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PHYSIOLOGY > Physio Compre Reviews > Flashcards

Physio Compre Reviews Flashcards

1
Q

Which of the following will occur as a result of residing at high
altitude?
A. Hypertrophy of the left ventricle
B. Shift to the right of the hemoglobin-oxygen dissociation
curve
C. Decreased 2,3-diphosphoglycerate concentration
D. Arterial pO2 greater than 100mmHg

A

B. Shift to the right of the hemoglobin-oxygen dissociation curve

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2
Q

As you examined a patient’s electrocardiogram, you noted
absence of P wave, but has normal QRS complex and a normal T
wave. Therefore, his pacemaker is located in the:
A. Sinoatrial node
B. Purkinje system
C. Atrioventricular node
D. Bundle of His

A

C. Atrioventricular node

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3
Q

Which of the following is a feature of the sympathetic, but not the
parasympathetic nervous system?
A. Postganglionic neurons release Acetylcholine
B. Preganglionic neurons originate in the thoracolumbar
spinal cord
C. Long preganglionic neurons
D. Ganglia located in the effector organs

A

Preganglionic neurons originate in the thoracolumbar spinal cord

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4
Q

When you moved from a supine position to a standing position,
which of the following circulatory compensatory changes occurs?
A. Decreased cardiac output
B. Increased contractility
C. Decreased total peripheral resistance
D. Decreased heart rate

A

Increased contractility

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5
Q

The fourth heart sound heard during atrial contraction is due to:
A. Opening of the AV valve
B. Rushing of blood through a patent foramen ovale
C. Tautness of the semilunar valves
D. Terminal inrush of blood into the ventricles

A

Terminal inrush of blood into the ventricles

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6
Q

Which of the following changes occurs during defecation?
A. External anal sphincter is contracted
B. Segmentation contractions predominate
C. Internal anal sphincter is relaxed
D. Rectal smooth muscle is relaxed

A

Internal anal sphincter is relaxed

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7
Q

Under resting condition, the velocity of blood flow:
A. Is directly proportional to the vascular crosssectional
area
B. averages 33cm/sec in the aorta
C. Is close to 1/10 in the capillaries than in the big arteries
D. Is around 5 cm/sec in the capillaries

A

Averages 33 cm/sec in the aorta

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8
Q

Which of the following is characteristic of saliva?
A. A lower bicarbonate concentration than plasma
B. The presence of proteases
C. Hypotonicity relative to plasma
D. Modification by the salivary ductal cells involves
reabsorption of potassium and bicarbonate

A

Hypotonicity relative to plasma

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9
Q

Partial recovery of the heart about a little over a week following
cardiac injury would manifest as:
E. High left atrial pressure
F. Tachycardia
G. Fluid retention
H. Normal cardiovascular dynamics with light activity

A

Fluid retention

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10
Q

Propylthiouracil can be used to reduce the synthesis of the
thyroid hormones in hyperthyroidism because it inhibits oxidation
of:
A. Thyroid stimulating hormone
B. Diiodotyrosine
C. Iodide
D. Thyroxine

A

Iodide

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11
Q

Which of the following changes occurs during strenuous
exercise?
A. Systemic arterial pO2 decreases to about 70mmHg
B. Ventilation rate and oxygen consumption increase to
the same extent
C. Systemic venous pCO2 decreases to about 20mmHg
D. Pulmonary blood flow decreases at the expense of
systemic blood flow

A

Ventilation rate and oxygen consumption increase to the same extent

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12
Q

Secretion of hydrochloric acid by gastric parietal cells is needed
for activation of:
A. intrinsic factor
B. salivary lipases
C. pancreatic lipases
D. pepsinogen to pepsin

A

Pepsinogen to pepsin

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13
Q

An infant was born to a mother who had rubella during the first
trimester of pregnancy. X-ray showed generalized
cardiac enlargement with increased pulmonary vascularity. The
infant is most likely having:
A. Coarctation of the aorta
B. Ventricular septal defect
C. Patent ductus arteriosus
D. Patent foramen ovale

A

Patent ductus arteriosus

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14
Q

Which is true in oogenesis?
A. Meiosis II of secondary oocyte is completed at
fertilization
B. At birth, the primary oocyte is arrested at metaphase
C. Oogonium divides by meiosis
D. Primary oocyte undergoes mitosis prior to ovulation

A

Meiosis II of secondary oocyte is completed at fertilization
OTHER CHOICES
B. At birth, the primary oocyte is arrested at metaphase
- Arrested at Prophase I (Specifically the Diplotene Stage)
C. Oogonium divides by meiosis
- Divides by Mitosis
- The Primary Oocyte and Secondary Oocyte undergo meiosis
D. Primary oocyte undergoes mitosis prior to ovulation
- Only the Oogonium undergoes Mitosis

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15
Q

Administration of which of the following drugs is contraindicated in
a 10-year old child with a history of asthma?
A. Isoproterenol
B. Albuterol
C. Propanolol
D. Epinephrine

A

Propanolol

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16
Q

Fast-twitch muscle fibers differ from slow-twitch fibers in the
following parameters:
A. Fast-twitch fibers are mainly organized for endurance
B. The number of capillaries is greater in the vicinity of
fast-twitch fibers than in the vicinity of slow-twitch fibers
C. Enzymes promoting rapid release of energy from
phosphagen and glycogen-lactic acid energy systems
are two to three times as active in fast-twitch fibers as
in slow twitch fibers
D. Slow-twitch fibers are about twice as large in diameter

A

Enzymes promoting rapid release of energy from phosphagen and
glycogen-lactic acid energy systems are two to three times as active in fast-twitch fibers as in slow twitch fibers

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17
Q

The physiologic function of the relatively slow conduction through
the atrioventricular node is to allow sufficient time for:
A. Contraction of the ventricles
B. Runoff of blood from the aorta to the arteries
C. Venous return to the atria
D. Filling of the ventricles

A

Filling of the ventricles

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18
Q

A 45-year old woman with Zollinger-Ellison syndrome presents
with:
A. Increased serum insulin levels
B. Decreased parietal cell mass
C. Peptic ulcer disease
D. Decrease serum gastric levels

A

Peptic ulcer disease

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19
Q

A patient came in with sudden onset abdominal pain. The clinician
suspects a gastric ulcer which perforated. What radiologic exam
would you request for?
A. Abdominal X-ray upright
B. Abdominal X-ray supine
C. Chest X-ray lateral
D. Chest X-ray PA upright

A

Chest X-ray PA upright

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20
Q

A post-operative patient consulted because of anemia. You were
considering intrinsic factor deficiency. Which of the following is
the site of secretion of intrinsic factor?
A. Duodenum
B. Ileum
C. Gastric antrum
D. Gastric fundus

A

Gastric fundus

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21
Q

A ballet dancer spins to the left. During the spin, her eyes snap
quickly to the left. This fast eye movement is:
A. Nystagmus
B. Post-rotatory nystagmus
C. Ataxia
D. Aphasia

A

Nystagmus

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22
Q

A 40-year old woman has hypocalcemia, hyperphosphatemia,
and decreased urinary phosphate excretion. Injection of
parathyroid hormone causes an increase in urinary cyclic
adenosine monophosphate. The most likely diagnosis is:
A. Primary hyperparathyroidism
B. Vitamin D deficiency
C. Hypoparathyroidism after thyroid surgery
D. Vitamin D intoxication

A

Hypoparathyroidism after thyroid surgery
OTHER CHOICES
B. Primary hyperparathyroidism
- Hypercalcemia, Hypophosphatemia, Increased Urinary Phosphate
Secretion
C. Pseudohyperparathyroidism
- Hypercalcemia, Hypophosphatemia, Increased Urinary Phosphate
Secretion
- Has Low PTH levels
D. Vitamin D deficiency
- Hypercalcemia, Hyperphosphatemia, Decreased Urinary Phosphate
Secretion

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23
Q

During the upstroke of the action potential:
A. There is net inward current and the cell interior
becomes less negative
B. There is net outward current and the cell interior
becomes less negative
C. There is net outward current and the cell
D. interior becomes more negative
E. There is net inward current and the cell interior
becomes more negative

A

There is net inward current and the cell interior becomes less negative

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24
Q

While waiting for your turn to receive Hepatitis B immunization
at the clinic, you remembered how impulses are perceived.
Which of the following refers to C fibers?
A. Are afferent nerves from Golgi tendon organs
B. Have the slowest conduction velocity of any nerve fiber
type
C. Have the largest diameter of any nerve fiber type
D. Are afferent nerves from muscle spindles

A

Have the slowest conduction velocity of any nerve fiber type

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25
Q

A 50-year old man is given a glucose tolerance test. In the
test, the plasma glucose concentration is increased and
glucose reabsorption and excretion are measured. When the
plasma glucose concentration is higher than occurs at
transport maximum (Tm), the:
A. Excretion rate of glucose equals the filtration rate of
glucose
B. Excretion rate of glucose increases with increasing
plasma glucose concentration
C. Reabsorption rate of glucose equals the filtration rate of
glucose
D. Clearance of glucose is zero

A

Excretion rate of glucose increases with increasing plasma glucose
concentration

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26
Q

Micelle formation is necessary for the intestinal absorption of:
A. Vitamin D
B. Galactose
C. Vitamin B12
D. Bile acids

A

Vitamin D

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27
Q

Which of the following is NOT TRUE regarding the venous
system?
A. Small veins have cross-sectional area up to over six
times that of arterioles
B. The venae cavae are less than four times the area of
the aorta
C. The cross-sectional area of the venules totals 250 cm2
D. Serves as storage area of most of the blood in the
circulation

A

Small veins have cross-sectional area up to over six times that of
arterioles.

