Download Pressure

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Fig. 13.5
CO2
O2
Brain
Circulation to brain
and tissues of head
Aorta
Circulation to
upper limbs
CO2
Pulmonary arteries
O2
Pulmonary trunk
Pulmonary vein
O2
CO2
Heart
Pulmonary
circulation
Digestive tract
circulation
Liver
circulation
Kidney
Renal
circulation
Circulation to
lower limbs
CO2
O2
Fig. 13.1-2
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Tunica
adventitia
Tunica media
(elastic tissue
and smooth muscle)
Connective tissue
Endothelium and
basement membrane
Tunica
intima
(a) Elastic arteries. The tunica media is mostly
elastic connective tissue. Elastic arteries
recoil when stretched, which prevents blood
pressure from falling rapidly.
Tunica adventitia
Elastic
connective tissue
Smooth muscle
Elastic
connective tissue
Connective tissue
Endothelium and
basement membrane
(b) Muscular arteries. The tunica media is
a thick layer of smooth muscle. Muscular
arteries regulate blood flow to different
regions of the body.
Tunica
media
Tunica
intima
Fig. 13.34
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Endothelium
Vessel wall
Atherosclerotic plaque
Fig. 13.1-4
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Tunica
adventitia
Tunica media
(elastic tissue
and smooth muscle)
Connective tissue
Tunica
intima
Endothelium and
basement membrane
(a) Elastic arteries. The tunica media is mostly
elastic connective tissue. Elastic arteries
recoil when stretched, which prevents blood
pressure from falling rapidly.
Tunica adventitia
Elastic
connective tissue
Smooth muscle
Elastic
connective tissue
Connective tissue
Tunica
media
Endothelium and
basement membrane
Tunica
intima
(b) Muscular arteries. The tunica media is
a thick layer of smooth muscle. Muscular
arteries regulate blood flow to different
regions of the body.
Tunica adventitia
Tunica media
Tunica intima
(c) Arterioles. All three tunics are present;
the tunica media consists of only one or
two layers of circular smooth muscle cells.
Endothelium
(d) Capillaries. Walls consist of only a
simple endothelium surrounded by
delicate loose connective tissue.
Fig. 13.3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Arteriole
Precapillary
sphincters
Capillaries
Capillary
network
Venule
Fig. 13.1
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Tunica
adventitia
Tunica
adventitia
Tunica media
(elastic tissue
and smooth muscle)
Tunica media
Connective tissue
Connective tissue
Tunica
intima
Endothelium and
basement membrane
Endothelium and
basement membrane
(a) Elastic arteries. The tunica media is mostly
elastic connective tissue. Elastic arteries
recoil when stretched, which prevents blood
pressure from falling rapidly.
Tunica
intima
(g) Large veins. All three tunics are present.
The tunica media is thin but can regulate vessel
diameter because blood pressure in the venous
system is low. The predominant layer is the
tunica adventitia.
Tunica adventitia
Elastic
connective tissue
Smooth muscle
Elastic
connective tissue
Connective tissue
Tunica adventitia
Tunica
media
Tunica media
Connective tissue
Tunica
intima
Endothelium and
basement membrane
(b) Muscular arteries. The tunica media is
a thick layer of smooth muscle. Muscular
arteries regulate blood flow to different
regions of the body.
Tunica
intima
Endothelium and
basement membrane
(f) Small and medium veins. All three
tunics are present.
Tunica adventitia
Tunica intima
Tunica media
Tunica intima
(c) Arterioles. All three tunics are present;
the tunica media consists of only one or
two layers of circular smooth muscle cells.
(e) Venules. Only the tunica
intima resting on a delicate
layer of dense connective
tissue is present.
Endothelium
(d) Capillaries. Walls consist of only a
simple endothelium surrounded by
delicate loose connective tissue.
Fig. 13.2
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
V
A
Tunica intima
Tunica media
Tunica adventitia
© Carolina Biological Supply/Visuals Unlimited
Fig. 13.4
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Valve closed
Vein
Valve open
Direction of
blood flow
Fig. 13.21
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
When the cuff pressure is high
enough to keep the brachial
artery closed, no blood flows
through it, and no sound is
heard.
Degree to which
brachial artery is
open during:
300
Systole
250
2
3
4
When cuff pressure decreases
and is no longer able to keep
the brachial artery closed, blood
is pushed through the partially
opened brachial artery,
producing turbulent blood flow
and a sound. Systolic pressure
is the pressure at which a sound
is first heard.
As cuff pressure continues to
decrease, the brachial artery
opens even more during
systole. At first, the artery is
closed during diastole, but as
cuff pressure continues to
decrease, the brachial artery
partially opens during diastole.
