Chapter 19 - The Cardiovascular System - Blood Vessels Flashcards
1
Q
Delivery system of dynamic structures that begins and ends at the heart are:
A
blood vessels
2
Q
The different blood vessels are:
A
- arteries
- capillaries
- veins
3
Q
What is the function of the arteries?
A
- carry blood away from the heart
2. they’re oxygenated except for pulmonary circulation and umbilical vessels of fetus
4
Q
What is the function of the capillaries?
A
- contact tissue cells
2. directly serve cellular needs
5
Q
What is the function of the veins?
A
carry blood toward the heart
6
Q
Pumping action of the heart generates:
A
blood flow
7
Q
Systemic blood pressure results when:
A
blood flow is opposed by resistance
8
Q
Systemic blood pressure is highest in:
A
the aorta
9
Q
Systemic blood pressure declines:
A
throughout pathway
10
Q
The systemic blood pressure in the right atrium is ____.
A
0 mm Hg
11
Q
The steepest drop of systemic blood pressure occurs in the ____.
A
arterioles
12
Q
Arterial blood pressure reflects two factors of arteries close to the heart. What are they?
A
- elasticity (compliance or distensibility)
2. volume of blood forced into them at any time
13
Q
Blood pressure near the heart is ____.
A
pulsatile
14
Q
What is the systolic pressure?
A
pressure exerted in the aorta during ventricular contraction
15
Q
What is the average systolic pressure in a normal adult?
A
120 mm Hg
16
Q
What is diastolic pressure?
A
the lowest level of aortic pressure
17
Q
What is pulse pressure?
A
The difference between systolic and diastolic pressure; the throbbing of arteries measures it (pulse)
18
Q
What is the mean arterial pressure (MAP)?
A
pressure that propels blood to tissues
19
Q
The mean arterial pressure is calculated by:
A
diastolic pressure + 1/3 pulse pressure
20
Q
Pulse pressure and MAP both decline when?
A
With increasing distance from the heart
21
Q
Capillary blood pressure ranges from:
A
17 to 35 mm Hg
22
Q
What is the desirable capillary blood pressure?
A
low
23
Q
What would happen with high capillary blood pressure?
A
High BP would rupture fragile, thin-walled capillaries
24
Q
Why is low capillary blood pressure desirable?
A
Most walls of capillaries are very permeable, so low pressure forces filtrate into interstitial spaces.
25
What are the characteristics of venous blood pressure?
1. changes little during the cardiac cycle
| 2. has a small pressure gradient; about 15 mm Hg
26
Low venous blood pressure is due to:
cumulative effects of peripheral resistance
27
What happens to the energy of venous blood pressure?
energy is lost as heat during each circuit
28
What are the factors aiding venous return?
1. muscular pump
2. respiratory pump
3. venoconstriction
29
What happens during the muscular pump?
skeletal muscles contract and "milk" blood toward the heart; valves prevent backflow
30
What happens during the respiratory pump?
pressure changes during breathing move blood toward the heart by squeezing abdominal veins as thoracic veins expand
31
What happens during venoconstriction?
under sympathetic control it pushes blood toward the heart
32
The structure of blood vessels:
1. lumen
2. three wall layers in arteries and veins
3. capillaries
33
The lumen of blood vessels is:
the central blood-containing space
34
The three wall layers in arteries and veins are:
1. tunica intima
2. tunica media
3. tunica externa
35
Capillaries are composed of:
endothelium with sparse basal lamina
36
What are the characteristics of the tunica intima?
1. the endothelium lines the lumen of all vessels
2. the endothelium is continuous with endocardium
3. the endothelium has a slick surface that reduces friction
4. there is a subendothelial layer in vessels larger than 1 mm
37
The subendothelial layer of the tunica intima has:
connective tissue basement membrane
38
What are the structural characteristics of the tunica media?
1. smooth muscle and sheets of elastin
| 2. sympathetic vasomotor nerve fibres
39
The sympathetic vasomotor nerve fibres of the tunica media do what?
1. control vasoconstriction and vasodilation of vessels
| 2. influence blood flow and blood pressure
40
The tunica externa is also known as:
tunica adventitia
41
What are the characteristics of the tunica externa?
1. collagen fibres protect and reinforce; anchor to surrounding structures
2. contains nerve fibres and lymphatic vessels
3. vasa vasorum of larger vessels nourishes external layer
42
Blood vessels vary in:
1. length
2. diameter
3. wall thickness
4. tissue makeup
43
The arterial system is divided into:
1. elastic arteries
2. muscular arteries
3. arterioles
44
What are the characteristics of elastic arteries?
