BP regulation Flashcards
1
Q
What is the equation for the mean arterial pressure?
A
CO x TPR
2
Q
What is the definition of BP?
A
Force exerted by the blood against any unit area of the vessel wall
3
Q
Pressure is directly related to the product of what two variables?
A
Flow and resistance
4
Q
True or false: CO is usually kept constant
A
True
5
Q
What is the variable that is usually regulated to control BP?
A
Resistance
6
Q
What is the cause of the dicrotic notch (incisura) in the arterial pressure waveform?
A
Due to closure of the aortic valve
“separation of the heart from the peripheral circulation”
7
Q
What is the diastolic run off?
A
The drop in BP d/t blood flowing downstream after the aortic valve has closed
8
Q
Increasing peripheral resistance (vasoconstriction), will change the slope of the diastolic run off curve how?
A
Decrease the slope d/t lowered flow
9
Q
Decreasing peripheral resistance (vasodilation), what will happen to the slope of the diastolic run off curve?
A
Increases the slope (increases flow)
10
Q
What is the equation for the estimated MAP?
A
1/3(SBP-DBP) + DBP
11
Q
Why is the DBP weighted more in the equation for the estimated?
A
Stays longer in diastole
12
Q
What is the equation for the pulse pressure?
A
SBP - DBP
13
Q
How do you measure BP?
A
Cuff, listening for Korotkoff sounds
14
Q
What are the limitations of measuring BP with a cuff?
A
Less accurate
Appropriate cuff size
15
Q
The pulse pressure generates what? (What enables feeling the pulse in the radial artery prior to blood actually arriving)
A
A wave that travels faster than the blood
16
Q
What are the two conditions that can lower the stroke volume output?
A
Persistent Ductus Arteriosus
Aortic regurg
17
Q
What are the two factors that can change the compliance of vessels?
A
Arteriosclerosis
Aortic stenosis
18
Q
The pressure wave is faster or slower with aortic distensibility?
A
Slower speed the more distensible
19
Q
What are the four factors that affect the wave propagation of the pressure pulse wave?
A
Velocity
Stroke volume
Aortic compliance
Distance to reflection pts
20
Q
What happens to the amplitude of the pressure pulse wave as you move downstream from the heart?
A
Increases since it is close to the point of reflection
21
Q
What happens to the reflected pressure pulse wave if the aortic compliance is reduced?
A
Increases speed, and thus a higher reflected wave
22
Q
What happens to the pressure pulse wave as we age?
A
Amplification d/t increased summation of the forward and reflected waves
23
Q
Why does the amplitude of the pressure pulse wave increase in decreased aortic compliance?
A
increased summation of the forward and reflected waves
24
Q
What happens to the incisura as you go distally?
A
Moves farther down the curve (felt later)
25
What happens to the wave oscillations as the pressure pulse wave hits the arterioles? What is the consequence of this on the capillaries?
Decreases to protect the delicate capillaries
26
Where is the resistance change the greatest in the blood circulation?
Arterioles
27
What happens to capillary pressure if the arteriole is constricted (increased resistance)? Why do you want to do this in skeletal muscle?
Decreases, to allow more time for the tissues to extract oxygen and nutrients
28
What happens to capillary pressure if the arteriole is dilated (lowered resistance)?
Increases
29
What are the acute changes in tone that can control blood flow control in tissues?
Vasoconstriction/dilation
30
What are the long term changes that can control the blood flow?
Change in size/number of capillaries in a tissue
31
Increasing metabolism in tissue (blanks) blood flow to those tissues
Increases
32
Decreasing oxygen saturation changes blood flow how?
Increases it
33
What is the myogenic theory of autoregulation of blood flow?
Stretching vessels will elicit contraction
34
What is the chemical that dilates arterioles, and is released from the endothelial cells of vessels?
NO (=EDRF)
35
What is the MOA of NTG?
"Donates" NO
36
What is the MOA of NO, bradykinin, and histamine?
Inhibit MLCK (myosin long chain kinase) and activates MLCP myosin long chain phosphatase)
37
What is the MOA of Endothelin, Norepi, angiotensin II, and vasopressin?
Inhibits MLCP (myosin long chain phosphatase)
38
Acute regulation of BP is mediated through change in what variable? Why part of the nervous system is responsible for this effect?
Resistance (acting on actin and myosin)
ANS
39
Long term changes in BP is mediated through what? What is the organ responsible for this?
Changes in salt and water reabsorption (changes volume)
Kidney effects this change
40
What is the SNS receptors on blood vessels? What is the effect they produce when stimulated?
