Ex Physiology Exam 3

The volume of gas that reaches the gas-exchange zone of the lung is termed

alveolar ventilation

A decline in arterial PO2 to 70 mm Hg or below would likely result in

an increase in alveolar ventilation

The primary adaptations that occur during heat acclimatization are

an increased plasma volume, earlier onset of sweating, and a higher sweat rate.

The ability of histidine to buffer hydrogen ions is because histidine contains

an ionizable group.

Which of the following events are not primary sources of hydrogen ions during rigorous exercise?

anaerobic production of 3-phosphoglucose during glycolysis

The respiratory system works in the regulation of acid-base balance by lowering

arterial PCO2

Which of the following statements about body temperature homeostasis is correct?

Body temperature is a balance between heat loss and heat gain.

Which of the following transporters in skeletal muscles are responsible for moving hydrogen ions across the sarcolemma?

Both sodium-hydrogen exchanger and monocarboxylate transporter are correct

The central chemoreceptors that influence the control of breathing respond to changes in the

PCO2 and H+ of cerebral spinal fluid.

An increase in alveolar ventilation (at rest) resulting in hyperventilation will reduce arterial ______ and increase ______.

PCO2; pHCarbon dioxide is transported in arterial blood principally as

The bicarbonate buffer system is involved in both intracellular buffering and blood buffering of hydrogen ions

True

In healthy and untrained subjects, the alinear rise in minute ventilation observed during incremental exercise (i.e., ventilatory threshold) could be due to

a decrease in arterial pH

Small changes in arterial PCO2 have ______________ effect on ventilation compared to small changes in PO2.

a greater

At a low PO2, myoglobin has _______________ affinity for O2 than hemoglobin.

a higher

An increase in blood temperature and a decrease in blood pH would result in ____ in the oxyhemoglobin dissociation curve.

a rightward shift

Studies reveal that ventilation drifts upward during constant-load submaximal exercise performed in a hot and humid environment. This is likely due to

a significant increase in blood temperature.

Calculate the total evaporation of sweat necessary to prevent heat gain in the body given the following information: Total body energy expenditure = 250 Kcal Exercise efficacy = 20% Evaporation of 1000 ml of sweat results in 580 Kcal of heat loss Therefore, the total evaporation of sweat necessary to prevent body heat gain in these conditions is

0.344 liters.

Muscle pH is generally

0.4-0.6 pH units lower than arterial pH.

During exercise at sea level, young, healthy untrained subjects generally maintain exercise arterial PO2 within

10-12 mm Hg of resting values

Under normal conditions at sea level, the partial pressure of oxygen in the alveoli region of the lung is

100 mm Hg

A single bout of resistance exercise training increases muscle protein synthesis by as much as ______% above resting levels

120-150

Endurance exercise training programs (e.g., 3 days/week @ 60% VO2 max for 12 weeks) lasting typically result in a ______% improvement in VO2 max.

15-20

A by-product of anaerobic glycolysis in red blood cells that shifts the O2-Hb dissociation curve to the right at high altitude is

2-3 DPG

Four-to-ten weeks of anaerobic training (high intensity exercise lasting 10-30 seconds) can increase the peak anaerobic capacity by ______ across individuals

3-25%

Prolonged exercise results in a significant increase in body core temperature. Calculate the increase in body core temperature during exercise given the following: Total energy expenditure during exercise = 600 Kcal Exercise efficiency = 20% Total heat stored during exercise = 192 Kcal Subject body weight = 60 Kg Amount of heat required to increase body temperature by 1°C = 0.83 kcal/kg Therefore, the total increase in body temperature following exercise would be

3.86 degrees Celsius

Which of the following conditions would result in the highest vapor pressure in the air?

30°C, 75% relative humidity

Following a single bout of resistance exercise training, muscle protein synthesis can remain elevated above baseline for as much as ______ in both trained and untrained individuals

40-50 hours

The average VO2 max value for the young (e.g., 21 years old) male sedentary population is approximately

45 ml· kg-1· min-1.

Heritability (i.e., genetics) determines approximately _____% of VO2 max variability in sedentary adults

50

High responders to endurance exercise training (i.e., individuals that achieve large increases in VO2 max) can achieve up to ______% improvement in VO2 max following a prolonged and intense training program.

