Cardiovascular Physiology III (EXAM III) Flashcards
(242 cards)
1
Q
Blood flow through the smallest vessels in the circulatory system (arterioles, venules, capillaries)
A
Microcirculation
2
Q
List whether the vessel description is characteristic of a vein or artery:
- Few layers of smooth muscle & connective tissue
- Many layers of smooth muscle & connective tissue
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 an arteriole to a venule, an arterior 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
Because veins lack tone
11
Q
What is the name for the largest arteries? List examples:
A
Elastic arteries
- aorta & pulmonary trunk
12
Q
What is 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 of 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 determines the radius of the vessel lumen?
A
Vascular tone
17
Q
____ in tone would lead to an 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 effect resistance?
A
Increases resistance
20
Q
How does a decrease in tone effect resistance?
A
Decreases resistance
21
Q
A change in vascular tone leads to a change in _____ and a changes in ______
A
Resistance & a change in blood flow through the vessel
22
Q
What is the equation for blood flow through a vessel?
A
Q= (change in pressure) / (resistance)
23
Q
What is the equation showing the relationship between resistance with length of the vessel & radius:
A
R= (8Ln)/(pi)(radius^4)
24
Q
Tone can be modified by (2):
A
- Paracrines from endothelial cells
- Autonomic nervous system
25
Gives three examples of paracrines from endothelial cells & explain their effects:
1. Nitric Oxide (NO) - decreases tone & relaxes smooth muscle
2. Prostayclin- decreases tone & relaxes smooth muscle
3. Endothelin-1 - increases tone & relaxes smooth muscle
26
Describe what scenarios the parasympathetic nervous would effect vascular tone:
Parasympathetic innervation mediates vasodilation only in the arteries supplying the penis & clitoris (therefore decreasing vascular tone)
This is the only situation in which the parasympathetic nervous system would have influence on vascular tone (never would it increase vascular tone)
27
Describe the sympathetic NS influence on vascular tone of smooth muscle:
Depends on neurotransmitter but most often will increase vascular tone
28
When an artery/arteriole is somewhat contracted in its resting state:
Basal tone
29
Basal tone is mediated by (2):
1. Paracrine secreted by endothelial cells
2. Tonic activity of sympathetic motor neurons
30
If ______ sympathetic activity to arteries and arterioles that would function to increase tone
If you ____ sympathetic activity to arteries & arterioles that would function to decrease tone
Increase; decrease
31
What allows arteries/arterioles to vasodilate & vasoconstrict from rest?
Due to their basal tone
32
Describe the basal tone in veins in venules:
Not present, they are fully relaxed in resting state
33
Due to veins/venules not exhibiting basal tone, they can only ____ from rest:
How do they do this?
Vasoconstrict
Mediated sympathetic nervous system
34
(High) Abnormal arterial tone=
Idiopathic hypertension (most common cause of HTN_
35
How easily a structure stretches:
Compliance
36
Equation for compliance:
Compliance = (change in volume) / (change in pressure)
37
Describe the compliance of vessels that can have large changes in volume with little changes in pressure:
Give an example
High compliance
Veins
38
Why do we describe veins as having high compliance:
Due to the ability to have large changes in volume with little changes in pressure
39
Describe compliance of vessel that can have large changes in pressure with little changes in volume:
Give an example
Low compliance
Arteries
40
Why do we describe arteries as having low compliance?
Due to the ability to have 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 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 smoothes 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?
Systole
Diastolic
47
The smoothing out of flow (no more pulsations) related resistance of blood flow & compliance of the vessel:
Dampening
48
What vessels have the greatest resistance to blood flow?
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 & compliance of a vessel
50
Corresponds to the peak pressure in the left ventricle during ventricular systole:
Systolic
51
Corresponds to the minimum pressure in the artery that is the pressure that the left ventricle has to overcome to open semilunar valves:
Diastolic
52
What is the driving force to get the blood to the capillaries (numerical value)
63 mmHg
53
Describe the location of the highest pressure vessels
Closest 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 into place
57
The elastic recoil of the aorta is essential to:
Assure the diastolic pressure does not fall too low
58
Elastic recoil maintains the:
Driving pressure (diastolic pressure)
59
Average driving pressure in systemic arteries:
MAP
60
Equation for mean arterial pressure:
MAP= Diastolic + 1/3 (Systolic - Diastolic)
61
What is the mean arterial pressure for a BP of 120/80?