Turbulent blood flow during
systole produces Korotkoff
sounds, although the pitch of
the sounds changes as the
artery becomes more open.
Eventually, cuff pressure
decreases below the
pressure in the brachial
artery, and it remains open
during systole and diastole.
Nonturbulent flow is
reestablished, and no
sounds are heard. Diastolic
pressure is the pressure at
which the sound disappears.
No sound
1
Diastole
Blocked
200
2
150
Systolic pressure
(120 mm Hg)
Korotkoff
sounds
100
Diastolic pressure
(80 mm Hg)
50
Arm
Elbow
3
Blocked or
partially
open
Sound
disappears.
No sound
0
Pressure
cuff
Sound is
first heard.
4
Open
Fig. 13.22
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140
Pulse
pressure
120
Systolic pressure
100
Mean blood
pressure
Pressure
(mm Hg)
80
60
40
20
Diastolic
pressure
Fig. 13.24
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
At the arterial end of the
capillary, the movement of
fluid out of the capillary due
to blood pressure is greater
than the movement of fluid
into the capillary due to
osmosis.
2 At the venous end of the
capillary, the movement of
fluid into the capillary due to
osmosis is greater than the
movement of fluid out of the
capillary due to blood
pressure.
3 Approximately nine-tenths of
the fluid that leaves the
capillary at its arterial end
reenters the capillary at its
venous end. About one-tenth
of the fluid passes into the
lymphatic capillaries.
One-tenth volume passes into lymphatic capillaries.
3
Nine-tenths volume returns to capillary.
Net
movement
of fluid
out of the
capillary
into the
interstitial
space
Outward movement of
fluid due to blood pressure
Inward movement of fluid
due to osmosis
Inward movement of
fluid due to osmosis
Outward movement of
fluid due to blood pressure
1
2
Blood flow
Arterial end
Venous end
Net
movement
of fluid
into the
capillary
from the
interstitial
space
Fig. 13.3
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Arteriole
Precapillary
sphincters
Capillaries
Capillary
network
Venule
Fig. 13.25
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
Blood flow
increases.
Smooth muscle of
precapillary sphincter
relaxes.
2
Blood flow
decreases.
Smooth muscle of
precapillary sphincter
contracts.
Blood
flow
Blood
flow
1 Relaxation of precapillary sphincters. Precapillary sphincters
relax as the tissue concentration of oxygen and nutrients, such
as glucose, amino acids, and fatty acids, decreases. The
sphincters also relax as the concentration of tissue metabolic
by-products increases as a result of increased CO2 and lactic
acid and decreased pH.
2 Contraction of precapillary sphincters. Precapillary sphincters
contract as the tissue concentration of oxygen and nutrients,
such as glucose, amino acids, and fatty acids, increases. The
sphincters also contract as the tissue concentration of metabolic
by-products decreases as a result of decreased CO2 and lactic
acid and increased pH.
Fig. 13.26
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Vasomotor center
in medulla oblongata
Spinal cord
Sympathetic
nerve fibers
Blood vessels
Sympathetic
chain
Fig. 13.27
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Carotid sinus
baroreceptors
1 Baroreceptors in the carotid
sinus and aortic arch monitor
blood pressure.
2 Sensory nerves conduct action
potentials to the
cardioregulatory and
vasomotor centers in the
medulla oblongata.
3
2
3 Increased parasympathetic
stimulation of the heart
decreases the heart rate.
4 Increased sympathetic
stimulation of the heart
increases the heart rate
and stroke volume.
Cardioregulatory
and vasomotor
centers in the
medulla oblongata
4
Sympathetic
nerves
5 Increased sympathetic
stimulation of blood vessels
increases vasoconstriction.
Sympathetic
chain
5 Blood vessels
1
Aortic arch
baroreceptors
Fig. 13.28
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
3
4
Baroreceptors in the carotid arteries
and aorta detect an increase in blood
pressure.
The effectors (the heart and
blood vessels) respond: Heart
rate and stroke volume
decrease; blood vessels dilate.
The cardioregulatory center and the
vasomotor center in the brain alter activity of
the heart and blood vessels (baroreceptor
reflex), and the adrenal medulla decreases
secretion of epinephrine.
1
Blood pressure
(normal range)
5
Blood pressure increases:
Homeostasis Disturbed
Blood pressure decreases:
Homeostasis Restored
6
Start here
Blood pressure decreases:
Homeostasis Disturbed
Blood pressure
(normal range)
2
Blood pressure increases:
Homeostasis Restored
Baroreceptors in the carotid arteries and
aorta detect a decrease in blood pressure.
The cardioregulatory center and the
vasomotor center in the brain alter activity of
the heart and blood vessels (baroreceptor
reflex), and the adrenal medulla increases
secretion of epinephrine (adrenal medullary
mechanism).