Alpha 1
Vasoconstriction (thus increase in resistance)
41
What is the SNS receptors on the heart? What is the effect that these produce?
Beta 1
Increase in contractility, HR
42
What are the SNS receptors on the kidney? Effects (2)?
Beta 2
Decreased GFR
Releases renin
43
What is the effect of angiotensin II, that is produced from Renin release by activation of the SNS?
Vasoconstriction
44
What is the effect of SNS stimulation of the adrenal glands?
(Nor)epi release
45
What is the effect of the PNS on the heat?
Decreased HR
M2 receptors!!
46
How do you pharmacologically decrease BP?
Decrease SNS (alpha 1) of the vessels
47
Is there PNS innervation of the blood vessels?
No
48
Stimulating SNS (increases/decreases) cutaneous capillary resistance? Through what receptors?
Increases through alpha 1
49
Nor epi acts on which receptors in the blood vessel to effect vasoconstriction?
Alpha 1
50
What is the effect of the SNS activation of arterioles? What is the effect this produces on blood flow through tissues?
Constricts Arterioles, increasing resistance, and leading to decrease blood flow through tissues, so that more oxygen can be extracted
51
What is the effect of the SNS activation of veins? What is the effect this produces on blood flow back to the heart?
Increasing venous return to the heart
Increases heart pumping to the periphery
52
What is the NTS?
The place in the CNS that receives all of the sensory information from the PNS relating to BP
This then sends projections to the cardioinhibitory center
53
What are the two bilateral structures in the NTS?
RVLM
| CVLM
54
Excitation of the RVLM produces what? Excitation of the CVLM?
```
RVLM = constrict
CVLM = dilate
```
55
What are the two main mechanisms through which BP is maintained?
(1) a system of rapidly acting vascular reflexes, and
| (2) a group of slower mechanisms that adjust fluid volume and indirectly affect arterial pressure.
56
What happens to capillary pressure if the vessels upstream are constricted?
Decreased
57
What happens to capillary pressure if the vessels upstream are dilated?
Increased
58
What is endothelin? What cells release it, and what is its effect?
Released from endothelium of the vessels, and causes vasoconstriction
59
Lowered SNS to the blood vessels causes what?
Vasodilation
60
What happens to the outlet pressure of an arteriole when it is constricted?
Decreases
61
What is the function of the CVLM?
Inhibits the RVLM, thus effecting vasodilation
62
What is the RVLM?
The vasoconstrictor center
63
What is the CVLM?
The vasodilatory center
64
What are the two cardiac centers in the medulla?
Cardioinhibitor centers
| Cardioexcitatory centers
65
What are the two inhibitory areas of the cardioinhibitor center?
Nucleus ambiguous
Dorsal motor nucleus of the vagus
66
What happens when the cardioinhibitory center is stimulated?
Increase in vagal tone to the heart
67
What happens when the cardioexcitatory center is activated?
these cells cause an increase in the activity of the sympathetic nervous system to the heart
68
Where are all of the baroreceptors synapses located? Where do the go from here?
At the NTS in the medulla
Then go to either CVLM or RVLM and/or the cardiogenic centers
69
What are the 5 steps of the parasympathetic pathway of BP regulation, starting with sensory input?
1. Sensory input
2. NTS
3. DMNV and NA
4. Vagus
5. Heart
70
What are the 7 steps of the sympathetic pathway of BP regulation, starting with sensory input?
1. Sensory input
2. NTS
3. CVLM
4. EVLM
5. IML
6. Symp chain
7. Effector
71
Where are the chemoreceptors located?
Carotid sinus
| Aortic bodies
72
Where are baroreceptor located?
In the aortic arch and in arteries
73
What are the three main reflexes that control arterial pressure?
Arterial baroreflex
Cardiopulmonary baroreflex
Chemoreflex
74
What is the arterial baroreflex activated by? Where are the receptors located? Is this a short term or long term response?
High pressure
Carotid sinus and aortic arch
Short term
75
What is the cardiopulmonary baroreflex activated by? Where are the sensors located?
Activated by low pressure (volume)
Sensors in the atria, pulmonary vessels
76
What is the chemoreflex activated by? What is the effect they produce?
Changes in [O2, CO2, pH]
77
Peripheral activation of chemoreceptors leads to what?
Changes in symp tone, and vasoconstriction
78
Central activation of chemoreceptors leads to what?
local dilation and change in symp tone in periphery to vasoconstrict
79
What are the five steps of activation of the arterial baroreflex, starting with stretch on vessel walls?
