c1. BASIC SCIence B (75-154) Flashcards Preview

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Flashcards in c1. BASIC SCIence B (75-154) Deck (77):
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76. The central chemoreceptors are primarily sensitive to:
a. increased PCO2
b. hypotension
c. H+ ions or pH
d. increased PaO2

c. H+ ions or pH
central chemoreceptors are thought to lie on the anterolateral surface of the medulla and respond to changes in hydrogen ion concentration in the CSF

1

75. all of the following respiratory abnormalities are associated with scoliosis except:
a. increase chest wall compliance
b. decreased PaO2 and increased PaCO2
c. pulmonary hypertension
d. decreased lung volumes

a. increased chest wall compliance
scoliosis is a lateral rotation and curvature of the spine and a deformity of the rib cage. It affects both cardiac and respiratory functions. Reduced lung volumes, pulmonary hyertension, decreased PO2 and increased PCO2 are common; chest wall compliance is DECREASED.

2

77. the peripheral chemoreceptors are primarily sensitive to:
a. increased PCO2
b. decreased PCO2
c. decreased PaO2
d. H+ ions

c. decreased PaO2
The carotid bodies are the principal peripheral chemoreceptors in humans and are sensitive to changes in PO2, PCO2, pH and arterial perfusion. Reductions in PO2 produce the most sensitive changes in chemoreceptors.

3

78. what is the significance of brown fat?
a. large amounts of iron are stored here
b. it is a source of nonshivering thermogenesis in infants
c. obeses patients have increased amounts of brown fat
d. it is the origin of sweating in infants before 1 year of age

b. it is the source of nonshivering thermogenesis in infants
nonshivering thermogenesis is an increase in metabolic heat production without an increase in mechanical muscle work. It occurs principally through the metabolism of brown fat, which comprises 2% to 6% of an infants total body weight

4

79. which of the following is not considered a triggering agent of malignant hyperthermia?
a. desflurane
b. halothane
c. succinylcholine
d. propofol

d. propofol
Inhalation agents (except for nitrous oxide) and succ are potent triggers of malignant hyperthermia. The induction agents are not considered triggers.

5

80. which agent augments nondepolarizing muscle relaxants?
a. sodium
b. magnesium
c. phosphorus
d. potassium

b. magnesium
rationale: magnesium augments NDMRs and sux to a lesser degree. Mechanism is unknown, but it may be related to decreased calcium levels caused by increased magnesium levels
(high mag=low calcium)

6

81. oxygen consumption of a neonate is how many times greater than in an adult?
a. 2x
b. 1x
c. 3x
d. 4x

a. 2x
rationale: the most important difference (physiologically) between adult and pediatric patients is O2 consumption. Neonates consumption of O2 is >6 ml/kg which is twice that of a 70 kg adult.

7

82. which of the following is true regarding the neonate's kidney function?
a. GFR is increased
b. urine output is high
c. renal blood flow is decreased
d. excretion of renal-eliminated drugs is delayed

d. excretion of renal eliminated drugs is delayed
rationale: the decrease in renal function that is common anmong neonates can also delay the excretion of drugs that depend on the kidney for elimination.

8

83. what is the average GFR for a term neonate?
a. 120 ml/min x 1.7m
b. 20 ml/min x 1.7m
c. 100 ml/min x 1.7m
d. 50 ml/min x 1.7m

b. 20 ml/min x 1.7m
rationale: the GFR is greatly decreased in neonates and increases 4 fold in 3-5 weeks.

9

84. In equipotent doses, which of the following produces the most cardiac depression?
a. thiopental
b. etomidate
c. propofol
d. midazolam

c. propofol
propofol causes the most cardiac and respiratory suppression and should be used in reduced doses (if at all) in cardiac and elderly patients.