1. large thick-walled arteries with elastin in all three tunics
2. large lumen offers low-resistance
45
An example of elastic arteries is:
aorta and its major branches
46
Are elastic arteries active or inactive during vasoconstriction?
inactive
47
Elastic arteries act as:
pressure reservoirs--they expand and recoil as blood is ejected from the heart; there is smooth pressure downstream
48
Where are muscular arteries located?
distal to elastic arteries
49
Muscular arteries deliver blood to:
body organs
50
What structure is different in muscular arteries?
thick tunica media; it has more smooth muscle
51
Are muscular arteries active or inactive during vasoconstriction?
active
52
What are the characteristics of arterioles?
1. smallest arteries
2. lead to capillary beds
3. control flow into capillary beds
53
Arterioles control flow into capillary beds via:
vasodilation and vasoconstriction
54
What are the structural characteristics of capillaries?
1. microscopic blood vessels
2. walls of thin tunica intima
3. have pericytes
4. provide direct access to almost every cell
55
In the smallest capillaries, the walls of thin tunica intima:
have a single cell that forms the entire circumference
56
What do the pericytes of capillaries do?
help stabilise their walls and control permeability
57
The diameter of capillaries allows:
only one single RBC to pass at a time
58
Where are the capillaries located?
in all tissues except for cartilage, epithelia, cornea, and lens of the eye
59
Capillaries exchange what?
1. gases
2. nutrients
3. wastes
4. hormones
between blood and interstitial fluid
60
Venules are formed when:
capillary beds unite
61
Larger venules have:
one or two layers of smooth muscle cells
62
The smallest part of venules are:
postcapillary venules
63
Venules consist of:
endothelium and a few pericytes
64
Venules are very porous; they allow for:
fluids and WBCs to pass into tissues
65
Veins are formed when:
venules converge
66
What are the characteristics of veins?
1. they have thinner walls, and larger lumens compared with corresponding arteries
2. blood pressure is lower than in arteries
3. thin tunica media
4. thick tunica externa of collagen fibres and elastic networks
67
Veins are also called:
capacitance vessels (blood reservoirs)
68
Why are veins called capacitance vessels?
they contain up to 65% of blood supply
69
The adaptations of veins ensure:
return of blood to the heart despite low pressure
70
Veins ensuring that blood is returned to the heart despite low pressure are a result of:
1. large-diameter lumens that offer little resistance
2. venous valves
3. venous sinuses
71
What do venous valves do?
prevent backflow of blood
72
Venous valves are most abundant in:
the veins of limbs
73
What are venous sinuses?
flattened veins with extremely thin walls
74
What are examples of venous sinuses?
1. coronary sinus of the heart
| 2. dural sinuses of the brain
75
What are vascular anastomoses?
interconnections of blood vessels
76
Arterial anastomoses provide ____ to a given body region.
alternate pathways (collateral channels)
77
Arterial anastomoses are common in:
1. joints
2. abdominal organs
3. brain
4. heart
78
There are no arterial anastomoses in:
1. retina
2. kidneys
3. spleen
79
What is an example of arteriovenous anastomoses?
vascular shunts of capillaries
80
The common anastomoses are:
venous anastomoses
81
Tissue perfusion through body tissues is involved in:
1. delivery of O2 and nutrients to, and removal of wastes from, tissue cells
2. gas exchange (lungs)
3. absorption of nutrients (digestive tract)
4. urine formation (kidneys)
82
Rate of blood flow through body tissues must be _____ to provide proper body function.
precisely right amount
83
The velocity of blood flow changes as it travels through the ______.
systemic circulation
84
Velocity of blood flow is inversely related to:
the total cross-sectional area
85
Blood flow is fastest in:
the aorta
86
Blood flow is slowest in:
capillaries
87
Blood flow increases in:
the veins
88
Slow capillary blood flow allows for what?
adequate time for exchange between blood and tissues
89
Respiratory gases and nutrients in capillaries are diffused down:
concentration gradients
90
O2 and nutrients travel from:
blood to tissues
91
CO2 and metabolic wastes travel from:
tissues to blood
92
Lipid-soluble molecules diffuse:
directly through endothelial membranes
93
Water-soluble solutes pass through:
clefts and fenestrations
94
Larger molecules, such as proteins, are actively transported in:
pinocytotic vesicles or caveolae
95
Fluid leaves capillaries at:
the arterial end
96
Fluid returns to capillaries at:
the venous end
97
Fluid movement in capillaries is important in determining:
relative blood volumes in blood and interstitial space
98
The direction and amount of fluid flow in capillaries depends on two opposing forces. What are they?
