Exercise Physiology Exam 2

Define direct calorimetry and explain how to do it

Measures heat produced by the body directly
Done with a calorimeter (insulated airtight chamber) to measure temp of the air entering and leaving the chamber

Define indirect calorimetry and explain how to do it

Estimating energy expenditure from O2 consumption (VO2) and CO2 production (VCO2)
Done with Douglas bag or modern computer systems

What are the benefits and limitations of direct calorimetry?

Benefits = direct measure of heat production, very accurate

Limitations = expensive, specialized equipment, not practical during most exercise

What are the benefits and limitations of indirect calorimetry?

Benefits = noninvasive, practical during exercise, can determine fuel source
Limitations = only accurate during steady-state aerobic exercise, equipment required

What is respiratory exchange ratio (RER)?

The ratio of the rate of CO2 release (VCO2) divided by the rate of oxygen consumption (VO2)
RER = VCO2 / VO2

Which food mixtures are being oxidized at different RER values?

0.70 RER = fat

0.85 RER = mixed fuel

1.00 RER = carbohydrate

What are the similarities and differences of the basal metabolic rate (BMR) and resting metabolic rate (RMR)?

Similarity = both estimate energy required to maintain life at rest

BMR = highly controlled conditions (overnight fast, complete rest)

RMR = less strict conditions, usually higher than BMR

What is an oxygen deficit?

Gap between oxygen needed and oxygen actually consumed at exercise onset (ATP-PCr and glycolytic systems fill the gap)

What is the excess postexercise oxygen consumption (EPOC)?

The volume of oxygen consumed during the minutes immediately after exercise ceases that is above that normally consumed at rest

What is lactate threshold and how is it measured?

The point at which blood lactate begins to substantially accumulate above resting concentrations during exercise of increasing intensity
Measured = blood lactate testing during graded exercise

What is economy of effort? Which runners (sprint, middle-distance, or distance runners) would exhibit the greatest economy of effort?

Oxygen cost of maintaining a given pace (better economy = less oxygen needed)
Greatest economy = distance runners

What is acute muscle soreness and what causes it?

Pain felt during and immediately after exercise

Results from accumulation of end products of exercise (H+) and tissue edema (swelling)

Explain delayed-onset muscle soreness (DOMS) and how to prevent it

Occurs 24-72 hours after exercise and varies from slight muscle stiffness to severe, debilitating pain that restricts movement
Prevention = start training at a very low intensity and progress slowly

Which muscle action (eccentric, concentric, or static action) is the primary initiator of DOMS?

Eccentric

Do DOMS assist or impede muscle fiber hypertrophy?

Assist, DOMS is most likely necessary to maximize the training response

What are exercise-associated muscle cramps (EAMCs)?

Painful involuntary muscle contractions that occur during or immediately after exercise

What are some methods to prevent and treat EAMCs?

Proper conditioning

Stretching

Hydration and electrolyte replacement

Reduce exercise intensity and duration at onset of muscle twitches

What is the path of blood through the right side of the heart (pulmonary circulation)?

Vena cava
Right atrium
Tricuspid valve
Right ventricle
Pulmonary valve
Pulmonary arteries
Lungs

What is the path of blood through the left side of the heart (systemic circulation)?

Lungs
Pulmonary veins
Left atrium
Mitral valve
Left ventricle
Aortic valve
Aorta
Body tissues

What are similarities and differences between cardiac and skeletal muscle?

Similarities = striated, actin and myosin, sarcomeres
Cardiac = involuntary, contract as single unit, one fiber type, contract due to calcium induced calcium release

Skeletal = voluntary, contract as separate units, multiple fiber types, contract due to action potential

Explain the cardiac conduction system and how signals are relayed

The cardiac conduction system is a specialized network of myocardial cells that generate and transmit electrical impulses
SA node → AV node → Bundle of His → Bundle branches → Purkinje fibers

Explain extrinsic control of heart activity (parasympathetic/sympathetic nervous system)

Parasympathetic = vagus nerve carries impulses to SA/AV nodes → releases ACh → decreases HR

Sympathetic = increases rate of depolarization and conduction speed of SA node → increases HR

What does the P wave represent on an ECG?

Atrial depolarization

What does the QRS complex represent on an ECG?

Ventricular depolarization

What does the T wave represent on an ECG?

Ventricular repolarization

What are the three basic components of an ECG

P wave, QRS complex, T wave

What is the cardiac cycle?

All the mechanical and electrical events that occur during one heartbeat

What is ventricular systole in the cardiac cycle?

Contraction phase, the ventricles contract and expel blood into the aorta and pulmonary arteries

What is ventricular diastole in the cardiac cycle?

Relaxation phase, the chambers fill with blood

What is stroke volume? Normal and exercise values? Equation?

The volume of blood pumped during one beat/contraction
Normal = ~70 mL/beat, Exercise = 100-200+ mL/beat
SV = EDV - ESV

What is ejection fraction? Normal and exercise values? Equation?