10

85. at what percentage should a neonate's Hct be maintained to optimize tissue oxygenation?
a. 50%
b. 45%
c. 25%
d. 40%

d. 40%
because of the decreased cardiac reserve of neonates and the leftward shift of the oxygen-hgb dissociation curve, it is useful to maintain the Hct at approximately 40%

11

86. the primary finction of surfactant is to:
a. maintain alveolar stability
b. bronchodilate
c. promote mucociliary transport
d. allow diffusion of gasses

a. maintain alveolar stability
the function of surfactant is to break surfact tension of water and therefore stabilize alveolar membranes and prevent their collapse. collapse of alveoli would lead to right to left intrapulmonary shunting, hypoxia and metabolic acidosis

12

87. surfactant is produced in specialized cells called
a. alveolar cells
b. type II pneumocytes
c. hyaline membrane cells
d. type I pneumocytes

b. type II pneumocytes
also called type 2 alveolar cells, great alveolar cells or septal cells. Granular in appearance and secrete surfactant. Before 26 weeks gestation, there are not enough of these cells to produce adeuate amounts of surfactant; but there is by 35 weeks gestation.
type I pneumocytes provide most of the walls of the alveoli and allow for gas exchange

13

88. which of the following is NOT a risk in preterm neonates
a. respiratory distress syndrome
b. retrolental fibroplasia
c. hypercalecmia
d. intracranial hemorrhage

c. hypercalcemia
neonates are actually prone to hypocalcemia (ca++ < 3.5 mEq/L) since fetal calcium stores are largely achieved through the last triester.

14

89. to reduce the risk of retrolental fibroplasia (retinopathy) in succeptible neonates; at what level should the PaO2 be maintained?
a. as close to 100 mmHg as possible
b. between 80-90 mmHg
c. between 60-80 mmHg
d. less than 60 mmHg

c. between 60-80 mmHg
the americal academy of pediatrics states the administeration of O2 to premature infants shoud be 50-80 mmHg; therefore 60-80 is safe for preventing retinopathy. This however can present a dilemma since neonates are prone to hypoxia. This low PO2 should be tempered with the realization that hypoxia can lead to brain injury.

15

90. total renal blood flow decreases what percent each decade of adult life?
a. 15%
b. 10%
c. 5%
d. 1%

b. 10%
total renal blood flow decreases by 10% each decade due to changes in the renal cortex with relative sparing of the renal medulla; also GFR decreases

16

91. All of the following statements are true regarding the pulonary system of the geriatric patient except:
a. closing volume decreases
b. FRC increases
c. residual volume increases
d. vital capacity decreases

a. closing volume decreases
closing volumes and closing capacity increase with aging and approach the FRC; this (and other factors) cause a widening alveolar gradient

17

92. All of the following statements are true regarding the renal function of the geriatric patient except:
a. renal blood flow decreases
b. GFR decreases
c. ability to concentrate urine is impaired
d. serum creatnine level increases

d. serum creatnine level increases
the serum creatnine in the elderly remains the same inspite of impaired GFR; this is partially d/t decreased muscle mass which decreases creatnine load

18

93. all are physiologic change that put the geriatric patient at risk for developing hypothermia except:
a. defecient thermostat control
b. ineffective shivering controls
c. decreased heat production
d. increased heat loss

b. ineffective shivering controls
the elderly shivering controls are intact; the patient is at higher risk d/t inability to retain heat, decreased heat production and heat regulation (thyroid etc.).

19

94. all of the following are signs and symptoms of thyroid storm except:
a. bradycardia
b. hyperreflexia
c. hypertension followed by hypotension
d. altered consciousness

a. bradycardia
thyroid storm is a medical emergency that carries a 10% to 50% mortality rate. S/S include mental status changes, arrhythmias, CHF, heat intolerance, fever, profuse swelling, n/v and diarrhea. Hypokalemia may be present; treatment is beta blockers, propylthiouracil and sodium iodide.

20

95. marked defeciency in circulating levels of thyroid hormone during fetal development can lead to:
a. addison's disease
b. cretinism
c. thyroid storm
d. thyroid goiter

b. cretinism
cretinism is a condition of extreme hypothyroidism during fetal life, infancy and childhood. It is characterized by growth failure and mental retardation especially. Skeletal growth is more inhibited than soft tissue growth, giving the appearance of an obese, stocky and short child.

