Exam 2 Part I - regulation of BP and CO Flashcards
(126 cards)
1
Q
Blood pressure is the function of ___, ___ and ___
A
Blood, vascular tree, heart
2
Q
The left ventricle creates and initial pressure that results in an
A
Aortic pressure
3
Q
Pulse pressure is (equation)
A
Systolic pressure (SBP) - diastolic pressure (DBP)
4
Q
Pulse pressure is ~
A
~40mm Hg
5
Q
Augmentation is seen in what kind of arteries?
A
Large arteries
6
Q
Augmentation is likely due to ________ in the arterial tree
A
Pulse reflection
7
Q
Pulse reflexion causes summation of pulse wave-forms and may correlate with a condition like
A
Aneurysm
8
Q
Systemic venous BP is also called
A
Central venous pressure
9
Q
Central venous pressure (CV) averages about
A
0 mmHg
10
Q
systemic vasculature has an average pressure about
A
100 mmHg
11
Q
Venous pump is a term that describes the combination of ____ and ____
A
Valves and skeletal muscles
12
Q
The primary role of valves is to prevent
A
Retrograde flow in low-pressure blood vessels
13
Q
What are the 2 pumps in the systemic circulatory systeM/
A
- Left ventricle
2. Collective venous pump
14
Q
What do left ventricles do?
A
Establish arterial pressure and flow to body tissues
15
Q
What does the collective venous pump do?
A
Establish a venous pressure and flow back to the heart
16
Q
What are hydrostatic forces?
A
Gravity — force due to pressure at rest
17
Q
In an average person of average height in a standing position at rest, the venous pressure rises to _____ in the feet
A
90 mmHg
18
Q
In an average person of average height WHILE WALKING, the venous pressure drops to _____ in the feet
A
25 mmHg
19
Q
What is the impact of hydrostatic forces in the head?
A
Negative venous pressure
20
Q
BP =
A
Cardiac output X peripheral resistance
21
Q
CO =
A
Stroke volume X heart rate
22
Q
Peripheral resistance is due to many factors including:
A
— blood volume
— viscosity
— size of vascular container (primarily r^4)
23
Q
When you put all the factors together (including cardiac output formula and peripheral resistance) you end up with, BP =
A
~ SC and HR and collective ‘r^4’
OR
BP = CO/ ‘r^4’
24
Q
Mean arterial blood pressure (MAP) is what?
A
Average blood pressure from left ventricle that is responsible for flow (Q) in the arterial tree
25
Mean arterial blood pressure (MAP) =
DBP + 1/3 (SBP - DBP)
In other words: MAP is diastolic pressure plus 1/3 * (systolic pressure - diastolic pressure)
26
Blood pressure control systems can be fast or slow acting; high or low “____”
Gain (power to correct)
27
There are two main systems of blood pressure control:
Nervous and renal mechanisms
28
Short term adjustments in BP are best done with ______
Rapid-acting ANS
29
Rapid-acting ANS (blood pressure control system) affects
Heart and vessels
30
Long term regulation is done by controlling
Volume of blood in vascular compartment
31
What are the pressure-sensors in the arterial tree close to the out put of the left ventricle?
Aortic and carotid baroreceptors
32
Where are signals from the aortic arch and carotid bifurcation baroreceptors delivered to in the brain?
Cardiovascular center in the brain medulla
33
When carotid sinus nerve impulses, what does that do to cardiac output?
Slows heart rate
| Decreases contractility
34
When vagus nerve impulses, what does that do to cardiac output?
Slows heart rate
| Decreases contractility
35
When carotid sinus OR vagus nerve impulses, what does that do to peripheral resistance?
Decreases vasoconstriction
36
When sympathetic cardiac nerve impulses, what does that do to cardiac output?
Accelerates heart rate
| Increases contractility
37
When sympathetic cardiac nerve impulses, what does that do to peripheral resistance?
Increases vasoconstriction
38
How fast and what kind of gain does arterial baroreceptor reflex get in controlling BP?
Fast and high gain
39
Arterial baroreceptor reflex reaches a peak within what length of time?
15 seconds
40
Arterial baroreceptor reflex has a responsiveness that is lose in what timeframe?
2-4 days
41
The function of arterial baroreceptor reflex is what?
Sudden changes in BP
42
What system is used for postural changes?
Arterial baroreceptor reflex
43
Aortic and carotid chemoreceptors are within small “organs” called
Aortic and carotid bodies
44
Aortic and carotid baroreceptors are used in _________ while aortic and carotid chemoreceptors are used in ________
Arterial baroreceptor reflex; arterial chemoreceptor reflex
45
How fast/slow and how effective is the arterial chemoreceptor reflex?