1. hydrostatic
| 2. colloid osmotic pressure
99
What does capillary hydrostatic pressure do?
tends to force fluids through capillary walls
100
Capillary hydrostatic pressure is greater at the _____ end of bed than at the ____ end.
arterial (35 mm Hg); venule (17 mm Hg)
101
Capillary hydrostatic pressure is also termed:
HPc; capillary blood pressure
102
What does capillary colloid osmotic pressure do?
it's created by nondiffusible plasma proteins, which draw water toward themselves
103
Capillary colloid osmotic pressure is ____ mm Hg.
~26
104
Capillary colloid osmotic pressure is also termed:
OPc; oncotic pressure
105
Hydrostatic-osmotic pressure interactions compose the:
net filtration pressure (NFP)
106
NFP comprises all forces:
acting on capillary bed
107
What is the equation for NFP?
NFP = HP - OP
108
Net fluid of NFP flows out at:
arterial end
109
Net fluid of NFP flows in at:
venous end
110
Does more blood leave or return in capillaries?
more leaves than is returned
111
Excess fluid of capillaries is:
returned to the blood via the lymphatic system
112
The three structural types of capillaries are:
1. continuous capillaries
2. fenestrated capillaries
3. sinusoid capillaries
113
Sinusoid capillaries are also known as:
sinusoids
114
Continuous capillaries are abundant in:
the skin and muscles
115
Continuous capillaries are unique in:
the brain
116
What are the characteristics of continuous capillaries in the skin and muscles?
1. tight junctions connect endothelial cells
| 2. intercellular clefts allow passage of fluids and small solutes
117
What do the continuous capillaries of the brain do?
their tight junctions are complete, which form the blood-brain barrier
118
Some endothelial cells of fenestrated capillaries contain:
pores (fenestrations)
119
How does the permeability of fenestrated capillaries compare to continuous capillaries?
they're more permeable
120
How do fenestrated capillaries function?
they function in absorption or filtrate formation (small, intestines, endocrine glands, and kidneys)
121
Characteristics of tight junctions in sinusoid capillaries:
1. fewer
2. usually fenestrated
3. larger intercellular clefts
4. large lumens
122
Speed of blood flow in sinusoid capillaries is:
sluggish--allows modification
123
Sluggish blood flow in sinusoid capillaries allows for:
large molecules and blood cells to pass between blood and surrounding tissues
124
Sinusoid capillaries are only found in:
1. the liver
2. bone marrow
3. spleen
4. adrenal medulla
125
Sinusoid capillaries have ____ in lining.
macrophages (to destroy bacteria)
126
Capillary beds have ____.
microcirculation
127
Microcirculation in capillary beds allows for:
interwoven networks of capillaries between arterioles and venules
128
Characteristics of microcirculation in capillary beds:
1. terminal arteriole leads to metarteriole
2. metarteriole is continuous with thoroughfare channel
3. thoroughfare channel leads to postcapillary venule that drains bed
129
the thoroughfare channel of capillary beds is
the intermediate between capillary and venule
130
Capillary beds contain:
1. true capillaries
2. vascular shunt
3. portal system
131
Characteristics of true capillaries of capillary beds:
1. 10 to 100 exchange vessels per capillary bed
| 2. they branch off metarteriole or terminal arteriole
132
The vascular shunt of capillary beds directly connects:
terminal arteriole and postcapillary venule
133
The portal system of capillary beds is where:
2 capillary beds are separated by vein (usually) or artery
134
True capillaries normally branch from ____ and return to ____.
metarteriole; thoroughfare channel
135
What do precapillary sphincters do?
they regulate blood flow into true capillaries
136
By precapillary sphincters, blood may go into ___ or ____.