The effectors (the heart and blood
vessels) respond: Heart rate and
stroke volume increase; blood
vessels constrict.
Fig. 13.29
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1 Chemoreceptors in the
carotid and aortic bodies
monitor blood O2, CO2, and
pH.
1
Aortic body
chemoreceptors
2 Chemoreceptors in the
medulla oblongata monitor
blood CO2 and pH.
3 Decreased blood O2,
increased CO2, and
decreased pH decrease
parasympathetic stimulation
of the heart, which
increases the heart rate.
4 Decreased blood O2,
increased CO2, and
decreased pH increase
sympathetic stimulation of
the heart, which increases
the heart rate and stroke
volume.
5 Decreased blood O2,
increased CO2, and
decreased pH increase
sympathetic stimulation of
blood vessels, which
increases vasoconstriction.
Carotid body
chemoreceptors
3
2
Chemoreceptors
in the medulla
oblongata
4
Cardioregulatory
and vasomotor
centers in the
medulla oblongata
Sympathetic
nerves
Sympathetic
chain
5
Fig. 13.30
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
Increased
stimulation
1 The same stimuli that increase sympathetic stimulation of the
heart and blood vessels cause action potentials to be carried to
the medulla oblongata.
2 Descending pathways from the medulla oblongata to the spinal
cord increase sympathetic stimulation of the adrenal medulla,
resulting in secretion of epinephrine and some norepinephrine.
Medulla
oblongata
Spinal
cord
2
Epinephrine
and
norepinephrine
Sympathetic
nerve fiber
Sympathetic
chain
Adrenal medulla
Fig. 13.31
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Liver
Decreased
blood pressure
1
1 The kidneys detect decreased
blood pressure, resulting in
increased renin secretion.
Angiotensinogen
2
Renin
2 Renin converts
angiotensinogen, a protein
secreted from the liver, to
angiotensin I.
Kidney
Angiotensin I
6
3
3 Angiotensin-converting
enzyme in the lungs converts
angiotensin I to angiotensin II.
Angiotensin-converting
enzyme in
lung capillaries
Aldosterone
4 Angiotensin II is a potent
vasoconstrictor, resulting in
increased blood pressure.
5
Adrenal
cortex
Angiotensin II
4
5 Angiotensin II stimulates the
adrenal cortex to secrete
aldosterone.
Vasoconstriction
6 Aldosterone acts on the
kidneys to increase Na+
reabsorption. As a result, urine
volume decreases and blood
volume increases, resulting in
increased blood pressure.
Increases water reabsorption
and decreases urine volume
Increased
blood pressure
Fig. 13.32
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Hypothalamic
nerve cells detect
increased
osmotic pressure.
Baroreceptors
(aortic arch,
carotid sinus)
detect decreased
blood pressure.
Hypothalamic
nerve cell
Posterior pituitary
ADH
Increased
reabsorption
of water
Blood vessel
Kidney
Vasoconstriction
Increased blood volume
Increased blood pressure
Fig. 18.16
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Increased blood
pressure in right atrium
ANH
Kidney
ANH secretion
Increased Na+
excretion and
increased water
loss result in
decreased BP.
Fig. 13.33
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4
3
Atrial natriuretic mechanism:
Cardiac muscle cells detect increased atrial
blood pressure; secretion of atrial natriuretic
hormone increases.
The effectors (blood vessels)
respond: Vasodilation decreases
peripheral resistance to blood flow.
More Na+ and water are lost in the
urine, decreasing blood volume.
Renin-angiotensin-aldosterone mechanism:
The kidneys detect increased blood pressure;
production of angiotensin II and secretion of
aldosterone from the adrenal cortex decrease.
2
Blood pressure increases:
Homeostasis Disturbed
5
6
Start here
Blood pressure decreases:
Homeostasis Disturbed
Blood presure
(normal range)
Blood presure
(normal range)
1
Blood pressure decreases:
Homeostasis Restored
Blood pressure increases:
Homeostasis Restored
Renin-angiotensin-aldosterone mechanism:
The kidneys detect decreased blood pressure;
production of angiotensin II and secretion of
aldosterone from the adrenal cortex increase.
ADH (vasopressin) mechanism:
Baroreceptors detect decreased blood pressure,
resulting in decreased stimulation of the
hypothalamus and increased ADH secretion by
the posterior pituitary.
The effectors (blood vessels)
respond: Vasoconstriction increases
peripheral resistance to blood flow.
Less Na+ and water are lost in the
urine, increasing blood volume.
Fig. 13.34
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Endothelium
Vessel wall
Atherosclerotic plaque