93 mmHg
62
Which pressure (systolic or diastolic) has the greatest influence on MAP? Why?
Diastolic- because the ventricle spends a lot more time in diastole than it does in systole
63
What is the standard normal driving pressure in systemic circulation?
93 mmHg
64
What happens to MAP with arteriosclerosis?
Arteriosclerosis is stiffening of the arteries so elastic recoil (snapping back of aorta) is compromised so these individuals have issues with venous return (getting blood back to the heart)
65
Mechanistic explanation of arteriosclerosis:
Because recoil of aorta is blunted, you wouldn't get as much of a "dicrotic notch" & the pressure would drop more than it normally would
66
How would heart function change to compensate in individuals with arteriosclerosis:
The heart would have to beat more forcefully if you want to have good perfusion through systemic circulation
67
Felt as the pulsation or throb in the arteries of the wrist or neck with each heartbeat:
Pulse pressure (PP)
68
Equation for pulse pressure:
PP= (SP-DP)
69
What would PP of BP 120/80 equal:
PP=(120-80)
= 40 mmHg
70
What are the most important factors in determining the magnitude of 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 decreases compliance will _____ pulse pressure
Anything that increases compliance will _____ pulse pressure
Increase
Decrease
73
In an individual with ateriosclerosis to maintain driving pressure their heart must contract more forcefully during systole. How will this affect MAP?
It will increase MAP
74
Diseased state characterized by the failure of the aortic valve to completely & fully open:
Aortic stenosis
75
Arteriosclerosis results in a reduced ______ while aortic stenosis results in a reduced ______
Compliance; SV
76
Why does aortic stenosis results in a reduced stroke volume?
You have to force blood out of the aorta through a narrow opening & this leads to a reduced stroke volume because you cannot efficiently pump blood out
77
We can SELECTIVELY vary the amount of blood flow to different tissues & organs by:
Adjusting the radius of the vessels
78
If we want to selectively increase blood flow to the liver but decrease blood flow to the kidneys how might this be accomplished?
Dilate vessels leading to liver
Constrict vessels leading to kidney
(overall selectively changing the radius of the vessel)
79
We can selectively increase or 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 blood 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 70 million Americans:
(T/F)
Both statements are true
83
HTN affects 1/5
(T/F)
F- 1 in 3
84
Describe what happens to the blood pressure when an individual starts to age:
Systolic starts to rise & diastolic starts to fall
85
A rise in systolic & fall in diastolic pressure as an individual starts to age represents:
Arterial stenosis
86
Normal blood pressure is considered:
Systolic less than 120
Diastolic less than 80
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+
Diastolic: 90+
90
Hypertensive crisis:
Systolic: 180+
Diastolic: 120+
91
What are the three factors that influence MAP?
1. Flow in & out of systemic arteries
2. Total blood volume
3. Distribution of blood in circulatory system
92
The flow IN to systemic arteries:
The flow OUT of systemic arteries:
CO
TPR
93
Vasoconstriction of arteries would function to increase:
Total peripheral resistance (TPR)
94
The sum of all the resistance of all systemic arterioles in the body:
Total peripheral resistance (TPR)
95
If:
Flow in > Flow out (due to increased CO or increased TPR) would have what affect on MAP?
Increase (due to accumulating volume)
96
If:
Flow in < Flow out (due to decreased CO or decreased TPR) would have what affect on MAP?
Decrease (due to volume depletion)
97
Equation involving CO & TPR:
MAP = CO x TPR
98
How would an increase in total blood volume affect MAP?
What is an example of something that might cause this?
Increase in MAP
Increased sodium intake (salty meal)
99
How would a decrease in total blood volume affect MAP?
What is an example of something that might cause this?
Decrease in MAP
Hemorrhage (bleeding out)
100
How can distribution of blood in circulatory system affect MAP?
