Cardiovascular Physiology 3- Blood Vessels, Blood Pressure, and Capillary Exchange Flashcards
(239 cards)
1
Q
Blood flow through the smallest vessels in the circulatory system (arterioles, venules, and capillaries):
A
microcirculation
2
Q
List whether the vessel description is characteristic of a vein or artery:
- few layers of smooth muscle and CT
- Many layers of smooth muscle and CT
A
- vein
- Artery
3
Q
List whether the vessel description is characteristic of a vein or artery:
- Several elastic layers:
- Few elastic layers:
A
- artery
- vein
4
Q
List whether the vessel description is characteristic of a vein or artery:
- Small lumen
- Wide lumen
A
- artery
- vein
5
Q
If you compare and arteriole to a venule, the arteriole still has more:
A
smooth muscle
6
Q
Simple squamous epithelial layer with smooth muscle on the outside:
A
arteriole
7
Q
Simple squamous endothelial layer with nothing on the outside:
A
capillary
8
Q
Simple squamous layer with some connective tissue on the outside:
A
venule
9
Q
The tissue that lines all vessels:
A
endothelial tissue (simple squamous epithelial layer)
10
Q
Why is the lumen of a vein more open compared to an artery?
A
Veins lack tone
11
Q
What is the name for the largest arteries? List examples:
A
Elastic arteries- aorta and pulmonary trunk
12
Q
What the name for the middle sized arteries? List examples:
A
Muscular/distribution arteries- arteries that branch off aorta and branch within the organs
13
Q
What is the name for the smallest arteries?
A
arterioles
14
Q
At each level, arteries compared to veins have: (3)
A
- thicker walls
- more elastic tissue
- more smooth muscle
15
Q
Level of vascular smooth muscle contraction =
A
vascular tone
16
Q
What determine the radius of the lumen of a vessel?
A
vascular tone
17
Q
_____ in tone would lead to an increase in vasoconstriction and a decrease in lumen diameter
A
Increase in tone
18
Q
____ in tone would lead to an increase in vasodilation and an increase in lumen diameter
A
Decrease in tone
19
Q
How does an increase in tone affect resistance?
A
Increases resistance
20
Q
How does a decrease in tone affect resistance?
A
Decreases resistance
21
Q
A change in vascular tone leads to a change in _____ which leads to a change in _____.
A
Change in resistance, and change in blood flow through the vessel
22
Q
What is the equation for blood flow through a vessel?
A
Q = (change in pressure) divided by resistance
23
Q
What is the equation showing the relationship between resistance with length of the vessel and radius?
A
R= 8(Ln) divided by pi(r) to the 4th
24
Q
Tone can be modified by what two things?
A
- Paracrines from endothelial cells
- Autonomic NS
25
Give three examples of paracrines from endothelial cells that can effect vascular tone and explain their effects:
1. Nitric oxide (NO)- decreases tone; relaxes smooth muscle
2. Prostacyclin- decreases tone; relaxes smooth muscle
3. Endothelin-1- increases tone and contracts smooth muscle
26
Describe what scenarios the parasympathetic nervous system would function in to decrease vascular tone. When would it increase vascular tone?
Parasympathetic innervation mediates vasodilation in the arteries supplying the penis and clitoris (therefore decreasing vascular tone). This is the only situation where the parasympathetic nervous system would have any influence on vascular tone (never would it increase vascular tone)
27
Describe the sympathetic nervous systems influence on vascular tone of smooth muscle:
Depends on NT but most often will increase the vascular tone
28
When an artery or arteriole is somewhat contracted in its resting state:
basal tone
29
Basal tone is mediated by: (2)
1. paracrines secreted by endothelial cells
2. Tonic activity of sympathetic motor neurons
30
If you _____ sympathetic activity to arteries and arterioles that would function to increase tone. If you ____ sympathetic activity to arteries and arterioles that would function to decrease tone.
increase; decrease
31
what allows arteries/arterioles to vasodilate and vasoconstrict from rest?
Due to their tone
32
Describe the basal tone in veins and venules?