1. Stretch on vessel walls (via carotid sinus and aortic arch)
2. Increased in BR firing
3. Signal to CNS (NTS)
4. Inhibition of vasoconstrictor center (via CVLM) and activation of the cardioinhibitory center
5. Vasodilation of vessels and decrease in HR/contractility
80
Which two nerves are used in the afferent nerves from the carotid sinus and aortic arch in the arterial baroreflex pathway?
CN X or XII
81
What are the two effector organs that the arterial baroreflex activate (via symp and parasymp)?
```
Symp = Heart, bloow vessels, kidnery, adrenal
Parasymp = heart
```
82
What is the net effect produced from the arterial baroreflex pathway? (start with the stimulus)
Increased BP leads to decreased HR, vasoconstriction, and increase in di/natriuresis
83
Increases in BP will increase or decrease afferent traffic? How about for efferent traffic?
Increases afferent traffic
| Decreases Efferent traffic (think inhibiting RVLM)
84
Baroreceptors are most reactive to what?
CHANGES in BP
85
The baroreflex is good for the short term or the long term?
Short term
86
How do the baroreceptors lower heart rate through the vagus nerve?
1. Send afferent nerves to the NTS
2. NTS stimulates the DMNVNA
3. Vagus signals heart to slow
87
True or false: the baroreflex can change, leading to HTN
True
88
What are the 4 steps of the chemoreflex, starting with decreased arterial BP?
1. Increased firing of chemoreceptors in response to low pH, O2 or increased CO2 (which is brought about from BP change)
2. increased firing to the CNS
3. Activation of the vasoconstriction center
4. Vasoconstriction
89
When does the chemoreflex take effect?
around 80 mmHg
90
What are the cells that are in chemoreflex receptors?
Glomus cells
91
The CNS also has a chemoreflex of its own. What are the 2 effects of this reflex?
1. Same as peripheral (increase SNA to increase BP)
| 2. Vasodilation of local blood vessels
92
What does the cardiopulmonary reflex react to?
Changes in blood volume produced by changes in the stretch of the atria
93
What two major things happen in the cardiopulmonary reflex when there is less atrial stretching (from decreased volume)?
1. Receptors fire to CNS to the RSNA. This causes vasoconstriction and increased ADH
2. ANP is not released, causing a decrease in naturesis
94
What is the effect of ADH that is released in response to the cardiopulmonary reflex?
Increase water reuptake
95
What is natuirusis?
Loss of Na through urination
96
Which nerve does the cardiopulmonary reflex travel through?
Vagus
97
What are the two hormones that are regulated via the cardiopulmonary reflex?
ANP
| ADH
98
What is the bainbridge reflex?
the reflex in the cardiopulmonary pathway that sends afferent signals through the Vagus to stimulate cardioexcitatory center
99
What are the effects of respiratory oscillation in blood pressure?
1. Signals from the respiratory center spill over into the vasomotor center
2. Inspiration decreases pressure in thoracic blood vessels, momentarily decreasing CO and AP
100
What is the mechanism for the long term regulation of BP?
Kidneys reduce volume through the enhanced excretion of salts and water
101
True or false: direct increased pressure to the kidney can affect BP
True
102
What are the two major mechanisms through which the kidneys effect long term BP changes?
Naturiesis
| Diuresis
103
What is the three horomne system that the kidneys have that regulate BP?
Renin-angiotensin- aldosterone
104
Increasing BP has what effect on urinary output?
Increases
105
True or false: the kidneys have a set point around which BP and urine output are maintained
true
106
How is HTN reflected in the BP/renal output curve?
Shift of the curve to the right
107
Is the long term BP/renal output curve more elastic or inelastic?
Inelastic
108
What are the two scenarios in which Renal water and salt output increase?
Increased NaCl intake
| HTN
109
Activation of the Renin-angiotensin system leads to what overall effect? What activates this?
Vasoconstriction/increased BP
Lower BP to kidney activates this
110
What are the two ways in which angiotensin II affects BP?
1. Regulates renal Na and H2O retention (volume)
| 2. Systemic vasoconstriction (resistance)
111
What is the enzyme that is needed to convert ANGI to II?
ACE 1
112
Why will renal artery stenosis lead to increased BP?
Increased Renin-angiotensin system
113
What are the three short term modulator systems of BP?
baroreceptors
Chemoreceptors
CNS ischemic response
114
What are the three mid-term modulator systems of BP?
Renin-angiotensin system
Stress-relaxation
Capillary fluid shift
115
What are the two long term regulatory mechanisms of BP?
Renal fluid mechanism
| Renal interactions with the Nervous system