Blood can be shifted from veins to arteries to increase MAP
101
When blood is shifted to veins (from arteries) we _____ MAP
When blood is shifted to arteries (from veins) we ____ MAP
Increase; Decrease
102
Normally ____% of blood volume is in arteries & ____% of blood volume is in veins`
11% Arteries
60% Veins
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
TPR
105
Arteriolar diameter is influenced by what three things?
1. Autoregulation
2. Local Control
3. Systemic/Reflex control
106
Regulation of TPR:
Autoregulation is a function of:
Blood vessel wall
107
Assures blood flow to tissue matches tissue demands:
Autoregulation (of arteriolar diameter)
108
Regulation of TPR:
Local control is a function of:
Paracrines
109
Matches tissue blood flow to metabolic demands:
Local control (of arteriolar diameter)
110
According to local control of arteriolar diameter regulation
Flow to tissue=
MAP/ Resistance of the tissue
111
In a tissue that is more metabolically active, if we want to increase blood flow:
We want reduce _______
We do NOT want to increase ______
Resistance
MAP
112
Arteriolar diameter regulator that functions to maintain MAP to assure adequate blood flow to the brain & heart:
Systemic/reflex control
113
What will be altered in systemic/reflex control of arteriolar diameter to keep map constant?
CO & TPR
114
Systemic/ Reflex control is a function of:
NS & ES
115
According to systemic/reflex control of arteriolar diameter:
MAP=
CO x TPR
116
Controls the flow into capillaries:
The resistance of arterioles
117
A function of arterioles that is a regulatory reflex that assures that blood flow into tissues does go up just because BP is increased:
Myogenic autoregulation
118
Reflex arteriolar constriction is a response to:
Increased MAP
119
Nearly all organs tend to keep their blood flow constants despite variations in:
Arterial pressure
120
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 BP goes up
121
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 an increase in tissue blood flow to that tissue
122
T/F: An increase in MAP leads to an increase in tissue blood flow
False
123
T/F: AN increase in MAP above 180 mmHg will lead to an increase in tissue blood flow; explain
True (out of myogenic autoregulation range)
124
The normal mean arterial pressure is 93 mmHg, describe where this sits in the myogenic autoregulation range:
Sits pretty far away from the high end & much closer to the lower end
125
Factors regulation arteriolar systemic resistance:
1. Myogenic autoregulation
2. Paracrines
3. Reflex control
126
Interstitial concentration of paracrine substances changes as cells become:
More or less metabolically active
127
Increased tissue metabolism results in:
Decreased O2
Increased CO2
Increased H+
Increased K+
All of this will lead to ____ of the arterioles
Vasodilation
128
Decreased tissue metabolism results in:
Increased O2
Decreased CO2
This will lead to ____ of the arterioles:
Vasoconstriction
129
Increased tissue metabolism leads to ____ blood flow to that tissue
Decreased tissue metabolism leads to ___ blood flow to that tissue
Increased
Decreased
130
Process in which an increase in tissue blood flow accompanies an increase in metabolic activity:
Active hyperemia
131
Once metabolic activity in the tissue goes up we see an increase in organ blood flow to match the metabolic demands, this is referred to as:
Active hyperemia
132
We DO NOT want blood flow to increase due to:
We DO want blood flow to increase due to:
Increasing BP
Increasing metabolic needs
133
Increased tissue blood flow following a period of low perfusion:
Reactive Hyperemia
134
If blood flow to a tissue space is occluded, _____ will accumulate in the interstitial space:
Give examples:
Paracrines
Decreased O2
Increased CO2
Increased H+
135
Hypoxia stimulates endothelial cells to secrete _____ which is a potent _____ that will accumulate in interstitial space:
NO
Vasodilator
136
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
137
The ________ mechanisms are how flow to to a tissue is matched to its metabolic activity
Local control mechanisms
138
What accumulate in the ECF during reactive hyperemia:
Metabolic vasodilators
139
Once the occlusion is removed in reactive hyperemia what happens to resistanvec & blood flow:
Resistance decreases
Blood flow increases
140
In reactive hyperemia, as the vasodilators are washed away by blood flow, arterioles _____ and blood flow _____
Constrict; returns to normal
141
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 AP)
5. Prostaglandins
6. Bradykinins
7. Nitric oxides (NO)
8. Low O2
142
