9Circulatory and lymphatic systems test w solutions

The diagram below illustrates the relationship between interstitial extracellular fluid pressure and lymph flow?. No, because the subsequent increase in interstitial fluid pressure would

BIOLOGY TOPICAL:

Circulatory and Lymphatic Systems

Test 1

Time: 23 Minutes*

Number of Questions: 18

* The timing restrictions for the science topical tests are optional If

you are using this test for the sole purpose of content

reinforcement, you may want to disregard the time limit

DIRECTIONS: Most of the questions in the following

test are organized into groups, with a descriptive passage preceding each group of questions Study the passage, then select the single best answer to each question in the group Some of the questions are not based on a descriptive passage; you must also select the best answer to these questions If you are unsure of the best answer, eliminate the choices that you know are incorrect, then select an answer from the choices that remain Indicate your selection by blackening the corresponding circle on your answer sheet A periodic table is provided below for your use with the questions

PERIODIC TABLE OF THE ELEMENTS

1

H

1.0

2

He

4.0 3

Li

6.9

4

Be

9.0

5

B

10.8

6

C

12.0

7

N

14.0

8

O

16.0

9

F

19.0

10

Ne

20.2 11

Na

23.0

12

Mg

24.3

13

Al

27.0

14

Si

28.1

15

P

31.0

16

S

32.1

17

Cl

35.5

18

Ar

39.9 19

K

39.1

20

Ca

40.1

21

Sc

45.0

22

Ti

47.9

23

V

50.9

24

Cr

52.0

25

Mn

54.9

26

Fe

55.8

27

Co

58.9

28

Ni

58.7

29

Cu

63.5

30

Zn

65.4

31

Ga

69.7

32

Ge

72.6

33

As

74.9

34

Se

79.0

35

Br

79.9

36

Kr

83.8 37

Rb

85.5

38

Sr

87.6

39

Y

88.9

40

Zr

91.2

41

Nb

92.9

42

Mo

95.9

43

Tc

(98)

44

Ru

101.1

45

Rh

102.9

46

Pd

106.4

47

Ag

107.9

48

Cd

112.4

49

In

114.8

50

Sn

118.7

51

Sb

121.8

52

Te

127.6

53

I

126.9

54

Xe

131.3 55

Cs

132.9

56

Ba

137.3

57

La *

138.9

72

Hf

178.5

73

Ta

180.9

74

W

183.9

75

Re

186.2

76

Os

190.2

77

Ir

192.2

78

Pt

195.1

79

Au

197.0

80

Hg

200.6

81

Tl

204.4

82

Pb

207.2

83

Bi

209.0

84

Po

(209)

85

At

(210)

86

Rn

(222) 87

Fr

(223)

88

Ra

226.0

89

Ac †

227.0

104

Rf

(261)

105

Ha

(262)

106

Unh

(263)

107

Uns

(262)

108

Uno

(265)

109

Une

(267)

*

58

Ce

140.1

59

Pr

140.9

60

Nd

144.2

61

Pm

(145)

62

Sm

150.4

63

Eu

152.0

64

Gd

157.3

65

Tb

158.9

66

Dy

162.5

67

Ho

164.9

68

Er

167.3

69

Tm

168.9

70

Yb

173.0

71

Lu

175.0

†

90

Th

232.0

91

Pa

(231)

92

U

238.0

93

Np

(237)

94

Pu

(244)

95

Am

(243)

96

Cm

(247)

97

Bk

(247)

98

Cf

(251)

99

Es

(252)

100

Fm

(257)

101

Md

(258)

102

No

(259)

103

Lr

(260)

GO ON TO THE NEXT PAGE.

