Download Diastolic pressure

Figure 21-8 An Overview of Cardiovascular Physiology
Cardiac Output
Venous Return
Arterial Blood
Pressure
Regulation
(Neural and Hormonal)
Venous
Pressure
Peripheral
Resistance
Capillary Pressure
Capillary
exchange
Interstitial fluid
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Pressure and Resistance
• Total capillary blood flow
• Equals cardiac output
• Is determined by
• pressure and resistance in the cardiovascular
system
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Pressure and Resistance
• An Overview of Cardiovascular Pressures
• Systolic pressure
• Peak arterial pressure during ventricular systole
• Diastolic pressure
• Minimum arterial pressure during diastole
• Pulse pressure
• Difference between systolic pressure and diastolic pressure
• Mean arterial pressure (MAP)
• MAP = diastolic pressure + 1/3 pulse pressure
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Figure 21-10a Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and
Blood Velocity within the Systemic Circuit
Vessel
diameter
(cm)
Vessel diameter
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Figure 21-10b Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and
Blood Velocity within the Systemic Circuit
Crosssectional
area
(cm2)
Total cross-sectional area of vessels
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Figure 21-10c Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and
Blood Velocity within the Systemic Circuit
Average
blood
pressure
(mm Hg)
Average blood pressure
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Figure 21-10d Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and
Blood Velocity within the Systemic Circuit
Velocity
of blood
flow
(cm/sec)
Velocity of blood flow
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Figure 21-11 Pressures within the Systemic Circuit
Systolic
Pulse
pressure
Mean arterial
pressure
Diastolic
mm Hg
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Pressure and Resistance
• Capillary Pressures and Capillary Exchange
• Vital to homeostasis
• Moves materials across capillary walls by
• Diffusion
• Filtration
• Reabsorption
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Pressure and Resistance
• Diffusion
• Movement of ions or molecules
• From high concentration
• To lower concentration
• Along the concentration gradient
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Pressure and Resistance
• Diffusion Routes
• Water, ions, and small molecules such as glucose
• Diffuse between adjacent endothelial cells
• Or through fenestrated capillaries
• Some ions (Na+, K+, Ca2+, Cl-)
• Diffuse through channels in plasma membranes
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Pressure and Resistance
• Diffusion Routes
• Large, water-soluble compounds
• Pass through fenestrated capillaries
• Lipids and lipid-soluble materials such as O2 and
CO2
• Diffuse through endothelial plasma membranes
• Plasma proteins
• Cross endothelial lining in sinusoids
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Pressure and Resistance
• Filtration
• Driven by hydrostatic pressure
• Water and small solutes forced through capillary wall
• Leaves larger solutes in bloodstream
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Pressure and Resistance
• Reabsorption
• The result of osmosis
• Blood colloid osmotic pressure
• Equals pressure required to prevent osmosis
• Caused by suspended blood proteins that are too large to
cross capillary walls
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Figure 21-12 Capillary Filtration
Capillary
hydrostatic
pressure
(CHP)
Amino acid
Blood protein
Glucose
Ions
Interstitial
fluid
Small solutes
Hydrogen
bond
Water
molecule
Endothelial
cell 1
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Endothelial
cell 2
Pressure and Resistance
• Capillary Exchange
• At arterial end of capillary
• Fluid moves out of capillary
• Into interstitial fluid
• At venous end of capillary
