CHAPTER 18, CARDIOVASCULAR Flashcards
1
Q
1) Which vessels typically carry blood away from the heart? A) venules B) arteries C) veins D) capillaries
A
B) arteries
2
Q
2) Place in order from superficial to deep the three tunics of a typical blood vessel.
A) tunica externa, tunica media, tunica intima
B) tunica intima, tunica media, tunica externa
C) tunica media, tunica intima, tunica externa
D) tunica externa, tunica intima, tunica media
A
A) tunica externa, tunica media, tunica intima
3
Q
3) Which blood vessel tunic is innervated by nerves from the sympathetic nervous system? A) tunica adventitia B) tunica intima C) tunica media D) tunica externa
A
C) tunica media
4
Q
4) Which of the following arteries has the smallest diameter? A) muscular artery B) metarteriole C) arteriole D) elastic artery
A
B) metarteriole
5
Q
5) What type of vessel is built to handle the highest pressure of any vessel in the cardiovascular system? A) muscular artery B) metarteriole C) arteriole D) elastic artery
A
D) elastic artery
6
Q
6) The closure of a precapillary sphincter prevents blood flow to tissues from: A) elastic arteries. B) venules. C) arterioles. D) muscular arteries.
A
C) arterioles.
7
Q
7) Which of the following is TRUE of veins?
A) Veins have thinner walls than arteries.
B) Veins have smaller lumens than arteries.
C) Veins have more elastic fibers than arteries.
D) Veins have more smooth muscle than arteries.
A
A) Veins have thinner walls than arteries.
8
Q
8) Which vessels serve as the blood reservoirs of the body? A) metarterioles B) arterioles C) muscular arteries D) veins
A
D) veins
9
Q
9) Which of the following connects vessels through vascular anastomoses? A) collaterals B) capillary beds C) precapillary sphincters D) postcapillary venules
A
A) collaterals
10
Q
10) The outward force that blood exerts on the walls of blood vessels is: A) cardiac output. B) blood pressure. C) blood flow. D) resistance.
A
B) blood pressure.
11
Q
11) Select the correct relationship between peripheral resistance and blood pressure.
A) As peripheral resistance increases, blood pressure decreases.
B) As peripheral resistance decreases, blood pressure increases.
C) As peripheral resistance increases, blood pressure increases.
D) Peripheral resistance has no effect on blood pressure.
A
C) As peripheral resistance increases, blood pressure increases.
12
Q
12) Peripheral resistance includes all of the following EXCEPT: A) blood viscosity. B) blood vessel length. C) vessel radius. D) blood type.
A
D) blood type.
13
Q
13) Which of the following will decrease peripheral resistance? A) increase in vessel obstructions B) increase in vessel radius C) increase in vessel length D) increase in blood viscosity
A
B) increase in vessel radius
14
Q
14) Which circuit has the greatest peripheral resistance? A) venous circuit B) pulmonary circuit C) hepatic circuit D) systemic circuit
A
D) systemic circuit
15
Q
15) What two factors determine the pressure gradient that drives circulation?
A) cardiac output and peripheral resistance
B) blood vessel radius and blood vessel length
C) diastolic pressure and systolic pressure
D) heart rate and stroke volume
A
A) cardiac output and peripheral resistance
16
Q
16) During exercise, our vessels constrict and vessel radius decreases. What impact does a decreased vessel radius have on blood flow?
A) Blood flow increases.
B) Blood flow remains the same.
C) Blood flow decreases.
D) Vessel radius has no impact on blood flow.
A
A) Blood flow increases.
17
Q
17) Which blood vessels experience the sharpest decrease in blood pressure? A) systemic arterioles B) systemic venules C) systemic veins D) systemic capillary beds
A
A) systemic arterioles
18
Q
18) Which blood vessels handle the highest blood pressure? A) pulmonary veins B) systemic arteries C) systemic veins D) pulmonary arteries
A
B) systemic arteries
19
Q
19) What two values are needed to calculate mean arterial pressure (MAP)?
A) diastolic pressure and systolic pressure
B) stroke volume and cardiac output
C) blood vessel length and blood vessel radius
D) heart rate and peripheral resistance
A
A) diastolic pressure and systolic pressure
20
Q
20) The average pressure in the systemic arteries during an entire cardiac cycle is known as: A) pulmonary circuit. B) systolic pressure. C) mean arterial pressure (MAP). D) venous pressure.