50

Evaporation of one liter of sweat would result in the loss of ________ kcal of heat.

580

Heat acclimatization occurs generally within

7-14 days

Using the Henderson-Hasselbalch equation, calculate the pH of blood given: pKa = 6.1 blood concentration of carbonic acid = 1.2 mEq/L blood concentration of bicarbonate = 24 mEq/L Your calculation reveals that the pH of blood is

7.4

During exercise ____________ of energy produced is released as heat.

70-80%

which of the following track running events would have the greatest risk of acid-base disturbance?

800 meter run

Which of the following is true of the pH of arterial blood?

A pH of 7.0 would be considered acidosis.

Activation of rectus abdominis muscles would result in

active expiration

Hyperventilation at rest can result in ___ due to _____

alkalosis; decreased blood levels of carbon dioxide

In a healthy individual resting at sea level, which of the following characteristics of arterial blood are correct?

all of these answers are correct

According to Fick's law of diffusion, the rate of diffusion of a gas across a tissue is directly proportional to the

all of these are correct

Cold acclimation results in which of the following physiological adaptations?

all of these are correct

Heat production can be increased through

all of these are correct

Regulation of body core temperature is important because

all of these are correct

The enhanced capacity of the trained muscle to use fatty acids as a fuel results in

all of these are correct

Which of the following could be a mechanism of heat gain in a hot and sunny environment?

all of these are correct

Which of the following events occurs during exercise at work rates above 60-80% VO2 max?

all of these are correct

Which of the following statements about a buffer is correct?

all of these are correct

Which of the following statements about myoglobin are true?

all of these are correct

Which of the following statements about pulmonary physiology is correct?

all of these are correct

Which of the following statements are true about heat shock proteins?

all of these are correct

The transfer of heat from the body into molecules of cooler objects in contact with its surface is called

conduction

An increase in body core temperature results in

cutaneous vasodilation

Hypothermia is defined as a significant

decrease in body core temperature

The most important muscle of inspiration is/are the

diaphragm

A high percentage of body fat results in an increased ability to lose body heat during exercise

false

Following endurance training, maximal cardiac output during exercise is increased due to an increase in the thickness of the left ventricular wall (i.e., ventricular muscle mass increases).

false

Research indicates that several months of endurance training results in significant changes in both lung structure and pulmonary function.

false

The evaporation of 1,000 ml of sweat results in the loss of 1,000 kcal of heat.

false

The initial decrease in VO2 max with detraining occurs because skeletal muscle adaptations (a-vO2 difference) are lost.

false

The majority of evidence demonstrates that resistance training-induced muscle hypertrophy is the result of muscle fiber hyperplasia.

false

The principal buffer against acidosis during exercise is intracellular phosphate groups.

false

The pulmonary system does not limit VO2 max in elite endurance athletes that exhibit exercise-induced hypoxemia.

false

In the standing position, blood flow to the base of the lung is ______________ blood flow to the apex.

greater than

Humans and other animals that maintain a rather constant body temperature are called

homeotherms

A single bout of resistance exercise training results in an increase in skeletal muscle protein synthesis. This exercise-induced increase in muscle protein synthesis can occur within _____ following the exercise session.

hours

Following an acute bout of endurance exercise training, the increase in mitochondrial biogenesis occurs within _____ following the completion of the exercise session.

hours

The body's thermostat is located in the

hypothalamus

Exercise-induced hypoxemia that often occurs in elite endurance athletes during heavy exercise is likely due to

impaired alveolar ventilation resulting in hypoventilation.

Metabolic acidosis can result from the overproduction of ketoacids, which can occur

in uncontrolled diabetes.