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28
Q

A 65-year old man is found to have pheochromocytoma that
secretes mainly epinephrine. Which of the following signs
would be expected in this patient?
A. Cold, clammy skin
B. Decreased excretion rate of 3-methoxy-
4hydroxymandelic acid
C. Decreased arterial blood pressure
D. Decreased heart rate

A

Cold, clammy skin

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29
Q

The mean pressure in the aorta equals:
A. 120 mmHg
B. 100 mmHg
C. 70 mmHg
D. 80 mmHg

A

100 mm Hg

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30
Q

Adenosine triphosphate is used indirectly for which of the
following processes?
A. Absorption of glucose by intestinal epithelial cells
B. Transport of potassium from extracellular to intracellular
fluid
C. Transport of sodium from intracellular to extracellular
fluid
D. Accumulation of calcium by the sarcoplasmic reticulum

A

Accumulation of calcium by the sarcoplasmic reticulum

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31
Q

Which of the following causes rigor mortis?
A. a decrease in ATP level
B. a decrease in intracellular calcium levels
C. an increase in adenosine triphosphate level
D. no action potentials in motoneurons

A

a decrease in ATP level

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32
Q

Renal acid secretion is altered by changes in:
A. K+ concentration
B. Carbonic anhydrase
C. Adrenocortical hormone concentration
D. All of the choices

A

All of the choices

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33
Q

Which of the following hormones acts on its target tissues by a
steroid hormone mechanism of action?
A. Thyroid hormone
B. Parathyroid hormone
C. Glucagon
D. Antidiuretuc hormone

A

Thyroid hormone

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34
Q

A man who has galactorrhea is found to have a prolactinoma.
His physician treats him with bromocriptine, which eliminates
the galactorrhea. The basis for the therapeutic action
bromocriptine is that it:
A. Enhances the action of prolactin on the breast
B. Enhances the action of dopamine on the anterior
pituitary
C. Antagonizes the action of prolactin on the breast
D. Inhibits prolactin release from the anterior pituitary

A

Inhibits prolactin release from the anterior pituitary

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35
Q

Administration of Digitalis to a decompensated heart causes the
following:
A. Cardiac output equal to 5.0 L/min
B. Diuresis
C. Spontaneous arteriovenous fistula formation
D. Increase in core body temperature

A

Diuresis

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36
Q

Absolute refractory period means that the cell will not be
responsive to any kind of stimulus. At what phase in the action
potential does it occur?
A. Phase 4
B. Phase 3 until start of Phase 4
C. Phase 0 until Phase 3
D. All phases in the action potential

A

Phase 0 until Phase 3

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37
Q

At the muscle end plate, Acetylcholine causes the opening
A. Potassium channels and depolarization toward the
potassium equilibrium potential
B. Sodium and potassium channels and depolarization to
a value halfway between the sodium and potassium
equilibrium potential
C. Sodium channels and depolarization toward the sodium
equilibrium potential
D. Calcium channels and depolarization toward the
calcium equilibrium potential

A

Sodium and potassium channels and depolarization to a value halfway
between the sodium and potassium equilibrium potential

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38
Q

The permeability of a solute in a lipid bilayer will be increased by
an increase in the:
A. concentration difference of the solute across the bilayer
B. molecular radius of the solute
C. oil/water partition coefficient of the solute
D. thickness of the bilayer

A

oil/water partition coefficient of the solute

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39
Q

Compared with the systemic circulation, the pulmonary circulation
has a:
A. higher arterial pressure
B. higher blood flow
C. lower resistance
D. higher capillary pressure

A

Lower resistance

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40
Q

Which of the following hormones originates in the anterior
pituitary?
E. Dopamine
F. Thyroid stimulating hormone
G. Oxytocin
H. Growth hormone-releasing hormone

A

Thyroid stimulating hormone

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41
Q

Which of the following lung volumes or capacities can be measured
by spirometry?
A. Vital capacity
B. Functional residual capacity
C. Residual volume
D. Physiologic dead space

A

Vital capacity

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42
Q

When measuring the force exerted by the blood against any unit
area of the vessel wall:
A. one millimeter of mercury pressure equals 1.36cm
water pressure
B. a mean reading is normally 100mmHg
C. best assured in mm H2O
D. readily reported in systole and diastole by palpation

A

One millimeter of mercury pressure equals 1.36 cm water pressure

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43
Q

Which of the following transport processes is involved if transport
of glucose from the intestinal lumen into a small intestinal cell is
inhibited by abolishing the usual sodium ion gradient across the
cell membrane?
A. Cotransport
B. Countertransport
C. Facilitated diffusion
D. Primary active transport

A

Cotransport

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44
Q

An increase in contractility of the heart is demonstrated on a
Frank-Starling diagram by:
A. Decreased cardiac output for a given enddiastolic
volume
B. Increased cardiac output for a given enddiastolic
volume
C. Increased cardiac output for a given end- systolic
volume
D. Decreased cardiac output for a given endsystolic
volume

A

Increased cardiac output for a given end diastolic volume

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45
Q

Hypoxemia produces hyperventilation by a direct effect on the:
A. Medullary chemoreceptors
B. Lung stretch receptors
C. Carotid and Aortic body chemoreceptors
D. J receptors

A

Carotid and aortic body chemoreceptors

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46
Q

Which of the following is released from neurons in the
gastrointestinal tract and produces smooth muscle relaxation?
A. Cholecystokinin
B. Vasoactive intestinal peptide
C. Gastrin
D. Secretin

A

Vasoactive intestinal peptide

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47
Q

A 40-year old male with duodenal ulcer is treated successfully
with cimetidine. The basis for cimetidine’s inhibition of gastric H+
secretion is:
A. Blocks muscarinic receptors on parietal cells
B. Blocks H2 receptors on parietal cells
C. Blocks H+, K+ adenosine triphosphatase
D. Increases intracellular cyclic adenosine
monophosphate levels

A

Blocks H2 receptors on parietal cells

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48
Q

Slow waves of the GI smooth muscles:
A. are action potentials
B. represent changes in resting membrane potentials
C. lead to muscle contraction
D. occur in similar frequencies throughout the GIT

A

Represent changes in resting membrane potentials

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49
Q

The velocity of conduction of action potentials along a nerve will
be increased by:
A. Decreasing the diameter of the nerve
B. Stimulating the Na+-K+ pump
C. Myelinating the nerve
D. Inhibiting the Na+-K+ pump

A

Myelinating the nerve

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50
Q

Mechanism that leads to reduction of the degree of
hyperammonemia in a patient with hepatic dysfunction:
A. Eradication of colonic bacteria
B. Replacement of senescent RBCs by blood transfusion
C. Increased dietary protein intake
D. Enhanced glutamine breakdown in renal tubules

A

Eradication of colonic bacteria
OTHER CHOICES
Replacement of senescent RBCs by blood transfusion = should give
HEMODIALYSIS to remove ammonia
Increased dietary protein intake = should be to DECREASE
Enhanced glutamine breakdown in renal tubules = will lead to
HYPERAMMONEMIA because glutamine is broken down to AMMONIA
ANG GLUTAMATE and AMMONIA is reabsorbed in the tubules

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51
Q

When a person is standing, blood flow in the lungs is
A. Lowest at the base because that is where alveolar
pressure is greater than arterial pressure
B. Equal at the apex and the base
C. Highest at the base because that is where the
difference between arterial and venous pressure is
greatest
D. Highest at the apex owing to the effects of gravity on
arterial pressure

A

Highest at the base because that is where the difference between arterial
and venous pressure is greatest

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52
Q

Cutting which structure causes blindness in the temporal fields
of the left and right eyes?
A. Optic chiasm
B. Optic tract
C. Geniculocalcarine tract
D. Optic nerve

A

Optic chiasm

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53
Q

The source of estrogen during the second and third trimesters of
pregnancy is/are the:
A. Corpus luteum
B. Fetal adrenal gland, fetal liver and placenta
C. Fetal ovaries
D. Maternal ovaries

A

Fetal adrenal gland, fetal liver and placenta

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54
Q

A 25-week old premature infant developed neonatal respiratory
distress syndrome. Which of the following would be expected in
this infant?
A. Lecithin:Sphingomyelin ratio of greater than 2:1 in
Amniotic fluid
B. Arterial pO2 of 100 mmHg
C. Increased lung compliance
D. Collapse of the small alveoli

A

Collapse of the small alveoli

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55
Q

The arterioles have strong muscular walls and:
A. Serve as major reservoir of extra blood
B. act as control conduits through which blood is released
into the capillaries
C. transport blood under high pressure to the tissues
D. are responsible in the exchange of fluid, nutrients,
electrolytes, hormones, and other substances between
the blood and the interstitial fluid

A

Act as control conduits through which blood is released into the
capillaries.

OTHER CHOICES
CAPILLARIES = are responsible in the exchange of fluid, nutrients, electrolytes, hormones, and other substances between the blood and the interstitial fluid

VEINS = serve as major reservoir of extra blood.

ARTERIES = transport blood under high pressure to the tissues.

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56
Q

Which of the following would be expected to increase after
surgical removal of the duodenum?
A. Absorption of lipids
B. Contraction of the gallbladder
C. Gastric emptying
D. Secretion of cholecystokinin

A

Gastric emptying

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57
Q

Among the autonomic receptors, which is blocked by
hexamethonium at the ganglia but not at the neuromuscular
junction?
A. Cholinergic nicotinic receptors
B. Adrenergic β2 receptors
C. Adrenergic β1 receptors
D. Adrenergic α receptors

A

Cholinergic nicotinic receptors

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58
Q

Pulse pressure is:
A. The highest pressure measured in the arteries
B. The lowest pressure measured in the arteries
C. Measured only during diastole
D. Determined by stroke volume

A

Determined by stroke volume

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59
Q

Carbon dioxide regulates blood flow to which of the following
organs?
A. Skeletal muscle during exercise
B. Heart
C. Brain
D. Skin

A

Brain

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60
Q

Which step in steroid hormone biosynthesis is stimulated by
adrenocorticotropic hormone?
A. Testosterone à Estradiol
B. Cholesterol àPregnenolone
C. 17-Hydroxypregnenolone àDehydroepiandrosterone
D. Progesterone à11-Deoxycorticosterone

A

Cholesterol àPregnenolone

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61
Q

Which of the following is a characteristic of nuclear bag fibers?
A. They are one type of extrafusal muscle fiber
B. They are innervated by α-motoneurons
C. They detect dynamic changes in muscle length
D. They give rise to group Ib afferents