Passage I (Questions 1–6)

While the coagulation factors necessary to initiate

clotting are always present in the blood, the formation of

a clot in the intact vascular system is prevented by three

properties of the vascular walls First, the endothelial

lining is smooth enough to prevent activation of the

clotting system, which is sensitive to vascular damage

Second, the inner surface of the endothelium is covered by

glycocalyx, a mucopolysaccharide that repels the clotting

factors and platelets in the blood Third, an endothelial

surface protein known as thrombomodulin binds

thrombin, the enzyme that converts fibrinogen into fibrin

in the final stage of clotting The binding of thrombin to

thrombomodulin reduces the amount of thrombin that can

participate in clotting Also, the

thrombomodulin-thrombin complex activates protein C, a plasma protein

that hinders clot formation by acting as an anticoagulant

If the endothelial surface of a vessel has been

roughened by arteriosclerosis or infection, and the

glycocalyx-thrombomodulin layer has been lost, the first

step of the intrinsic blood clotting pathway (Figure 1)

will be triggered A protein known as Factor XII changes

shape to become “activated” Factor XII, setting off a

cascade of reactions that culminates in the formation of

thrombin and the subsequent conversion of fibrinogen to

fibrin Simultaneously, platelets release platelet factor 3, a

lipoprotein that helps to activate the coagulation factors

A thrombus, which is an abnormal blood clot that

develops in blood vessels, may diminish or obstruct

vascular flow A thrombus that dislodges and travels in

the bloodstream is referred to as an embolus Typically, an

embolus will travel through the circulatory system until it

becomes trapped at a narrow point, resulting in vessel

blockage

blood trauma or contact with collagen

platelet phospholipids and factor 3

XII activated XII

XI activated XI

IX activated IX

Ca 2+

VIII thrombin

Ca 2+

X activated X

thrombin Ca 2+

V prothrombin activator prothrombin thrombin

Ca 2+

fibrinogen fibrin

Figure 1

1 According to Figure 1, the role that Factor VIII plays

in the activation of Factor X is that of:

A an enzyme.

B a cofactor.

C a proenzyme.

D a substrate.

2 Which of the following is most likely to be the

origin of a pulmonary embolus that blocks the pulmonary artery?

A Veins of the lower legs

B Left side of the heart

C Aorta

D Pulmonary veins

GO ON TO THE NEXT PAGE.

3 The initial formation of thrombin in the intrinsic

clotting pathway:

A causes a deficiency of prothrombin and platelets.

B has a positive feedback effect on thrombin

formation

C deactivates the blood factors.

D enhances the conversion of Factor XII to

activated Factor XII

4 All of the following would cause prolonged clotting

time in a human blood sample EXCEPT:

A addition of a calcium deionizing agent.

B removal of Factor VIII.

C addition of activated Factor X.

D removal of platelets and platelet phospholipids.

5 Based on information in the passage, which of the

following is the most likely mechanism of action of

protein C?

A Negative feedback regulation of thrombomodulin

B Promotion of the formation of prothrombin

C Activation of Factors X and XII

D Deactivation of activated Factors V and VIII

6 Clinicians inject small quantities of heparin in

patients with a history of pulmonary emboli in order

to prevent further thrombus formation Heparin

greatly increases the activity of antithrombin III, the

blood’s primary inhibitor of thrombin One possible

adverse side effect of heparin administration is:

A increased blood pressure.

B partial destruction of existing emboli.

C minor bleeding.

D dizziness.

GO ON TO THE NEXT PAGE.

Questions 7 through 11 are

NOT based on a descriptive

passage

7 If a patient’s lymphatic channels have been obstructed

by the spread of malignant tumors, which of the

following consequences will result?

A Increased leakage of fluid from the capillaries into

extracellular spaces

B Decreased concentration of proteins in the

extracellular spaces

C Increased fluid pressure in the extracellular spaces

D Decreased risk of metastasis

8 The spleen can be considered the largest lymph node,

even though it is not part of the lymphatic system

Like all lymph nodes, the spleen:

A acts as a blood reservoir for the circulatory

system

B intercepts antigenic agents in the circulating

blood

C is composed entirely of large aggregates of

lymphocytes

D contains the cells responsible for humoral and

cell-mediated immunity

9 Which of the following is NOT a function of the

lymphatic system?

A Removal of proteins from interstitial spaces

B Absorption of fats from the gastrointestinal tract

C Drainage of excess cerebrospinal fluid from the

brain

D Removal and destruction of foreign particles

1 0 B cells remain dormant in the lymph nodes and other

lymphoid tissue regions until activated by an antigen

for which the lymphocytes are specific Once

activated, the B cells ultimately give rise to:

A antibodies.

B macrophages.

