Ex Physio Exam 3

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.

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 KgAmount 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°C

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

30°C, 75% relative humidity

In most subjects, stroke volume continues to increase during incremental exercise up to approximately

40% of VO2 max

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

580

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

6.8-7.0.

Heat acclimatization occurs generally within

7 to 14 days.

Using the Henderson-Hasselbalch equation, calculate the pH of blood given:pKa = 6.1blood concentration of carbonic acid = 1.2 mEq/Lblood concentration of bicarbonate = 24 mEq/LYour 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

An increase in body core temperature typically results in

?

In the transition from rest to exercise, what is the distribution of cardiac output to the heart?

?

Withdrawal of parasympathetic influence on the heart results in

?

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

A pH of 7.0 would be considered acidosis.

During a graded exercise test, the increase in ventilation during the transition from rest to moderate exercise is achieved by

An increase in both breathing frequency and tidal volume.

Which of the following represents the correct order of events of the flow of blood after it leaves the left ventricle and before it returns to the right atrium?

Blood flows through the aorta, oxygen moves out of the capillaries, blood flows through the venules, blood enters the veins.

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 statements about hemoglobin's buffering capacity are true?

Both Hemoglobin has six times the buffering capacity of plasma proteins because of it's concentration and Deoxyhemoglobin is a better buffer than oxyhemoglobin are correct.

Which of the following statements about skeletal muscle buffer systems is correct?

Both Two monocarboxylate transporters exist in human skeletal muscle fibers and High intensity exercise training has been reported to improve muscle buffer capacity by increasing both carnosine and hydrogen ion transporters in skeletal muscle are correct

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

Which of the following statements about sex differences in breathing are correct?

Both when matched for age and body weight, women have smaller airways compared to men and the energy requirement for breathing during exercise is higher for women compared to men are correct.

The relationship between oxygen uptake, cardiac output, and the arterial-venous oxygen difference is described mathematically by the

Fick equation.

The fact that an increase in end-diastolic ventricular volume increases the stroke volume of the heart is an illustration of the

Frank-Starling law of the heart.

If a person with ischemic heart disease experiences chest pain when their double product exceeds 20,000, which of the following combinations will produce angina?

HR = 150, BP = 150/80

The age-dependent decrease in maximal heart rate can be estimated via the Karvonen formula

HR max = 220 - age.

Which of the following statements about heart rate variability (HRV) is NOT true?

HRV decreases in response to regular aerobic exercise training.

How do changes in muscle pH affect exercise performance?

Hydrogen ions compete with calcium ions for binding sites on troponin, thereby hindering the contractile process

Which of the following statements are true about the changes in ventilatory patterns during exercise?

Increasing tidal volume during exercise ensures that dead space ventilation remains small, Changes in breathing patterns during exercise are important to ensure that optimal mechanics of breathing are realized during exercise, Changes in breathing patterns during exercise are designed to reduce the risk of respiratory muscle fatigue (all of the above)

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; pH

Which of the following most accurately describes changes in autonomic control of heart rate during incremental exercise (from rest to VO2 max)?

PNS withdrawal is followed by SNS outflow

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

Production of 3-phosphoglucose during glycolysis

The __________ represents ventricular repolarization during a recording of the electrical activity (i.e., ECG) of the heart.

T wave

Which of the following is the correct order of events pertaining to contraction of the left ventricle?

The bundle branches depolarize, the ventricle contracts, the ventricular pressure increases, and blood exits the ventricle.

Which of the following statements about pulmonary physiology is correct?

The percentage of O2 in the air at sea level is the same as at high altitude., The PO2 of inspired air at sea level is approximately 159 mm Hg., The percentage of CO2 in the air is 0.0003. (all of the above)

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

They stabilize and refold damaged cellular proteins., Repeated bouts of exercise in warm or hot environments increase their synthesis in cells., They assist cells in tolerating heat stress. (all of the above)

Which of the following conditions and/or diseases can result in metabolic acidosis or alkalosis?