A

They detect dynamic changes in muscle length

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62
Q

In the presence of a functional X chromosome, which event
occurs when the SRY gene is absent in the embryo?
A. Mesonephric ducts develop and differentiate
B. Primitive cords in the indifferent gonad degenerate
C. Tunica albuginea proliferates and thickens
D. Paramesonephric ducts may become paraovarian cysts

A

Primitive cords in the indifferent gonad degenerate

OTHER CHOICES
A. Mesonephric ducts develop and differentiate
- The mesonephric ducts (Wolffian ducts) will differentiate into the upper urinary tract for both sexes, and into the (1) Seminal Vesicles, (2) Epididymis, (3) Ejaculatory Duct and (3) Ductus Deferens in the presence of the SRY gene
- Mnemonic: SEED
C. Tunica albuginea proliferates and thickens
- This happens with the presence of SRY Gene
D. Paramesonephric ducts may become paraovarian cysts
- In the absence of the SRY gene, the Paramesonephric duct will develop into the (1) Uterus, (2) Fallopian Tubes, (3) Cervix, and
(4) Upper 2/3 of the Vagina

MALE
* With SRY Gene
* Primary sex cords (middle): Coiled, solid testis cords.
* Primary sex cords (ends): Stay straight, join near hilum = rete testes.
* Rete testes + mesonephric tubule remnants: efferent
ductules.
* Mesenchyme thickening:
tunica albuginea.
* Mesothelial cells: Sertoli cells
* Mesothelial cells between testis cords: Interstitial cells (Leydig cells)

FEMALE
* Without SRY Gene
* Primary sex cords:
Degenerate.
* Cortical sex cords: Break up into a single layer of mesothelial follicular cells surrounding each germ cell (primordial follicles)
* Primordial germ cells:
Differentiate to oogonia and undergo mitosis to increase their numbers.
* Mesenchyme: Connective tissue stroma for follicular support.

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63
Q

Which autonomic receptor mediates increase in heart rate?
A. Adrenergic β1 receptors
B. Adrenergic β2 receptors
C. Cholinergic muscarinic receptors
D. Cholinergic nicotinic receptors

A

Adrenergic β1 receptors

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64
Q

The concentration difference between the substance’s maximum
renal reabsorption and its appearance in the urine is termed:
A. renal threshold
B. splay
C. titration reabsorption
D. tubular maximum

A

Splay

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65
Q

A patient came in and revealed that she has a 35-day menstrual
cycle. She would want to know when her ovulation occurs. You
informed her that it is most likely on day:
A. 17
B. 14
C. 21
D. 12

A

21

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66
Q

In order to obtain a good quality ECG tracing, you need to make
sure that there is no outside interference as this can create
artifact. The interference noted upon seeing the reaction of the
technician when tracing is taken is:
A. Wandering baseline
B. Mains interference
C. Lead interference
D. Patient movement

A

Patient movement

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67
Q

Which gastrointestinal secretion is hypotonic, has a high
bicarbonate concentration, and has its production inhibited
by vagotomy?
A. Bile
B. Gastric secretion
C. Pancreatic secretion
D. Saliva

A

Saliva

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68
Q

A harsh, blowing murmur best heard at the pulmonary artery area and waxes and wanes with each beat of the heart is known as:
A. Machinery murmur
B. Murmur of patent ductus arteriosus
C. Gibson’s murmur
D. All of the choices

A

All of the choices

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69
Q

Degeneration of dopaminergic neurons has been implicated in:
A. Curare poisoning
B. Schizophrenia
C. Myasthenia gravis
D. Parkinson’s disease

A

Parkinson’s disease

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70
Q

A 50-year old woman with severe muscle weakness is
hospitalized. The only abnormality in her laboratory values is an
elevated serum potassium concentration. The elevated serum
potassium causes muscle weakness because:
A. The potassium channels are opened by depolarization
B. The potassium equilibrium potential is hyperpolarized
C. The sodium channels are closed by depolarization
D. The resting membrane potential is hyperpolarized

A

The sodium channels are closed by depolarization

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71
Q

Your neighbor consulted because his examination showed
elevated prostate-specific antigen. Among the conditions that
you would consider to cause such elevation would include:
A. benign prostatic hypertrophy
B. prostate cancer
C. prostatitis
D. all of the above

A

All of the above

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72
Q

Which of the following is true about the secretion from the
exocrine pancreas?
A. Pancreatic bicarbonate ion secretion is increased by
gastrin
B. It is stimulated by the presence of bicarbonate ions in
the duodenum
C. Pancreatic enzyme secretion is increased by
cholecystokinin
D. It has a higher chloride ion concentration than does
plasma

A

Pancreatic enzyme secretion is increased by cholecystokinin

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73
Q

Sequence of events in the inflammatory response:
1– Tissue Repair
2– Vasodilatation
3– Chemotaxis
4– Phagocytosis
A. 1, 2, 3, 4
B. 2, 3, 4, 1
C. 3, 4, 2, 1
D. 4, 2, 3, 1

A

Vasodilatation
Chemotaxis
Phagocytosis
Tissue Repair

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74
Q

This law explains the interaction of pressure difference, radius
and length of a vessel and viscosity of the blood in relation with
the rate of blood flow.
A. Ohm’s Law
B. Fourth Power Law
C. Reynold’s Law
D. Poiseuille’s Law

A

Poiseuille’s Law

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75
Q

As you observe the colorful painting in a museum, your lecture on
rods and cones flashed in your mind. You tried to recall: when
compared with the cones of the retina, the rods:
A. Are primarily involved in color vision
B. Are more sensitive to low-intensity light
C. Are most highly concentrated on the fovea
D. Adapt to darkness before the cones

A

Are more sensitive to low-intensity light

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76
Q

The principal reaction producing NH4+ in the cells is:
A. all of the choices
B. due to conversion of glutamate to glutamine
C. glutamic anhydrase dependent
D. catalyzed by glutaminase

A

catalyzed by glutaminase

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77
Q

A patient arrives at the emergency room with hypotension,
reduced tissue turgor, and the following arterial blood values:
pH = 7.69
[HCO3
-] = 57 mEq/L
PCO2 = 48 mmHg
Which of the following responses would also be expected to occur
in this patient?
A. Exchange of intracellular H+ for extracellular K+
B. Increased ratio of H2PO4- to HPO4-2 in urine
C. Hyperventilation
D. Decreased K+ secretion by the distal tubules

A

Exchange of intracellular H+ for extracellular K+

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78
Q

Your patient is taking phosphodiesterase inhibitor for impotence.
You cautioned him on a side effect brought about by
phosphodiesterase VI inhibition which is:
A. blurring of vision
B. headache
C. transient inability to discriminate between blue and
green
D. uncontrolled movement of the eyelids

A

Transient inability to discriminate between blue and green

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79
Q

Which of the following is NOT TRUE about circulatory function?
A. The cardiac output is controlled mainly by the sum of all
the local tissue flows.
B. The rate of blood flow to the tissues is controlled by
tissue need.
C. The heart can increase its cardiac output up to more
than four to seven times greater than resting levels.
D. The arterial pressure is controlled independently of
either local blood flow control or cardiac output control.

A

The heart can increase its cardiac output up to more than four to seven
times greater than resting levels.

80
Q

Which of the following would be expected to increase after
surgical removal of the duodenum?
A. Gastric emptying
B. Contraction of the gallbladder
C. Absorption of lipids
D. Secretion of cholecystokinin

A

Gastric emptying
Duodenum produces CCK
CCK inhibits gastric emptying, contracts bladder
No duodenum = no CCK = increased gastric emptying

81
Q

Rheumatic fever commonly involves the mitral valve because:
A. Antibodies stay longer at the left ventricle
B. Group A hemolytic streptococci have a predilection to
the leaflets of the mitral valve
C. It receives more trauma during valvular action
D. Reticuloendothelial cells are more numerous in the
endocardium of the left side of the heart

A

It receives more trauma during valvular action

82
Q

The pH of venous blood is only slightly more acidic than the pH of
arterial blood because:
A. Carbon dioxide is a weak base
B. The H+ generated from carbon dioxide and water is
buffered by deoxyhemoglobin in venous blood
C. There is no carbonic anhydrase in venous blood
D. Oxyhemoglobin is a better buffer for H+ than is
deoxyhemoglobin

A

The H+ generated from carbon dioxide and water is buffered by
deoxyhemoglobin in venous blood

83
Q

A patient consulted because her urine seemed darker than usual.
You wanted to check on the kidneys ability to concentrate
urine. You requested for urinalysis and focused on:
A. Casts formed
B. Crystals
C. Pigments
D. specific gravity

A

Specific gravity

84
Q

When parietal cells are stimulated, they secrete:
A. HCl and pepsinogen
B. HCO3- and intrinsic factor
C. HCl and HCO3-
D. HCl and intrinsic factor

A

HCl and intrinsic factor

85
Q

The tendency for turbulence to occur is inversely related to:
A. density
B. vessel diameter
C. viscosity
D. mean velocity

A

Viscosity

86
Q

A woman runs a marathon in 32oC weather and replaces all
volume lost in sweat by drinking distilled water. After the
marathon, she will have:
A. decreased total body water
B. decreased plasma osmolarity
C. decreased hematocrit
D. decreased intracellular fluid volume

A

Decreased plasma osmolarity

87
Q

Which of the following temporal sequences is correct for
excitation-contraction coupling in skeletal muscle?
A. Action potential in the muscle membrane;
depolarization of the T tubules; release of calcium from
the sarcoplasmic reticulum
B. Action potential in the muscle membrane; splitting of
adenosine triphosphate; binding of calcium to troponin C
C. Release of calcium from the sarcoplasmic reticulum;
depolarization of the T tubules; binding of calcium to
troponin C
D. Increased intracellular calcium; action potential in the
muscle membrane; cross bridge formation

A

Action potential in the muscle membrane; depolarization of the T tubules;
release of calcium from the sarcoplasmic reticulum

88
Q

Along the respiratory tract, which is the site of highest airway
resistance?
A. Alveoli
B. Medium-sized bronchi
C. Largest bronchi
D. Smallest bronchi

A

Medium-sized bronchi

89
Q

In contraction of gastrointestinal smooth muscle, which of the
following events occurs after binding of calcium to calmodulin?
A. Depolarization of the sarcolemmal membrane
B. Increased myosin-light chain kinase
C. Calcium release
D. Increased intracellular calcium concentration

