UNC BIOL 253L exam 2 UPDATED Exam
Questions and CORRECT Answers
What changes would you predict in your measurements of depth and rate of respiration if your
airways decreased in radius? - CORRECT ANSWER - If the airways decreased in radius,
the depth and rate of respiration would increase. This is because decreasing the radius of airways
increases the resistance of the airways. The body would not be able to move as much air because
of the increased resistance slowing down the flow of the air. Therefore, the body will compensate
with deeper respirations at a faster rate.
Describe what is happening to the relative concentration of oxygen in the in the pulmonary veins
when you hold your breath - CORRECT ANSWER - When we inhale, we bring O2 into
the lungs, which then gets absorbed into the blood and then carried throughout the body. The O2
is used or made into energy to carry out bodily functions. What remains is CO2, which is carried
back into your lungs by the circulating blood and then released when we exhale. When we hold
our breath, we get the accumulation of CO2 in our cells, so our relative concentration of O2 will
decrease when we hold our breath
How does the pulse rate change during the breathing cycle? Describe the mechanism that leads
to this change - CORRECT ANSWER - During a breathing cycle, air moves in and out of
the lungs by bulk flow. The respiratory muscles are responsible for the changes in the shape and
volume of the chest cavity that cause the air movements in breathing. Heart rate varies with
respiratory pattern i.e. faster with inspiration, slower with expiration.
o The negative pressure in the chest during inspiration sucks up blood from the lower
extremities, causing an increase in blood returning to the right atrium. The heart rate speeds up to
circulate this extra blood.
o Respiratory sinus arrhythmia helps to match pulmonary blood flow to lung inflation and
maintain an appropriate diffusion gradient of oxygen in the lungs.
What other ideas could you test with regard to the relationship between breathing and heart rate?
Design a follow up experiment using the technology we used today in lab (get creative!). Be sure
to describe hypothesis, testing protocol and controls - CORRECT ANSWER -
If exercise had consisted of isometric contractions (like holding a plank for 2 minutes), would
breathing patterns change from a baseline? Why, why not? Would recovery be similar to what we
,saw with the star jumps? - CORRECT ANSWER - · Isometric contractions would change
breathing pattern from baseline
o Muscles still require oxygen
Recovery would be similar to the star jumps due to the amount of oxygen required by the
muscles is less vs. an aerobic based exercise
Why is the forced vital capacity less than the vital capacity? If your data do not show this
pattern, what could have gone wrong? - CORRECT ANSWER - While forcing air out of
the lungs, the pressure outside the airways increases rapidly and substantially. If this external
pressure exceeds the pressure within the airways, unsupported airways can collapse. This results
in air being trapped within alveoli, and it is unable to be expired and measured.
Compare the rate of breathing with hyperinflated lungs with that in normal breathing. What
effect will this have had on blood gases? - CORRECT ANSWER - When you increase the
rate of breathing, you increase the minute volume required to ventilate the anatomical dead
space. For example, if the rate increases from 20 to 40 breaths/min, dead space ventilation will
have doubled from 3 (20 breaths/min x 0.15 L) to 6 L/min (40 breaths/min x 0.15 L). If you do
this calculation for your data you will find that the increased minute volume will largely reflect
this increased dead space ventilation. Therefore, alveolar ventilation will be relatively unchanged
and blood gases unaffected.
Examine the table from your lab activity showing respiratory rate and tidal volume after
breathing normally and with hyperinflated lungs. Has respiratory rate or tidal volume changed?
How do you account for this? - CORRECT ANSWER - Your data will likely show that
breathing has become faster and shallower. The volunteer perceives breathing to be more
difficult and attempts to compensate for this by hyperventilating.
Describe the physiological significance of the FEV1/FVC ratio. What variables might contribute
to a high or low ratio? Give examples of conditions that might influence these variables -
CORRECT ANSWER - The ratio is an indication of an airway's diameter. The higher the
value, the faster air can flow through the airway. Therefore, the lower the resistance and the
wider the airway.
What happened to the RR interval and the heart rate during heavy exercise and during recovery?
- CORRECT ANSWER - The RR interval increases. The increase in the RR interval
, means that heart rate (BPM) is decreasing. The greater the amount of time in recovery the closer
heart rate returns to resting heart rate levels.