true capillaries; shunt
137
Blood flow through capillary beds is regulated by:
chemical conditions and vasomotor nerves
138
Blood flow is defined as:
the volume of blood flowing through vessel, organ, or entire circulation in a given period
139
Blood flow is measured as:
ml/min
140
Blood flow is equivalent to:
cardiac output for entire vascular system
141
Blood flow is relatively constant when:
at rest
142
Blood flow varies:
widely through individual organs, based on needs
143
Blood pressure is defined as:
the force per unit area exerted on wall of blood vessel by blood
144
Blood pressure is expressed in:
mm Hg
145
Blood pressure is measured as ____ near heart:
systemic arterial BP in large arteries
146
The pressure gradient of blood pressure provides:
a driving force that keeps blood moving from higher to lower pressure areas
147
Resistance in blood circulation is:
opposition to flow
148
Resistance in blood circulation in measured by:
amount of friction blood encounters with vessel walls, generally in peripheral (systemic) circulation
149
Resistance in blood circulation is also known as:
peripheral resistance
150
The three important sources of resistance are:
1. blood viscosity
2. total blood vessel length
3. blood vessel diameter
151
Factors that remain relatively constant in resistance are:
1. blood viscosity
| 2. blood vessel length
152
Increased viscosity of blood leads to:
increased resistance
153
The "stickiness" of blood in viscosity is due to:
formed elements and plasma proteins
154
Longer blood vessel leads to ____ resistance.
greater
155
The greatest influence on resistance is:
blood vessel diameter
156
Frequent changes of blood vessel diameter alter:
peripheral resistance
157
Blood vessel diameter varies inversely with:
fourth power of vessel radius
158
If blood radius vessel is doubled, the resistance is ____ as much.
1/16
159
Vasoconstriction of blood vessels leads to:
increased resistance
160
Major determinants of peripheral resistance are:
small-diameter arterioles
161
Abrupt changes in diameter or fatty plaques from atherosclerosis affect resistance how?
dramatically increase resistance
162
Because diameter or fatty plaques are changed from atherosclerosis, how is flow changed?
1. Laminar flow is disrupted and causes turbulent flow
| 2. Irregular fluid motion leads to increased resistance
163
Maintaining blood pressure requires:
1. cooperation of heart, blood vessels, and kidneys
| 2. supervision by brain
164
The main factors influencing blood pressure are:
1. cardiac output
2. peripheral resistance
3. blood volume
165
Which factors control blood pressure?
1. short-term neural and hormonal controls
| 2. long-term renal regulation
166
How do short-term neural and hormonal controls affect blood pressure?
they counteract fluctuations in blood pressure by altering peripheral resistance and CO
167
How does long-term renal regulation affect blood pressure?
it counteracts fluctuations in blood pressure by altering blood volume
168
Neural controls of peripheral resistance do what?
1. maintain MAP
2. Alter blood distribution to organs
3. Operate via reflex arcs
169
Neural controls of peripheral resistance maintain MAP by:
altering blood vessel diameter
170
If blood volume gets low, MAP is maintained by:
all vessels being constricted except those to heart and brain
171
Neural controls of peripheral resistance alter blood distribution to organs in response to:
specific demands
172
Neural controls operate via reflex arcs that involve:
1. baroreceptors
2. cardiovascular centre of medulla
3. vasomotor fibres to heart and vascular smooth muscle
4. sometimes input from chemoreceptors and higher brain centres
173
Clusters of sympathetic neurons in medulla oversee:
changes in CO and blood vessel diameter
174
The cardiovascular centre consists of:
cardiac centres and vasomotor centre
175
The vasomotor centre sends steady impulses via _____ to blood vessels. This leads to what?
sympathetic efferents; moderate constriction
176
The moderate constriction via the vasomotor centre to blood vessels is known as:
vasomotor tone
177
The cardiovascular centre receives inputs from:
1. baroreceptors
2. chemoreceptors
3. higher brain centres
178
Baroreceptors are located in:
1. carotid sinuses
2. aortic arch
3. walls of large arteries of neck and thorax
179
Increased blood pressure stimulates baroreceptors to:
increase input to vasomotor centre
180
After increased blood pressure stimulates baroreceptors to increase input to vasomotor centre, what happens?
1. vasomotor and cardioacceleratory centres are inhibited, causing arteriole dilation and venodilation
2. cardioinhibitory centre is stimulated
3. ---> decreased blood pressure
181
Decrease in blood pressure is due to:
1. arteriolar vasodilation
2. venodilation
3. decreased cardiac output
182
If MAP is low, what happens?