A
C) mean arterial pressure (MAP).
21
Q
1) What is the average value for mean arterial pressure (MAP)? A) 80 mm Hg B) 95 mm Hg C) 120 mm Hg D) 150 mm Hg
A
B) 95 mm Hg
22
Q
22) Determine the mean arterial pressure (MAP) given a systolic pressure of 130 mm Hg and diastolic pressure of 70 mm Hg. A) 70 mm Hg B) 90 mm Hg C) 130 mm Hg D) 200 mm Hg
A
B) 90 mm Hg
23
Q
23) When arterial blood pressure is measured in the arm with a sphygmomanometer, which vessel is used to measure pressure? A) ulnar artery B) subclavian artery C) brachial artery D) axillary artery
A
C) brachial artery
24
Q
24) Which of the following vessels has the lowest blood pressure? A) elastic arteries B) aorta C) inferior vena cava D) capillary beds
A
C) inferior vena cava
25
```
25) Archie took several deep breaths of air. By breathing deeply, what mechanism did he assist to return venous blood to his heart?
A) respiratory pump
B) mean arterial pressure (MAP)
C) skeletal muscle pump
D) Korotkoff sounds
```
A) respiratory pump
26
```
26) Which of the following does NOT assist the return of venous blood to the heart?
A) respiratory pump
B) venous valves
C) skeletal muscle pump
D) elastic fibers
```
D) elastic fibers
27
```
27) Which vessels increase peripheral resistance when they vasoconstrict in response to epinephrine and norepinephrine?
A) venules
B) muscular arteries
C) capillaries
D) systemic arterioles
```
D) systemic arterioles
28
```
28) Which nervous system promotes increased peripheral resistance and increased blood pressure through the vasoconstriction of systemic arterioles?
A) sympathetic nervous system
B) sensory nervous system
C) parasympathetic nervous system
D) somatic nervous system
```
A) sympathetic nervous system
29
```
29) Which of the following decreases heart rate, and thus cardiac output and blood pressure?
A) angiotensin-II
B) acetylcholine
C) epinephrine
D) norepinephrine
```
B) acetylcholine
30
```
30) The Valsalva maneuver causes a drop in blood pressure which should be detected by:
A) thermoreceptors.
B) baroreceptors.
C) chemoreceptors.
D) nociceptors.
```
B) baroreceptors.
31
```
31) How do parasympathetic neurons in the medulla respond to increased blood pressure?
A) Cardiac output is increased.
B) Heart rate is increased.
C) Vasoconstriction is promoted.
D) Sympathetic activity is inhibited
```
D) Sympathetic activity is inhibited
32
```
32) Which of the following stimuli is detected by a chemoreceptor?
A) stretch in the walls of arteries
B) vasodilation of arterioles
C) increased blood pressure
D) decreased blood oxygen concentration
```
D) decreased blood oxygen concentration
33
33) Central chemoreceptors detect a decrease in pH in interstitial fluids in the brain. What is the response of the medulla to maintain delivery of oxygen to cells?
A) A feedback loop is initiated that indirectly increases parasympathetic activity which results in vasoconstriction and a rise in blood pressure.
B) A feedback loop is initiated that indirectly increases sympathetic activity which results in vasoconstriction and a rise in blood pressure.
C) A feedback loop is initiated that indirectly decreases sympathetic activity which results in vasodilation and a decrease in blood pressure.
D) A feedback loop is initiated that indirectly increases parasympathetic activity which results in vasodilation and a decrease in blood pressure.
B) A feedback loop is initiated that indirectly increases sympathetic activity which results in vasoconstriction and a rise in blood pressure.
34
```
34) What hormone is released to decrease blood pressure?
A) angiotensin-II
B) atrial natriuretic peptide (ANP)
C) aldosterone
D) antidiuretic hormone (ADH)
```
B) atrial natriuretic peptide (ANP)
35
```
35) Which organ system regulates blood volume by altering the amount of fluid released in urine?
A) urinary system
B) respiratory system
C) digestive system
D) nervous system
```
A) urinary system
36
```
36) Hypertension is defined as:
A) high blood pressure.