Fast and high gain
46
What is the peak timeframe of arterial chemoreceptor reflex?
60 seconds
47
Arterial chemoreceptor reflex is very strong when
MAP drops below 80 mmHg
48
Atrial stretch reflex uses stretch-receptors in the walls of the
Right atrium
49
Atrial stretch receptors are not pressure receptors, they are actually
Volume receptors
50
How fast/slow and what gain is atrial stretch reflex?
Fast and unknown gain
51
Bainbridge reflex dominates when _______; baroreceptors dominate when _______
Blood volume rises; blood volume diminishes
52
Intravenous infusion leads to...
Increased R atrial pressure —> atrial receptor stimulation —> Bainbridge reflex and INCREASED heart rate
BUT ALSO
Increased cardiac output —> increased arterial pressure —> baroreceptor reflex and DECREASED heart rate
53
What serves to minimize venous damming of blood?
Bainbridge reflex
54
Atrial stretch can cause a hormonal effect from
Atrial natriuretic factor (ANF)
55
Atrial natriuretic factor (ANF) is released with increased
Atrial pressure/stretch
56
Atrial natriuretic factor (ANF) functions to
Decrease blood volume and decrease BP
57
A nervous control “system” that involves neurons of cardiovascular control center:
CNS Ischemic Response
58
How fast/slow and what kind of gain does the CNS Ischemic Response get?
Fast and high gain — aka last ditch effort
59
CNS Ischemic Response uses neurons of the
Medullary “pressor” area due to cerebral ischemia
60
The CNS Ischemic Response is a reflex triggered from
Very slow moving blood that fails to remove CO2 from cardiovascular center
61
What does the pressor region do?
Evokes vasoconstriction, cardiac acceleration, and myocardial contractility
62
In the pressor region, vasoconstrictor sub-areas are
Topically active and responsible for vasomotor tone
63
The depressor region functions to
Inhibit Pressor area
Decrease sympathetic outflow and increase parasympathetic activity
64
Withdrawal of sympathetic tone is the primary mechanism for nervous-induced
peripheral vasodilation and low BP
65
Humoral control system that uses hormones from adrenal medulla that act as sympathetic neurotransmitters
Epinephrine system
66
Epinephrine system uses what neurotransmitters?
Epinephrine (80%) and norepinephrine (20%)
67
Epinephrine and norepinephrine land on what kind of receptors?
Alpha and beta adrenergic receptors
68
When epinephrine and norepinephrine land on alpha and beta adrenergic receptors, it causes
Peripheral vasoconstriction and increased cardio output
69
How fast is the Epinephrine system? And what is the gain?
Fast-acting and unknown gain
70
Epinephrine system is under what kind of control?
Smooth muscle control
71
What is a property of the arterial system (and vascular smooth muscle) that causes an increase or decrease in constant pressure on arterial vessel that results in a change in contractile state?
Stress-relaxation behavior
72
Stress-relaxation behavior has what kind of speed and gain?
Slow acting, low gain
73
What system is a property of the capillaries of the body?
Capillary fluid shift (edema)
74
How fast and what kind of gain does capillary fluid shift get?
Slow acting and low gain
75
What system can account for peripheral edema in pathological states?
Capillary fluid shift
76
A humoral control system that uses hormones from kidney and blood
Renin-angiotensin system
77
What hormones does the renin-angiotensin system use?
Renin and angiotensin II
78
Renin-angiotensin system works closely with what system?
Aldosterone system
79
Renin-angiotensin system is how fast and what kind of gain?
Slow-acting and low gain
80
The renin-angiotensin system’s participation is modified by
- increase or decrease in BP at different arterioles
- increase or decrease in sympathetic stimulation to kidneys
- increase or decrease in sodium levels in nephron
81
What are the effects of angiotensin?
- Cause cardiac myocytes to hypertrophy
- cause thirst
- stimulate nephron to retain Na+ and H2O
- cause efferent arteriolar vasoconstriction and increase glomerular filtration
- stimulate release of ADH from posterior pituitary
** all to increase BP **
82
A humoral control system that uses a hormone from the adrenal cortex
Aldosterone system
83
Aldosterone works closely with what other BP regulatory system
Renin-angiotensin system
84
The aldosterone system is how fast and what kind of gain?
Slow-acting and low gain
85
Aldosterone system’s participation is modified by:
- increase or decrease in angiotensin II levels
| - K+ levels to adrenal cortex
86
A humoral control system that uses osmotically sensitive neurons in hypothalamus to produce a hormone that is released from posterior pituitary gland
Vasopressin system
87
What is the alternate name for vasopressin?