• Fluid moves into capillary
• Out of interstitial fluid
• Transition point between filtration and reabsorption
• Is closer to venous end than arterial end
• Capillaries filter more than they reabsorb
• Excess fluid enters lymphatic vessels
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Pressure and Resistance
• Interplay between Filtration and Reabsorption
• Hydrostatic pressure
• Forces water out of solution
• Osmotic pressure
• Forces water into solution
• Both control filtration and reabsorption through
capillaries
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Pressure and Resistance
• Net Hydrostatic Pressure
• Is the difference between
• Capillary hydrostatic pressure (CHP)
• And interstitial fluid hydrostatic pressure (IHP)
• Pushes water and solutes
• Out of capillaries
• Into interstitial fluid
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Pressure and Resistance
• Net Colloid Osmotic Pressure
• Is the difference between
• Blood colloid osmotic pressure (BCOP)
• And interstitial fluid colloid osmotic pressure (ICOP)
• Pulls water and solutes
• Into a capillary
• From interstitial fluid
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Pressure and Resistance
• Net Filtration Pressure (NFP)
• The difference between
• Net hydrostatic pressure
• And net osmotic pressure
NFP = (CHP – IHP) – (BCOP – ICOP)
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Figure 21-13 Forces Acting across Capillary Walls
KEY
CHP (Capillary
hydrostatic pressure)
BCOP (Blood colloid
osmotic pressure)
Arteriole
NFP (Net filtration
pressure)
Filtration
24 L/day
35
mm
Hg
25
mm
Hg
NFP  10 mm Hg
CHP  BCOP
Fluid forced
out of capillary
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Venule
Reabsorption
No net fluid
movement
25
mm
Hg
20.4 L/day
18
25
mm mm
Hg Hg
25
mm
Hg
NFP  0
NFP  7 mm Hg
CHP  BCOP
No net
movement
of fluid
BCOP  CHP
Fluid moves
into capillary
Figure 21-14 Short-Term and Long-Term Cardiovascular Responses
Autoregulation
Autoregulation is due
to opening and closing
precapillary sphincters
due to local release of
vasodilator or
vasoconstrictor
chemicals from
the tissue.
HOMEOSTASIS
RESTORED
Local decrease
in resistance
and increase in
blood flow
HOMEOSTASIS
Local vasodilators
released
Inadequate
local blood
pressure and
blood flow
HOMEOSTASIS DISTURBED
• Physical stress (trauma,
high temperature)
• Chemical changes
(decreased O2 or pH,
increased CO2 or
prostaglandins)
• Increased tissue activity
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Normal
blood pressure
and volume
Start
Figure 21-14 Short-Term and Long-Term Cardiovascular Responses
Central Regulation
Central regulation involves
neuroendocrine mechanisms
that control the total systemic
circulation. This regulation
involves both the
cardiovascular centers
and the vasomotor centers.
Neural
mechanisms
Stimulation of
receptors sensitive
to changes in
systemic blood
pressure or
chemistry
Stimulation
of endocrine
response
Activation of
cardiovascular
centers
Short-term
elevation of blood
pressure by
sympathetic
stimulation of the
heart and
peripheral
vasoconstriction
Long-term increase
in blood volume
and blood pressure
Endocrine mechanisms
If autoregulation is ineffective
HOMEOSTASIS
RESTORED
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Figure 21-15 Baroreceptor Reflexes of the Carotid and Aortic Sinuses
Cardioinhibitory
centers stimulated
Cardioacceleratory
centers inhibited
Responses to Increased
Baroreceptor Stimulation
Decreased
cardiac
output
Vasomotor centers
inhibited
Baroreceptors
stimulated
Vasodilation
occurs
HOMEOSTASIS
DISTURBED
HOMEOSTASIS
RESTORED
Rising blood
pressure
Blood pressure
declines
Start
HOMEOSTASIS
Normal range
of blood
pressure
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Figure 21-15 Baroreceptor Reflexes of the Carotid and Aortic Sinuses
HOMEOSTASIS
Start
Normal range
of blood
pressure
HOMEOSTASIS
DISTURBED
HOMEOSTASIS
RESTORED
Falling blood
pressure
Blood pressure
rises