List the vasoconstricting paracrines (leading to a decrease in tissue blood flow) (3):
1. O2 (tissue isn't doing a whole lot if it is not utilizing O2_
2. Endothelin
3. Thromboxanes
143
Factors regulating arteriolar resistance:
Maintains MAP as constant as possible to have adequate blood flow to brain & heart:
Reflex control
144
In situations, if necessary reflex control can overide:
Local control
145
Reflex control is a function of:
Nervous system & endocrine systems (getting big dogs & whole body involved)
146
Sympathetic postganglionic neurons to skeletal muscle arterioles release ______ which binds to ______
Norepinephrine
Alpa-1 receptors
147
When the sympathetic postganglionic neurons release NE that binds to the Alpha-1 receptors, this results in:
Vasoconstriction
148
The adrenal medulla secretes ____ into blood which can bind to _____ & cause _____ or can bind to _____ & cause _____ in the smooth muscle in skeletal muscle arterioles
Epinephrine
Alpha-1 receptors ---> Vasoconstriction
Beta-2 receptors --> Vasodilation
149
The sympathetic post-ganglionc neurons to skeletal muscle arterioles release the norepinephrine to cause an increase in NE in the ______
The adrenal medulla secretes epinephrine into the blood to cause an increase in epi in the _____
ECF
Plasma
150
Describe the location of Beta-1 receptors in tissues:
Only found in very specific tissue spaces-
Coronary vessels, skeletal muscle arterioles, superficial skin vessels
151
Overall we have more vasoconstriction than vasodilation so ______ will go up when the SNS is activated:
TPR
152
Other hormones that act as vasoconstrictors include:
Anti-diuretic hormone (ADH)
Angiotensin II (ANGII)
153
Other hormones that act as vasodilators include:
Atrial natruretic peptide (ANP)
154
The hormone ANP functions to:
Reduce blood volume & blood pressure:
155
Not only does ANP act on the kidney to promote ______, it acts on vascular smooth muscle to increase ______ and ultimately decrease _______.
Decreased blood volume; Vasodilation, decrease MAP
156
Lots of hormones are designed to maintain blood volume & blood pressure but only ______ is designed to BRING IT DOWN
ANP
157
The reflex control regulating arteriolar resistance uses ____ & _____ controls
Neural & hormonal
158
What equation can be used to describe REFLEX CONTROL:
MAP = CO x TPR
159
What equation can be used to describe local control?
Qtissue= MAP / Resistance of arterioles
160
Beta-1 receptors in the heart are activated by norepinephrine & epinephrine & function to:
Increase HR & Stroke volume
161
Increase in blood pressure has what effect on resistance?
Increases resistance
162
Anything that increases venous return will also increase, SV, CO, MAP, EDV
Starling's law of the heart
163
Intrinsic generation of heart rate can be modulated by:
Sympathetic & parasympathetic motor neurons
164
Stroke volume can be modulated by:
+ inotropic agents
165
Veins have _____ distinct layers (tunics)
Three
166
The walls of veins are _____ compared to arteries so they often appear collapsed in histological slides
Thinner
167
Compared to arteries veins have (3):
1. Less smooth muscle
2. Less elastic tissue
3. Higher compliance
168
Veins are highly distensible so they are called ______ that act as _____
Capacitance vessels; Blood reservoirs
169
Pressure gradient available for venous return is around _____
This is not sufficient to ____
15 mmHg; To move blood back to heart
170
Mechanisms supporting venous return include (4):
1. Venous valves
2. Respiratory pump
3. Skeletal muscle pump
4. Venoconstriction
171
Explain how the respiratory pump functions in supporting venous return:
Every time we breath in we lower thoracic pressure, this creates greater pressure gradient which functions to increase venous return
(the faster you breath in, the faster you return blood back to heart)
172
Explain how the skeletal muscle pump functions in supporting venous return:
Contracting skeletal muscle squeezes on vein which move blood towards heart (one-way valves function here)
173
Explain how venoconstriction functions in supporting venous return:
Sympathetic NS & adrenal medulla release NE & E (respectively) which binds to alpha-1 adrenergic receptors and this causes venoconstriction, which reduces compliances & increases pressure & ultimately promote venous return
174
When one-way valves do not function:
(could be due to dilation of veins or leaky veins, however causes blood accumulation in the veins)
Varicose veins
175
About _____ % of adults suffer from varicose veins and it is most prominent in the _____
15%; lower limbs
176
What are the four determinants to increase peripheral venous pressure?