21

96. The patient with myxedema would likely exhibit which of the following s/s?
a. heat intolerence
b. sunken facial features
c. hypertension
d. slowed mentation

d. slowed mentation
myxedema is caused by severe hypofunction of the thyroid gland. It is characterized by a general slowing of the metabolic function, swelling of facial structures, cold intolerance and drowziness. Treatment= thyroid replacement

22

97. fibrinogen is synonymous with what clotting factor?
a. factor II
b. factor VIII
c. factor I
d. factor IX

c. factor I
fibrinogen is also called factor I; during blood coagulation, fibrinogen is converted to fibrin by factor IIA

23

98. the extrinsic pathway integrity can be measured by what test.
a. prothrombin time
b. partial thromboplastin time
c. bleeding time
d. activated clotting time

a. prothrombin time (PT)
the formation of prothrombin activator by the extrinsic pathway is rapid and often within 15 seconds. The prothrombin time reflects the integrity of the extrinsic pathway.
(extrinsic=PT; intrinsic=PTT (if it has more "i"'s, its intrinsic)

24

99. The intrinsic pathway is normally tested by which labaratory test?
a. activated clotting time
b. bleeding time
c. prothrombin time
d. partial thromboplastin time

d. partial thromboplastin time
The intrinsic pathway proceeds slowly, usually requiring 2-6 minutes to cause clotting. A variety of inhibitors act at different sites in the intrinsic pathway. The partial thromboplastin time reflects the integrity of the intrinsic pathway.

25

100. The most common reaction to occur after a non-autologous blood transfusion is:
a. allergic reaction
b. hemolytic reaction
c. febrile reaction
d. activation of the clotting cascade

c. febrile reaction
white blood cell or platelet sensitization is typically manifested as a febrile reaction. Such reactions are relatively common and occur in 1% to 3% of transfusions. They are characterized by an increase in temperature without evidence of hemolysis. Use of a 20-40 micrometer filter helps to reduce this reaction.

26

101. intracellular fluid volume represents what percent of total body weight?
a. 40%
b. 20%
c. 60%
d. 80%

a. 40%
total body water is 60% of total body weight or 42L in a 70kg patient. The intracellular fluid volume constitutes 40% of TBW and extracellular fluid constitutes 20% of TBW.

27

102. extracellular fluid volume represents what percent of total body weight?
a. 20%
b. 40%
c. 60%
d. 5%

a. 20%
60% of total body weight is water; of the 60%, 20% is extracellular

28

103. the predominant intracellular ion is?
a. PO4-
b. Na+
c. K+
d. Cl-

c. K+
the predominant intracellular cation is potassium, with the intracellular concentration being about 150meq/L; in contrast extracellular K+ is about 4meq/L

29

104. water represents what percent of TBW?
a. 60%
b. 80%
c. 50%
d. 90%

a. 60%
total body water is 60% (42L in a 70 kg patient).

30

105. the prodominant extracellular cation is:
a. cl-
b.K+
c. PO4-
d. Na+

d. Na+
extracellular fluid contains the most sodium in the body. The sodium concentration is approximately 140 meq/L, with intracellular concentration approx 10 meq/L

31

106. clinical manifestations of hypernatremia include all except:
a. seizures
b. hyporeflexia
c. hyperreflexia
d. thirst

b. hyporeflexia
signs of hypernatremia include thirst, neurological weakness, hemorrhage,

32

107. the most common cause of hyperkalemia is:
a. drugs
b. excess potassium intake
c. insulin deficiency
d. catecholamine insufficiency

a. drugs
drugs are the most common cause of hyperkalemia. Drugs that may limit K+ excretion include NSAIDS, ACE inhibitors, cyclosporine, K+ sparing diuretics

33

108. hyperkalemia may reslut from all of the following except:
a. mineralcorticoid deficiency
b. insulin excess
c. renal tubular dysfunction
d. catecholamine insuffeciency

b. insulin excess
insulin deficiency will most commonly result in hyperkalemia. Insulin in a dose dependent fashion, causes cellular reuptake of potassium by increasing the activity of the sodium-potassium pump. This effect works best at high insulin levels and therefore, administration of insulin will reduce the serum potassium concentration.