Vomiting, Kidney diseases that result in a loss of acids, Uncontrolled diabetes (all of the above)

Which of the following statements about a buffer is correct?

a buffer resists pH change, buffers often consist of a weak acid and its conjugate base, a buffer removes hydrogen ions from solution (all of the above)

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.

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

a decrease in plasma bicarbonate concentration, a decrease in blood pH, an increase in blood lactic acid concentration (all of the above)

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

a diffusion limitation secondary to a rapid red blood cell transit time.

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

a higher

A significant increase in blood temperature (i.e. from 37ºC to 39ºC) 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 body temperature.

Gas exchange in the lungs occurs

across approximately 300 million alveoli.

Contraction of the rectus abdominis muscles would result in

active expiration.

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

alveolar ventilation.

Which of the following would not result in an increase in stroke volume during exercise?

an increase in afterload

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

an increase in alveolar ventilation.

In order to meet the increased oxygen demands of muscle during exercise, two major adjustments in blood flow must be made:

an increase in cardiac output and a redistribution of blood flow from inactive tissues to skeletal muscles.

Which of the following is NOT a mechanism for increasing venous return during exercise?

an increase in stroke volume

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.

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

arterial PCO2.

The greatest resistance to blood flow is in the

arterioles.

Which of the following factors contribute to "fine-tuning" of cardiovascular control during exercise?

baroreceptors, muscle chemoreceptors, and muscle mechanoreceptors

Which of the following statements about beta-adrenergic blocking medications are true?

beta blocking drugs compete with epinephrine and norepinephrine for beta-adrenergic receptors in the heart., beta blockade reduces the vigor of ventricular contraction., beta blocking drugs reduce heart rate during exercise. (all of the above)

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

bicarbonate

Carbon dioxide is transported in arterial blood principally as

bicarbonate.

The most important of the blood buffers is/are

bicarbonate.

The increase in cardiac output that occurs during exercise is due to

both an increase in mean arterial pressure and a decrease in vascular resistance.

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

Skeletal and cardiac muscle are similar in which of the following ways?

both muscles are composed of striated fibers containing actin and myosin

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

both peripheral vasoconstriction and shivering are correct

All gas exchange between the vascular system and tissues occurs in

capillaries

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

conduction.

At high environmental temperatures, which of the following variables impact the amount of heat loss by evaporation?

convective currents., amount of exposed skin., ambient temperature and relative humidity. (all of the above)

The primary purpose of the cardiovascular system is to

deliver adequate levels of oxygen and remove wastes from body tissues.

Which of the following factors has the greatest influence on blood flow to a skeletal muscle during exercise?

diameter of the arterial blood vessels leading to the muscle

The most important muscle of inspiration is/are the

diaphragm.

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

diffusion coefficient of the gas., difference in partial pressure of the gas on the two sides of the tissue., tissue area.

Small increases in arterial PCO2 have a ______________ effect on ventilation compared to small decreases in PO2.

greater

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

greater than

Regulation of body core temperature is important because

high temperature can alter the structure and function of enzymes., low temperatures can promote abnormal cardiac function (e.g., arrhythmias)., cellular structures and metabolic pathways are affected by temperature. (all of the above)

The central command theory of cardiovascular control proposes that initial signal to the cardiovascular control center comes from

higher brain centers.

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

homeotherms.

Athletes involved in sports that require high intensity exercise have experimented with numerous supplements to improve buffering capacity and enhance performance. Which of the following supplements has NOT been shown to improve muscle buffering capacity?

hydrogen peroxide

Cold acclimation results in which of the following physiological adaptations?

improved ability to prevent large decreases in skin temperature during cold exposure., increased nonshivering thermogenesis., improved ability to sleep in cold environments. (all of the above)

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

in uncontrolled diabetes.

According to the Fick equation, if cardiac output doubles during exercise and the arterial-mixed venous oxygen difference remains constant, body oxygen consumption would

increase by 100%.

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

increased free radical production in the active skeletal muscles.

