine, norepinephrine, insulin, and glucagon.

• Slow-Acting Hormones: Hormones that elicit a slower, more sustained response, such as thyroxine, cortisol, and growth hormone.

• Steroid Hormones: Hormones derived from cholesterol, such as testosterone, estrogen, and cortisol.

• Non-Steroid Hormones: Hormones derived from amino acids or proteins, such as insulin, glucagon, and epinephrine.

• Adrenocorticotropic hormone (ACTH): Hormone that stimulates cortisol release from your adrenal glands.

• Follicle stimulating hormone (FSH): Hormone that controls sperm production for males and ovulation for females.

• Luteizing hormone (LH): Hormone that controls testosterone in males and estrogen in females.

• Melanocyte stimulating hormone: Controls skin pigmentation in your hair and skin.

• Thyroid stimulating hormone (TSH): Controls thyroid hormone released from the thyroid gland.

• Prolactin: Milk production.

• Growth hormone: Growth and metabolism.

• Oxytocin: Speeds up those uterine contractions and allows the the baby to move down the birth canal during labor.

• Antidiuretic hormone: Controls water volume and blood pressure.

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