Chapter 15a
Blood Flow and the
Control of Blood
Pressure
About this Chapter
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The blood vessels
Blood pressure
Resistance in the arterioles
Distribution of blood to the tissues
Exchange at the capillaries
The lymphatic system
Regulation of blood pressure
Cardiovascular disease
Functional Model of the Cardiovascular System
Elastic arteries
Aorta
Aortic valve
Left ventricle
Left heart
Mitral valve
Left atrium
Arteriole with
variable radius
Pulmonary veins
Lungs
Exchange of
material with
cells
Capillaries
Pulmonary artery
Pulmonary valve
Right ventricle
Right heart
Venules
Tricuspid valve
Right atrium
Venae cavae
Expandable veins
Figure 15-1
Blood Vessel Structure
Figure 15-2
Blood Vessel Structure & Function
PLAY
Interactive Physiology® Animation: Cardiovascular
System: Anatomy Review: Blood Vessel Structure &
Function
Metarterioles Regulate Flow into Capillary Beds
• Capillaries lack
smooth muscle and
elastic tissue
reinforcement, which
facilitates exchange
Collateral
arteries
Vein
Venule
Arteriole wall is smooth muscle.
Metarterioles can act as
bypass channels.
Capillaries
Small
venule
Precapillary
sphincters
Arteriovenous
bypass
Figure 15-3
Angiogenesis
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New blood vessel development
Necessary for normal development
Wound healing and uterine lining growth
Controlled by cytokines
• Stimulate (mitogens): VEGF and FGF
• Inhibit: angiostatin and endostatin
• Coronary heart disease
• Collateral circulation
Elastic Recoil in Arteries
Arterioles
1
2
3
1
Ventricle contracts.
2
Semilunar valve opens.
3 Aorta and arteries expand and
store pressure in elastic walls.
(a) Ventricular contraction
Figure 15-4a
Elastic Recoil in Arteries
1
Ventricle contracts.
Arterioles
1
(a) Ventricular contraction
Figure 15-4a, step 1
Elastic Recoil in Arteries
Arterioles
1
1
Ventricle contracts.
2
Semilunar valve opens.
2
(a) Ventricular contraction
Figure 15-4a, steps 1–2
Elastic Recoil in Arteries
Arterioles
1
2
3
1
Ventricle contracts.
2
Semilunar valve opens.
3 Aorta and arteries expand and
store pressure in elastic walls.
(a) Ventricular contraction
Figure 15-4a, steps 1–3
Elastic Recoil in Arteries
1 Isovolumic ventricular
relaxation
2
1
Semilunar valve shuts, preventing
flow back into ventricle.
2
3
3
Elastic recoil of arteries sends
blood forward into rest of
circulatory system.
(b) Ventricular relaxation occurs.
Figure 15-4b
Elastic Recoil in Arteries
1 Isovolumic ventricular
relaxation
1
(b) Ventricular relaxation occurs.
Figure 15-4b, step 1
Elastic Recoil in Arteries
1 Isovolumic ventricular
relaxation
2
1
Semilunar valve shuts, preventing
flow back into ventricle.
2
(b) Ventricular relaxation occurs.
Figure 15-4a, steps 1–2
Elastic Recoil in Arteries
1 Isovolumic ventricular
relaxation
2
1
Semilunar valve shuts, preventing
flow back into ventricle.
2
3
3
Elastic recoil of arteries sends
blood forward into rest of
circulatory system.
(b) Ventricular relaxation occurs.
Figure 15-4a, steps 1–3
Review of Blood Flow
Table 15-1
Pressure Throughout the Systemic Circulation
• Blood pressure is highest in the arteries and
decreases continuously as it flows through
the circulatory system
Figure 15-5
Blood Pressure
• Pulse Pressure = systolic P – diastolic P
• Valves ensure one-way flow in veins
• MAP = diastolic P + 1/3(systolic P – diastolic P)
PLAY
Interactive Physiology® Animation: Cardiovascular
System: Measuring Blood Pressure
Measurement of Arterial Blood Pressure
(a)
Cuff pressure
> 120 mm Hg
Inflatable
cuff
Pressure
gauge
(b)
Cuff pressure
between 80 and
120 mm Hg
Stethoscope
(c)
Cuff pressure
< 80 mm Hg
Figure 15-7
Blood Pressure
• Mean arterial pressure is a function of cardiac
output and resistance in the arterioles
Mean arterial pressure
Cardiac output
Left ventricle
Variable resistance
Arterioles
Elastic arteries
Mean arterial pressure  cardiac output  resistance
Figure 15-8
Blood Pressure
• Blood pressure control includes rapid
responses from the cardiovascular system
and slower responses by the kidneys
Blood Pressure
Blood
volume
leads to
KEY
Stimulus
Integrating center
Blood
pressure
Tissue response
Systemic response
triggers
Fast response
Slow response
Compensation
by
cardiovascular
system
Vasodilation
Compensation
by kidneys
Excretion of fluid in urine
blood volume
Cardiac output
Blood
pressure
to normal
Figure 15-9
Factors that Influence Mean Arterial Pressure
Figure 15-10
Factors that Influence Mean Arterial Pressure
PLAY
Interactive Physiology® Animation: Cardiovascular
System: Factors That Affect Blood Pressure