Anti-diuretic hormone (ADH)
88
What does vasopressing / ADH do?
Acts as both a cardiovascular pressor agent and renal fluid retention agent
89
V1 receptors on vascular smooth muscle can cause
vasoconstriction
90
What speed and gain is vasopressin system?
Slow-acting and unknown gain
91
A fluid (and humoral) control system that uses the kidney
Renal-blood fluid (volume pressure) system
92
The renal-blood fluid system involves what?
Nephron and renin-angiotensin system
93
The renal-blood fluid (volume pressure) system is how fast and what kind of gain?
Slow-acting and very high gain
94
Which BP control system is the ultimate mechanism?
Renal-blood fluid (volume pressure) system
Because it works by adjusting the amount of fluid in the vascular compartment, rather than just manipulating existing fluids of the body.
95
Pressure diuresis
Increased arterial BP leads to increased water disposal
96
Pressure natriuresis
Increased arterial BP leads to increased salt/sodium disposal
97
Diuresis
Formation of urine
98
What system relies on diuresis?
Renal-blood fluid (volume pressure) system
99
A moment-to-moment adjustment process that attempts to stabilize and match input and output (of both salt and water)
Renal output curve
100
ADH causes kidneys to
Retain water
101
How does salt intake increase extra cellular fluid volume?
- Stimulates hypothalamic thirst center
- Stimulates hypothalamic production of anti-diuretic hormone (ADH)
- ADH causes kidneys to retain water
102
2 primary determinants of long-term arterial pressure
1. Level of water and salt intake (net fluid vol)
| 2. Behavior of kidneys as represented in the acute renal output curve
103
Renal output curve can be changed by
- addition of hormonal controls
| - abnormalities of nephrons
104
Angiotensin acts directly on kidneys to
Retain salt and water
105
Angiotensin acts on adrenal glands to
Increase aldosterone secretion which increases salt and water retention in the kidneys
106
The pressure in the system is created primarily from
The heart
107
Cardiac output =
Venous return
108
What determines CO?
By the end-diastolic volume which is dictated by venous return
109
What determines venous return?
The size of peripheral vascular tubes
110
What determines the r^4 (all vessels of the body) / size of vascular container?
Release of local factors from metabolizing tissues
In other words, metabolizing tissues determines venous return which determines C.O.
111
If there is increased tissue metabolism, what are the next steps?
- Increased in local metabolites
- Increased vasodilation
- Increased flow into venous system
- Increased venous return
- Increased cardiac output
- Increased flow to original metabolizing tissues
112
If there were 2 outputs in the cardiovascular system and cardiac output is 1 them, what is the other?
Tissue output (from the body) coupled with venous pump
*this is another way to think about it
113
If you think of the systemic circulation as having 2 pumps with the left ventricle for Cardiac Output being 1, what is the other?
Collective skeletal muscles of the body (for venous return)
114
Remember the equation:
Q = ∆P * r^4 where Q is flow, ∆P is pressure and r^4 is the size of all the vessels/vascular container...
∆P must be maintained, how is it maintained?
By the many BP regulatory systems that regulate the redistribution (and a few manage the volume) of blood
115
Given the limited supply of blood and changing needs of the body, what becomes an important balancing act?
Distribution of blood
116
What system can modify both cardiac output and the peripheral resistance and manage the distribution of blood?
Sympathetic nervous system
117
If the body has an increased work-load, what will happen to CO and BP?
Increase
118
How does changing blood chemistry alter breathing?
Increased H+ leads to increased ventilation
119
Breathing serves as additional venous pumping
Respiratory pump
120
“Warming down”
Continue to move though not fully exercising that is needed to prevent sudden post-exercise pooling of blood through venous pumping
121
Exercise and related metabolism of skeletal muscles is often measured by amount of oxygen consumed by the body
VO2, volume of O2 consumed per minute
122
VO2 levels at rest? But can rise to?
250 ml/min at rest
| 3,000 ml/min or more
123
A maximum aerobic limit of VO2 is called
maxVO2
124
A-V O2 difference is
Measure of tissue metabolism (or O2 extraction)
A-V O2 = Atriovenous oxygen difference
125
In exercise, as total body Q increases, what happens?
Redistribution
- increased Q to skin for sweating
- stable Q to brain
- increased Q to heart
- decreased Q to gut
- decreased Q to kidneys
Q = flow
126
During exercise, CO can raise from ~5 l/m to
> 25 l/m
See graph on Pg 35 if Beck doesn’t insert it here