B) excess aldosterone.
C) low blood pressure.
D) high blood sugar.
```
A) high blood pressure.
37
```
37) Which of the following is NOT a treatment for hypertension?
A) stop smoking
B) increase physical activity
C) increase intake of sugar
D) limit alcohol intake
```
C) increase intake of sugar
38
```
38) Which mechanism allows lipid-soluble substances to move through the membranes of endothelial cells of capillaries?
A) transcytosis
B) facilitated diffusion
C) osmosis
D) diffusion
```
D) diffusion
39
```
39) What type of capillary has large pores within their endothelial cells and are the leakiest?
A) sinusoidal capillaries
B) continuous capillaries
C) closed capillaries
D) fenestrated capillaries
```
A) sinusoidal capillaries
40
```
40) Which capillary would be least likely to allow substances to enter or exit the blood due to tight junctions that join the endothelial cells?
A) continuous capillaries
B) closed capillaries
C) sinusoidal capillaries
D) fenestrated capillaries
```
A) continuous capillaries
41
```
41) Under what conditions will the myogenic mechanism slow blood flow into a capillary bed?
A) rising hydrogen ion levels
B) rising arteriolar pressure
C) dropping arteriole pressure
D) rising carbon dioxide levels
```
B) rising arteriolar pressure
42
```
42) Water crosses capillary beds from high to low hydrostatic pressure by:
A) diffusion.
B) transcytosis.
C) filtration.
D) facilitated diffusion.
```
C) filtration.
43
```
43) Blood pressure is equivalent to:
A) hydrostatic pressure.
B) net filtration pressure.
C) colloid osmotic pressure.
D) oncotic pressure.
```
A) hydrostatic pressure.
44
```
44) At the arteriolar end of the capillary, which pressure is the greatest?
A) colloid osmotic pressure
B) capillary hydrostatic pressure
C) interstitial fluid osmotic pressure
D) oncotic pressure
```
D) oncotic pressure
45
45) Which pressure pulls water into the capillary?
A) interstitial fluid osmotic pressure
B) capillary hydrostatic pressure
C) interstitial fluid hydrostatic pressure
D) colloid osmotic pressure
D) colloid osmotic pressure
46
46) Which pressure is created by the presence of large proteins in the blood, such as albumin?
A) interstitial fluid hydrostatic pressure
B) hydrostatic pressure
C) colloid osmotic pressure
D) interstitial fluid osmotic pressure
C) colloid osmotic pressure
47
47) Determine fluid movement when hydrostatic pressure exceeds colloid osmotic pressure at the arteriolar end of the capillary.
A) Water is pushed into the capillary by absorption.
B) Water is pushed off the capillary by filtration.
C) There is no net movement of water.
D) Water is pulled into the capillary by absorption.
B) Water is pushed off the capillary by filtration.
48
```
48) Determine the process that drives water movement across a capillary when net filtration pressure is negative.
A) diffusion
B) endocytosis
C) filtration
D) absorption
```
D) absorption
49
```
49) Determine the net filtration pressure (NFP) if capillary hydrostatic pressure is 40 mm Hg and the colloid osmotic pressure is 25 mm Hg.
A) 15 mm Hg
B) −15 mm Hg
C) 45 mm Hg
D) 25 mm Hg
```
A) 15 mm Hg
50
```
50) What is edema?
A) net filtration pressure
B) absorption
C) dehydration
D) swelling
```
D) swelling
51
51) Which of the following situations creates edema?
A) an increase in the colloid osmotic pressure
B) a decrease in the capillary hydrostatic pressure gradient
C) a negative net filtration pressure (NFP)
D) an increase in the capillary hydrostatic pressure gradient
D) an increase in the capillary hydrostatic pressure gradient
52
```
52) What is the largest artery in the body?
A) left subclavian artery
B) aorta
C) left common carotid artery
D) pulmonary trunk
```
B) aorta
53
```
53) Which division of the aorta gives rise to the right and left common iliac arteries?
A) ascending aorta
B) aortic arch
C) descending abdominal aorta
D) descending thoracic aorta
```
C) descending abdominal aorta
54
```
54) Which of the following is NOT an artery that branches off the aortic arch?