C cytotoxic T cells.

D lymphokines.

1 1 The diagram below illustrates the relationship

between interstitial (extracellular) fluid pressure and lymph flow Would an increase in interstitial fluid protein cause an increase in lymph flow?

1 10

interstitial fluid pressure

20

-6 -4 -2 0 2 4

A Yes, because fluid movement out of the

capillaries would increase interstitial fluid pressure

B Yes, because the increased interstitial fluid

protein would reduce interstitial fluid volume

C No, because fluid movement into the capillaries

would decrease interstitial fluid pressure

D No, because the subsequent increase in interstitial

fluid pressure would reduce lymph flow

GO ON TO THE NEXT PAGE.

Passage II (Questions 12–18)

A condition know as persistent pulmonary

hypertension of the newborn (PPHN) is currently being

experimentally treated with inhaled nitric oxide (NO) gas

NO is released by vascular endothelial cells, and causes

relaxation of vascular tissue via direct interaction with

vascular smooth muscle When NO(g) is inhaled, it is

delivered directly to the pulmonary vasculature and results

in a reversal of pulmonary hypertension without affecting

systemic blood pressure

In PPHN, increased pulmonary vascular resistance

leads to right-to-left shunting of blood through the

foramen ovale and ductus arteriosus This right-to-left

circulation results in severe systemic hypoxemia: the

blood is not adequately oxygenated because it is not

properly transported to the lungs via the pulmonary

circulation

Figure 1 shows data from an experiment in which

patients inhaled NO(g) at the concentrations and durations

indicated The patients in Group A and Group C were

newborns suffering from PPHN Group A completely

recovered, while PPHN symptoms persisted in Group C

The patient in Group B was a 5-month-old infant who

suffered from a sudden onset of unexplained PPHN

During treatment, this patient experienced a temporary

reversal of pulmonary hypertension; the hypertension

returned immediately following treatment

0

NO(g) concentration (ppm)

15

25

20

5

10

35

45

40

30

Group A: 6 patients Group B: 1 patient Group C: 3 patients

Figure 1

1 2 Blood shunted in right-to-left circulation travels

directly from:

A the pulmonary vein to the pulmonary artery.

B the right lung to the left lung.

C the superior vena cava to the aorta.

D the right atrium to the left atrium.

1 3 Right-to-left circulation of blood, which is a normal

element normal of fetal circulation in utero, does

NOT lead to oxygen depletion because:

A very little oxygen is required by the fetus in

utero.

B fetal blood is not oxygenated via circulation

through the pulmonary vasculature in utero.

C sufficient oxygen is supplied by fetal cellular

respiration in utero.

D the direction of blood flow in fetal circulation is

opposite the direction of blood flow in adult circulation

1 4 Which of the following is the most likely

explanation for why Group B’s treatment was ultimately unsuccessful?

A The concentration of NO(g) administration was

too low

B The concentration of NO(g) administration was

too high

C The patient was not a newborn.

D The patient had a congenital heart defect that led

to a form of PPHN

1 5 NO(g) would have the greatest vasodilatory effect by

direct action on the:

A aorta.

B glomerulus.

C alveolar capillaries.

D hepatic portal vein.

GO ON TO THE NEXT PAGE.

1 6 In the fetus, which of the following vessels transports

the most recently oxygenated blood?

A Umbilical artery

B Umbilical vein

C Pulmonary artery

D Pulmonary vein

1 7 At birth, following clamping of the umbilical cord,

all of the following factors influence the stimulation

of the newborn’s first breath EXCEPT:

A increased plasma CO2 concentration in the

newborn

B increased plasma pH in the newborn.

C decreased plasma O2 concentration in the

newborn

D decreased body temperature in the newborn.