A

Increased myosin-light chain kinase

90
Q

A person with myasthenia gravis notes increased muscle strength
when he is treated with an Acetylcholinesterase inhibitor. The
basis for this improvement is:
A. Amount of acetylcholine released from motor nerves
B. Amount of norepinephrine released from motor nerves
C. Levels of acetylcholine at the muscle end plates
D. Number of acetylcholine receptors on the muscle end
plates

A

Levels of acetylcholine at the muscle end plates

91
Q

Immediately following myocardial infarction, the pumping ability of
the heart is depressed. This leads to:
A. Compensated increase in cardiac output
B. Decrease in right atrial pressure
C. Increase in venous pressure
D. Stimulation of the parasympathetic nervous system

A

Increase in venous pressure

92
Q

Which of the following causes a decrease in renal calcium
clearance?
A. Treatment with chlorothiazide
B. Extracellular fluid volume expansion
C. Treatment with furosemide
D. hypoparathyroidism

A

Treatment with chlorothiazide

93
Q

The greatest pressure decrease in the circulation occurs across
the arterioles because:
A. they have the greatest surface area
B. they have the greatest cross-sectional area
C. they have the greatest resistance
D. the velocity of blood flow through them is highest

A

They have the greatest resistance

94
Q

This is the ability of the tubules to increase Na+ and Water
reabsorption in response to increased Na+ load:
A. Renal clearance
B. Ultrafiltration
C. Autoregulation
D. Tubuloglomerular balance

A

Tubuloglomerular balance

95
Q

A 13-year old boy has severe asthmatic attack with wheezing. He
experiences rapid breathing and becomes cyanotic. His arterial
PO2 is 60 mmHg and his PCO2 is 30 mmHg. In treating this patient,
you administer:
A. A muscarinic agonist
B. An α1-adrenergic antagonist
C. A β1-adrenergic antagonist
D. A β2-adrenergic agonist

A

β2-adrenergic agonist
Self explanatory

96
Q

During intra-abdominal surgery, you noted peristaltic movement of
the small intestine. This phenomenon:
A. Involves contraction of circular smooth muscle behind
and in front of the food bolus
B. Involves contraction of circular smooth muscle behind
the food bolus and relaxation of circular smooth muscle
in front of the bolus
C. Is coordinated by the central nervous system
D. Is responsible for mixing of food bolus

A

Involves contraction of circular smooth muscle behind the food bolus and
relaxation of circular smooth muscle in front of the bolus

97
Q

While examining a patient with bipedal edema, you recalled that
the tendency for edema to occur will be increased by:
A. Increased venous pressure
B. Increased plasma protein concentration
C. Arteriolar constriction
D. Muscular activity

A

Increased venous pressure

98
Q

Clot retraction is mainly a function of:
A. Vessel
B. Platelets
C. Clotting factors
D. Fibrin

A

Platelets

99
Q

Stool culture of your patient showed Vibrio cholerae. This
organism causes diarrhea because it:
A. Increases bicarbonate secretory channels in intestinal
epithelial cells
B. Increases chloride secretory channels in crypt cells
C. Inhibits cyclic adenosine monophosphate production in
intestinal epithelial cells
D. Prevents the absorption of glucose and causes water to
be retained in the intestinal lumen isosmotically

A

Increases chloride secretory channels in crypt cells

100
Q

The correct temporal sequence for events at the neuromuscular
junction is:
A. Uptake of calcium ions into the presynaptic terminal;
release of acetylcholine; depolarization of the muscle
end plate
B. Release of acetylcholine; action potential in the muscle
end plate; action potential in the muscle
C. Release of acetylcholine; action potential in the motor
nerve; action potential in the muscle
D. Action potential in the motor nerve; depolarization of the
muscle end plate; uptake of calcium ions into the
presynaptic nerve terminal

A

Uptake of calcium ions into the presynaptic terminal; release of
acetylcholine; depolarization of the muscle end plate

101
Q

A person with myasthenia gravis notes increased muscle strength
when he is treated with an acetylcholinesterase inhibitor. The basis
for this improvement is:
A. Amount of acetylcholine released from motor nerves
B. Amount of norepinephrine released from motor nerves
C. Levels of acetylcholine at the muscle end plates
D. Number of acetylcholine receptors on the muscle end
plates

A

Levels of acetylcholine at the muscle end plates

102
Q

The correct temporal sequence for events at the neuromuscular
junction is:
A. Action potential in the motor nerve; depolarization of the
muscle end plate; update of calcium ions into the
presynaptic nerve terminal
B. Release of acetylcholine; action potential in the motor
nerve; action potential in the muscle
C. Release of acetylcholine; action potential in the muscle
end plate; action potential in the muscle
D. Update of calcium ions into the presynaptic terminal;
release of acetylcholine; depolarization of the muscle end
plate

A

Update of calcium ions into the presynaptic terminal; release of
acetylcholine; depolarization of the muscle end plate

103
Q

During the upstroke of the action potential
A. There is net inward current and the cell interior becomes
less negative
B. There is net inward current and the cell interior becomes
more negative
C. There is net outward current and the cell interior becomes
less negative
D. There is net outward current and the cell interior becomes
more negative

A

There is net inward current and the cell interior becomes less negative

104
Q

Which of the following is a feature of the sympathetic, but not the
parasympathetic, nervous system?
A. Ganglia located in the effector organs
B. Long preganglionic neurons
C. Preganglionic neurons originate in the thoracolumbar
spinal cord
D. Postganglionic neurons release acetylcholine

A

Preganglionic neurons originate in the thoracolumbar spinal cord

105
Q

A ballet dancer spins to the left. During the spin, her eyes snap
quickly to the left. This fast eye movement is:
A. Aphasia
B. Ataxia
C. Nystagmus
D. Post-rotatory nystagmus

A

Nystagmus

106
Q

When a person is standing, blood flow in the lungs is:
A. Equal at the apex and the base
B. Highest at the apex owing to the effects of gravity on
arterial pressure
C. Highest at the base because that is where the difference
between arterial and venous pressure is greatest
D. Lowest at the base because that is where alveolar
pressure is greater than arterial pressure

A

Highest at the base because that is where the difference between
arterial and venous pressure is greatest

107
Q

Hypoxemia produces hyperventilation by a direct effect on the:
A. Carotid and aortic body chemoreceptors
B. J receptors
C. Lung stretch receptors
D. Medullary chemoreceptors

A

Carotid and aortic body chemoreceptors

108
Q

Under resting condition, the velocity of blood flow:
A. averages 33 cm/sec in the aorta
B. is around 5 cm/sec in the capillaries
C. is close to 1/10 in the capillaries than in the big arteries.
D. is directly proportional to the vascular cross-sectional
area

A

Averages 33 cm/sec in the aorta

109
Q

This law explains the interaction of pressure difference, radius and
length of a vessel and viscosity of the blood in relation with the
rate of blood flow.
A. Fourth Power Law
B. Ohm’s Law
C. Poiseuille’s Law
D. Reynold’s Law

A

Poiseuille’s Law

110
Q

When measuring the force exerted by the blood against any unit
area of the vessel wall:
A. a mean reading is normally 100 mm Hg
B. best measured in mm H₂O
C. one millimeter of mercury pressure equals 1.36 cm water
pressure
D. readily reported in systole and diastole by palpation

A

One millimeter of mercury pressure equals 1.36 cm water pressure

111
Q

Which of the following changes occurs during defecation?
A. External anal sphincter is contracted
B. Internal anal sphincter is relaxed
C. Rectal smooth muscle is relaxed
D. Segmentation contractions predominate

A

Internal anal sphincter is relaxed

112
Q

Which of the following is true about the secretion from the exocrine
pancreas?
A. It has a higher chloride ion concentration than does
plasma
B. It is stimulated by the presence of bicarbonate ions in the
duodenum
C. Pancreatic bicarbonate ion secretion is increased by
gastrin
D. Pancreatic enzyme secretion is increased by
cholecystokinin

A

Pancreatic enzyme secretion is increased by cholecystokinin

113
Q

Which of the following is NOT TRUE regarding the venous system?
A. Serves as storage area of most of the blood in the
circulation
B. Small veins have cross-sectional area up to over six times
that of arterioles.
C. The cross sectional area of the venules totals 250 cm².
D. The venae cavae are less than four times the area of the
aorta.

A

Small veins have cross-sectional area up to over six times that of
arterioles.

114
Q

A patient suffered massive hemorrhage during delivery and goes
into shock. After she recovers, she displays symptoms of
hypopituitarism. Which of the following will not be expected in this
patient?
A. Cachexia
B. Infertility
C. Low basal metabolic rate
D. Pallor

A

Pallor
NO GH = Cachexia
NO LH FSH = Infertility
NO GH = Low basal metabolic rate

115
Q

A 35-year-old man who has galactorrhea is found to have a
prolactinoma. His physician treats him with bromocriptine, which
eliminates the galactorrhea. The basis for the therapeutic action of
bromocriptine is that it:
A. Antagonizes the action of prolactin on the breast
B. Enhances the action of prolactin on the breast
C. Inhibits prolactin release from the anterior pituitary
D. Inhibits prolactin release from the hypothalamus

A

Inhibits prolactin release from the anterior pituitary

116
Q

Theoretically, lysis of red blood cells results with infusion of large
volumes of this solution:
A. 150 mM CaCl2
B. 150 mM NaCl
C. 300 mM mannitol
D. 300 mM urea

A

300 mM urea

117
Q

The velocity of conduction of action potentials along a nerve will be
increased by:
A. Decreasing the diameter of the nerve
B. Inhibiting the Na+-K+ pump
C. Myelinating the nerve
D. Stimulating the Na+-K+ pump

A

Myelinating the nerve

118
Q

Among the autonomic receptors, which is blocked by
hexamethonium at the ganglia but not at the neuromuscular
junction?
A. Adrenergic α receptors
B. Adrenergic β1 receptors
C. Adrenergic β2 receptors
D. Cholinergic nicotinic receptors