Not present, they are fully relaxed in resting state
33
Due to veins/venules having no basal tone, they can only ____ from rest.
How do they doe this?
vasoconstrict- mediated by sympathetic nervous system
34
High abnormal arterial tone=
idiopathic HTN (most common cause of HTN)
35
How easily a structure stretches=
compliance
36
Equation for compliance:
Compliance = (change in volume) divided by (change in pressure)
37
Describe the compliance of vessels that can have large changes in volume with little changes in pressure:
What structures demonstrate this?
High compliance- veins
38
Why do we describe veins of having high compliance?
Due to the ability of having large changes in volume with small changes in pressure
39
Describe the compliance of vessels that can have large changes in pressure with little changes in volume:
What structures demonstrate this?
Low compliance- arteries
40
Why doe we describe arteries as having low complaince?
Due to the ability of having large changes in pressure with little changes in volume
41
Anytime we vasoconstrict the veins we:
we ____ venous return
we ____ EDV
we ____ SV
we ____ CO
Increase all of these
42
What is the driving force for blood flow in the circulatory system?
Pressure gradient
43
Pressure in the arterial vessels is ______, producing ____ & _____ pressures.
pulsatile; systolic & diastolic
44
What happens to pulsation once it reaches the capillaries?
It smooths out
45
Why does pulsation "smooth out" once we hit the capillaries:
1.Due to decreasing elastic/collagen tissue
2. Increasing resistance as you move through arteries to capillaries
46
What is the maximum of the pulsatile pattern of pressure? What is the minimum of the pulsatile pattern of pressure?
Systolic
Diastolic
47
The smoothing out of flow (no more pulsations) related to resistance of the blood flow and compliance of the vessel
damening
48
What vessels have the greatest resistance to bloodflow? Because of this what do we see once blood reaches this location?
Arterioles; greatest drop of pressure due to greatest amount of dampening
49
The degree of dampening in a vessel is directly related to:
Resistance of blood flow and compliance of the vessel
50
_____ corresponds to the peaks pressure in the left ventricle during ventricular systole
systolic
51
____ corresponds to the minimum pressure in the artery that is the pressure the left ventricle has to overcome to open the semilunar valves:
diastolic
52
What is the driving force to get blood to the capillaries? (numerical value)
63mmHg
53
Describe the location of the highest pressured vessels:
close to left ventricle
54
Arteries can be described as ____ compliance, _____ elastance vessels.
low; high
55
Represents the elastic recoil of the aorta:
dicrotic notch
56
The elastic recoil of the aorta is caused by:
The walls of the aorta snapping back from stretched position back to place
57
The elastic recoil of the aorta is essential to:
make sure the diastolic pressure DOES NOT fall too low
58
Elastic recoil maintains the:
driving pressure
59
Average driving pressure in systemic arteries:
MAP (Mean Arterial Pressure)
60
Equation for MAP:
Diastolic P + 1/3 (Systolic P- Diastolic P)
61
What is the mean arterial pressure for a BP of 120/80?
93mmHg
62
Which pressure (systolic or diastolic) has the greatest influence on MAP?
Diastolic- because the ventricle spends a lot more time in systole than it does diastole
63
What is the standard normal driving pressure in systemic circulation?
93mmHg
64
What happens to MAP with arteriosclerosis?
Arteriosclerosis is stiffening of the arteries, so the ability of the aorta to snap back is compromised (elastic recoil) and these people have issues with venous return
65
Mechanistic explanation for arteriosclerosis:
Because recoil of aorta is blunted you wouldn't get as much of a "dicrotic notch" and the pressure would drop more than it normally would
66
How will heart function change to compensate a patient with arteriosclerosis?
The heart would have to beat more forcefully if you are going to want to have good perfusion through systemic circulation
67
Felt as a pulsation or throb in the arteries of the wrist or neck with each heartbeat
pulse pressure
68
Equation for pulse pressure:
PP= SP- DP
69
hat would the pulse pressure for someone with a BP of 120/80 =
PP = 120-80
PP= 40mmHg
70
What are the most important factors in determining the magnitude of the pulse pressure?