Which of the following factors does NOT contribute to the endurance exercise training-induced increases in fat metabolism during exercise?

increased fat storage in the liver

Exercise in the heat is associated with accelerated fatigue due, in part, to

increased free radical production in the active skeletal muscles

Which of the following endurance training adaptations does NOT result in lower lactate production in the contracting muscles

increased glycogen utilization

Which of the following physiological factors does NOT contribute to the endurance exercise training-induced increase in the maximal a-vO2 difference?

increased hemoglobin in the blood

Which of the following factors contributes to the endurance exercise training-induced improvement in VO2 max?

increased maximal stroke volume

Which of the following endurance training adaptations assist in maintaining acid-base balance during exercise?

increased mitochondrial volume in skeletal muscle

Studies reveal that exercise training improves muscle buffering capacity. Which of the following exercise-induced changes is NOT responsible for training-induced improvements in muscle buffering capacity?

increased muscle levels of citrate synthase

Which of the following factors does NOT contribute to the endurance exercise training-induced improvement in stroke volume during exercise?

increased peripheral resistance

Endurance training has been shown to reduce the oxygen deficit in subjects performing a submaximal exercise. This is due to

increases in the number of mitochondria and capillaries.

Exercise-induced asthma could impair pulmonary gas exchange by

increasing airway resistance.

Sodium bicarbonate has been ingested by athletes in an attempt to improve performance by

increasing blood buffering capacity.

The first line of defense in protecting against pH change during exercise is

intracellular buffers

Most of the O2 contained in the blood

is bound to hemoglobin as oxyhemoglobin

The most common and strongest acid produced in skeletal muscle during heavy exercise is ________________ acid.

lactic

The higher the relative humidity, the __________ vapor pressure gradient between the skin and the environment.

lower

After a 15-week program of endurance exercise training, which of the following cardiovascular variables does NOT decrease after 14 days of detraining?

maximal heart rate

The term ventilation refers to the

mechanical process of moving air in and out of the lungs.

The respiratory control center is located in the

medulla oblongata

Following an acute bout of endurance exercise training, the rise in the activity of calcinurin, calmodulin kinase, and AMP kinases occurs within _____ following the exercise session

minutes

Endurance exercise training results in an increased turnover of mitochondria in skeletal muscle. The process of removing old and damaged mitochondria is called ______.

mitophagy

Acids are defined as

molecules that release hydrogen ions (H+).

An increase in PCO2 in the blood results in the formation of bicarbonate in the red blood cell. Because bicarbonate carries a negative charge (anion), the removal of negatively charged molecule from the red blood cell is required to prevent an electrochemical imbalance across the cell membrane. This problem is avoided by

movement of chloride molecules into the red blood cell.

During the first 10 weeks of a resistance training program, the initial increase in muscular strength are due primarily to

neural adaptations

Several mechanisms have been proposed to explain why concurrent endurance and resistance (strength) training impedes strength development compared to strength training alone. Which of the following mechanisms have NOT been proposed to explain why concurrent training impedes strength development?

none of the above is correct

Acidosis can occur due to

none of these

Repeated bouts of high intensity exercise (e.g., interval training) can reduce arterial pH to levels as low as

none of these are correct

The primary drive to increase ventilation during exercise is due to

none of these are correct

Which of the following training adaptations does NOT occur in skeletal muscles following 4-10 weeks of anaerobic exercise training?

none of these are correct

The carotid bodies are chemoreceptors that are sensitive to changes in arterial

pH, PCO2, and PO2

It is well known that resistance exercise training promotes an increase in muscle protein synthesis by activating the mechanistic target of rapamyosin (mTOR) which results in increased protein synthesis. Recent evidence suggests that two signaling molecules interact to directly activate mTOR. These molecules are:

phosphatidic acid and Ras homologue enriched brain (Rheb)

The principal means of heat loss at rest in a cool indoor environment (20°C/low humidity) is via

radiation

Which of the following could be a mechanism of heat gain in a hot and sunny environment?

radiation

According to the Henderson-Hasselbalch equation, the pH of a weak acid solution is determined by

ratio of the concentration of the base in solution to the concentration of the acid.

An increase in blood levels of carbon dioxide results in a decrease in blood pH because an increase in PCO2

reacts with water to form carbonic acid, which dissociates to release H+

Exercise performance in endurance events is impaired in a hot and humid environment. Which of the following physiological factors does NOT have a negative impact on exercise performance in a hot and humid environment?

respiratory dysfunction

Which of the following plays an important role in acid-base balance during exercise?

respiratory system

Compared to exercise in a cool environment, prolonged exercise in the heat

results in a more rapid onset of muscular fatigue

Endurance training results in increased mitochondrial and capillary density in muscle but has no effect on muscle glycolytic capacity. This is an example of what training principle?

specificity

Cross-sectional studies demonstrate that the physiological variable responsible for the large variation in VO2 max across the normal population is maximal

stroke volume

In a pulmonary function test, a FEV1/FVC ratio of 0.60 is

suggestive of airway obstruction

A ventilation-perfusion (V/Q) ratio of 0.64 would indicate

that blood flow is higher than ventilation in this region of the lung.