1 8 In the normal newborn, the PO2 in both the

pulmonary vein and the left atrium is approximately

100 mmHg However, in the newborn suffering from

PPHN, the PO2 in the left atrium is less than 100

mmHg This results from all of the following

EXCEPT:

A the movement of deoxygenated blood through the

foramen ovate

B the movement of deoxygenated blood through the

ductus arteriosus

C the movement of deoxygenated blood through the

ductus venosus

D diminished circulation through the pulmonary

vasculature

END OF TEST

ANSWER KEY:

CIRCULATORY AND LYMPHATIC SYSTEMS TEST 1 EXPLANATIONS

Passage I (Questions 1-6)

According to the passage and the figure, the intrinsic clotting pathway consists of a series of reactions in which proteins, such as Factor X, are converted from their inactive, proenzyme forms, to their active, enzyme, forms In this step, Factor X is the proenzyme, choice C, that is undergoing the transformation Factor X serves as the substrate, choice D, for activated Factor IX, which is the enzyme, choice A, that catalyzes the conversion of Factor X to its active form So choices

A, C, and D are all incorrect Factor VIII, Ca2+, platelet phospholipids, and factor 3 all serve as cofactors for the reaction: they accelerate the conversion of Factor X to its active form

Based on the information in the last paragraph, a pulmonary embolus is an abnormal blood clot that has been dislodged from its point of origin and carried through the circulatory system to the lungs, where it blocks the pulmonary artery or one of its branches Since the movement of an embolus is halted as soon as it reaches a narrow point in the system, the number of possible areas from which a pulmonary embolism could originate is limited The embolus couldn't, for example, have come from the left side of the heart, choice B, because the journey through the systemic circulation to the right side of the heart and then to the pulmonary arteries would be a virtually impossible one for the embolus to make; it would almost certainly lodge in some systemic vessel An embolus coming from the aorta, choice C, or the pulmonary veins, choice D, would similarly end up lodged somewhere in a systemic vessel, perhaps in the upper limbs, the lower extremities,

or the brain Most pulmonary emboli originate in the veins of the lower legs: they flow freely with venous blood up into the right side of the heart and then into the pulmonary arteries, where they typically lodge

Although this isn't specified in Figure 1, when the cascade of reactions begins, Factor V and Factor VIII are initially inactive because no thrombin is present As soon as clotting begins and thrombin is formed, however, this early thrombin activates Factors V and VIII; Factors V and VIII serve as cofactors in the reactions that activate Factor X and prothrombin activator Thus, thrombin itself will speed up its own synthesis The initial formation of thrombin, therefore, has a positive feedback effect, perpetuating a cycle of accelerated thrombin formation, and so choice B is correct Choice A is wrong because thrombin has no effect on the number of circulating platelets and it increases prothrombin synthesis, leading to its own synthesis Choice C is wrong because, as discussed, thrombin is responsible for the activation of several of the factors involved in the clotting pathway Choice D is wrong because it is blood trauma or contact with collagen that enhances the activation of Factor XII

Prolonged clotting time would result from any sort of interference in the intrinsic pathway shown in Figure 1 A deficiency of any of the clotting factors, including Factor VIII or a deficiency of platelets or platelet phospholipids will make

it more difficult for the blood to coagulate and for a clot to form Therefore, choice B and choice D are wrong Calcium ions are required for the promotion of all but the first two reactions in the pathway, so clotting would also be slowed or prevented entirely by reducing the calcium ion concentration in the blood with the addition of a calcium de-ionizing agent; so choice A

is wrong However, addition of activated Factor X would not increase clotting time, since activated Factor X is one of the key components in the intrinsic pathway Therefore, choice C is the right answer

According to the passage, protein C is an anticoagulant, something that works to prevent clotting from taking place Choices A, B, and C are all mechanisms that would make protein C a procoagulant, not an anticoagulant Choice A is wrong because negative feedback regulation of thrombomodulin would serve to facilitate clotting, since thrombomodulin acts to slow the process Choice B and choice C are wrong since promotion of the formation of prothrombin and activation of Factors X and XII would clearly speed clotting, as can be seen in Figure 1

Deactivation of activated Factors V and VIII, on the other hand, would prevent thrombin from having a positive feedback effect on its own formation, which, as discussed in the explanation to Question 3, is essential to clot formation Deactivation of these factors, which is the actual mechanism of protein C function, makes protein C an effective anticoagulant So, choice D is correct