1. stroke volume
2. arterial compliance
71
Describe the relationship of pulse pressure to:
1. stroke volume
2. arterial compliance
1. directly related to
2. inversely related to
72
Anything that decrease decreases compliance will ____ pulse pressure
(and vice versa)
Increase
73
In an individual with ateriosclerosis, to maintain driving pressure, their heart must contract more forcefully during systole. How will this effect MAP?
increase MAP
74
Diseased state characterized by the failure of the aortic valve to completely and fully open:
aortic stenosis
75
Arteriosclerosis results in a reduced _____. While aortic stenosis results in a reduced _____.
Compliance; SV
76
Why does aortic stenosis result in a reduced stroke volume?
You have to force blood out of the aorta through a narrow opening leading to a reduced stroke volume because you can't efficiently pump blood out
77
We can SELECTIVELY vary the amount of blood flow to different organs/tissues by:
Adjusting the radius of the vessels
78
If we want to selectively increase blood flow to the liver, but decrease the bloodflow to the kidneys how might we do that?
Dilate vessels leading to liver but constrict vessels leading to kidneys
(overall change the radius of the vessels)
79
We can selectively increase of reduce blood flow to a tissue due to the blood vessels being in:
parallel
80
Average driving pressure in systemic circulation to move blood through the vessels:
MAP
81
Increased MAP results in what diseased state?
HTN
82
HTN is caused by an increase in systolic and or diastolic pressure. HTN affects 70 million americans.
(Describe the truth of these statements)
Both statements true
83
HTN affects 1:5 individuals (true or false)
False 1:3
84
Describe what happens to systolic and diastolic pressures as a patient starts to age
systolic starts to rise and diastolic starts to fall
85
A rise in systolic pressure and a fall in diastolic pressure as an individual starts to age respresents:
arterial stenosis
86
Normal blood blood pressure is considered:
Less than 120 systolic
Less than 80 diastolic
87
Elevated blood pressure is considered:
systolic: 120-129
diastolic: less than 80
88
Stage 1 HTN:
systolic: 130-139
diastolic: 80-89
89
Stage 2 HTN:
systolic: 140 or higher
diastolic: 90 or higher
90
Hypertensive crisis:
systolic higher than 180
diastolic higher than 120
91
What are the 3 factors that influence MAP?
1. flow in and out of systemic arteries
2. total blood volume
3. distribution of blood in circulatory system
92
1. The flow IN to systemic arteries=
2. The flow OUT of systemic arteries=
1. CO
2. TPR
93
Vasoconstriction of arteries would function to increase:
total peripheral resistance
94
The sum of all the resistance of all systemic arterioles in the body
TPR (total peripheral resistance)
95
If: Flow in > Flow out (due to increased CO or Increase TPR) would have what effect on MAP?
Increase due to accumulating volume
96
If: Flow in < Flow out (due to decrease CO or decreased TPR) would have what effect on MAP?
Decrease due to volume depletion?
97
MAP equation involving CO and TPR:
MAP = CO x TPR
98
How would an increase in total blood volume effect MAP?
What is an example of something that may cause this?
Increase MAP; Increased sodium intake
99
How would a decrease in total blood volume effect MAP?
What is an example of something that may cause this?
Decreased MAP; Hemorrhage
100
How can distribution of blood in circulatory system effect MAP?
Blood can be shifted from veins to arteries to increase MAP
101
When blood is shifted to veins we ____ MAP.
When blood is shifted to arteries we ____ MAP.
decrease; increase
102
Normally ___% of blood volume is in arteries and ___% of blood volume is in veins
11; 60
103
TPR is directly related to:
The sum of resistance in the arterioles
104
Factors that change arteriolar diameter change the _____ of arterioles which ultimately changes ____.
Resistance of arterioles which ultimately changes TPR
105
Arteriolar diameter is regulated by what 3 things?