The fraction of blood pumped out of the left ventricle in relation to the amount of blood that was in the ventricle before contraction

Normal = 60%
EF = SV / EDV x 100

What is cardiac output? Normal and exercise values? Equation?

The total volume of blood pumped by the ventricle per minute

Normal = ~5 L/min, Exercise = 20-40 L/min

Q = HR × SV

What is blood pressure? What is SBP and DBP?

The pressure exerted by the blood on the arterial walls

Systolic = highest pressure in the artery during ventricular systole

Diastolic = lowest pressure in the artery during ventricular diastole

What is mean arterial pressure?  How can you calculate it?

The average pressure exerted by the blood as it travels through the arteries

MAP = 2/3 DBP + 1/3 SBP

How is blood flow determined and what are the factors that affect it?

Flow = ΔPressure / Resistance
Factors = pressure gradient, vessel radius, blood viscosity, vessel length

Describe the distribution of venous blood and how each mechanism (valves, muscle pumps, and respiratory pumps) assist venous return to the heart

Sympathetic stimulation of the venules and veins causes vessels to constrict
Valves = prevent backflow

Muscle pumps = contracting muscles squeeze veins

Respiratory pumps = breathing creates pressure changes that move blood toward the heart

What is the function of blood?

Transport oxygen from the lungs to the tissues and transport carbon dioxide back to the lungs to be exhaled

What is the function of red blood cells (erythrocytes)? White blood cells (leukocytes)? Plasma?

Red blood cells = transport oxygen

White blood cells = protect body from infection

Plasma = liquid matrix that suspends blood cells

What is plasma primarily composed of?

90% water

What is hematocrit?

The percentage of the total blood volume composed of cells or formed elements

What is an average hematocrit for adult men and adult women?

42% for adult men
38% for adult women

What happens to blood flow when levels of hematocrit approach 60%?

Blood becomes viscous and blood flow decreases

What is pulmonary ventilation, how does it work (inspiration, expiration), and what are the parts of the body affected?

Movement of air into and out of the lungs
Inspiration = diaphragm contracts, thoracic volume increases
Expiration = diaphragm relaxes, thoracic volume decreases

Define tidal volume

The amount of air entering and leaving the lungs with each breath

Define vital capacity

The greatest amount of air that can be expired after a maximal inspiration

Define residual volume

The amount of air remaining in the lungs after a maximal expiration

Define functional residual capacity

The amount of air remaining in the lungs after a normal expiration

Define total lung capacity

The sum of the vital capacity and the residual volume

What are the main purposes for pulmonary diffusion?

The exchange of oxygen and carbon dioxide between the lungs and blood

How does the pressure differ between the pulmonary and systemic circulation?

Pulmonary = low pressure

Systemic = high pressure

What are partial pressures of gases?

The individual pressures from each gas in a mixture (PO2, PCO2)

What is Dalton’s Law?

Total pressure = sum of partial pressures of all gases

What is Fick’s Law?

Gas diffusion increases = larger surface area, larger pressure gradient
Gas diffusion decreases = thicker membrane

What is Henry’s Law?

Amount of gas dissolved depends on = partial pressure, solubility of gas

How is oxygen transportated in the blood? What is hemoglobin?

~98% bound to hemoglobin
Hemoglobin = protein in RBCs that transports oxygen

What is the oxygen-hemoglobin dissociation curve?

The amount of hemoglobin saturated with oxygen at different PO2 values

What effects do changing blood pH and blood temperature have on the oxyhemoglobin dissociation curve?

Decreasing blood pH and increasing blood temperature cause the curve to shift downward and to the right (enhanced unloading)

What is the Bohr effect? What affect does it have on the dissociation curve and why?

Increased CO₂ and H⁺ decrease hemoglobin's affinity for oxygen, shifting the curve right and enhancing oxygen delivery to active tissues

How is carbon dioxide transported in the blood?

70% bicarbonate
23% bound to hemoglobin
7% dissolved in plasma

What does carbon dioxide bind to in hemoglobin?

Amino acids in the globin part (oxygen binds to heme group)

What factors influence O2 delivery and uptake?

O2 content
Blood flow
Temperature
pH
PO2 gradient

What is the (a-v)O2 difference?

The difference in oxygen content between arterial and venous blood

How is O2 transported in the muscle to the mitochondria?

Hemoglobin → plasma → myoglobin → mitochondria

How is CO2 removed from muscles?

Diffuses into blood, transported mainly as bicarbonate

What are central and peripheral mechanisms of ventilatory regulation?

Central = respiratory centers in the medulla and pons
Peripheral = chemoreceptors monitor O2, CO2, pH

Where are chemoreceptors and baroreceptors located?

Chemoreceptors = medulla, aortic bodies, carotid bodies
Baroreceptors = aortic arch, carotid arteries