1. Increase activity of sympathetic nerves to veins
2. Increase blood volume
3. Increase skeletal muscle pump
4. Increase inspiration movements
177
An increase in venous pressure has what effect on venous return?
Increased venous return
178
An increase in venous return has what effect on atrial pressure?
Increased atrial pressure
179
An increase in atrial pressure has what effect on end diastolic ventricular volume (EDV)?
Increased end diastolic ventricular volume
180
An increase in EDV has what effect on stroke volume?
Increased stroke volume
181
Valsalvas maneuver has what effect on VR?
Decreases venous return
182
Mechanistic explanation to why blood flow is slowest in the capillaries:
Due to greatest total cross-sectional area
183
Teleological explanation to why blood flow is slowest in the capillaries:
We want blood flow to take time here so maximum exchange can occur
184
Blood flow velocity is fastest in the ____ & slowest in the _____
Fastest in the arteries
Slowest in the capillaries
185
Blood volume is highest in the _____ & lowest in the _____
Venules/Veins
Arterioles
186
Diastolic & systolic blood pressure is highest in the _____ & lowest in the _____
Arteries
Venules/Veins
187
Vascular resistance is highest in the ______ & lowest in the ______
Arterioles
Venules/Veins
188
What is the amount of driving force pressure to get the blood through the capillaries (numerical value)
20 mmHg
189
Capillaries are big enough to let ______ RBC(s) through at a time
One
190
Describe the anatomy of a capillary
1. Single layer of endothelial cells (capillary wall)
2. Basement membrane
3. Single nucleus
191
Because capillaries are NOT connected via ______ they contain ___ that serve as a mechanism for capillary exchange
Tight junctions; narrow water-filled spaces
192
Movement of fluid & dissolved substances via bulk flow occurs ______ in capillaries & serves as a mechanism of capillary exchange
Down a pressure gradient
193
In capillaries vesicles may fuse to form _____ which connects the _____ to the _____
Water-filled channel
Lumen of capillary to interstitial fluid
194
What process can occur in the water-filled channels of capillaries?
Bulk flow down a pressure gradient
195
______ & ______ transport are two mechanisms of capillary exchange that will either use vesicles or passive and active processes in the cell membrane
Transcytosis & Transepithelial transport
196
Simple diffusion in capillaries is a mechanism of capillary exchange to transport ________ substances
Hydrophobic
197
What is the difference between plasma & interstitial fluid?
Plasma contains more protein than interstitial fluid because the protein is too big to fit through capillary spaces
198
What is NOT small enough to fit through the capillary spaces?
Blood cells & large plasma proteins
199
As blood move through the capillary bed ____ is dumped off & ____ is picked up
O2
CO2
200
Part of the capillary made of intermittent smooth muscle & is the MOST DIRECT ROUTE between arterioles & venules
(some exchange does occur here)
Metarteriole/Thoroughfare Channel
201
Branch off ateriole & metarteriole and take alternate paths to go from arteriole to venule side:
Capillaries
202
Describe pre-capillary sphincters:
Made of smooth muscle & function to control the entrance to capillaries
203
Not a capillary, rather a direct connection between arteriole & vein in which exchange DOES NOT occur:
Ateriovenous anastomosis
204
If i am talking about a more direct route without exchange I am referring to ______
This path allows for things like ____ & ____ to go from ateriole to venule side
Ateriovenous anastamosis
WBCs & large proteins
205
Amount of blood & pathway the blood travels through a capillary bed varies moment to moment based on:
Tissues metabolic activity
206
Metarteriole & pre-capillary sphincters fluctuate between:
Contracted & relaxed state
207
The rate of fluctuation of contraction/relaxation in metarteriole & pre-capillary sphincters is primarily controlled by:
O2 in the tissue
208
When the concentration of O2 in the tissues is low, smooth muscle spends more time in a _____ state & the blood takes a ____ path through the capillary bed
Relaxed; convoluted
209
When the concentration of O2 in tissues is high, smooth muscle spends more time in a ____ state & blood takes a more ____ path through the capillary bed
Contracted; direct
210
In times of high metabolic activity in tissues what do the paracrines function to do (2):
1. Paracrines function to dilate the arteriole in the process of active hyperemia
2. Paracrines function to relax pre-capillary sphincters
211
In 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
212
In a not very metabolically active tissue describe the pre-capillary sphincters:
Lack of paracrines causes pre-capillary sphincters to close off, therefore less perfusion occurs
213
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
(ateriovenous anastamosis)
214
What is the driving force to get blood through the capillaries?