The RR interval consists of the sum of QRS, ST, TP, and PR periods. Which one of these became
appreciably shorter when the heart rate increased? What is the physiological significance of your
observation? - CORRECT ANSWER - The TP interval becomes shorter compared to the
other components making up the cardiac cycle. This indicates that as heart rate increases it is
diastole (relaxation period) that decreases more than systole (contraction period). This is because
systole is active and is harder to shorten further, whilst diastole, which at rest is primarily
passive, has the capacity to become more active and thus shorten more.
Explain the relationship between cardiac output and stroke volume and how they change with
exercise. - CORRECT ANSWER - Cardiac output (Q) = stroke volume (SV) x heart rate
(HR)
SV reaches its maximum at a relatively low intensity during exercise, therefore heart rate
remains the most practical indicator of the heart's work and the functions of cardiovascular
system during exercise.
How is blood re-directed throughout the body during heavy exercise? What is epinephrine's role
in this process? - CORRECT ANSWER - During rest only 15-20% of the cardiac output of
the heart goes to the skeletal muscles, but during exercise, that number reverses with the other
areas of the body, feeding the muscles nearly 85% of the total output of the heart. Muscles like
the kidney, brain, and liver eat up nearly 65% of the total blood flow at rest.
During exercise, the hormone epinephrine activates α1 receptors in the skin, gut, and kidney to
cause vasoconstriction (and decreased blood flow), and β1 receptors in the heart and skeletal
muscle to cause vasodilation (and increased blood flow). In the heart, it also increased cardiac
output.
What happened to blood gases during exercise? How did breathing patterns respond in turn? -
CORRECT ANSWER - Blood gases change for only a very short period, the body will
quickly stimulate a faster breathing rate to make up for any differences, so blood gases should
remain relatively the same during exercise.
What is meant by pulse pressure? What happened during light and heavy exercise to the pulse
pressure? Was this what you expected to happen? - CORRECT ANSWER - Pulse pressure
refers to the difference between systolic and diastolic blood pressure. During light exercise both
Questions and CORRECT Answers
What changes would you predict in your measurements of depth and rate of respiration if your
airways decreased in radius? - CORRECT ANSWER - If the airways decreased in radius,
the depth and rate of respiration would increase. This is because decreasing the radius of airways
increases the resistance of the airways. The body would not be able to move as much air because
of the increased resistance slowing down the flow of the air. Therefore, the body will compensate
with deeper respirations at a faster rate.
Describe what is happening to the relative concentration of oxygen in the in the pulmonary veins
when you hold your breath - CORRECT ANSWER - When we inhale, we bring O2 into
the lungs, which then gets absorbed into the blood and then carried throughout the body. The O2
is used or made into energy to carry out bodily functions. What remains is CO2, which is carried
back into your lungs by the circulating blood and then released when we exhale. When we hold
our breath, we get the accumulation of CO2 in our cells, so our relative concentration of O2 will
decrease when we hold our breath
How does the pulse rate change during the breathing cycle? Describe the mechanism that leads
to this change - CORRECT ANSWER - During a breathing cycle, air moves in and out of
the lungs by bulk flow. The respiratory muscles are responsible for the changes in the shape and
volume of the chest cavity that cause the air movements in breathing. Heart rate varies with
respiratory pattern i.e. faster with inspiration, slower with expiration.
o The negative pressure in the chest during inspiration sucks up blood from the lower
extremities, causing an increase in blood returning to the right atrium. The heart rate speeds up to
circulate this extra blood.
o Respiratory sinus arrhythmia helps to match pulmonary blood flow to lung inflation and
maintain an appropriate diffusion gradient of oxygen in the lungs.
What other ideas could you test with regard to the relationship between breathing and heart rate?