34

109. Hemophelia A is characterized by deficiency of what blood factor?
a. VII
b. X
c. XI
d. VIII

d. VIII
hemophilia A is a deficiency in factor VIII (8), which is known as the hemophilia factor. Treatment is usually with cryoprecipitate

35

110. bleeding time is a measurement of the:
a. thrombin time
b. platelet function only
c. platelet number and function
d. time to clot lysis

c. platelet number and function
the bleeding time, the most widely excepted clinical test of platelet function, measures both quality and quantity. the normal bleeding time is 3 to 8 minutes

36

111. a normal bleeding time is
a. 1-2 minutes
b. 3-8 minutes
c. 10 minutes
d. 12-15 minutes

b. 3-8 minutes

37

112. the atrial contraction component generally accounts for what percentage of ventricular filling?
a. 20% but may increase to 40% with pathology
b. 40% in all individuals
c. varies from 30-60%
d. accounts for 100%

a. 20% (can increase to 40% with pathology)
the majority of blood drains directly into the ventricles upon entering the heart. The atria contract to deliver the remaining blood to the ventricle. This "atrial kick" is lost during atrial fibrillation and contributes to the reduction in stroke volume that accompanies this phenomenon.

38

113. in regard to aortic insufficiency, all of the following are true except:
a. it is usually rheumatiod in origin
b. concentric hypertrophy develops
c. compliance is increased
d. bradycardia increases regurgitant flow

b. concentric hypertrophy
with aortic insufficiency, ECCENTRIC hypertrophy develops. this is characterized by dilated chambers. It also includes a slow heart rate increased SVR and occasionally hypotension and pulmonary edema

39

114. in regard to the pathophysiology behind mitral stenosis:
a. pulmonary HTN is common
b. right sided heart failure is an uncommn finging
c. atrial fibrillation is an uncommon concurrent finding
d. pulmonary vascular resistance is decreased

a. pulmonary HTN is common
in mitral stenosis, as the orifice of the valve narrows, the left atrium experiences pressure overload. This elevated atrial pressure is transmitted to the pulmonary circuit, leading to pulmonary HTN and right sided heart failure

40

115. in chronic mitral regurgitaton all of the following are true except :
a. left ventricular systolic pressure decreases
b. left ventricle shows signs of overload
c. pulmonary HTN is common
d. concentric hypertrophy occurs

d. concentric hypertrophy occurs
In chronic mitral regurg, the left ventricle and atrium show volume overload which leads to eccentric hypertrophy

41

116. all of the following are hormonal changes commonly found with stress or trauma except:
a. increased cortisol
b. decreased glucagon
c. hyperglycemia
d. increased catecholamines

b. decreased glucagon
after a trauma injury it is expected that there will be an increase in adrenocorticoids, glucocorticoids and catecholamines

42

117. the most common metabolic complication of TPn is
a. alkalosis
b. hyperkalemia
c. acidosis
d. hyperglycemia

d. hyperglycemia
the most common metabolic complication of TPN is hyperglycemia with glucosuria being common as well. Monitor glucose and urine especially at the start of TPN.

43

118. What causes the first heart sound (S1)?
a. aortic valves
b. closure of the mitral and tricuspid valves
c. closure of the aortic and pulmonic valves
d. closure of the semilunar valves

b. closure of the mitral and tricuspid valves
the vibration of the valves immediately after closure along with the vibration of the adjacent blood and walls of the heart travel through the chest wall and can be heard with a stethoscope

44

119. What causes the second heart sound (S2)?
a. closure of the aortic and pulmonic valves
b. closure of the mitral and tricuspid valves
c. closure of the mitral valve only
d. closure of the atrioventricular valves

a. closure of the aortic and pulmonic valves
the second heart sound results from sudden closure of the aortic and pulmonary valves. Similar to S1, the valve closing reverberates through the tissues in the chest wall and can be heard with a stethoscope

45

120. in a myocardial infarction, which area of the heart is usually damaged first?
a. transmural myocardium
b. epicardium
c. subendocardium
d. endocardium

c. subendocardium
the subendocardium becomes infarcted before any other part of the heart muscle. Under normal conditions, this layer of the muscle has difficulty obtaining adequate blood flow because of the intense compression by contraction of the heart. Any condition that compromisis blood flow to the heart causes damage to the subendocardium first, then spreads out toward the epicardium.

