Chapter 14 Flashcards
1
Q
Flow Rule
A
- Flow occurs from high pressure to low pressure
- P is the force pushing blood against the various factors resisting the flow of liquid in a pipe
- flow = p/r
2
Q
Pressure gradients drive flow from ___ pressure to ___ pressure
A
high; low
3
Q
P =
(systemic circuit)
A
pressure in aorta minus pressure in vena cava just before it empties into right atrium
4
Q
Pressure in aorta =
A
mean arterial pressure (MAP) = 90 mm Hg
5
Q
Pressure in vena cava =
A
central venous pressure (CVP) = 0 mm Hg
6
Q
Pressure gradient across the circuits formula
A
P = MAP – CVP = 90 – 0 = 90 mm Hg
7
Q
P =
( pulmonary circuit)
A
pressure in pulmonary arteries minus pressure in pulmonary veins
8
Q
Pulmonary arterial pressure =
A
15 mm Hg
9
Q
Pulmonary venous pressure =
A
0 mm Hg
10
Q
Which pressure gradient is larger systemic or pulmonary
A
systemic
11
Q
T/F: Flow through both circuits is equal (systemic v. Diastole)
A
true
12
Q
Factors affecting resistance to flow
A
- Radius of vessel
- Length of vessel
- Viscosity of fluid, depends on amount of RBCs and proteins
13
Q
Total peripheral resistance
A
combined resistance of all blood vessels within the systemic circuit
14
Q
Vasoconstriction in network ->______ ->_______
A
increased resistance; decreased flow
15
Q
Vasodilation in network-> ______-> _______
A
decreased resistance; increased flow
16
Q
Flow =
A
cardiac output (CO)
17
Q
P =
A
mean arterial pressure (MAP)
18
Q
R =
A
total peripheral resistance (TPR)
19
Q
CO =
A
MAP / TPR
20
Q
Arteries
A
carry blood away from heart
21
Q
whats involved in microcirculation
A
Arterioles
Capillaries: site of exchange
Venules
22
Q
Veins:
A
return blood to heart
23
Q
label artery and vein diagram
A
24
Q
____ cells line inner layer of all blood vessels
A
Endothelial
25
components of blood vessel walls:
Smooth muscle
Fibrous connective tissue
Collagen
Elastic connective tissue
Elastin
26
Arteries
- Rapid transport pathway
- Large diameter
- Little resistance
- Walls contain elastic and fibrous tissue
- Under high pressure
- Muscular arteries
27
Arteries expand as blood? And Recoil?
enters arteries during systole; during diastole
28
Compliance
measure of how the pressure of a vessel will change with a change in volume
29
Small increase in blood volume causes a
large increase in pressure
30
Large increase in blood volume is required to
produce a large increase in pressure
31
Systolic blood pressure =
maximum pressure
32
Diastolic blood pressure =
minimum pressure
33
Diastolic blood pressure =
minimum pressure
34
Arterial Blood Pressure
- Pressure in the aorta
- Varies with cardiac cycle
- Not zero due to elastic recoil
35
Pressure cuff and sphygmomanometer
- Compressed artery
- Turbulent flow produces Korotkoff sound
- Pressure at first Korotkoff sound = systolic blood pressure
36
Uncompressed artery
- Laminar flow, no sound
- Pressure when sound disappears = diastolic blood pressure
37
The measured BP is shown as
SP/DP
38
Pulse pressure =
SP – DP
39
MAP =
SP + (2DP) / 3
40
Arterioles
- resistant vessels
- Part of microcirculation
- Connect arteries to capillaries
- Contain rings of smooth muscle to regulate radius and, therefore, resistance
41
____ provide greatest resistance to blood flow
Arterioles
42
Arteriolar tone
Contraction level (radius) is independent of extrinsic influences
43
Vasoconstriction
Increased contraction = decreased radius
44
Vasodilation
Decreased contraction = increased radius
45
Functions of varying arteriole radius
- Controlling blood flow to individual capillary beds
- Regulating mean arterial pressure
46
Changes associated with increased metabolic activity generally cause
vasodilation
Carbon dioxide
Potassium
Hydrogen ions
47
Changes associated with decreased metabolic activity generally cause
vasoconstriction
48
Active hyperemia
increased blood flow in response to increased metabolic activity
49
Steady state
(active hyperemia)
- O2 is delivered as fast as it is consumed
- CO2 is removed as fast as it is produced
50
Increased metabolic rate
(active hyperemia)
- O2 is consumed faster than it is delivered
- CO2 is produced faster than it is removed
51
Response to low O2 and high CO2
- Vasodilation
- Vasodilation increases blood flow
52
Increased blood flow
Delivers more O2
Removes more CO2
53
Reactive hyperemia
increased blood flow in response to a previous reduction in blood flow
54
Blockage of blood flow to tissues causes?
- Metabolites increase and oxygen decreases
- Vasodilation
55
When blockage is released what occurs?
