169 Ch 21_lecture_presentation

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PowerPoint®
Lecture Presentations prepared by
Jason LaPres
Lone Star College—North Harris
21
Blood Vessels and
Circulation

An Introduction to Blood Vessels and
Circulation
• Learning Outcomes
• 21-1 Distinguish among the types of blood vessels
based on their structure and function, and
describe how and where fluid and dissolved
materials enter and leave the cardiovascular
system.
• 21-2 Explain the mechanisms that regulate blood
flow through vessels, describe the factors that
influence blood pressure, and discuss the
mechanisms that regulate movement of fluids
between capillaries and interstitial spaces.

Circulation
• 21-3 Describe the control mechanisms that regulate
blood flow and pressure in tissues, and explain
how the activities of the cardiac, vasomotor, and
respiratory centers are coordinated to control
blood flow through the tissues.
• 21-4 Explain the cardiovascular system’s
homeostatic response to exercise and
hemorrhaging, and identify the principal blood
vessels and functional characteristics of the
special circulation to the brain, heart, and lungs.

Circulation
• 21-5 Describe the three general functional patterns
seen in the pulmonary and systemic circuits of
the cardiovascular system.
• 21-6 Identify the major arteries and veins of the
pulmonary circuit.
• 21-7 Identify the major arteries and veins of the
systemic circuit.

Circulation
• 21-8 Identify the differences between fetal and adult
circulation patterns, and describe the changes
in the patterns of blood flow that occur at birth.
• 21-9 Discuss the effects of aging on the
cardiovascular system, and give examples of
interactions between the cardiovascular system
and other organ systems.

Circulation
• Blood Vessels
• Are classified by size and histological organization
• Are instrumental in overall cardiovascular regulation

21-1 Classes of Blood Vessels
• Arteries
• Carry blood away from heart
• Arterioles
• Are smallest branches of arteries
• Capillaries
• Are smallest blood vessels
• Location of exchange between blood and interstitial fluid
• Venules
• Collect blood from capillaries
• Veins
• Return blood to heart

21-1 Blood Vessels
• The Largest Blood Vessels
• Attach to heart
• Pulmonary trunk
• Carries blood from right ventricle
• To pulmonary circulation
• Aorta
• Carries blood from left ventricle
• To systemic circulation

21-1 Blood Vessels
• The Smallest Blood Vessels
• Capillaries
• Have small diameter and thin walls
• Chemicals and gases diffuse across walls

21-1 Blood Vessels
• The Structure of Vessel Walls
• Walls have three layers
1. Tunica intima
2. Tunica media
3. Tunica externa

21-1 Blood Vessels
• The Tunica Intima (Inner Layer)
• Includes:
• The endothelial lining
• Connective tissue layer
• Internal elastic membrane
• In arteries, is a layer of elastic fibers in outer margin of
tunica intima

21-1 Blood Vessels
• The Tunica Media (Middle Layer)
• Contains concentric sheets of smooth muscle in loose
connective tissue
• Binds to inner and outer layers
• External elastic membrane of the tunica media
• Separates tunica media from tunica externa

21-1 Blood Vessels
• The Tunica Externa (Outer Layer)
• Anchors vessel to adjacent tissues in arteries
• Contains collagen fibers
• Elastic fibers
• In veins
• Contains elastic fibers
• Smooth muscle cells
• Vasa vasorum (“vessels of vessels”)
• Small arteries and veins
• In walls of large arteries and veins
• Supply cells of tunica media and tunica externa

Figure 21-1 Comparisons of a Typical Artery and a Typical Vein
Tunica externa
Tunica media
Tunica intima
Smooth muscle
Internal elastic
membrane
External
elastic
membrane
Endothelium
ARTERY
Elastic fiber
Lumen
of vein
Lumen
of
artery
Artery and vein LM × 60

Figure 21-1 Comparisons of a Typical Artery and a Typical Vein
Lumen
of vein
Lumen
of
artery
Artery and vein LM × 60
Tunica media
Tunica intima
Smooth
muscle
Endothelium
Tunica externa
VEIN

Table 21-1 Key Terms and Relationships Pertaining to Blood Circulation

21-1 Blood Vessels
• Differences between Arteries and Veins
• Arteries and veins run side by side
• Arteries have thicker walls and higher blood pressure
• Collapsed artery has small, round lumen (internal space)
• Vein has a large, flat lumen
• Vein lining contracts, artery lining does not
• Artery lining folds
• Arteries more elastic
• Veins have valves

21-1 Structure and Function of Arteries
• Arteries
• Elasticity allows arteries to absorb pressure waves that come
with each heartbeat
• Contractility
• Arteries change diameter
• Controlled by sympathetic division of ANS
• Vasoconstriction
• The contraction of arterial smooth muscle by the ANS
• Vasodilation
• The relaxation of arterial smooth muscle
• Enlarging the lumen