1. reflex vasoconstriction
2. ---> increased CO
3. ---> increased blood pressure
183
Example of MAP going from low back to increase is:
Upon standing baroreceptors of the carotid sinus reflex protect blood to brain; in systemic circuit as whole aortic reflex maintains blood pressure
184
Baroreceptors are ineffective if:
altered blood pressure is sustained
185
Chemoreceptors in aortic arch and large arteries of neck detect:
increase in CO2, or drop in pH or O2
186
Chemoreceptors cause increase in blood pressure by:
1. signaling cardioaccelatory centre ---> increased CO
| 2. signaling vasomotor centre ---> increased vasoconstriction
187
Hypothalamus and cerebral cortex can modify arterial pressure via:
relays to medulla
188
What is the function of the hypothalamus?
1. increases blood pressure during stress
| 2. mediates redistribution of blood flow during exercise and changes in body temperature
189
Hormonal controls are regulated short-term via:
changes in peripheral resistance
190
Hormonal controls are regulated long-term via:
changes in blood volume
191
When hormonal controls cause increased blood pressure, what happens?
1. epinephrine and norepinephrine from the adrenal gland lead to increased CO and vasoconstriction
2. angiotensin II stimulates vasoconstriction
3. high ADH levels cause vasoconstriction
192
When hormonal controls cause lowered blood pressure, what happens?
Atrial natriuretic peptide causes decreased blood volume by antagonising aldosterone
193
Long-term mechanisms control BP by:
altering blood volume via kidneys
194
Kidneys regulate arterial blood pressure by:
1. direct renal mechanism
| 2. indirect renal (renin-angiotensin-aldosterone) mechanism
195
In long-term renal regulation, baroreceptors are ineffective because:
baroreceptors quickly adapt to chronic high or low BP
196
What is the function of direct renal mechanism?
alters blood volume independently of hormones
197
When BP or blood volume is increased, direct renal mechanism causes:
elimination of more urine, thus reducing BP
198
When BP or blood volume is decreased, direct renal mechanism causes:
kidneys to conserve water, and BP rises
199
The indirect mechanism (renin-angiotensin-aldosterone mechanism) causes:
1. lowered arterial blood pressure which leads to release of renin
2. renin catalyses conversion of angiotensinogen from liver to angiotensin I
3. angiotensin converting enzyme, especially from lungs, converts angiotensin I to angiotensin II
200
The functions of angiotensin II are:
1. increases blood volume
| 2. causes vasoconstriction directly increasing blood pressure
201
Angiotensin II increases blood volume by:
1. stimulating aldosterone secretion
2. causing ADH release
3. triggering hypothalamic thirst centre
202
Blood flow to each tissue is adjusted automatically according to:
the relative varying of its requirements
203
Autoregulation is controlled intrinsically by:
modifying the diameter of local arterioles feeding capillaries
204
Diameter modification of local arterioles is independent of ____, which is controlled as needed to maintain constant pressure.
MAP
205
Organs regulate their own blood flow by:
varying resistance of their own arterioles
206
There are two types of autoregulation. What are they?
1. metabolic controls
| 2. myogenic controls
207
Both types of autoregulation determine:
final autoregulatory response
208
In metabolic controls, vasodilation of arterioles and relaxation of precapillary sphincters occurs in response to:
1. declining tissue O2
| 2. substances from metabolically active tissues (H+, K+, adenosine, and prostaglandins) and inflammatory chemicals
209
The effects of vasodilation of arterioles and relaxation of precapillary sphincters are:
1. relaxation of vascular smooth muscle
| 2. release of NO (powerful vasodilator) by endothelial cells
210
In metabolic controls, the endothelium releases:
endothelins
211
What are endothelins?
potent vasoconstrictors
212
In blood flow, ___ and ___ are balanced, unless blood flow is inadequate, then ___ wins.
NO; endothelins; NO
213
Inflammatory chemicals cause ____.
vasodilation
214
What do myogenic controls do?
They keep tissue perfusion constant despite most fluctuations in systemic pressure.
215
What are the characteristics of vascular smooth muscle response to stretch in myogenic controls?
1. Passive stretch promotes increased tone and vasoconstriction
2. Reduced stretch promotes vasodilation and increases blood flow to the tissue
216
Passive stretch is:
increased intravascular pressure
217
Long-term autoregulation occurs when:
short-term autoregulation can not meet tissue nutrient requirements
218
One factor of long-term autoregulation is:
angiogenesis
219
What are the characteristics of angiogenesis?
1. number of vessels to region increases and existing vessels enlarge
2. it is common in heart when coronary vessel is occluded, or throughout body in people in high-altitude areas