A

Cholinergic nicotinic receptors

119
Q

As you observe the colorful painting in a museum, your lecture on
rods and cones flashed in your mind. You tried to recall: When
compared with the cones of the retina, the rods:
A. Adapt to darkness before the cones
B. Are more sensitive to low-intensity light
C. Are most highly concentrated on the fovea
D. Are primarily involved in color vision

A

Are more sensitive to low-intensity light

120
Q

While waiting for your turn to receive hepatitis B immunization at the
clinic, you remembered how impulses are perceived. Which of the
following refers to C fibers?
A. Are afferent nerves from Golgi tendon organs
B. Are afferent nerves from muscle spindles
C. Have the largest diameter of any nerve fiber type
D. Have the slowest conduction velocity of any nerve fiber
type

A

Have the slowest conduction velocity of any nerve fiber type

121
Q

Your concentration was disturbed when the microphone was
suddenly turned on and a piercing sound was heard. You tried to
explain how sound waves are sensed. Which of the following best
describes the basilar membrane of the Organ of Corti?
A. High frequencies produce maximal displacement of the
basilar membrane near the helicotrema
B. The apex responds better to low frequencies than the
base does
C. The base is more compliant than the apex
D. The base is wider than the apex

A

The apex responds better to low frequencies than the base does

122
Q

Inspiration “splits” the second heart sound because:
A. The aortic valve closes before the pulmonic valve
B. The mitral valve closes before the tricuspid valve
C. The pulmonic valve closes before the aortic valve
D. The tricuspid valve closes before the mitral valve

A

The aortic valve closes before the pulmonic valve

OTHER CHOICES
First heart sound = Mitral valve closes before the tricuspid valve

123
Q

A 25-week-old premature infant developed neonatal respiratory
distress syndrome. Which of the following would be expected in this infant?
A. Decreased lung compliance
B. Decreased work of breathing
C. Lecithin:sphingomyelin ratio of greater than 2:1 in amniotic fluid
D. Surface tension of the small alveoli is too low

A

Decreased lung compliance

124
Q

A 13-year-old patient has severe asthmatic attack with wheezing.
She presented with rapid breathing and became cyanotic. Her
arterial Po2 is 60 mm Hg and her Pco2 is 30 mm Hg. Which of the
following statements is most likely to be true:
A. Her arterial Pco2 is lower than normal because hypoxemia
is causing him to hyperventilate
B. Her arterial Pco2 is higher than normal because of
inadequate gas exchange
C. Her residual volume is decreased
D. Forced expiratory volume1 / forced vital capacity (FEV1 /
FVC) is increased

A

Her arterial Pco2 is lower than normal because hypoxemia is causing
him to hyperventilate

125
Q

While rushing to the examination room, you noted your respiration to be deep and rapid. During such rapid inflation of the lungs, there is:
A. Decrease in elastic recoil
B. Increased concentration of surfactant in the surface of the alveoli
C. Reduction in surface density of surfactant
D. Reduction in surface tension

A

Reduction in surface tension
OTHER CHOICES
Decrease in elastic recoil = Should be INCREASE in elastic recoil
Reduction in surface density of surfactant = should remain
CONSTANT
Increased concentration of surfactant in the surface of the alveoli =
should be UNCHANGED

126
Q

Along the respiratory tract, which is the site of highest airway
resistance?
E. Alveoli
F. Medium-sized bronchi
G. Largest bronchi
H. Smallest bronchi

A

Medium-sized bronchi

127
Q

Secretion of K+ by the distal tubule will be decreased by:
A. A high-K+ diet
B. Hyperaldosteronism
C. Metabolic alkalosis
D. Spironolactone administration

A

Spironolactone administration

128
Q

A 45-year-old woman develops severe diarrhea while on vacation.
What is your impression if presented with the following arterial blood
gas result?
pH = 7.25
Pco2 = 24 mm Hg
[HCO3-] = 10 mEq/L
Venous blood samples show decreased blood [K+] and a normal
anion gap
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis
D. Respiratory alkalosis

A

Metabolic acidosis

129
Q

The reabsorption of filtered HCO3-

A. Acidifies tubular fluid to a pH of 4.4
B. Is directly linked to excretion of H+ as NH4
+
C. Is inhibited by decreases in arterial Pco2
D. Results in reabsorption of less than 50% of the filtered
load when the plasma concentration of HCO3
- is 24 mEq/L

A

Is inhibited by decreases in arterial Pco2

130
Q

patient arrives at the emergency room with hypotension, reduced
tissue turgor, and the following arterial blood values:
pH = 7.69
[HCO3-] = 57 mEq/L
Pco2 = 28 mm Hg

Which of the following responses would also be expected to occur in
this patient?
A. Decreased K+ secretion by the distal tubules
B. Exchange of intracellular H+ for extracellular K+
C. Hyperventilation
D. Increased ratio of H2PO4- to HPO4-2 in urine

A

Exchange of intracellular H+ for extracellular K+

131
Q

To maintain normal H+ balance, total daily excretion of H+ should
equal the daily:
A. Fixed acid production plus fixed acid ingestion
B. HCO3- excretion
C. HCO3- filtered load
D. Titratable acid excretion

A

Fixed acid production plus fixed acid ingestion

132
Q

A 50-year-old man is given a glucose tolerance test. In the test, the
plasma glucose concentration is increased and glucose reabsorption
and excretion are measured. When the plasma glucose
concentration is higher than occurs at transport maximum (Tm), the:
A. Clearance of glucose is zero
B. Excretion rate of glucose equals the filtration rate of
glucose
C. Excretion rate of glucose increases with increasing
plasma glucose concentrations
D. Reabsorption rate of glucose equals the filtration rate of
glucose

A

Excretion rate of glucose increases with increasing plasma glucose
concentrations

133
Q

Selective destruction of the zona fasciculata of the adrenal cortex
would produce a deficiency of a:
A. Catecholamine
B. Glucocorticoid
C. Mineralocorticoid
D. Tyrosine derivative

A

Glucocorticoid

134
Q

A 35-year-old man with untreated diabetes mellitus type I is brought
to the emergency room. An injection of insulin would be expected to
cause an increase in his:
A. Blood glucose concentration
B. Blood pH
C. Blood potassium excretion
D. Urine glucose concentration

A

Blood pH

135
Q

Which of the following functions of the Sertoli cells mediates
negative feedback control of follicle-stimulating hormone secretion?
A. Aromatization of testosterone
B. Maintenance of the blood-testes barrier
C. Synthesis of inhibin
D. Synthesis of testosterone

A

Synthesis of inhibin

136
Q

You always wondered why no pregnant mother is breastfeeding the elder child of her present pregnancy. Which of the following explains the suppression of lactation during pregnancy?
A. Blood levels of estrogen and progesterone are high
B. Blood prolactin levels are too low for milk production to
occur
C. Human placental lactogen levels are too low for milk
production to occur
D. The fetal adrenal gland does not produce sufficient estriol

A

Blood levels of estrogen and progesterone are high

137
Q

Which of the following decreases the conversion of 25-
hydroxycholecalciferol to 1,25-dihydrocholecalciferol?
A. A diet low in calcium
B. Chronic renal failure
C. Hyperparathyroidism
D. Hyperphosphatemia

A

Chronic Renal Failure

138
Q

A 45-year-old woman with paroxysmal hypertension, tachycardia,
headache, sweating, anxiousness, tremor, and glucose intolerance
may need to be worked up to rule in:
A. Pheochromocytoma
B. Primary adrenocortical insufficiency
C. Primary overproduction of ACTH
D. Thyrotoxicosis

A

Pheochromocytoma

139
Q

Motility of the large intestine achieves both propulsive movement
and reservoir function. These phenomena are characterized as
follows:
A. Distinct fasting and fed patterns of contractions are seen
in the colon.
B. Mass peristalsis is responsible for the colonic
haustrations.
C. Nonpropulsive segmentation and mass peristalsis occur in
the proximal colon.
D. Parasympathetic control of the descending and
rectosigmoid is mediated by the vagus nerve.

A

Nonpropulsive segmentation and mass peristalsis occur in the
proximal colon.

OTHER CHOICES
SEGMENTAL CONTRACTION is responsible for the colonic
haustrations.
Distinct fasting and fed patterns of contractions are seen in the colon =
SAME ONLY
Parasympathetic control of the descending and rectosigmoid is
mediated by the PELVIC NERVES

140
Q

A 65-year-old man undergoes total pancreatectomy because of the
presence of a tumor. Which of the following outcomes would not be
expected after he recovers from the operation?
A. Hyperglycemia
B. Metabolic acidosis
C. Steatorrhea
D. Weight gain

A

Weight gain

141
Q

Following a gastrojejunostomy, your patient noted discomfort after
meals. This “dumping” syndrome is due in part to:
A. Hypoglycemia
B. Increased blood pressure
C. Increased secretion of cholecystokinin
D. Increased secretion of glucagon

A

Hypoglycemia

142
Q

Which of the following would best distinguish an otherwise healthy
person with severe water deprivation from a person with the
syndrome of inappropriate antidiuretic hormone?
A. Circulating levels of antidiuretic hormone
B. Free-water clearance
C. Plasma osmolarity
D. Urine osmolarity

A

Plasma osmolarity

143
Q

Which of the following would cause an increase in both glomerular
filtration rate and renal plasma flow?
A. A ureteral stone
B. Dilatation of the afferent arteriole
C. Dilatation of the efferent arteriole
D. Hyperproteinemia

A

Dilatation of the afferent arteriole

144
Q

A woman runs a marathon in 32˚C weather and replaces all volume lost in sweat by drinking distilled water. After the marathon, she will have:
A. Decreased intracellular fluid volume
B. Decreased total body water
C. Increased hematocrit
D. Increased plasma osmolarity

A

Increased hematocrit
OTHER CHOICES
Intracellular fluid volume = Will increase
Total body water = Unchanged
Increased plasma osmolarity = Will Decrease

145
Q

The repolarization phase of the action potential of ventricular muscle
fibers is caused by the opening of which of the following channels?
A. Ca2+
B. Cl-
C. K+
D. Na+

A

K+

146
Q

If the Po2 of arterial blood is 100 mm Hg, what is the concentration of
dissolved O2 in blood, given that the solubility of O2 is 0.003 ml O2
/100 ml blood per mm Hg?
A. 0.3 ml/100 ml blood
B. 0.03 ml/100 ml blood
C. 0.3 ml/ml blood
D. 0.03 ml/ml blood

A

0.3 ml/100 ml blood

147
Q

Which of the following is released from neurons in the
gastrointestinal tract and produces smooth muscle relaxation?
A. Cholecystokinin
B. Gastrin
C. Secretin
D. Vasoactive intestinal peptide

A

Vasoactive intestinal peptide

148
Q

While caring for your one-month-old brother, you noted that he often
defecates following a meal. This phenomenon is best described by
the following:
A. Distention of the stomach increases the frequency of
segmentation contractions in the large intestine.
B. Histamine mediated hydrochloric acid secretion potently
primes the rectum to evacuate its contents.
C. Increased peristaltic contractions indicates immaturity of
development of the large intestine
D. The efferent limb of the reflex is mediated by cholecystokinin and gastrin.