• Vasoconstriction and Vasodilation
• Affect:
1. Afterload on heart
2. Peripheral blood pressure
3. Capillary blood flow

• Arteries
• From heart to capillaries, arteries change
• From elastic arteries
• To muscular arteries
• To arterioles

• Elastic Arteries
• Also called conducting arteries
• Large vessels (e.g., pulmonary trunk and aorta)
• Tunica media has many elastic fibers and few muscle
cells
• Elasticity evens out pulse force

• Muscular Arteries
• Also called distribution arteries
• Are medium sized (most arteries)
• Tunica media has many muscle cells

• Arterioles
• Are small
• Have little or no tunica externa
• Have thin or incomplete tunica media

• Artery Diameter
• Small muscular arteries and arterioles
• Change with sympathetic or endocrine stimulation
• Constricted arteries oppose blood flow
• Resistance (R)
• Resistance vessels - arterioles

• Aneurysm
• A bulge in an arterial wall
• Is caused by weak spot in elastic fibers
• Pressure may rupture vessel

Figure 21-2 Histological Structure of Blood Vessels
Large Vein
Medium-Sized Vein
Venule Arteriole
Muscular Artery
Elastic Artery
Fenestrated Capillary Capillaries Continuous Capillary
Pores
Endothelial cells
Basement membrane Basement membrane
Endothelial
cells
Tunica externa
Endothelium
Tunica externa
Tunica media
Endothelium
Tunica intima
Tunica externa
Tunica media
Endothelium
Tunica intima
Internal elastic
layer
Endothelium
Tunica
intima
Tunica media
Tunica externa
Tunica externa
Tunica media
Endothelium
Tunica intima
Smooth muscle cells
(Media)
Endothelium
Basement membrane

Large Vein
Medium-Sized Vein
Venule
Tunica externa
Endothelium
Tunica externa
Tunica media
Endothelium
Tunica intima
Tunica externa
Tunica media
Endothelium
Tunica intima

Arteriole
Muscular Artery
Elastic Artery
Internal elastic
layer
Endothelium
Tunica
intima
Tunica media
Tunica externa
Tunica externa
Tunica media
Endothelium
Tunica intima
Smooth muscle cells
(Media)
Endothelium
Basement membrane

Fenestrated Capillary Capillaries Continuous Capillary
Pores
Endothelial cells
Basement membrane Basement membrane
Endothelial
cells

Figure 21-3a A Plaque within an Artery
Tunica externa
Lipid deposits
(plaque)
Tunica media
Coronary artery
A cross-sectional view
of a large plaque
LM × 6

Figure 21-3b A Plaque within an Artery
Plaque deposit
in vessel wall
A section of a coronary
artery narrowed by plaque
formation

21-1 Structure and Function of Capillaries
• Capillaries
• Are smallest vessels with thin walls
• Microscopic capillary networks permeate all active
tissues
• Capillary function
• Location of all exchange functions of cardiovascular
system
• Materials diffuse between blood and interstitial fluid

• Capillary Structure
• Endothelial tube, inside thin basement membrane
• No tunica media
• No tunica externa
• Diameter is similar to red blood cell

• Continuous Capillaries
• Have complete endothelial lining
• Are found in all tissues except epithelia and cartilage
• Functions of continuous capillaries
• Permit diffusion of water, small solutes, and lipid-
soluble materials
• Block blood cells and plasma proteins

• Specialized Continuous Capillaries
• Are in CNS and thymus
• Have very restricted permeability
• For example, the blood–brain barrier

• Fenestrated Capillaries
• Have pores in endothelial lining
• Permit rapid exchange of water and larger solutes
between plasma and interstitial fluid
• Are found in:
• Choroid plexus
• Endocrine organs
• Kidneys
• Intestinal tract

• Sinusoids (Sinusoidal Capillaries)
• Have gaps between adjacent endothelial cells
• Liver
• Spleen
• Bone marrow
• Endocrine organs
• Permit free exchange
• Of water and large plasma proteins
• Between blood and interstitial fluid
• Phagocytic cells monitor blood at sinusoids

Figure 21-4 Capillary Structure
Basement
membrane
Nucleus
Endothelial cell
Endosomes
Boundary
between
endothelial
cells
Fenestrations,
or pores
Boundary
between
endothelial
cells
Basement
membrane
Endosomes
Basement
membrane
Gap between
adjacent cells
SinusoidFenestrated capillaryContinuous capillary

Figure 21-4a Capillary Structure
Basement
membrane
Nucleus
Endothelial cell
Boundary
between
endothelial
cells
Endosomes
Basement
membrane
Continuous capillary