A) right subclavian artery
B) left subclavian artery
C) brachiocephalic artery
D) left common carotid artery
```
A) right subclavian artery
55
```
55) A cerebrovascular accident (CVA, or stroke) can occur due to a blockage in the:
A) axillary artery.
B) facial artery.
C) basilar artery.
D) occipital artery.
```
C) basilar artery.
56
```
56) Which of the following vessels gives rise to the common hepatic artery, left gastric artery, and splenic artery?
A) intestinal arteries
B) superior epigastric artery
C) celiac trunk
D) superior mesenteric artery
```
C) celiac trunk
57
```
57) Which artery supplies the small intestine with blood?
A) hepatic artery
B) inferior mesenteric artery
C) superior mesenteric artery
D) middle mesenteric artery
```
C) superior mesenteric artery
58
```
58) Which of the following arteries gives rise to all others listed?
A) ulnar artery
B) brachial artery
C) radial artery
D) axillary artery
```
D) axillary artery
59
```
59) What name does the femoral artery take as it emerges in the posterior thigh?
A) posterior tibial artery
B) anterior tibial artery
C) popliteal artery
D) dorsalis pedis artery
```
C) popliteal artery
60
```
60) Which of the following vessels can be used for taking the pulse?
A) renal artery
B) internal iliac artery
C) brachial artery
D) celiac trunk
```
C) brachial artery
61
```
61) Damage to the external iliac artery will affect delivery of blood to the:
A) abdominal organs.
B) lower limb.
C) upper limb.
D) brain.
```
B) lower limb.
62
```
62) Into which vein does blood in the external jugular vein drain?
A) internal jugular vein
B) vertebral vein
C) inferior vena cava
D) subclavian vein
```
D) subclavian vein
63
63) Most veins below the diaphragm drain into the: A) superior mesenteric vein.
B) superior vena cava.
C) inferior vena cava.
D) hepatic vein.
C) inferior vena cava.
64
```
64) Cerebrospinal fluid drains into:
A) dural sinuses.
B) external jugular vein.
C) facial vein.
D) the azygos system.
```
A) dural sinuses.
65
65) The azygos system collects blood from the:
A) abdominopelvic cavity.
B) superior thoracic cavity.
C) anterior thoracic and abdominal walls.
D) posterior thoracic and abdominal walls.
D) posterior thoracic and abdominal walls.
66
```
66) Which of the following veins does NOT drain directly into the inferior vena cava?
A) hepatic vein
B) renal vein
C) common iliac vein
D) hepatic portal vein
```
D) hepatic portal vein
67
```
67) Into what vein do the splenic, gastric, superior mesenteric, and inferior mesenteric veins drain?
A) hepatic vein
B) inferior vena cava
C) inferior epigastric vein
D) hepatic portal vein
```
D) hepatic portal vein
68
```
68) Which of the following is NOT a function of the liver via the hepatic portal system?
A) erythropoiesis
B) destruction of red blood cells
C) detoxification reactions
D) storage of glucose
```
A) erythropoiesis
69
69) The union of the radial and ulnar veins forms the: A) basilic vein.
B) brachial vein.
C) axillary vein.
D) median cubital vein.
B) brachial vein.
70
```
70) The anterior and posterior tibial veins merge to form the:
A) external iliac vein.
B) medial plantar vein.
C) femoral vein.
D) great saphenous vein.
```
C) femoral vein.
71
71) Which of the following represents the systemic flow of most blood?
A) arteriole, artery, capillary bed, venule, vein
B) artery, arteriole, capillary bed, venule, vein
C) arteriole, artery, capillary bed, vein, venule
D) artery, arteriole, capillary bed, vein, venule
B) artery, arteriole, capillary bed, venule, vein
72
72) Arteries in the systemic circuit carry oxygenated blood while arteries in the pulmonary circuit transport deoxygenated blood.
Answer:
TRUE
73
73) Veins regulate blood pressure and control blood flow to organs.
FALSE
74
74) Vessels with a smaller radius will have an increased resistance to blood flow.
TRUE
75
75) Cross-sectional area increases as arteries branch into smaller vessels, causing the blood to flow more slowly.
