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LRA Final Exam | LRA Exam Latest 2024 Questions and Correct Answers Rated A+
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LRA Final Exam 2024-2025 | LRA ExamLatest 2024 Questions and Correct
Answers Rated A+
Damage to the sinoatrial (SA) node in humans would ________.
A. disrupt the rate and timing of cardiac muscle contractions.
B. block conductance between the bundle branches and the Purkinje fibers.
C. have a negative effect on peripheral resistance.
D. have a direct effect on blood pressure monitors in the aorta. -ANSWER-
A. disrupt the rate and timing of cardiac muscle contractions.
A human red blood cell in an artery of the left arm is on its way to deliver
oxygen to a cell in the thumb. To travel from the artery to the thumb and
then back to the left ventricle, this red blood cell must pass through
________.
A. one capillary bed.
B. two capillary beds.
C. three capillary beds.
D. four capillary beds. -ANSWER-B. two capillary beds.
Blood is pumped at high pressures in arteries from the heart to ensure that
all parts of the body receive adequate blood flow. Capillary beds, however,
would hemorrhage under direct arterial pressures. How does the design of
the circulatory network contribute to reducing blood pressure to avoid this
scenario?
A. Blood flow through the capillaries is essentially frictionless, and this
reduces the amount of pressure on their walls.
B. Fluid loss from the arteries is high enough that pressure drops off
significantly by the time blood reaches the capillaries.
C. Capillary beds have the thickest walls of any blood vessel to resist these
high pressures.
,D. The total cross-sectional diameter of the arterial circulation increases
with progression from artery to arteriole to capillary, leading to a reduced
blood pressure. -ANSWER-D. The total cross-sectional diameter of the
arterial circulation increases with progression from artery to arteriole to
capillary, leading to a reduced blood pressure.
In order for blood to always flow unidirectionally through a closed
circulatory system, the ________.
A. blood vessels farthest from the heart must have valves.
B. capillaries must have a thick endothelium.
C. arteries must be elastic.
D. pressure in all vessels must be equal. -ANSWER-A. blood vessels
farthest from the heart must have valves.
Large blood proteins such as albumin remain in capillaries rather than
diffusing out, resulting in the ________.
A. loss of osmotic pressure in the capillaries.
B. loss of fluid from capillaries.
C. development of an osmotic pressure difference across capillary walls.
D. None of the above -ANSWER-C. development of an osmotic pressure
difference across capillary walls.
Blood cells that function to fight infection are called ________.
A. platelets
B. leukocytes
C. thrombi
D. erythrocytes -ANSWER-B. leukocytes
You cut your finger, and after putting pressure on the wound for several
minutes, you notice that it is still bleeding profusely. What may be the
problem?
A. Mast cells are not releasing their chemical messengers.
B. There are too many antigens to allow clotting.
C. Hemoglobin levels are too high to allow clotting.
,D. Platelets are not functioning properly, or there are too few to be
effective. -ANSWER-D. Platelets are not functioning properly, or there are
too few to be effective.
Blood returning to the mammalian heart in a pulmonary vein drains first into
the _____.
A. right atrium.
B. right ventricle.
C. left atrium.
D. left ventricle -ANSWER-C. left atrium.
The greatest difference in the concentration of respiratory gases is found in
which of the following pairs of mammalian blood vessels?
A. the pulmonary vein and the superior vena cava.
B. the veins from the right and left legs.
C. the pulmonary artery and the inferior vena cava.
D. the pulmonary vein and the aorta. -ANSWER-A. the pulmonary vein and
the superior vena cava.
To become bound to hemoglobin for transport in mammals, atmospheric
molecules of oxygen must cross ________.
A. one membrane—that of the lining in the lungs—and then bind directly to
hemoglobin, a protein dissolved in the plasma of the blood.
B. two membranes—in and out of the cell lining the lung—and then bind
directly to hemoglobin, a protein dissolved in the plasma of the blood.
C. four membranes—in and out of the cell lining the lung, in and out of the
endothelial cell lining an alveolar capillary—and then bind directly to
hemoglobin, a protein dissolved in the plasma of the blood.
D. five membranes—in and out of the cell lining the lung, in and out of the
endothelial cell lining an alveolar capillary, and into the red blood cell—to
bind with hemoglobin. -ANSWER-D. five membranes—in and out of the cell
lining the lung, in and out of the endothelial cell lining an alveolar capillary,
and into the red blood cell—to bind with hemoglobin.
, Which of the following represents the correct flow of air into the lung of a
mammal?
A. trachea → bronchioles → bronchi → alveoli
B. larnyx → trachea → bronchi → bronchioles → alveoli
C. trachea → tracheoles → bronchi → alveoli
D. alveoli → tracheoles → bronchi → trachea -ANSWER-B. larnyx →
trachea → bronchi → bronchioles → alveoli
Carbon dioxide levels in the blood and cerebrospinal fluid affect blood pH.
This enables the organism to sense a disturbance in gas levels as
________.
A. the brain directly measures and monitors oxygen levels and causes
breathing changes accordingly.
B. the brain alters the pH of the cerebrospinal fluid to force the animal to
retain more or less carbon dioxide.
C. the medulla oblongata, which is in contact with cerebrospinal fluid,
monitors pH and uses this measure to control breathing.
D. stretch receptors in the lungs cause the medulla oblongata to speed up
or slow breathing. -ANSWER-C. the medulla oblongata, which is in contact
with cerebrospinal fluid, monitors pH and uses this measure to control
breathing.
Most of the carbon dioxide produced by humans is ________.
A. bound to hemoglobin.
B. transported in the erythrocytes as carbonic acid.
C. converted to bicarbonate ions.
D. simply dissolved in the plasma. -ANSWER-C. converted to bicarbonate
ions.
If a molecule of CO2 released into the blood in your left toe is exhaled from
your nose, it must pass through all of the following except
A. the pulmonary vein.
B. the trachea.
C. the right atrium.
D. the right ventricle. -ANSWER-A. the pulmonary vein.
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