1. auto regulation
2. local control
3. systemic/reflex control
106
Regulation of TPR:
Autoregulation is a function of: _____
Assures blood flow to _____ matches _____ demands
- blood vessel wall
- tissues; tissue
107
Regulation of TPR:
Local control matches tissue blood flow to:
metabolic demands
108
Regulation of TPR:
The flow of the tissue =
MAP divided by resistance of tissue
109
Regulation of TPR:
Local control is a function of:
paracrines
110
In a tissue that is more metabolically active, if we want to increase blood flow we want to reduce ______, we do not want to increase ____.
Reduce resistance; increase MAP
111
Arteriolar diameter regulator that functions to maintain MAP to assure adequate blood flow to the brain and heart:
systemic/reflex control
112
What will be altered in systemic/reflex control in order to keep MAP constant?
CO and TPR
113
Systemic/Reflex control is a function of:
NS and ES
114
According to systemic/reflex control of arteriolar diameter, MAP=
CO x TPR
115
Controls the flow into capillaries:
Resistance of arterioles
116
A function of arterioles that is a regulatory reflex that assures that blood flow into tissues does not go up just because BP is increased:
Myogenic autoregulation
117
Reflex arteriolar constriction is a response to:
increased MAP
118
Nearly all organs tend to keep their blood flow constant despite variations in:
arterial pressure
119
When is the only time we would want to increase blood flow to an organ? When would we not want to increase blood flow to an organ?
If the organ is more metabolically active; if blood blood pressure goes up
120
What is the myogenic autoregulation range? What does this mean?
80-180 mmHG
This means that changes in MAP in the range of 80-180 will not result in a increase in blood flow to that tissue
121
True or false: An increase in MAP leads to an increase in tissue blood flow
False
122
True of false: An increase in MAP above 180mmHg will lead to an increase in tissue blood flow:
True (out of myogenic autoregulation range)
123
The normal MAP is 93mmHg. Describe where this sits in the myogenic autoregulation range:
It sits pretty far away from the high end
124
Factors regulating systemic arteriole resistance:
1. Myogenic regulation
2. Paracrines
3. Reflex control
125
Interstitial concentrations of paracrine substances changes as cells becomes:
more or less metabolically active
126
Increased tissue metabolism results in decreased O2, increased CO2, increased H+, increased K+, will all lead to:
vasodilation of arterioles
127
Decreased tissue metabolism results in increased O2, decreased CO2, decreased H+, decreased K+, will all lead to:
vasoconstriction of teh arterioles
128
Increased tissue metabolisms leads to _____ blood flow to that tissue.
Decreased tissue metabolism leads to ____ blood flow to that tissue.
increased; decreased
129
Process in which an increase in tissue blood flow accompanies an increase metabolic activity
Active Hyperemia
130
Once metabolic activity in a tissue goes up we see an increase in organ blood flow to match metabolic demands, this is referred to as:
active hyperemia
131
We don't want blood flow to increase due to:
We do want blood flow to increase due to:
Increase in BP
Increasing metabolic needs
132
Increased tissue blood flow following a period of low perfusion:
Reactive hyperemia
133
If blood flow to a tissue space is occluded, ____ will accumulate in the interstitial space:
give examples:
paracrines
- decreased O2
- increased CO2
- increased H+
134
Hypoxia stimulates endothelial cells to secrete _____ which is a potent ____ that will accumulate in the interstitial space
NO; vasodilator
135
Once occlusion is removed, paracrines cause _____ and increase in _____ until paracrines are washed away and arteriolar diameter returns to _____.
vasodilation; tissue blood flow; resting state
136
The ____ mechanisms are how flow to a tissue is matched to its metabolic activity
local control mechanisms
137
What accumulate in the ECF during reactive hyperemia?
metabolic vasodilators
138
Once the occlusion is removed in reactive hyperemia, what happens to resistance and blood flow?