TRUE
76
76) Mean arterial pressure generally measures around 120/80 mm Hg.
FALSE
77
77) Increase or decrease in blood oxygen concentration triggers the baroreceptor reflex, which is regulated by the medulla of the brainstem.
FALSE
78
78) Atrial natriuretic peptide (ANP) causes vasodilation resulting in a mild decrease in peripheral resistance and blood pressure.
TRUE
79
79) Increased sympathetic activity leads to vasodilation and a decrease in blood pressure.
FALSE
80
80) Fenestrations in capillaries are small pores that allow water and small substances to move through freely.
TRUE
81
81) The myogenic mechanism counters changes in blood flow through capillary beds by altering arterial resistance.
TRUE
82
82) Filtration occurs in capillaries when colloid osmotic pressure is greater than capillary hydrostatic pressure.
FALSE
83
83) The vertebral and external jugular veins drain into the subclavian vein.
TRUE
84
84) The hepatic portal system delivers blood to the hepatic portal vein in the spleen.
FALSE
85
85) Identify the internal carotid artery.
| SEE DIAGRAM OF SKULL WITH ARTERIES
D
86
86) Identify the superficial temporal artery.
| SEE DIAGRAM OF SKULL WITH ARTERIES
A
87
87) Identify the common carotid artery.
| SEE DIAGRAM OF SKULL WITH ARTERIES
E
88
88) Identify the external carotid artery.
| SEE DIAGRAM OF SKULL WITH ARTERIES
C
89
89) Identify the maxillary artery.
| SEE DIAGRAM OF SKULL WITH ARTERIES
B
90
90) Identify the axillary artery.
| SEE DIAGRAM OF ARM
B
91
91) Identify the ulnar artery.
| SEE DIAGRAM OF ARM
D
92
92) Identify the popliteal vein.
| SEE DIAGRAM OF THE LEG
C
93
92) Identify the popliteal vein.
| SEE DIAGRAM OF THE LEG
D
94
94) Identify the femoral vein.
| SEE DIAGRAM OF THE LEG
A
95
95) Identify the great saphenous vein.
| SEE DIAGRAM OF THE LEG
B
96
96) Identify the posterior tibial vein.
| SEE DIAGRAM OF THE LEG
E
97
97) Describe the structure of the three tunics of a blood vessel.
The innermost tunica intima is composed of endothelium, which consists of a sheet of simple squamous tissue and its basal lamina. Deep to the endothelium is a layer of subendothelial connective tissue and a layer of elastic fibers that provide distensibility and elasticity. The middle tunica media is composed of smooth muscle cells and the external elastic lamina. The muscle cells are innervated by vasomotor nerves of the sympathetic nervous system that cause vasoconstriction and vasodilation. The outermost tunica externa is composed of supportive connective tissue.
98
98) Summarize the function of vascular anastomoses.
Anastomoses are locations where vessels connect via pathways called collateral vessels. These anastomoses allow more than one route for blood to flow through a particular tissue.
99
99) List the three variables that mainly determine peripheral resistance.
The three variables that mainly determine peripheral resistance are 1) blood vessel radius, 2) blood viscosity, and 3) blood vessel length.
100
100) Summarize the relationship between the radius of a blood vessel and blood pressure..
As the radius of a blood vessel increases, the resistance to blood flow decreases, and vice versa. Peripheral resistance is directly proportional to blood pressure. Thus, as resistance to blood flow decreases, blood pressure also decreases. Likewise, as resistance to blood flow increases, blood pressure also increases.
101
101) Explain why blood pressure in the pulmonary circuit is lower than in the systemic circuit.
One reason blood pressure in the pulmonary circuit is lower than in the systemic circuit is because vessels in the pulmonary circuit are shorter and therefore offer less resistance to blood flow. In the pulmonary circuit, we see that as peripheral resistance decreases, blood pressure decreases.
102
102) Calculate the mean arterial pressure (MAP) given a diastolic pressure of 60 mm Hg and a systolic pressure of 100 mm Hg.
Mean arterial pressure is calculated as follows:
MAP = diastolic pressure + 1/3 (systolic pressure − diastolic pressure)
MAP = 60 mm Hg + 1/3 (100 mm Hg − 60 mm Hg)
MAP = 73 mm Hg
The mean arterial pressure (MAP) based upon these values is 73 mm Hg.