The purpose of heparin is to prevent the formation of abnormal blood clots, and it does so, as the question stem explains, by enhancing the activity of the anticoagulant antithrombin III Antithrombin III interferes with the intrinsic pathway, which means that the ability of the blood to clot is greatly reduced by heparin injection Minor damage to the patient's blood vessels will not be automatically repaired, as it normally is, and the patient may experience minor vascular bleeding as a result Therefore, choice C is correct Choice A is wrong because interfering with a patient's blood clotting would not be expected to increase blood pressure Furthermore, choice D is wrong because there is no reason to believe that the oxygen-carrying capability of the blood, or for that matter, the integrity of the blood vessels, would be compromised Thus, dizziness is an unlikely choice As for choice B, existing blood clots, or emboli, must be destroyed by fibrinolytic enzymes Interfering with the blood clotting pathway will have no effect on clots that already exist So, choice B is wrong Again, choice C is correct

Discretes (Questions 7-11)

The lymphatic system drains excess fluid from the (extracellular) interstitial spaces of body tissue and carries the fluid, called lymph, to the venous system If malignant tumors obstruct lymphatic channels, there is no way for the fluid to drain out of the extracellular spaces So, choice C is correct Choice A is wrong, because as fluid accumulates in the extracellular spaces, the increased fluid pressure there will decrease, not increase, the amount of fluid leakage from the capillaries into the extracellular spaces Choice B is wrong because the lymphatic system normally carries excess proteins from the extracellular spaces back to circulation Since the obstructed lymphatic channels cannot do this, protein concentration in the tissue spaces will increase, not decrease Choice D is wrong because the very fact that malignant tumors are present in the lymphatic system means that the risk of metastasis is increased Metastasis is the spread of a disease from the site of origin to another part of the body

The spleen can be considered a large lymph node because it contains white pulp filled with B lymphocytes and T lymphocytes, the cells responsible for humoral and cell-mediated immunity These lymphocytes function in exactly the same way in the spleen as they do in the lymph nodes Therefore, choice D is correct Contrary to choice C, though, the spleen is not made up entirely of lymphocytes; the spleen also has venous sinuses and red pulp that serve as reservoirs for red blood cells So choice C is out Choice A and choice B are wrong because the lymph nodes do not function as blood reservoirs, nor

do they intercept antigenic agents in the circulating blood

As was mentioned in the discussion of Question 8, the lymphatic system carries excess fluid and proteins from the interstitial spaces back to circulation, so choice A can be eliminated since it is a function of the lymphatic system The lymphatics are also important in the absorption of nutrients, particularly fats, from the gastrointestinal tract via specialized lymph vessels called lacteals So, choice B is wrong Choice D is wrong because the lymphatic channels carry the lymph through lymph nodes, where it is filtered; macrophages in the lymph nodes engulf bacteria and other foreign particles However, the lymphatic system does not drain excess fluid from the central nervous system, from superficial portions of the skin, from deeper peripheral nerves, or from bone Therefore, choice C is correct

1 0 A

When exposed to a specific antigen, B cells, or B lymphocytes, differentiate and proliferate Some become memory cells, while others become plasma cells The plasma cells produce antibodies that recognize and bind specifically to the antigen that activated the original B lymphocytes Choice A is therefore correct Macrophages, choice B, do not originate from lymphocytes Cytotoxic T cells, choice C, and lymphokines, choice D, both come from T cells, or T lymphocytes, not

B lymphocytes Cytotoxic T cells destroy antigens directly, while lymphokines, which are secreted by helper T cells, activate other B cells, T cells, and macrophages So choices B, C, and D are all incorrect

1 1 A

According to the diagram, lymph flow increases when interstitial fluid pressure increases Thus, to determine whether

an increase in interstitial fluid protein would increase lymph flow, you have to determine whether an increase in interstitial fluid protein would increase interstitial fluid pressure Remember how osmosis works: water diffuses from a region of lower solute concentration to a region of higher solute concentration When proteins leak out of the capillaries into the interstitial spaces, this makes the interstitial spaces a region of higher solute concentration Fluid will then flow out of the capillaries and into the interstitium, increasing both the interstitial fluid volume and the interstitial fluid pressure So choice B is wrong The increase in interstitial fluid pressure then increases lymph flow (up to a point), according to the graph So, choice D is wrong, and choice A is correct Choice C is wrong, because while fluid movement from the interstitial spaces into the