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

The arterial-venous oxygen difference

increases as a function of exercise intensity.

Exercise-induced asthma could impair pulmonary gas exchange by

increasing airway resistance.

Sodium bicarbonate has been ingested by athletes before competition in an effort to improve performance by

increasing blood buffering capacity.

Electrical impulses are conducted between heart muscle cells by

intercalated discs.

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

intracellular buffers within muscle fibers.

Most of the O2 contained in the blood

is bound to hemoglobin as oxyhemoglobin.

During exercise, the time spent in diastole and systole

is decreased, with the greatest decrease occurring in diastole.

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

lactic

The relationship between cardiac output and metabolic rate is

linear and positively correlated.

Sympatholysis refers to

local inhibition of sympathetic-induced vasoconstriction.

Autoregulation of blood flow to contracting muscles during exercise is due to

locally produced factors such as nitric oxide, prostaglandins, and adenosine.

The higher the relative humidity and air temperature, the __________________.

lower the vapor pressure gradient between the skin and the environment

The term ventilation refers to the

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

The cardiovascular control center is located in the

medulla oblongata.

The respiratory control center is located in the

medulla oblongata.

Acids are defined as

molecules that release hydrogen ions (H+).

To ensure adequate hydration, athletes should

monitor fluid loses during exercise., consume fluids every 15-20 minutes during exercise., consume fluids (after exercise) equal to approximately 150% of weight loss. (all of the above)

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.

The metabolic demand of the heart can be estimated by

multiplying heart rate by systolic blood pressure, the rate-pressure product, and the double product

The muscle of the heart is referred to as the

myocardium.

Which of the following statements about myoglobin are true?

myoglobin binds oxygen., myoglobin shuttles oxygen from the cell membrane to the mitochondria., myoglobin exists in relatively large quantities in slow-twitch muscle fibers. (all of the above)

The primary drive to increase ventilation during exercise is due to

none of these answers is correct.

Acidosis can occur due to

none of these.

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

oxyhemoglobin saturation of 97-98%., oxygen content of 20 ml O2/100 ml blood., PO2 of approximately 100 mm Hg. (all of the above)

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

pH, PCO2, and PO2

The body's thermostat is located in the

preoptic-anterior hypothalamus.

The difference between systolic and diastolic blood pressure is called the

pulse pressure.

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

radiation

Which of the following is a potential mechanism of heat gain on a hot and sunny day outside?

radiation

Diffusion is defined as

random movement of molecules from area of high concentration to an area of lower concentration.

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+.

At rest, voluntary hyperventilation can result in ___________ due to ____________.

respiratory alkalosis; decreased blood levels of carbon dioxide

Endurance exercise performance 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 organs 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.

Backflow of blood from the arteries into the heart ventricles is prevented by the

semilunar valves.

Heat production can be increased through

shivering., the action of thyroxine and catecholamines on cellular heat production., non-shivering thermogenesis. (all of the above)

In a healthy heart, the time spent in systole is generally _______ diastole.

shorter than

The normal pacemaker of the heart is the

sinoatrial node.

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

suggestive of airway obstruction.

Which of the following factors can decrease blood pressure?

systemic vasodilation.

The contraction phase of the heart is called

systole.

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 right shift in the oxyhemoglobin dissociation curve due to a rise in hydrogen ion concentration is called

the Bohr effect.

The primary source of heat production during exercise is

the contracting skeletal muscles.

The most important variable that determines resistance to blood flow is

the diameter of the blood vessel.

Most of the increase in mean arterial blood pressure that occurs during dynamic (isotonic) incremental exercise is due to

the increase in systolic blood pressure.

Atrial repolarization occurs during which phase of the cardiac cycle as observed on an ECG?

the qrs complex

The pH scale is a measure of

the relative concentration of hydrogen ions and hydroxyl ions in a solution.

The amount of gas moved per breath is termed

tidal volume.

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

to cool the airways.

A local increase in the nitric oxide concentration around arterioles would result in

vasodilation.