A

The efferent limb of the reflex is mediated by cholecystokinin and
gastrin.

149
Q

A 50-year-old male with severe Crohn’s disease has been
unresponsive to drug therapy and undergoes ileal resection. After
the surgery, he will have steatorrhea because:
A. Chylomicrons do not form in the intestinal lumen
B. Dietary triglycerides cannot be digested
C. Micelles do not form in the intestinal lumen
D. The liver bile acid pool increases

A

Micelles do not form in the intestinal lumen
OTHER CHOICES
The liver bile acid pool increases = should be DECREASES
Chylomicrons do not form in the intestinal lumenc= Should be FORMS
in the intestinal lumen
Dietary triglycerides cannot be digested = Should be digested as
FREE FATTY ACIDS and MONOGLYCERIDES

150
Q

A 40-year-old woman has hypocalcemia, hyperphosphatemia, and
decreased urinary phosphate excretion. Injection of parathyroid
hormone causes an increase in urinary cyclic adenosine
monophosphate. The most likely diagnosis is:
A. Hypoparathyroidism after thyroid surgery
B. Primary hyperparathyroidism
C. Vitamin D deficiency
D. Vitamin D intoxication

A

Hypoparathyroidism after thyroid surgery

151
Q

Of the gases found in inspired air, which one is carried only in
dissolved form and never bound or chemically modified?
A. Nitrogen
B. Hydrogen
C. Halogen
D. Bicarbonate

A

Nitrogen

Source: Costanzo Respiratory

152
Q

Diffusion-limited gas exchange may be observed in the following,
except:
A. During strenuous exercise
B. Emphysema
C. Fibrosis
D. Pulmonary embolism

A

Pulmonary embolism

153
Q

Which of the following parts of the body has
cortical motoneurons with the largest
representation on the primary motor cortex
(area4)?
(A) Shoulder
(B) Ankle
(C) Fingers
(D) Elbow
(E) Knee

A

Answer: C. FINGERS
Ratio:
● Representation on the motor homunculus is greatest for those
structures that are involved in the most complicated movements-the
fingers, hands, and face.

154
Q

Which autonomic receptor mediates
secretion of epinephrine by the adrenal
medulla?
(A) Adrenergic a1 receptors
(B) Adrenergic B1 receptors
(C) Adrenergic B2 receptors
(D) Cholinergic muscarinic receptors
(E) Cholinergic nicotinic receptors

A

Answer: E. Cholinergic nicotinic receptors

Ratio:
● Preganglionic sympathetic fibers synapse on the chromaffin cells of
the adrenal medulla at a nicotinic receptor. Epinephrine and, to a
lesser extent, norepinephrine are released into the circulation.

155
Q

Cutting which structure on the right side
causes blindness in the temporal field of the
left eye and the nasal field of the right eye?
(A) Optic nerve
(B) Optic chiasm
(C) Optic tract
(D) Geniculocalcarine tract

A

Answer: C
Ratio:
● Fibers from the left temporal field and the right nasal field ascend
together in the right optic tract

156
Q

A ballet dancer spins to the left. During the
spin, her eyes snap quickly to the left. This
fast eye movement is
(A) nystagmus
(B) postrotatory nystagmus
(C) ataxia
(D) aphasia

A

Answer: A. nystagmus
Ratio:
● The fast eye movement that occurs during a spin is nystagmus. It
occurs in the same direction as the rotation. After the spin,
postrotatory nystagmus occurs in the opposite direction

157
Q

Which of the following has a much lower
concentration in the cerebrospinal fluid (CSF)
than in cerebral capillary blood?
(A) Na+
(B) K+
(C) Osmolarity
(D) Protein
(E) Mg2+

A

Answer: D
Ratio:
● Cerebrospinal fluid (CSF) is similar in composition to the interstitial
fluid of the brain. Therefore, it is similar to an ultrafiltrate of plasma
and has a very low protein concentration because large protein
molecules cannot cross the blood brain barrier. There are other
differences in composition between CSF and blood that are created
by transporters in the choroid plexus, but the low protein
concentration of CSF is the most dramatic difference.

CSF = BLOOD
[Na+ Cl- HCO3- Osmolarity]

CSF < Blood
[K+ Ca2+ Glucose *Cholesterol *Protein *Negligible

CSF > Blood
Mg2+
Creatinine

158
Q

Which of the following autonomic drugs
acts by stimulating adenylate cyclase?
(A) Atropine
(B) Clonidine
(C) Curare
(D) Norepinephrine
(E) Phentolamine
(F) Phenylephrine
(G) Propranolol

A

Answer: D
Ratio:
● Among the autonomic drugs, only B1 and B2 adrenergic agonists act
by stimulating adenylate cyclase.
● Norepinephrine is a B1 agonist.
● Atropine is a muscarinic cholinergic antagonist.
● Clonidine is an a2 adrenergic agonist.
● Curare is a nicotinic cholinergic antagonist.
● Phentolamine is an a1 adrenergic antagonist.
● Phenylephrine is an a1 adrenergic agonist.
● Propranolol is a B1 and B2 adrenergic antagonist.

159
Q

Which of the following is a step in
photoreception in the rods?
(A) light converts all-trans retinal to 11-cis
retinal
(B) Metarhodopsin II activates transducin
(C) Cyclic guanosine monophosphate (cGMP)
levels increase
(D) Rods depolarize
(E) Glutamate release increases

A

Answer: B
Ratio:
● Photoreception involves the following steps.
● Light converts 11-cis retinal to all-trans retinal, which is converted to
such intermediates as metarhodopsin II. Metarhodopsin II activates a
stimulatory G protein (transducin), which activates a
phosphodiesterase. Phosphodiesterase breaks down cyclic guanosine
monophosphate (cGMP), so intracellular cGMP levels decrease,
causing closure of Na+ channels in the photoreceptor cell membrane
and hyperpolarization. Hyperpolarization of the photoreceptor cell
membrane inhibits release of the neurotransmitter, glutamate. If the
decreased release of glutamate interacts with ionotropic receptors on
bipolar cells, there will be inhibition (decreased excitation). If the
decreased release of glutamate interacts with metabotropic
receptors on bipolar cells, there will be excitation (decreased
inhibition).

160
Q

Pathogens that produce fever cause
(A) decreased production of interleukin-1 (IL-1)
(B) decreased set-point temperature in the
hypothalamus
(C) shivering
(D) vasodilation of blood vessels in the skin

A

Answer: C
Ratio:
● Pathogens release interleukin-1 (IL-1) from phagocytic cells. IL-l then
acts to increase the production of prostaglandins, ultimately raising
the temperature set point in the anterior hypothalamus. The
hypothalamus now “thinks” that the body temperature is too low
because the core temperature is lower than the new set-point
temperature) and initiates mechanisms for generating heat-shivering,
vasoconstriction, and shunting of blood away from the venous plexus
near the skin surface.

161
Q

Which of the following statements about the
olfactory system is true?
(A) The receptor cells are neurons
(B) The receptor cells are sloughed off and
are not replaced
(C) Ax.ons of cranial nerve (CN) I are A-delta
fibers
(D) Ax.ons from receptor cells synapse in the prepiriform cortex
(E) Fractures of the cribriform plate can cause
inability to detect ammonia

A

Answer: A
Ratio:
● Cranial nerve (CN) I innervates the olfactory epithelium. Its axons are
C fibers. Fracture of the cribriform plate can tear the delicate
olfactory nerves and thereby eliminate the sense of smell (anosmia);
however, the ability to detect ammonia is left intact Olfactory
receptor cells are unique in that they are true neurons that are
continuously replaced from undifferentiated stem cells.

162
Q

A lesion of the chorda tympani nerve would
most likely result in
(A) impaired olfactory function
(B) impaired vestibular function
(C) impaired auditory function
(D) impaired taste function
(E) nerve deafness

A

Answer: D
Ratio:
● The chorda tympani (cranial nerve [CN] Vll) is involved in taste; it
innervates the anterior two-thirds of the tongue.

163
Q

Which of the following would produce
maximum excitation of the hair cells in the
right horizontal semicircular canal?
(A) Hyperpolarization of the hair cells
(B) Bending the stereocilia away from the
kino cilia
(C) Rapid ascent in an elevator
(D) Rotating the head to the right

A

Answer: D
Ratio:
● The semicircular canals are involved in angular acceleration or
rotation. Hair cells of the right semicircular canal are excited
(depolarized) when there is rotation to the right. This rotation causes
bending of the stereocilia toward the kino cilia, and this bending
produces depolarization of the hair cell. Ascent in an elevator would
activate the saccules, which detect linear acceleration.

164
Q

The inability to perform rapidly alternating
movements (dysdiadochokinesia) is
associated with lesions of the
(A) premotor cortex
(B) motor cortex
(C) cerebellum
(D) substantia nigra
(E) medulla

A

Answer: C
Ratio:
● Coordination of movement (synergy) is the function of the
cerebellum. Lesions of the cerebellum cause ataxia, lack of
coordination, poor execution of movement, delay in initiation of
movement, and inability to perform rapidly alternating movements.
The premotor and motor cortices plan and execute movements.
Lesions of the substantia nigra, a component of the basal ganglia,
result in tremors, lead-pipe rigidity, and poor muscle tone (Parkinson
disease).