20 mmHg
215
The capillaries are made of a _____ layer of _____ cells (makes up the capillary wall)
Single layer of endothelial cells
216
Mechanism of capillary exchange that is due to the capillaries not being connected via tight junctions:
narrow water filled spaces
217
In a capillary what travels through the narrow water filled spaces?
Fluid & dissolved substances
218
The movement of fluid & dissolved substances in capillary exchange occurs via:
Bulk flow
219
The mechanism of capillary exchange (bulk flow) occurs:
Down a pressure gradient
220
Mechanism of capillary exchange in which vesicles fuse to form water filled channels connects:
Lumen of capillary to interstitial fluid
221
When vesicles fuse to form water filled channels that connects the lumen of the capillary to the interstitial fluid, the movement of substances through this channel occurs via:
Bulk flow (down a pressure gradient)
222
Mechanism of capillary exchange in which vesicles are used to move substances across the cell or passive & active processes in the cell membrane:
Transcytosis & Transepithelial transport
223
A mechanism of capillary exchange used for hydrophobic substances:
Simple diffusion
224
What is not small enough to fit through the capillary channels through the capillary wall spaces?
Blood cells & large plasma proteins
225
What is the difference between plasma & interstitial fluid?
Plasma has more proteins than interstitial fluid
226
As blood moves through the capillary bed ____ is dumped off & _____ is picked up:
O2
CO2
227
Most direct route between arteriole & venule; intermittent smooth muscle; some exchange does occur here:
Metarteriole/Thoroughfare channel
228
Branch off arteriole & metarteriole:
Capillaries
229
Capillaries take ____ paths to go from arteriole side to venule side:
Alternative paths
230
Control entrance to capillaries:
Pre-capillary sphincters
231
Pre-capillary sphincters are made of:
smooth muscle
232
Direct connection between arteriole & vein
Ateriovenous anastamosis
233
Describe the exchange that occurs in the ateriovenous anastamosis:
No exchange occurs
234
Arteriovenous anastomosis are NOT capillaries & allow things like ____ to go from the arteriole side to the venule side via a direct path WITHOUT exchange
WBCs & large proteins
235
The amount of blood & pathway the blood travels through the capillary bed varies ______ based on the tissue's ______
Moment to moment; metabolic activity
236
Metarteriole and pre-capillary sphincters fluctuate between:
Contracted & relaxed state
237
The rate of fluctuation between contracted & relaxed states of the metarteriole and pre-capillary sphincters is controlled primarily by the:
Concentration of oxygen in the tissue
238
When the concentration of oxygen is low in the capillary network, smooth muscle spends more time in the _____ state & blood takes the ____ path through the capillary bed
Relaxed; convoluted
239
When the concentration of oxygen is high in the capillary network, smooth muscle spends more tine in the ____ state & blood takes the ___ path through the capillary bed
Contracted; Direct
240
When tissue becomes more metabolically active oxygen is decreased and H+, CO2 & paracrines become _____
The paracrines will function to _____ the arteriole through the process of ____
What affects do the paracrines have on pre-capillary sphincters?
Increased
Vasodilate; active hyperemia
They relax the precapillary sphincters
241
Velocity is the _____ in capillary beds
Why?
Slowest; because they have the greatest cross-sectional area
242
The path the blood travels through the capillary is dependent on the:
Metabolic state (active or nonactive) of the tissue