The primary source of heat production during exercise is

the contracting skeletal muscles.

The increase in VO2 max that occurs following 4 months of endurance exercise training results from an increase in both maximal cardiac output and maximal a-vO2 difference. Relatively short durations of endurance exercise training (e.g., 1-4 months) increases VO2 max primarily by increasing

the maximal cardiac output.

The amount of gas moved per breath is called

tidal volume

Which of the following is NOT an important function of the pulmonary system?

to cool the airways

The heart rate and ventilatory responses to a fixed submaximal work rate are lower (i.e., lower heart rate and lower minute ventilation) following an endurance training program. This training-induced adaptation is primarily due to changes in the

trained skeletal muscles.

A lack of the enzyme carbonic anhydrase would affect the ability of the body to both buffer the blood and to transport CO2.

true

According to Dalton's law, the total pressure of a gas mixture is equal to the sum of pressures of each gas in the mixture.

true

An example of a strong base is bicarbonate (HCO3-).

true

An increase in the hydrogen ion concentration in contracting skeletal muscle can impair performance by hydrogen ions competing with calcium ions for binding sites on troponin.

true

Cold acclimatization results in an improved ability to sleep in a cold environment.

true

Dehydration that results in a loss of 1-2% of body weight is sufficient to impair exercise performance.

true

During exercise in a hot and humid environment, heat loss via evaporation is decreased compared to exercise in a cool and low humidity environment.

true

During exercise, a right shift in the oxyhemoglobin disassociation curve insures that more oxygen is unloaded from hemoglobin to the working muscle compared to rest.

true

During exercise, body temperature is regulated by making adjustments in the amount of heat that is lost.

true

During resting conditions, the intrapleural pressure is typically lower than the intrapulmonary pressure.

true

Following endurance training, afterload decreases during maximal exercise because there is a decrease in sympathetic vasoconstrictor activity in the arterioles of the exercising muscles

true

In a "two-legged" maximal cycle ergometer test, if each leg were to vasodilate to the extent experienced in a one-legged VO2 max test, mean arterial blood pressure would fall below normal levels

true

In general, during exercise in a thermoneutral environment, the increase in core temperature is directly related to the exercise intensity.

true

Individuals with a high percentage of body fat have an advantage over lean individuals in tolerance to cold

true

One of the principal means by which the kidneys regulate acid-base balance is by increasing or decreasing the bicarbonate concentration of the blood.

true

Pre-cooling the body before performing prolonged exercise in a hot and humid environment has been shown to significantly improve performance.

true

Reducing the number of motor units required to perform an exercise task may reduce the heart rate and ventilation required to perform the task.

true

Research indicates that anyone can increase his or her VO2 max with training, yet a genetic predisposition is required to have a VO2 max comparable to that of an elite endurance athlete

true

Training in a cool environment while wearing warm clothing (e.g., sweats) promotes heat acclimatization

true

In resting skeletal muscle fibers, Ras homologue enriched brain (Rheb) activation of mTOR is inhibited by ______.

tuberous sclerosis complex 2 (TSC2)

Carbon dioxide is transported in arterial blood principally as

bicarbonate

The most important of the blood buffers is/are

bicarbonate

Which of the extracellular buffers contributes the most to the cell's buffering capacity?

bicarbonate

Gas exchange in the lungs occurs

both across approximately 300 million alveoli and in the respiratory zone are correct answers

Compared to the oxyhemoglobin dissociation curve, the myoglobin dissociation curve _____

both is much steeper at PO2's below 20 mm Hg and reaches a plateau at a much lower PO2 are correct

In response to a decrease in body temperature, humans often exhibit ____________ upon response to cold.

both peripheral vasoconstriction and shivering are correct

In theory, concurrent resistance and endurance exercise training can impair muscle protein synthesis following a bout of resistance exercise. The proposed mechanism to explain this inhibition is ___.

AMP kinase activation of TSC2