Design a follow up experiment using the technology we used today in lab (get creative!). Be sure
to describe hypothesis, testing protocol and controls - CORRECT ANSWER -
If exercise had consisted of isometric contractions (like holding a plank for 2 minutes), would
breathing patterns change from a baseline? Why, why not? Would recovery be similar to what we
,saw with the star jumps? - CORRECT ANSWER - · Isometric contractions would change
breathing pattern from baseline
o Muscles still require oxygen
Recovery would be similar to the star jumps due to the amount of oxygen required by the
muscles is less vs. an aerobic based exercise
Why is the forced vital capacity less than the vital capacity? If your data do not show this
pattern, what could have gone wrong? - CORRECT ANSWER - While forcing air out of
the lungs, the pressure outside the airways increases rapidly and substantially. If this external
pressure exceeds the pressure within the airways, unsupported airways can collapse. This results
in air being trapped within alveoli, and it is unable to be expired and measured.
Compare the rate of breathing with hyperinflated lungs with that in normal breathing. What
effect will this have had on blood gases? - CORRECT ANSWER - When you increase the
rate of breathing, you increase the minute volume required to ventilate the anatomical dead
space. For example, if the rate increases from 20 to 40 breaths/min, dead space ventilation will
have doubled from 3 (20 breaths/min x 0.15 L) to 6 L/min (40 breaths/min x 0.15 L). If you do
this calculation for your data you will find that the increased minute volume will largely reflect
this increased dead space ventilation. Therefore, alveolar ventilation will be relatively unchanged
and blood gases unaffected.
Examine the table from your lab activity showing respiratory rate and tidal volume after
breathing normally and with hyperinflated lungs. Has respiratory rate or tidal volume changed?
How do you account for this? - CORRECT ANSWER - Your data will likely show that
breathing has become faster and shallower. The volunteer perceives breathing to be more
difficult and attempts to compensate for this by hyperventilating.
Describe the physiological significance of the FEV1/FVC ratio. What variables might contribute
to a high or low ratio? Give examples of conditions that might influence these variables -
CORRECT ANSWER - The ratio is an indication of an airway's diameter. The higher the
value, the faster air can flow through the airway. Therefore, the lower the resistance and the
wider the airway.
What happened to the RR interval and the heart rate during heavy exercise and during recovery?
- CORRECT ANSWER - The RR interval increases. The increase in the RR interval
, means that heart rate (BPM) is decreasing. The greater the amount of time in recovery the closer
heart rate returns to resting heart rate levels.
The RR interval consists of the sum of QRS, ST, TP, and PR periods. Which one of these became
appreciably shorter when the heart rate increased? What is the physiological significance of your
observation? - CORRECT ANSWER - The TP interval becomes shorter compared to the
other components making up the cardiac cycle. This indicates that as heart rate increases it is
diastole (relaxation period) that decreases more than systole (contraction period). This is because
systole is active and is harder to shorten further, whilst diastole, which at rest is primarily
passive, has the capacity to become more active and thus shorten more.
Explain the relationship between cardiac output and stroke volume and how they change with
exercise. - CORRECT ANSWER - Cardiac output (Q) = stroke volume (SV) x heart rate
(HR)
SV reaches its maximum at a relatively low intensity during exercise, therefore heart rate
remains the most practical indicator of the heart's work and the functions of cardiovascular
system during exercise.
How is blood re-directed throughout the body during heavy exercise? What is epinephrine's role
in this process? - CORRECT ANSWER - During rest only 15-20% of the cardiac output of
the heart goes to the skeletal muscles, but during exercise, that number reverses with the other
areas of the body, feeding the muscles nearly 85% of the total output of the heart. Muscles like
the kidney, brain, and liver eat up nearly 65% of the total blood flow at rest.
During exercise, the hormone epinephrine activates α1 receptors in the skin, gut, and kidney to
cause vasoconstriction (and decreased blood flow), and β1 receptors in the heart and skeletal
muscle to cause vasodilation (and increased blood flow). In the heart, it also increased cardiac
output.
What happened to blood gases during exercise? How did breathing patterns respond in turn? -
CORRECT ANSWER - Blood gases change for only a very short period, the body will
quickly stimulate a faster breathing rate to make up for any differences, so blood gases should
remain relatively the same during exercise.
What is meant by pulse pressure? What happened during light and heavy exercise to the pulse
pressure? Was this what you expected to happen? - CORRECT ANSWER - Pulse pressure
refers to the difference between systolic and diastolic blood pressure. During light exercise both