46

121. the coronary arteries are perfused during what phase of the cardiac cycle?
a. presystolic
b. systolic
c. diastole
d. postdiastolic phase

c. diastole
the coronary blood flow is approx. 225 ml/min which is 4% to 5% of the cardiac output. During diastole, the cardiac muscle relaxes completely and no longer obstructs the blood flow through the left ventricle capillaries

47

122. the main determinants of cardiac output are all of the following except:
a. compliance
b. preload
c. afterload
d. body surface area

d. BSA
cardiac output is the volume of blood pumped from the heart per minute. It is the product of heart rate and stroke volume. The cardiac output is determined by preload, afterload, heart rate, contractility and ventricular compliance
BSA is involved with cardiac index (C.O. divided by bsa)

48

123. Normal cardiac index is:
a. 2.5-4.0
b. 2.0-5.0
c. 1.5-2.5
d. 2.5-6.0

a. 2.5-4.0
cardiac index is the C.O. divided by the BSA. the normal is 2.5-4 L/min/sq meter of body surface area

49

124. Normal ejection fraction is:
a. 0.4-0.6
b. 0.4-1.0
c. 0.6-0.7
d. 0.7-0.9

c. 0.6-0.7
the ejection fraction (normally 60-70%) is the ratio of the stroke volume to the end-diastolic volume. Severe impairment is present when the ejection fraction is less than 0.4. The ejection fraction is determined by the end-systolic volume minus the end systolic volume divided by the end diastolic volume.
[(ESV-EDV)/EDV]

50

125. normal SVR is:
a. 900-1500 dynes/cm/sec
b. 1200-2500 dynes/cm/sec
c. 1000-1200 dynes/cm/sec
d. 1500-2000 dynes/cm/sec

a. 900-1500 dynes/cm/sec to the -5 power
SVR= [(MAP - CVP) / C.O.] x 80
SVR is said to be between 700-1500 to 1200-1500 (900-1500 is most common although Nag says 1200-1500).

51

126. normal pulmonary vascular resistance (PVR) is:
a. 100-500 dynes/cm/sec
b. 100-300 dynes/cm/sec
c. 0.50-150 dynes/cm/sec
d. 200-600 dynes/cm/sec

b. 100-300 dynes/cm/sec
PVR is [(PA - PCWP) / C.O.] x 80
(PCWP=wedge pressure)

52

127. The reflex that causes an increase in arterial pressure secondary to cerebral ischemia
a. chemoreceptor reflex
b. bezold-jarisch reflex
c. cushing's reflex
d. bainbridge reflex

c. cushing's reflex
increased cerebrospinal fluid pressure compresses cerebral arteries causing ischemia. The response is a natural reflex to increase arterial pressure to reperfuse the brain.

53

128. The reflex in which noxious stimuli to the ventricular wall causes hypotension and bradycardia:
a. bezold-jarisch reflex
b. cushing's reflex
c. bainbridge reflex
d. muller manuver

a. bezold-jarisch reflex
this reflex induces hypotension and bradycardia and vagally influences coronary vasodilation. Reperfusion of previously ischemic myocardial tissue also elicits the reflex.

54

129. peripheral chemoreceptors sensitive to decreasing oxygenation are located in the:
a. peripheral chemoreceptors
b. carotid body
c. aortic arch
d. carotid and aortic bodies

d. carotid and aortic bodies
peripheral chemoreceptors are usually minimally active. However, occlusion of the carotid artery decreases oxygen supply and activates the reflex to increase vantilation and blood pressure while decreasing heart rate. Stimulation of the aortic bodies causes tachycardia.

55

130. During a valsalva maneuver:
a. venous return to the right ventricle decreases
b. venous pressure in the extremities decreases
c. cardiac output increases
d. intrathoracic pressure decreases

a. venous return to the right ventricle decreases
the valsalva maneuver involves voluntary closing of the glottis while performing a forced expiration, which increases intrathoracic pressure. Venous pressure in the head and the extremities increases while venous return to the right ventricle decreases. Blood pressure decreases and heart rate increases then decreases if tachycardic.

56

131. The heart receives approximately what percentage of cardiac output?
a. 10%
b. 4%
c. 20%
d. 25%

b. 4%
the cardiac output is distributed to organ systems as follows; brain (12%); heart (4%); liver (24%); kidneys (20%); muscle (23%); skin (6%); intestines (8%).