Resistance decreases and blood flow increases
139
In reactive hyperemia as the vasodilators are washed away by blood flow, arterioles _____ and blood flow ____.
arterioles constrict and blood flow returns to normal
140
List the vasodilating paracrines (leading to an increase in tissue blood flow) (8)
1. CO2
2. H+ (Lactic acid)
3. Adenosine (from ATP usage)
4. K+ (due to action potentials)
5. Prostaglandins
6. Bradykinin
7. Nitric Oxide (NO)
8. Low O2
141
List the vasoconstricting paracrines leading to a decrease in tissue blood flow: (3)
1. O2 (tissue isn't doing a whole lot if it's not utilizing O2)
2. Endothelin
3. Thromboxanes
142
Factors regulating arteriolar resistance:
Maintains MAP as constant as possible to have adequate blood flow to brain and heart
Reflex control
143
If necessary reflex control can override:
local control
144
Reflex control is a function of:
Nervous system and Endocrine system (getting the big dogs involved- whole body)
145
Sympathetic post-ganglionic neurons to skeletal muscle arterioles release _____ which binds to ____.
Norepinephrine which binds to alpha 1 receptors
146
When the sympathetic post-ganglionic neurons release NE that binds to the alpha 1 receptors on smooth muscle in skeletal muscle arterioles this results in:
vasoconstriction
147
The adrenal medulla secretes _____ into the blood, which can bind to ______ and cause _____ or can bind to _____ and cause _____ in the smooth muscle in skeletal muscle arterioles
Epinephrine
alpha-1 receptors---> vasoconstriction
beta-2 receptors----> vasodilation
148
The sympathetic postganglionic neurons to skeletal muscle arterioles release the norepinephrine to cause an increase in NE in the ______. The adrenal medulla secretes EPI into the blood to cause an increase in EPI in the _____.
ECF; plasma
149
Describe the location of B2 receptors in tissues:
only found in very specific tissue spaces
- coronary vessels
- skeletal muscle arterioles
- superficial skin vessels
150
Overall we have more vasoconstriction than vasodilation, so _____ will go up when the SNS is activated
TPR
151
Other hormones that act as vasoconstrictors include:
ADH (antidiuretic hormone/arginine vasopressin)
ANGII (angiotensin II)
152
Other hormones that act as vasodilators include:
ANP (atrial naturetic peptide)
153
ANP functions to:
reduce blood volume and BP
154
Not only does ANP act on the kidney to promote ______. It also acts on vascular smooth muscle to increase ______ and ultimately decrease _____.
decreased blood volume; vasodilation, decrease MAP
155
Lots of hormones are designed to maintain BP and blood volume, but ____ is the only hormone that functions to BRING IT DOWN.
ANP
156
Reflex control regulating arteriolar resistance uses _____ & _____ controls
neural and hormonal
157
What equation can be used to describe REFLEX CONTROL:
MAP = CO x TPR
158
What equation can be used to describe LOCAL CONTROL:
Qtissue= MAP/Resistance of arterioles
159
Beta 1 receptors in the heart are activated by NE and Epi and function to:
increase HR and stroke volume
160
Increase in blood pressure has what effect on resistance?
Increases resistance
161
anything that increases venous return, will also increase stroke volume, and increase cardiac output, and increase MAP and increase EDV
starlings law of the heart
162
163
veins have ____ distinct layers or tunics
3
164
The walls of veins are ____ compared to arteries so they often appear collapsed in histological slides
thinner
165
Compared to arteries veins have (3)
1. Less smooth muscle
2. Less elastic tissue
3. Higher compliance
166
Veins are highly distensible, so they are called ____ that act as _____.
capacitance vessels; blood resevoirs
167
Pressure gradient available for venous return is around ____. This is not sufficient to _____.
15mmHg; to move blood back to heart
168
Mechanisms supporting venous return include: (4)
1. venous valves
2. respiratory pump
3. skeletal muscle pump
4. venoconstriction
169
explain how the respiratory pump functions in supporting venous return:
every time we breathe in we lower thoracic pressure, this creates a greater pressure gradient which functions to increase venous return (the faster you breathe in the faster you return blood back to the heart)
170
explain how the skeletal muscle pump function in supporting venous return:
contracting skeletal muscle will squeeze on the vein which moves the blood towards the heart (one way valves function here)
171
explain how venoconstriction functions in supporting venous return:
The sympathetic nervous system and adrenal release NE and E respectively which binds to alpha 1 adrenergic receptors and this causes venoconstriction, which reduces compliance and increases pressure, ultimately promoting venous return
172
When one way valves do not function (could be due to dilation or leaky veins, however causes blood accumulation in the veins):
varicose veins
173
About ___% of adults suffer from varicose veins and it is most prominent in the:
15%; lower limbs
174
What are the 4 determinants to increase peripheral venous pressure?