165
Q

Which autonomic receptor is activated by low concentrations of epinephrine released from the adrenal medulla and causes vasodilation?
(A) Adrenergic a1 receptors
(B) Adrenergic B1 receptors
(C) Adrenergic B2 receptors
(D) Cholinergic muscarinic receptors
(E) Cholinergic nicotinic receptors

A

Answer: C
Ratio:
● B2 Receptors on vascular smooth muscle produce vasodilation.
● a1 Receptors on vascular smooth muscle produce vasoconstriction.
● Because B2 receptors are more sensitive to epinephrine than are α
receptors, low doses of epinephrine produce vasodilation, and high
doses produce vasoconstriction.

166
Q

Complete transection of the spinal cord at the
level of T1would most likely result in
(A) temporary loss of stretch reflexes below
the lesion
(B) temporary loss of conscious
proprioception below the lesion
(C) permanent loss of voluntary control of
movement above the lesion
(D) permanent loss of consciousness above
the lesion

A

Answer: A
Ratio:
● Transection of the spinal cord causes “spinal shock’’ and loss of all reflexes below the level of the lesion. These reflexes, which are local
circuits within the spinal cord, will return with time or become
hypersensitive. Proprioception is permanently (rather than temporarily) lost because of the interruption of sensory nerve fibers.
Fibers above the lesion are intact.

167
Q

Which of the following structures has a
primary function to coordinate rate, range,
force, and direction of movement?
(A) Primary motor cortex
(B) Premotor cortex and supplementary
motor cortex
(C) Prefrontal cortex
(D) Basal ganglia
(E) Cerebellum

A

Answer: E
Ratio:
● Output ofPurkinje cells from the cerebellar cortex to deep cerebellar
nuclei is inhibitory. This output modulates movement and is
responsible for the coordination that allows one to “catch a fly.”

168
Q

Which reflex is responsible for polysynaptic
excitation of contralateral extensors?
A) Stretch reflex (myotatic)
B) Golgi. tendon reflex (inverse myotatic)
C) Flexor withdrawal reflex
D) Subliminal occlusion reflex

A

Answer: C
Ratio:
● Flexor withdrawal is a polysynaptic reflex that is used when a person
touches a hot stove or steps on a tack. On the ipsilateral side of the
painful stimulus, there is flexion (withdrawal); on the contralateral
side, there is extension to maintain

169
Q

Muscle stretch leads to a direct increase in
firing rate of which type of nerve?
A) a-Motoneurons
B) y-Motoneurons
C) Group Ia fibers
D) Group Ib fibers

A

Answer: C
Ratio:
● Group Ia afferent fibers innervate intrafusal fibers of the muscle
spindle. When the intrafusal fibers are stretched, the group Ia fibers
fire and activate the stretch reflex, which causes the muscle to return
to its resting length.

170
Q

Patients are enrolled in trials of a new
atropine analogue. Which of the following
would be expected?
(A) Increased AV node conduction velocity
(B) Increased gastric acidity
(C) Pupillary constriction
(D) Sustained erection
(E) Increased sweating

A

Answer: A
Ratio:
● An atropine analogue would block muscarinic receptors and thus
block actions that are mediated by muscarinic receptors. Muscarinic
receptors slow AV node conduction velocity; thus, muscarinic blocking
agents would increase AV node conduction velocity. Muscarinic
receptors increase gastric acid secretion, constrict the pupils, mediate
erection, and cause sweating (via sympathetic cholinergic innervation
of sweat glands); thus, blocking muscarinic receptors will inhibit all of
those actions.

171
Q

At which site is systolic blood pressure the
highest?
A. Aorta
B. Central vein
C. Pulmonary artery
D. Right atrium
E. Renal artery
F. Renal vein

A

Answer: E [II G, H, I]
Ratio:
● Pressures on the venous side of the circulation (e.g., central vein, right atrium, renal vein) are lower than pressures on the arterial side.
Pressure in the pulmonary artery (and all pressures on the right side of the heart) are much lower than their counterparts on the left side of the heart. In the systemic circulation, systolic pressure is actually slightly higher in the downstream arteries (e.g., renal artery) than in
the aorta because of the reflection of pressure waves at branch
points.

172
Q

A person’s electrocardiogram (ECG) has no P
wave, but has a normal QRS complex and a
normal T wave. Therefore, his pacemaker is
located in the
A. sinoatrial (SA) node
B. atrioventricular (AV) node
C. bundle of His
D. Purkinje system
E. ventricular musc

A

Answer: B [III A]
Ratio:
● The absent P wave indicates that the atrium is not depolarizing and,
therefore, the pacemaker cannot be in the sinoatrial (SA) node.
Because the QRS and T waves are normal, depolarization and
repolarization of the ventricle must be proceeding in the normal
sequence. This situation can occur if the pacemaker is located in the
atrioventricular (AV) node. If the pacemaker were located in the
bundle of His or in the Purkinje system, the ventricles would activate
in an abnormal sequence (depending on the exact location of the
pacemaker) and the QRS wave would have an abnormal
configuration. Ventricular muscle does not have pacemaker
properties.

173
Q

An electrocardiogram (ECG) on a person
shows ventricular extrasystoles.
The extrasystolic beat would produce
A. increased pulse pressure because
contractility is increased
B. increased pulse pressure because
heart rate is increased
C. decreased pulse pressure because
ventricular filling time is increased
D. decreased pulse pressure because
stroke volume is decreased
E. decreased pulse pressure because
the PR interval is increased

A

Answer: D [V G]
Ratio:
● On the extrasystolic beat, pulse pressure decreases because there is inadequate ventricular filling time—the ventricle beats “too soon.” As a
result, stroke volume decreases.

174
Q

An increase in contractility is demonstrated
on a Frank-Starling diagram by
A. increased cardiac output for a given
end- diastolic volume
B. increased cardiac output for a given
end- systolic volume
C. decreased cardiac output for a given
end-diastolic volume
D. decreased cardiac output for a given
end-systolic volume

A

Answer: A [IV D 5 a]
Ratio:
An increase in contractility produces an increase in cardiac output for
a given end-diastolic volume, or pressure. The Frank-Starling
relationship demonstrates the matching of cardiac output (what
leaves the heart) with venous return (what returns to the heart). An
increase in contractility (positive inotropic effect) will shift the curve
upward.

175
Q

The aortic valve closes at point
A. 1
B. 2
C. 3
D. 4

A

Answer: C [IV 1 c]
Ratio:
● Closure of the aortic valve occurs once ejection of blood from the ventricle has occurred and the left ventricular pressure has decreased to less than the aortic pressure.

176
Q

The first heart sound corresponds to point
A. 1
B. 2
C. 3
D. 4

A

Answer: A [V B]
Ratio:
● The first heart sound corresponds to closure of the atrial–ventricular
valves. Before this closure occurs, the ventricle fills (phase 4 → 1).
After the valves close, isovolumetric contraction begins and
ventricular pressure increases (phase 1 → 2).

177
Q

If the heart rate is 70 beats/min, then the
cardiac output of this ventricle is closest to
A. (a) 3.45 L/min
B. (B) 4.55 L/min
C. (C) 5.25 L/min
D. (d) 8.00 L/min
E. (e) 9.85 L/min

A

Answer: C [IV E 1, G 1, 2]
Ratio:
● Stroke volume is the volume ejected from the ventricle and is
represented on the pressure–volume loop as phase 2 → 3;
end-diastolic volume is about 140 mL and end-systolic volume is
about 65 mL; the difference, or stroke volume, is 75 mL. Cardiac
output is calculated as stroke volume × heart rate or 75 mL × 70 beats
/min = 5250 mL/min or 5.25 L/min.

178
Q

If Kf is 0.5 mL/min/mm Hg, what is the
rate of water flow across the capillary wall?
A. 0.06 mL/min
B. 0.45 mL/min
C. 4.50 mL/min
D. 9.00 mL/min
E. (e18.00 mL/min

A

Answer: C [VII C 1
Ratio:
● Kf is the filtration coefficient for the capillary and describes the intrinsic water permeability.

Water flow = Kf x net Pressure
= 0.5 mL/min/mm Hg x 9 mm Hg
= 4.5 mL/min

179
Q

A 66-year-old man, who has had a
sympathectomy, experiences a greaterthan-
normal fall in arterial pressure upon
standing up. The explanation for this
occurrence is
A. an exaggerated response of the
renin– angiotensin–aldosterone
system
B. a suppressed response of the renin–
angiotensin–aldosterone system
C. an exaggerated response of the
baroreceptor mechanism
D. a suppressed response of the
baroreceptor mechanism

A

Answer: D [IX A]

180
Q

Which of the following is an effect of
histamine?
A. Decreased capillary filtration
B. Vasodilation of the arterioles
C. Vasodilation of the veins
D. Decreased Pc
E. Interaction with the muscarinic
receptors on the blood vessels

A

Answer: B [VIII B 2 a]
Ratio:
● Histamine causes vasodilation of the arterioles, which increases Pc
and capillary filtration. It also causes constriction of the veins, which
contributes to the increase in Pc. Acetylcholine (ACh) interacts with
muscarinic receptors (although these are not present on vascular
smooth muscle).

181
Q

Carbon dioxide (CO2) regulates blood flow to
which one of the following organs?
A. Heart
B. Skin
C. Brain
D. Skeletal muscle at rest
E. Skeletal muscle during exercise

A

Answer: C [VIII C, D, E 2, F]
Ratio:
● Blood flow to the brain is autoregulated by the Pco2. If metabolism
increases (or arterial pressure decreases), the Pco2 will increase and
cause cerebral vasodilation. Blood flow to the heart and to skeletal
muscle during exercise is also regulated metabolically, but adenosine
and hypoxia are the most important vasodilators for the heart.
Adenosine, lactate, and K+ are the most important vasodilators for
exercising skeletal muscle. Blood flow to the skin is regulated by the
sympathetic nervous system rather than by local metabolites.

182
Q

The physiologic function of the relatively slow
conduction through the atrioventricular (AV)
node is to allow sufficient time for
A. runoff of blood from the aorta to the
arteries
B. venous return to the atria
C. filling of the ventricles
D. contraction of the ventricles
E. repolarization of the ventricles

A

Answer: C [III C]
Ratio:
● The atrioventricular (AV) delay (which corresponds to the PR interval)
allows time for filling of the ventricles from the atria. If the ventricles
contracted before they were filled, stroke volume would decrease.