57

134. what is the normal stroke volume in mL of a 70 kg man (answer= mL/beat)?
a. 75-110 mL
b. 50-75 mL
c. 100-120 mL
d. 60-90 mL

d. 60-90 mL
stroke volume is equal to the cardiac output divided by the heart rate (since C.O.= HR x SV). A normal adult averages 60-90 mL per beat

58

135. an increase in atrial pressure causes a reflex increase in heart rate known as:
a. cushing's reflex
b. vasomotor reflex
c. bainbridge reflex
d. stanley reflex

c. bainbridge
bainbridge is a reflexive increase in HR when vagal tone is high and when the right atrium or central vein is distended. The response depends on pre-existing heart rate. During tachycardia it does not occur, but volume loading and a slow heart rate will elicit the reflex.
(high CVP with low heart rate CAN cause the bainbridge).

59

136. aortic and carotid chemoreceptors are sensitive to all except:
a. increased H+
b. modest hypotension with systolic BP > 90 mmHg
c. increased CO2
d. decreased PAO2

136. b modest hypotension with systolic > 90 mmHg
the chemoreceptors are chemosensitive cells that respond to a lack of oxygen, excess carbon dioxide or excess hydrogen

60

137. angiotensin I is converted to angiotensin II:
a. in the kidney tubules
b. in the juxtamedullary cells
c. in the adrenal glands
d. in the lung

d. in the lung
Renin is synthesized in the juxtulomedular cells of the kidneys. It acts on angiotensin to form angiotensin I. Angiotensin I is converted to angiotensin II in the lungs by ACE.

61

139. hypertension of unknown origin is called:
a. essential hypertension
b. neurogenic hypertension
c. malignant hypertension
d. spontaneous hypertension

a. essential hypertension
approximately 90% of all persons who have hypertension are said to have essential hypertension, which means that its origin is unknown. (EH is #1).

62

140. all of the following are true of heart rate excpet:
a. it is strongly influenced by humoral stimulation
b. it is primarily determined by the sinus node
c. parasympathetic stimulation causes bradycardia
d. sympathetic stimulation can cause tachycardia

a. it is strongly influenced by humoral stimulation
Heart rate is primarily influenced by the automaticity of the sinoatrial node. Neurologic influences are paramount, but hormonal influences are minimal. Neurologic influences are mediated through the autonomic nervous system.

63

141. All of the following are characteristics fetal hemoglobin (HgF) except:
a. newborns have 70% to 90% HgF
b. its affinity for oxygen is greater than that of adult Hgb
c. it is released more readily to the tissues
d. the P50 of HgF is 20 mmHg

c. it is released more readily to the tissues
the most important difference between hemoglobin F and adult hemoglobin is its high affinity for oxygen. HgF limits tissue oxygen delivery and hypoxic conditions due to a high oxygen binding ability

64

142. newborn hemogolbin is:
a. 18-19 g/dL
b. 14-15 g/dL
c. 10-12 g/dL
d. 8-10 g/dl

a. 18-19 g/dL
fetal hgb is high at birth (14-24 g/dL range) and gradually declines to 10-11 g/dL during the first few months of life as fetal hemoglobin is replaced. It then gradually increases to its maximum at around 14 yrs. of age.

65

143. All of the following congenital heart lesions result in an increased pulmonary blood flow except:
a. ASD (atrial septal defect)
b. tetrology of fallot
c. VSD (ventricular septal defect)
d. PDA (patent ductus arteriosus)

b. Tetrology of fallot
Congenital heart defects are classified as either increasing or decreasing pulmonary blood flow. Those exhibiting an increase in pulmonary flow include ASD,VSD, PDA, endocardial cushion, and aortal pulmonary windows. Those exhibiting a decrease in pulmonary blood flow include tetrology of fallot, pulmonary atresia, tricuspid atresia and Ebstein's abnormality

66

144. the safe dose of epinephrine for local infiltration in a child anesthetized with halothane is:
a. 0.1 mg/kg
b. 0.1 mcg/kg
c. 10 mcg/kg
d. 0.001 mg/kg

c. 10 mcg/kg
halothane sensitizes the heart to the action of many sympathomimetics. If epinephrine is administered, dysrhythmias are unlikely with doses of 10 mcg/kg or less.