1. increase in activity of sympathetic nerves to veins
2. increase blood volume
3. increased skeletal muscle pump
4. increased inspiration events
175
An increase in venous pressure has what effect on venous return?
increased venous return
176
An increase in venous return has what effect on atrial pressure?
increased atrial pressure
177
An increase in atrial pressure has what effect on end diastolic ventricular volume? (EDV)
increased EDV
178
An increase in EDV has what effect on SV?
Increased SV
179
Valsalvas maneuver has what effect on VR?
decreases venous return
180
Mechanistic explanation for why blood flow is slowest in the capillaries:
due to greatest total cross-sectional surface area
181
Teleological explanation for why blood flow is slowest in the capillaries:
We want blood flow to take time as it moves through the capillaries so maximum exchange can occur
182
Blood flow velocity is fasted in the ____ and slowest in the _____.
fastest: arteries
slowest: capillareis
183
Blood volume is highest in the _____ and lowest in the _____.
highest: venules/veins
lowest: arterioles
184
Diastolic and systolic pressure is highest in the _____ and lowest in the _____.
highest: arteries
lowest: veins and venules
185
Vascular resistance is the highest in the _____ and the lowest in the _____.
highest: arterioles
lowest: venules/veins
186
What is the amount of driving force pressure to get the blood through the capillaries? (numerical value)
20 mmHg
187
Capillaries are big enough to let _____ red blood cell(s) to get through at a time
one
188
Describe the anatomy of a capillary:
1. single layer of endothelial cells (capillary wall)
2. basement membrane
3. single nucleus
189
Because capillaries are NOT connected via _____ they contain _____ that serve as a mechanism for capillary exchange
tight junctions; narrow water-filled spaces
190
Movement of fluid and dissolved substances via bulk flow occurs:
Down a pressure gradient
191
In capillaries vesicles may fuse to form ____ which connects the ___ to the ____.
water-filled channel; lumen of capillary to interstitial fluid
192
What process can occur in the water filled channels of capillaries?
Bulk flow down a pressure gradient
193
_____ and _____ transport are two mechanisms of capillary exchange that will either use vesicles or passive and active processes in the cell membrane
transcytosis and transepithelial transport
194
Simple diffusion in capillaries is a mechanism of capillary exchange that transports _____ substances
hydrophobic
195
What is the difference between plasma and interstitial fluid?
Plasma has more protein than interstitial fluid because the protein is too big to fit through the capillary spaces
196
What is not small enough to fit through the capillary channels through the capillary wall spaces?
Blood cells and large plasma proteins
197
As blood moves through the capillary bed, ____ is dumped off and _____ is picked up
O2 is dumped off and Co2 is picked up
198
Part of the capillary made of intermittent smooth muscle and is the MOST DIRECT ROUTE between arteriole and venules (some exchange does occur)
Metarteriole/Thoroughfare Channel
199
Branch off arteriole and metarteriole and take alternate paths to go from arteriole to venule side
capillaries
200
Describe pre-capillary sphinctors:
made of smooth muscle and function to control the entrance into capillaries
201
Not a capillary, rather a direct connection between arteriole and vein in which exchange DOES NOT occur:
Arteriovenous anastomosis
202
If I am talking about a more direct route without exchange, I am referring to ______
This path allows for things such as ____ and ____ to go from arteriole to venule side
arteriovenous anastomosis
large proteins and WBCs
203
The amount of blood and pathway the blood travels through the capillary bed varies ______ and is based on _____.