- Increased blood flow due to low resistance
- Metabolites removed, oxygen delivered
56
Myogenic response:
change in vascular resistance in response to stretch of blood vessels in the absence of external factors
57
Myogenic autoregulation of blood flow
- Increased perfusion pressure increases blood flow and pressure in arterioles
- Increased pressure in arteriole stretches arteriole wall
- Stretch of vascular smooth muscle induces contraction of vascular smooth muscle—inherent property of smooth muscle
- Vasoconstriction decreases blood flow
58
Purpose of Myogenic autoregulation of blood flow
keep blood flow constant (autoregulate)
59
Radius of arterioles is regulated by
extrinsic mechanisms to control mean arterial pressure
60
Extrinsic Control of Arteriole Radius and Mean Arterial Pressure is sympathetic or parasympathetic
sympathetic
61
Epinephrine
Released from adrenal medulla
62
Vasopressin (ADH)
- Secreted by posterior pituitary
- Increases water reabsorption by kidneys
- Vasoconstriction
63
Angiotensin II
- Vasoconstriction
- Increases TPR
64
Capillaries
Site of exchange between blood and tissue
65
Capillary walls
- One cell layer
- Small diffusion barrier
- Have greatest total cross-sectional area
- Have slowest velocity of blood flow, which enhances exchange
66
Continuous capillaries
- Most common
- Small gaps between endothelial cells
- Allow small water-soluble molecules to move through
67
Fenestrated capillaries
- Large gaps between endothelial cells forming pores or fenestrations (windows)
- Allow proteins, and in some cases blood cells, to move through
68
Metarterioles
- Intermediate between arterioles and capillaries
- Directly connect arterioles to venules
- Function as shunts to bypass capillaries
69
Contraction of metarterioles->
increase blood flow through capillaries
70
Relaxation of metarterioles
decrease blood flow through capillaries
71
Precapillary sphincters
- Rings of smooth muscle that surround capillaries on the arteriole end
- Contract and relax in response to local factors only
72
Contraction of precap sphincters ->
constricts capillary decreases blood flow
73
Relaxation of precap sphnicters->
increases blood flow
74
Metabolites cause
relaxation
75
label venule and arteriole diagram
76
Lipophilic
across membrane
77
Lipophobic
through channels
78
Transcytosis
exchangeable proteins
79
Bulk flow of fluid across capillary wall based on?
pressure gradients
80
Protein-free plasma moves across _____
capillaries
81
Filtration =
movement out of capillary into interstitial space
82
Absorption =
movement into capillary from interstitial space
83
Forces for bulk flow
hydrostatic and osmotic pressures
84
Hydrostatic pressure gradient
force due to fluid
85
Osmotic pressure:
osmotic force exerted on water by nonpermeating solutes
86
Only nonpermeating solute
proteins
87
Oncotic pressure
osmotic force of proteins
88
Capillary hydrostatic pressure
- capillary BP
- Arteriole end = 38 mm Hg
- Venous end = 16 mm Hg
- Favors filtration
89
Interstitial hydrostatic pressure =
0–1 mm Hg
Favors reabsorption
90
Capillary oncotic osmotic pressure
25 mm Hg
Favors reabsorption
91
Interstitial fluid oncotic osmotic pressure
0–1 mm Hg
Favors filtration
92
Osmotic pressure gradient
25 – 0 = 25 mm Hg
Favors reabsorption
93
Net filtration pressure =
filtration pressure – absorption pressure
94
Net across capillary:
filtration > absorption
95
Factors affecting filtration and absorption across capillaries
- Standing on feet
- Injuries
- liver disease
- kidney disease
- heart disease
- venules
- veins
96
Veins
- Expand with little change in pressure
- Function as blood reservoir
- 60% total blood volume in systemic veins at rest
97
Skeletal muscle pump
- Squeezes on veins, increasing pressure
- Blood moves toward heart
- Blood cannot move backward due to valves
98
Factors That Influence Venous Pressure and Venous Return
- skeletal muscle pump
- respiratory pump
- Blood volume
- Venomotor tone
99
Inspiration
- Decreases pressure in thoracic cavity
- Increases pressure in abdominal cavity
100
Pressure on veins in abdominal cavity creates gradient favoring?
blood movement to thoracic cavity
101
Increased blood volume->
increased venous pressure
102
Decreased blood volume->
decreased venous pressure
103
Venomotor tone
-Smooth muscle tension in the veins
- Increases central venous pressure
- Decreases venous compliance
- Increases venous return
104
Smooth muscle in walls of veins is innervated by
sympathetic nervous system
105
Lymphatic System
-system of vessels, nodes, and organs
- Vessels are involved in returning excess filtrate to circulation
- Vessels form an open system starting at the capillaries
- Lymph moves from capillaries to veins
- Lymphatic veins drain into the thoracic duct, which empties into the right atrium
- Lymph moves through the lymphatic veins in the same way as blood flows through regular veins
- Also part of immune system (macrophages)
106
Determinants of Mean Arterial Pressure
Heart rate
Stroke volume
Total peripheral resistance
107
Short-term regulation of MAP
- Regulates cardiac output and total peripheral resistance
- Involves the heart and blood vessels
- Primarily neural control
108
Long-term regulation of MAP
- minutes to days
- Regulates blood volume
- Involves the kidneys
- Primarily hormonal control
109
Baroreceptors
- pressure receptors
- Sometimes called stretch receptors
110
Arterial baroreceptors
- sinoaortic receptors
- Aortic arch
-Carotid sinuses
- Respond to stretching due to pressure changes in arteries
111
Regulation of Mean Arterial Pressure
- Cardiovascular control center
- Medulla oblongata
- Integration center for blood pressure regulation
112
Cardiovascular control center: Input
Arterial baroreceptors
Low-pressure baroreceptors
Chemoreceptors
Proprioceptors
Higher brain centers
113
Autonomic output to cardiovascular effectors
Parasympathetic input to
SA node (decreases HR)
114
Sympathetic input to
- SA node (increases HR)
- Ventricular myocardium (increases contractility)
- Arterioles (increases resistance)
- Veins (increases venomotor tone)
115
Baroreceptor reflex
negative feedback loop to maintain blood pressure at normal level
116
Hemorrhage
- Decreases blood volume
- Triggers the baroreceptive reflex
- Increases sympathetic activity
- Decreases parasympathetic activity
117
Adrenal medulla releases?
epinephrine in response to sympathetic activity
118
Vasopressin and angiotensin II
Vasoconstrictors
Increase TPR
Increase MAP