103
103) Describe four mechanisms that assist in the return of venous blood to the heart.
Four mechanisms that help return venous blood to the heart are: (1) Venous valves prevent backward flow of blood in the veins. (2) Smooth muscle in the walls of veins that may contract under sympathetic nervous system stimulation to increase the rate of venous return. (3) The skeletal muscle pump involves the skeletal muscle surrounding the deeper veins of the upper and lower limbs that squeeze the blood in the veins and propel it upward (toward the heart) as they contract and relax. (4) The respiratory pump is driven by the rhythmic changes in pressure in the thoracic and abdominopelvic cavities that occur with ventilation. During inspiration, high pressure in the abdominopelvic cavity creates a pressure gradient that pushes blood in the abdominal veins upward, and low pressure in the thoracic cavity allows thoracic veins to expand. The reverse occurs during expiration—abdominal veins expand and fill with blood while thoracic veins are squeezed.
104
104) Describe the hormones that increase cardiac output.
Hormones that increase cardiac output include epinephrine, norepinephrine, and thyroid hormone. The effects of epinephrine and norepinephrine produced by the adrenal medulla are identical to the effects of these chemicals produced by the sympathetic nervous system—they increase both heart rate and contractility. The effects of thyroid hormone, which is the body's primary regulator of the metabolic rate, are less direct. It causes the cardiac muscle cells to produce more receptors for epinephrine and norepinephrine, which allows these two chemicals to have a greater impact on cardiac output.
105
105) Describe how an increase in blood pressure is returned to normal using the baroreceptor reflex.
The baroreceptor reflex is a negative feedback loop that responds to an increase in blood pressure. When blood pressure increases, parasympathetic neurons in the medulla inhibit sympathetic activity, inducing vasodilation and decreased heart rate, lowering cardiac output. Note that the parasympathetic neurons have no direct effect on most blood vessels.
106
06) Explain the role of peripheral chemoreceptors in the maintenance of blood flow to tissues.
Peripheral chemoreceptors, located in the carotid arteries and aorta, respond mostly to the level of oxygen in the blood. A significant decrease in blood oxygen concentration triggers a series of feedback loops that indirectly stimulate an increase in heart rate and cause vasoconstriction. Vasoconstriction causes an increase in peripheral resistance, blood pressure and the delivery of oxygenated blood to cells and tissues.
107
107) The spleen filters and removes worn-out blood cells from circulation. Determine the type of capillary that would allow the transfer of blood cells between the blood and interstitial fluid.
Sinusoidal capillaries are the leakiest capillaries due to large pores in their endothelium. These capillaries are larger in diameter than other capillaries, and often have an irregular shape because their boundaries are determined by the organ in which they reside. Their size, shape, and sluggish blood flow allow them to facilitate the transfer of blood cells between blood and interstitial fluid.
108
108) Explain the influence of arterial blood pressure on tissue perfusion.
The blood flow to a tissue through a capillary bed is known as tissue perfusion. Tissue perfusion is largely a function of arterial blood pressure. For instance, if arterial blood pressure is too high, blood will not be adequately delivered to the tissues and they will be poorly perfused. Increases in arterial pressure lead to arterial vasoconstriction. Blood flow slows via the myogenic mechanism so that tissue perfusion can be maintained at a constant level.
109
109) Explain how hydrostatic pressure and colloid osmotic pressure are created.
Hydrostatic pressure is the force that a fluid exerts on the wall of a container. Blood is the fluid in the vessel that creates hydrostatic, or blood, pressure. Colloid osmotic pressure is created almost entirely by large proteins, such as albumin, present in the blood.
110
110) Explain fluid movement when the net filtration pressure (NFP) is a negative value.
A negative net filtration pressure (NFP) means that water will flow from the tissue into the capillary, a process called absorption. A negative NFP indicates that colloid osmotic pressure is greater than hydrostatic pressure, so water is pulled into the capillary toward the greater osmotic pressure.
111
11) Describe the blood vessels and contribution of anastomoses that constitute the cerebral arterial circle (circle of Willis).