Vasoconstriction
occurs
Baroreceptors
inhibited
Vasomotor centers
stimulated
Responses to Decreased
Baroreceptor Stimulation
Cardioacceleratory
centers stimulated
Cardioinhibitory
centers inhibited
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Increased
cardiac
output
Figure 21-16 The Chemoreceptor Reflexes
Respiratory centers in
the medulla oblongata
stimulated
Increasing CO2 levels,
decreasing pH
and O2 levels
Effects on
Cardiovascular Centers
Reflex Response
Chemoreceptors
stimulated
Respiratory Response
Respiratory rate
increases
Cardiovascular
Responses
Cardioacceleratory
centers stimulated
Cardioinhibitory
centers inhibited
Vasomotor centers
stimulated
Start
Vasoconstriction
occurs
HOMEOSTASIS
DISTURBED
HOMEOSTASIS
RESTORED
Elevated CO2 levels,
decreased pH and O2
levels in blood and CSF
Decreased CO2 levels,
increased pH and O2
levels in blood and CSF
HOMEOSTASIS
Normal pH, O2,
and CO2 levels in
blood and CSF
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Increased cardiac
output and blood
pressure
Figure 21-17a The Hormonal Regulation of Blood Pressure and Blood Volume
HOMEOSTASIS
HOMEOSTASIS
DISTURBED
Start
Decreasing blood
pressure and
volume
Normal blood
pressure and
volume
Blood pressure
and volume fall
HOMEOSTASIS
RESTORED
Blood pressure
and volume rise
Short-term
Long-term
Sympathetic activation
and release of adrenal
hormones E and NE
Endocrine Response
of Kidneys
Renin release leads
to angiotensin II
activation
Erythropoietin (EPO)
is released
Increased cardiac
output and
peripheral
vasoconstriction
Angiotensin II Effects
Antidiuretic hormone
released
Aldosterone secreted
Factors that
compensate for
decreased blood
pressure and
volume
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Thirst stimulated
Increased red blood
cell formation
Combined Short-Term
and Long-Term Effects
Increased
blood
pressure
Increased
blood
volume
Figure 21-17b The Hormonal Regulation of Blood Pressure and Blood Volume
Responses to ANP
and BNP
Increased Na loss in
urine
Increased water loss in
urine
Natriuretic
peptides released
by the heart
Reduced thirst
Combined
Effects
Inhibition of ADH,
aldosterone, epinephrine,
and norepinephrine
release
Reduced blood
volume
Peripheral vasodilation
HOMEOSTASIS
DISTURBED
HOMEOSTASIS
RESTORED
Rising blood
pressure and
volume
Declining blood
pressure and
volume
Increasing blood
pressure and
volume
Factors that compensate for
increased blood pressure and
volume
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HOMEOSTASIS
Normal
blood pressure
and volume
Table 21-2 Changes in Blood Distribution during Exercise
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21-4 Cardiovascular Adaptation
Table 21-3
Effects of Training on Cardiovascular Performance
Subject
Heart
Weight
(g)
Stroke
Volume
(mL)
Heart
Rate
(BPM)
Cardiac Blood Pressure
Output (systolic/
(L/min) diastolic)
Nonathlete (rest)
300
60
83
5.0
120/80
104
192
19.9
187/75
100
53
5.3
120/80
167
182
30.4
200/90*
Nonathlete
(maximum)
Trained athlete
(rest)
Trained athlete
(maximum)
500
*Diastolic pressures of athletes during maximum activity have not been
accurately measured.
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Figure 21-18 Cardiovascular Responses to Hemorrhaging and Blood Loss
HOMEOSTASIS
Normal blood
pressure and
volume
HOMEOSTASIS
DISTURBED
Blood pressure
and volume rise
Extensive bleeding
reduces blood
pressure and
volume
Falling blood
pressure and
volume
Elevation
of blood
volume
Responses
coordinated by the
endocrine system
Responses
directed by the
nervous system
Pain, stress,
anxiety, fear
Long-Term Hormonal Response
Cardiovascular Responses
ADH, angiotensin II, aldosterone,
and EPO released
Peripheral
vasoconstriction;
mobilization of
venous reserve
Stimulation of
baroreceptors and
chemoreceptors
Higher Centers
Stimulation of
cardiovascular
centers
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HOMEOSTASIS
RESTORED
General
sympathetic
activation
Increased
cardiac
output