183
Q

Blood flow to which organ is controlled
primarily by the sympathetic nervous system
rather than by local metabolites?
A. Skin
B. Heart
C. Brain
D. Skeletal muscle during exercise

A

Answer: A [VIII C–F]
Ratio:
● Circulation of the skin is controlled primarily by the sympathetic
nerves. The coronary and cerebral circulations are primarily regulated
by local metabolic factors. Skeletal muscle circulation is regulated by
metabolic factors (local metabolites) during exercise, although at rest
it is controlled by the sympathetic nerves.

184
Q

A 72-year-old woman, who is being treated
with propranolol, finds that she cannot
maintain her previous exercise routine. Her
physician explains that the drug has reduced
her cardiac output. Blockade
of which receptor is responsible for the
decrease in cardiac output?
A. α1 Receptors
B. β1 Receptors
C. β2 Receptors
D. Muscarinic receptors
E. Nicotinic receptors

A

Answer: B [III 3; Table 3.1]
Ratio:
● Propranolol is an adrenergic antagonist that blocks both β1 and β2
receptors. When propranolol is administered to reduce cardiac output,
it inhibits β1 receptors in the sinoatrial (SA) node (heart rate) and in
ventricular muscle (contractility).

185
Q

Which receptor mediates slowing of the
heart?
A. α1 Receptors
B. β1 Receptors
C. β2 Receptors
D. Muscarinic receptors

A

Answer: D [III E 2 a; Table 3.1]
Ratio:
● Acetylcholine (ACh) causes slowing of the heart via muscarinic
receptors in the sinoatrial (SA) node.

186
Q

Which of the following agents or changes has
a negative inotropic effect on the heart?
A. Increased heart rate
B. Sympathetic stimulation
C. Norepinephrine
D. Acetylcholine (ACh)
E. Cardiac glycosides

A

Answer: D [IV C]
Ratio:
A negative inotropic effect is one that decreases myocardial
contractility. Contractility is the ability to develop tension at a fixed
muscle length. Factors that decrease contractility are those that
decrease the intracellular [Ca2+]. Increasing heart rate increases
intracellular [Ca2+] because more Ca2+ ions enter the cell during the
plateau of each action potential. Sympathetic stimulation and
norepinephrine increase intracellular [Ca2+] by increasing entry
during the plateau and increasing the storage of Ca2+ by the
sarcoplasmic reticulum (SR) [for later release]. Cardiac glycosides
increase intracellular [Ca2+] by inhibiting the Na+–K+ pump, thereby
inhibiting Na+–Ca2+ exchange (a mechanism that pumps Ca2+ out of
the cell). Acetylcholine (ACh) has a negative inotropic effect on the
atria.

187
Q

Which agent is released or secreted after a
hemorrhage and causes an increase in renal
Na+ reabsorption?
A. Aldosterone
B. Angiotensin I
C. Angiotensinogen
D. Antidiuretic hormone (ADH)
E. Atrial natriuretic peptide

A

Answer: A [VI C 4; IX C]
Ratio:
● Angiotensin I and aldosterone are increased in response to a
decrease in renal perfusion pressure. Angiotensinogen is the precursor
for angiotensin I. Antidiuretic hormone (ADH) is released when atrial
receptors detect a decrease in blood volume. Of these, only
aldosterone increases Na+ reabsorption. Atrial natriuretic peptide is
released in response to an increase in atrial pressure, and an increase
in its secretion would not be anticipated after blood loss.

188
Q

Which of the following lung volumes or
capacities can be measured by spirometry?
A. Functional residual capacity (FRC)
B. Physiologic dead space
C. Residual volume (RV)
D. Total lung capacity (TLC)
E. Vital capacity (VC)

A

Answer: E [I A 4, 5, B 2, 3, 5].
Ratio:
● Residual volume (RV) cannot be measured by spirometry. Therefore,
any lung volume or capacity that includes the RV cannot be
measured by spirometry. Measurements that include RV are
functional residual capacity (FRC) and total lung capacity (TLC). Vital
capacity (VC) does not include RV and is, therefore, measurable by spirometry. Physiologic dead space is not measurable by spirometry
and requires sampling of arterial Pco2 and expired CO2*

189
Q

An infant born prematurely in gestational week 25 has neonatal respiratory distress
syndrome. Which of the following would be
expected in this infant?
A. Arterial Po2 of 100 mm Hg
B. Collapse of the small alveoli
C. Increased lung compliance
D. Normal breathing rate
E. Lecithin:sphingomyelin ratio of
greater than 2:1 in amniotic fluid

A

Answer: B [II D 2]

Ratio:
● Neonatal respiratory distress syndrome is caused by lack of
adequate surfactant in the immature lung. Surfactant appears
between the 24th and the 35th gestational week. In the absence of
surfactant, the surface tension of the small alveoli is too high. When
the pressure on the small alveoli is too high (P = 2T/r), the small
alveoli collapse into larger alveoli. There is decreased gas exchange
with the larger, collapsed alveoli; and ventilation/perfusion (V/Q) mismatch, hypoxemia, and cyanosis occur. The lack of surfactant also
decreases lung compliance, making it harder to inflate the lungs, increasing the work of breathing, and producing dyspnea (shortness of breath). Generally, lecithin: sphingomyelin ratios greater than 2:1signify mature levels of surfactant

190
Q

In which vascular bed does hypoxia cause
vasoconstriction?
A. Coronary
B. Pulmonary
C. Cerebral
D. Muscle
E. Skin

A

Answer: B [VI C]
Ratio:
● Pulmonary blood flow is controlled locally by the Po2 of alveolar air.
Hypoxia causes pulmonary vasoconstriction and thereby shunts
blood away from unventilated areas of the lung, where it would be
wasted. In the coronary circulation, hypoxemia causes vasodilation.
The cerebral, muscle, and skin circulations are not controlled directly
by Po2

191
Q

A 12-year-old boy has a severe asthmatic attack with wheezing. He experiences rapid breathing and becomes cyanotic. His
arterial Po2 is 60 mm Hg and his Pco2 is 30mmHg.

Which of the following statements about
this patient is most likely to be true?
A. Forced expiratoryvolume1/forced vital capacity (FEV1/FVC) is increased
B. Ventilation/perfusion (V/Q) ratio is
increased in the affected areas of his
lungs
C. His arterial Pco2 is higher than
normal because of inadequate gas
exchange
D. His arterial Pco2 is lower than normal
because hypoxemia is causing him to
hyperventilate
E. His residual volume (RV) is decreased

A

Answer: D [VIII B 2 a]
Ratio:
● The patient’s arterial Pco2 is lower than the normal value of 40 mm
Hg because hypoxemia has stimulated peripheral chemoreceptors to
increase his breathing rate; hyperventilation causes the patient to
blow off extra CO2 and results in respiratory alkalosis. In an
obstructive disease, such as asthma, both forced expiratory volume
(FEV1) and forced vital capacity (FVC) are decreased, with the larger decrease occurring in FEV1* Therefore, the FEV1/FVC ratio is decreased. Poor ventilation of the affected areas decreases the ventilation/perfusion (V/Q) ratio and causes hypoxemia. The patient’s
residual volume (RV) is increased because he is breathing at a higher
lung volume to offset the increased resistance of his airways.

192
Q

Which of the following is the site of highest
airway resistance?
A. Trachea
B. Largest bronchi
C. Medium-sized bronchi
D. Smallest bronchi
E. Alveoli

A

Answer: C [II E 4]
Ratio:
● The medium-sized bronchi actually constitute the site of highest
resistance along the bronchial tree. Although the small radii of the
alveoli might predict that they would have the highest resistance, they
do not because of their parallel arrangement. In fact, early changes in
resistance in the small airways may be “silent” and go undetected
because of their small overall contribution to resistance.

193
Q

The pH of venous blood is only slightly
more acidic than the pH of arterial blood
because
A. CO2 is a weak base
B. There is no carbonic anhydrase in
venous blood
C. The H+generated from CO2 and H20
is buffered by HC03- in venous blood
D. The H+generated from CO2 and H20
is buffered by deoxyhemoglobin in
venous blood
E. Oxyhemoglobin is a better buffer for
H+than is deoxyhemoglobin

A

Answer: D [VB]
Ratio:
● In venous blood, CO2 combines with H20 and produces the weak acid
H2C03, catalyzed by carbonic anhydrase. The resulting H+is buffered
by deoxyhemoglobin, which is such an effective buffer for H+
(meaning that the pK is within 1.0 unit of the pH of blood) that the pH
of venous blood is only slightly more acid than the pH of arterial
blood. Oxyhemoglobin is a less effective buffer than is
deoxyhemoglobin

194
Q

Secretion of K by the distal tubule will be
decreased by:
A. Metabolic alkalosis
B. A high K diet
C. Hyperaldosteronism
D. Spironolactone administration
E. Thiazide diuretic administration

A

Answer: D [V B 4 b]
Ratio:
● Distal K+ secretion is decreased by factors that decrease the driving
force for passive diffusion of K+ across the luminal membrane.
● Because spironolactone is an aldosterone antagonist, it reduces
K+ secretion.
● Alkalosis, a diet high in K+, and hyperaldosteronism all increase [r]
in the distal cells and thereby increase r secretion.
● Thiazide diuretics increase flow through the distal tubule and dilute
the luminal [K+] so that the driving force for K+ secretion is increased.

195
Q

Which of the following substances or
combinations of substances could be used to
measure interstitial fluid volume?
A. Mannitol
B. D2O alone
C. Evans blue
D. Inulin and D2O
E. Inulin and radioactive albumin

A

Answer: E [I B 2 b-d]
Ratio:
● Interstitial fluid volume is measured INDIRECTLY by determining the
difference between extracellular fluid (ECF) volume and plasma
volume.
Inulin, a large fructose polymer that is restricted to the extracellular
space, is a marker for ECF volume.
● Radioactive albumin is a marker for plasma volume.

PHYSIOLOGY (1 decks)

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