Exam 1 Study Guide

Question 1

Explain the rationale for substituting the blood lactate threshold for to predict endurance performance.

Answer 1

Changes in endurance performance with training often relate more closely to training-induced changes in the exercise-induced level for OBLA (peripheral adaptations) than to changes in VO2max (central circulatory adaptations).

Question 2

Describe how hyperventilation extends breath-holding time

Answer 2

Alveolar Pco2 with hyperventilation may decrease. Consequently, a larger than normal amount of carbon dioxide leaves the blood, decreasing arterial Pco2, reduced Pco2 extends the breath-hold until it reaches normal levels again

Question 3

Graph relationships among pulmonary ventilation, blood lactate concentrations, and oxygen uptake during incremental physical activity.

Answer 3

Shows that exercise intensity or oxygen uptake where blood lactate begins to increase above a baseline level of about 4mM indicates the point of onset blood lactate accumulation (OBLA)

Question 4

List and quantify three mechanisms for carbon dioxide transport in blood.

Answer 4

Physical solution in plasma (7% to 10%), loose combination with Hb (20%), combined with water as bicarbonate (70%)

Question 5

Identify three major factors that regulate pulmonary ventilation during rest and physical activity.

Answer 5

Neural information from higher brain centers, lungs, and mechanical and chemical sensors throughout the body regulates pulmonary ventilation.

Question 6

Describe the dynamics of inspiration and expiration during rest and physical activity.

Answer 6

During inspiration, the chest cavity increases in size because the ribs rise and the muscular diaphragm lowers. During exhalation, the ribs swing down, and the diaphragm returns to a relaxed position. During physical activity, inspiration causes the scalene and external intercoastal muscles between the ribs contract. Expiration, the internal intercostal muscles and abdominal muscles act powerfully on the ribs and abdominal cavity to produce a rapid and greater exhalation depth.

Question 7

Define and quantify static and dynamic lung function measures and their relation to physical performance.

Answer 7

Static lung volume tests evaluate the dimensional component for air movement within the pulmonary tract and impose no time limitation on the individual. In contrast, dynamic lung volume measures assess the power component of pulmonary performance during different phases of the ventilatory excursion.

Question 8

Describe the Valsalva maneuver and its physiologic consequences.

Answer 8

It stabilizes the abdominal wall and thoracic cavities to enhance muscle action. Performing a prolonged Valsalva maneuver during static or isometric straining type movements dramatically reduces venous return and arterial blood pressure. These two effects diminish the brain’s blood supply, often producing dizziness, “spots before the eyes,” or fainting.

Question 9

State three potential benefits of aerobic activity for treating moderate hypertension.

Answer 9

Following a bout of sustained light-to-moderate-intensity physical activity, SBP temporarily decreases below pre-exercise levels for up to 12 hours in normal and hypertensive subjects.

Question 10

Identify two intrinsic and extrinsic factors that regulate heart rate during rest and physical activity.

Answer 10

Intrinsic: the electrical impulse system, SA and AV nodes.
Extrinsic: sympathetic nervous system (epinephrine, norepinephrine) and parasympathetic nervous system (ACH)

Question 11

Identify two neural and local metabolic factors that regulate blood flow during rest and physical activity.

Answer 11

Local: increases in temperature, CO2 acidity, adenosine, nitric oxide, magnesium and potassium ions enhance regional blood flow.

Neural: sympathetic and parasympathetic portions of ANS override vasoregulation afforded by local factors to provide central vascular control.

Question 12

Explain three physiologic mechanisms that affect the heart’s stroke volume.

Answer 12

Enhanced cardiac filling (in diastole followed by more forceful systolic contraction), neurohormonal influence (causes normal ventricular filling with forceful ejection and emptying during systole), training adaptations (expand blood volume and reduce resistance to blood flow in peripheral tissues)

Question 13

Describe the relationship between maximal cardiac output and maximal oxygen uptake among individuals with varied aerobic fitness levels.

Answer 13

Endurance athletes have a higher cardiac output and oxygen uptake than sedentary people

Question 14

Explain how exercise training modifies muscle fibers and fiber types.

Answer 14

Individual differences prevalent in muscle fiber type distribution, genetic code largely determines the predominant fiber type, specific training improves metabolic capacity of each fiber type.

Question 15

Describe the sequence of chemical and mechanical events during skeletal muscle contraction and relaxation.

Answer 15

1. Sac-like vesicles within terminal axon release Ach.
2. Muscle action potential depolarizes transverse tubules.
3. T-tubule system depolarization causes Ca2+ release.
4. Ca2+ binds to troponin
5. Actin joins myosin ATPase to split ATP with energy release during muscle action.
6. A muscle shortening occurs after ATP binds to the myosin crossbridge
7. Ca2+ concentration remains high to inhibit troponin – tropomyosin action.
8. When muscle stimulation ceases, Ca2+ moves back into the sarcoplasmic reticulum lateral sacs through active transport via ATP hydrolysis.
9. Ca2+ removal restores troponin – tropomyosin inhibitory action

Question 16

Contrast slow- and fast-twitch muscle fiber characteristics, including subdivisions.

Answer 16

Slow twitch (type 1) muscle fibers are slow-oxidative fibers, resist fatigue and power in prolonged anerobic PA, fast twitch (type IIa) exhibits fast shortening speed and well-developed capacity for energy transfer from aerobic and anaerobic sources (fast oxidative-glycolytic fibers). Type IIx fibers possess greatest anaerobic potential and rapid shortening velocity (fast-glycolytic fiber)

Question 17

Describe the main function of muscle spindles and Golgi tendon organs.

Answer 17

Muscle spindles provide mechanosensory information about changes in muscle fiber length and tension. Golgi tendon organs protect muscle and its connective tissue harness from injury by sudden, excessive load or stretch

Question 18

List the hormones secreted by the anterior and posterior pituitary glands, and explain how acute and chronic physical activity affect their release.

Answer 18

Anterior pituitary: Growth hormone, corticotropic (training increases ACTH levels during PA), prolactin, FSH, LH, testosterone (PA reduces reproductive hormones in men and women)

Posterior pituitary: Antidiuretic hormone, oxytocin, thyroid hormones (moderate physical activity provides a potent stimulus for ADH secretion)

Question 19

Describe how hormones alter cellular reaction rates of specific target cells.

Answer 19

Change intracellular proteins synthesis rate, alter enzyme activity rate, modify cell membrane transport, influence secretory activity.

Question 20

Outline five benefits of regular physical activity for a type 2 diabetic.

Answer 20

Improves glycemic control, cardiovascular function, body composition, psychological profile, reduces broad array of risks for heart disease.

Question 21

Explain three general training effects on endocrine function.

Answer 21

Changes in hepatic and extrahepatic hormone clearance rates, differential rates of hormone secretion with accompanying fluid shifts around the receptor sites, altered receptor-site activation via neurohumoral control.