67

145. All of the following are true of infants physiology of temperature homeostasis except:
a. they rely on shivering thermogenesis
b. they lack insulating subcutaneous fat
c. they lose heat rapidly
d. they have a large surface area relative to body weight

a. they rely on shivering thermogenesis
Infants rely on NON-SHIVERING thermogenesis to help maintain their body temperature because of their high level of brown fat which produces heat without affecting muscle metabolism.
----
they DOhave alot of sq fat;
they DO lose heat rapidly &
they DO have a large surface area to body weight ratio

68

146. flow through the ductus arteriosus is insignificant by:
a. 2-3 days
b. 2 hours
c. 15 hours
d. 5-7 days

c. 15 hours
Patent ductus arteriosus is common in the premature infant but is usually insignificant in the newborn within the first 24 hours. It is characterized by a murmur at the left sternal border radiating to the back, bounding pulses and increased pulmonary blood flow. Pharmacologic closure with indomethacin may be attempted before surgical intervention if the patient is severely symptomatic.

69

147. All of the following are true of the neonate except:
a. Pulmonary vascular resistance is dramatically increased
b. systemic vascular resistance is dramatically increased
c. blood flow to the lungs increases as the cord is cut
d. flow through the ductus arteriosus reverses

a. PVR is dramatically increased
when the lungs first expand with air at birth, pulmonary vascular resistance falls markedly by approximately 80% from prenatal levels within a few minutes of normal indication of ventilation. As PVR falls, blood flow to the lungs in the pulmonary veins close to the atrial septum over the foramen ovale.

70

148. neonates exposed to hypoxemia suffer all of the following except:
a. systemic vasoconstriction
b. pulmonary vasodilation
c. bradycardia
d. reduced cardiac output

b. pulmonary vasodilation
neonates exposed to hypoxia suffer from pulmonary vasoCONSTRICTion and systemic vasoCONSTRICTion as well as bradycardia and decreased cardiac output. Because of their high metabolic rate for oxygen, hypoxemia develops more rapidly in the neonate.

71

149. newborns fatigue more easily during periods of increased respiration due to:
a. decreased levels of type I muscle fibers
b. increased levels of type I muscle fibers
c. decreased levels of type II muscle fibers
d. increased levels of type II muscle fibers

a. decreased levels of type I muscle fibers
a newborn's muscles of ventilation are subject to fatigeue. This tendency is determined by the types of muscle fibers present. In preterm infants, less than 10% of the fibers in the diaphragm are type I (slow twitch/ highly oxidative/ fatigue resistant). In term infants, 30% are type I; in adults, 55% are type I. A child reaches adult proportions in type I diaphragmatic fibers at approximately age 1 year.

72

150. Slow-twitch, highly oxidative, fatigue resistant muscle fibers are type:
a. III
b. IV
c. II
d. I

d. I
type I muscle fibers are:
-slow twitch
-highly oxidative
-fatigue resistant

73

151. The principal surfactant in the lung is:
a. lysine
b. sphingomyelin
c. lecithin
d. glycine

c. lecithin
surfactant lowers surface tension and prevents alveoli from collapsing. Lecithin is produced by type II pneumo-
(incomplete)

74

152. all of the following are true of the infant airway except:
a. the larynx is at level C6
b. the epiglottis is stiff and "U" shaped
c. the tongue is large
d. the larynx is relatively anterior

a. the larynx is at level C6
Infants have a large head and short tongue, and narrow nasal passages. The larynx is at C4 and anterior when compared with that of adults. The airway is narrowist at the cricoid cartilage (thus no need for cuffed ET tubes).

75

153. retinopathy of prematurity is more common in all of the following except:
a. infants who have had major surgery
b. infants exposed to high levels of oxygen
c. gestational age

a. infants who have had major surgery
Major surgery does not lead to disorder. Judicious use of oxygen during surgery with arterial tensions below 140 mmHg is generally considered safe?

76

154. surfactant production occurs at:
a. 32 weeks
b. 24 weeks
c. 22 weeks
d. 34-36 weeks

c. 22 weeks
surfactant begins to be produced at 22 weeks gestation. It increases sharply at 35 to 36 weeks as the lung matures.