moment to moment
tissues metabolic activity
204
Metarteriole and precapillary sphincters flucturate between:
contracted and relaxed state
205
The rate and fluctuation of contraction/ relaxation in met-arteriole and pre-capillary sphincters is primarily controlled by:
O2 in the tissue
206
When the concentration of O2 in tissues is low, smooth muscle spends more time in a _____ state; and blood takes a _____ path through the capillary bed
relaxed state; convoluted
207
When the concentration of O2 in tissues is high, smooth muscle spends more time in a ____ state and blood takes a more _____ path through the capillary bed
contracted; direct
208
In times of high metabolic activity in tissues, what do the paracrines function to do? (2 things)
1. paracrines function to dilate the arteriole in the process of active hyperemia
2. paracrines function to relax pre-capillary sphincters
209
In a really metabolically active tissue, describe the pre-capillary sphincters:
Stays open longer, closes less, resulting in more of the capillary bed to be perfused with blood flow
210
In a not very metabolically active tissue, describe the pre-capillary sphinctors:
lack of paracrines causes the pre-capillary sphincters to close off, therefore less perfusion occurs
211
In the case that the tissue is not metabolically active and pre-capillary sphincters are closed off, how might the blood travel to the venous side?
Direct route is the only option in this case
(arteriovenous anastamosis)
212
What is the driving force to get blood through the capillaries?
20mmHg
213
The capillaries are made of a _____ layer of ____ cells (makes up the capillary wall)
single layer of endothelial cells
214
Mechanism of capillary exchange that is due to capillaries not being connected via tight junctions:
narrow water filled spaces
215
In a capillary bed, what travels through the narrow water filled spaces?
fluid and dissolved substances
216
The movement of fluid and dissolved substances in capillary exchange occurs via:
bulk flow
217
The mechanism of capillary exchange "bulk flow" occurs:
down a pressure gradient
218
Mechanism exchange in which vesicles fuse to form a water filled channel connects:
lumen of capillary to interstitial fluid
219
When the vesicles fuse to form a water filled channel that connects the lumen of the capillary to the interstitial fluid, the movement of the substances through this channel occurs via:
bulk flow (down a pressure gradient)
220
Mechanism of capillary exchange in which vesicles are used to move substances across the cell OR passive and active processes in the cell membrane:
Transcytosis and Transepithelial Transport
221
A mechanism of capillary exchange that moves hydrophobic substances:
simple diffusion
222
What is not small enough to fit through capillary channels through capillary wall spaces?
blood cells and large plasma proteins
223
What is the difference between plasma and interstitial fluid?
Plasma has more protein that interstitial fluid
224
As blood moves through the capillary bed, ____ is dumped off, and ____ is picked up
O2; CO2
225
Most direct route between arteriole and venule; intermittent smooth muscle; some exchange does occur here:
metarteriole/throroughfare channel
226
Branch off arteriole and metarteriole:
capillaries
227
Capillaries take ____ paths to go from arteriole side to venule side
alternate paths
228
Control the entrance to capillaries:
pre-capillary sphincters
229
Pre capillary sphincters are made of:
smooth muscle
230
Direct connection between arteriole and vein
arteriovenous anastomosis
231
Describe the exchange in arteriovenous anastomosis:
No exchange occurs
232
Arteriovenous ansastomosis are not capillaries and allow for things like ____ to go from the arterial side to the venule side via a direct path WITHOUT exchange
WBCs
233
The amount of blood and pathway the blood travels through the capillary bed varies _____ based on the tissue's ____.
moment to moment; metabolic activity
234
Metarteriole and pre-capillary sphincters fluctuate between:
contracted and relaxed state
235
The rate of fluctuation between the contracted and relaxed states of the metarteriole and pre-capillary sphincters is controlled primary by the:
concentration of oxygen in the tissue
236
When the concentration of oxygen is low in the capillary network, the smooth muscle spends more time in the _____ state and blood takes the ____ path through the capillary bed
relaxed state; convoluted
237
When the concentration of O2 is high in the capillary network, the smooth muscle spends more time in the ____ state and blood takes the ____ path through the capillary bed
contracted state; direct
238
As a tissue becomes more metabolically active, the amount of oxygen in that tissue space becomes ___ and the amount of CO2 and H+ becomes _____.
decrease/depleted; increased
239
Velocity is the _____ in capillary beds:
Why?
The slowest; becuase they have a greater cross-sectional area