The cerebral arterial circle is made up of the anterior and posterior communicating arteries, the anterior and posterior cerebral arteries, and the internal carotid artery. Anastomoses serve a dual purpose: they help equalize pressure in the arteries of the brain and minimize changes in systemic arterial pressure. Second, anastomoses provide collateral circulation that allows blood to continue flowing to the brain even if blood flow in one of the brain's major arteries is disrupted.
112
112) List the three arteries that branch off of the aortic arch.
The three branches of the aortic arch (in order as they branch off) are the brachiocephalic artery, left common carotid artery, and left subclavian artery.
113
113) Besides blood, what other fluid returns to the dural sinuses of the brain? To what vein do the dural sinuses return these fluids?
Blood from the brain drains into the dural sinuses, which also receive cerebrospinal fluid from the arachnoid granulations. Blood from the dural sinuses drains into the internal jugular veins.
114
114) Describe blood flow through the hepatic portal circulation.
The splenic, gastric, superior mesenteric, and inferior mesenteric veins merge and drain into a vein that enters the liver, the hepatic portal vein. This vein branches extensively in the liver to form capillary beds creating the hepatic portal system. The processed blood exits the liver by the hepatic vein and joins the rest of the blood in the systemic circuit in the inferior vena cava.
115
115) Dehydration increases blood viscosity. Determine the effect of dehydration on blood pressure.
Blood has a relatively high viscosity due to the number of proteins and cells it contains. Generally, blood viscosity remains relatively constant, but it can be altered by states that change either the number of cells or proteins in the blood or the amount of water in blood, such as dehydration. Peripheral resistance is increased by conditions that increase blood viscosity. As peripheral resistance increases, blood pressure increases.
116
116) Post-operative surgical patients are often fitted with pneumatic compression boots that increase the pressure around limbs, such as the legs. Determine the effect of these boots on blood flow in the limbs.
These compression boots increase pressure around limbs, such as the legs, to create a pressure gradient. Normally, blood flows down its pressure gradient from the area of higher pressure (near the heart) to the area of lower pressure in the peripheral vasculature. These boots are intended to aid in the return of low-pressured venous blood back to the heart, and work to like the skeletal muscle pump. These boots are intended to help prevent thrombosis.
117
117) During defecation, we hold our breath, bear down, and strain. Explain the effects of holding one's breath on blood pressure.
During the Valsalva maneuver, a subject bears down and tries to expire against a closed glottis (the airway in the larynx). We perform the Valsalva maneuver during coughing, sneezing, defecation, and heavy lifting. The Valsalva maneuver raises the pressure in the thoracic cavity and reduces the return of venous blood to the heart, which causes a drop in blood pressure. This should trigger the baroreceptor reflex and generate an increase in heart rate.
118
118) A medication called an angiotensin-converting enzyme (ACE) inhibitor can be used to treat hypertension as it prevents the formation of angiotensin-II. Determine why this medication would be an effective treatment for high blood pressure.
ACE inhibitor medications prevent the formation of angiotensin-II, a powerful vasoconstrictor that increases peripheral resistance and blood pressure. Angiotensin-II induces thirst, causes sodium retention, and as a result increases blood volume. Angiotensin-II also triggers the secretion of aldosterone from the adrenal gland, which causes the retention of sodium ions and water from the kidney, increasing blood volume. As blood volume increases, blood pressure increases. Therefore, by inhibiting the formation of angiotensin-II, blood volume and blood pressure can be reduced.
119
119) Determine the effects on fluid movement and capillary net filtration pressure (NFP) when a liver disorder prevents adequate formation of plasma proteins, such as albumin.
When the liver fails, production of plasma proteins decreases and colloid osmotic pressure decreases. NFP remains positive since hydrostatic pressure is greater than colloid osmotic pressure. Fluids are pushed from the capillary into the interstitial fluid of the abdomen, known as ascites.
120
120) Predict how a blockage in the common carotid artery affects blood flow.
Blood flow to the head, face, and brain would be affected if the common carotid artery becomes blocked. The majority of the arterial supply to the head and neck comes from the right and left common carotid arteries, although the subclavian arteries provide contributions as well. The common carotid arteries split into two branches: the external carotid artery, which supplies the superficial structures of the head and face, and the internal carotid artery, which supplies the brain.