Figure 21-4b Capillary Structure
Basement
membrane
Nucleus
Endothelial cell
Endosomes
Boundary
between
endothelial
cells
Fenestrations,
or pores
Basement
membrane
Fenestrated capillary

Figure 21-4c Capillary Structure
Gap between
adjacent cells
Sinusoid

• Capillary Beds (Capillary Plexus)
• Connect one arteriole and one venule
• Precapillary Sphincter
• Guards entrance to each capillary
• Opens and closes, causing capillary blood to flow in
pulses

Figure 21-5a The Organization of a Capillary Bed
Smooth
muscle cells
Collateral
arteries
Arteriole
Metarterioles
Thoroughfare
channel
Vein
Venule
Capillaries
Section of
precapillary
sphincter
Precapillary
sphincters
Arteriovenous
anastomosis
A typical capillary bed. Solid arrows indicate
consistant blood flow; dashed arrows indicate
variable or pulsating blood flow.
Small
venule
KEY
Consistent
blood flow
Variable
blood flow

Figure 21-5b The Organization of a Capillary Bed
Capillary bed LM × 125
A micrograph of a number of capillary beds.
Capillary
beds
Metarterioles
Arteriole
Small
artery

• Thoroughfare Channels
• Direct capillary connections between arterioles and
venules
• Controlled by smooth muscle segments
(metarterioles)

• Collaterals
• Multiple arteries that contribute to one capillary bed
• Allow circulation if one artery is blocked
• Arterial anastomosis
• Fusion of two collateral arteries
• Arteriovenous anastomoses
• Direct connections between arterioles and venules
• Bypass the capillary bed

• Angiogenesis
• Formation of new blood vessels
• Vascular endothelial growth factor (VEGF)
• Occurs in the embryo as tissues and organs develop
• Occurs in response to factors released by cells that are
hypoxic, or oxygen-starved
• Most important in cardiac muscle, where it takes place in
response to a chronically constricted or occluded vessel

• Vasomotion
• Contraction and relaxation cycle of capillary
sphincters
• Causes blood flow in capillary beds to constantly
change routes

21-1 Structure and Function of Veins
• Veins
• Collect blood from capillaries in tissues and organs
• Return blood to heart
• Are larger in diameter than arteries
• Have thinner walls than arteries
• Have lower blood pressure

• Venules
• Very small veins
• Collect blood from capillaries
• Medium-sized veins
• Thin tunica media and few smooth muscle cells
• Tunica externa with longitudinal bundles of elastic
fibers

• Large Veins
• Have all three tunica layers
• Thick tunica externa
• Thin tunica media
• Venous Valves
• Folds of tunica intima
• Prevent blood from flowing backward
• Compression pushes blood toward heart

Figure 21-6 The Function of Valves in the Venous System
Valve
closed
Valve
closed
Valve opens above
contracting muscle
Valve closes below
contracting muscle

21-1 Blood Vessels
• The Distribution of Blood
• Heart, arteries, and capillaries
• 30–35% of blood volume
• Venous system
• 60–65%
• 1/3 of venous blood is in the large venous networks
of the liver, bone marrow, and skin

Figure 21-7 The Distribution of Blood in the Cardiovascular System
Pulm
onary
arteries
3%
Large venous
networks (liver,
bone marrow, skin)
21%
Venules and
medium-sized veins
25%
Pulm
onary
circuit9%
Heart7%
System
ic
Pulm
onary
capillaries
2%
Pulmonary veins 4%
Heart 7%
Aorta 2%Elastic arteries 4%
Systemiccapillaries7%
Muscular arteries 5%
Arterioles
2%
Large veins
18%
Systemic
capillaries 7%
arterialsystem13%
Systemicvenoussystem64%

21-1 Blood Vessels
• Capacitance of a Blood Vessel
• The ability to stretch
• Relationship between blood volume and blood
pressure
• Veins (capacitance vessels) stretch more than
arteries

21-1 Blood Vessels
• Venous Response to Blood Loss
• Vasomotor centers stimulate sympathetic nerves
1. Systemic veins constrict (venoconstriction)
2. Veins in liver, skin, and lungs redistribute venous
reserve

21-2 Pressure and Resistance
• Total Capillary Blood Flow
• Equals cardiac output
• Is determined by:
• Pressure (P) and resistance (R) in the
cardiovascular system

Figure 21-8 An Overview of Cardiovascular Physiology
Cardiac Output
Venous Return
Regulation
(Neural and Hormonal)
Venous
Pressure
Arterial Blood
Pressure
Peripheral
Resistance
Capillary Pressure
Capillary
exchange
Interstitial fluid

• Pressure (P)
• The heart generates P to overcome resistance
• Absolute pressure is less important than pressure
gradient
• The Pressure Gradient (∆P)
• Circulatory pressure
• The difference between:
• Pressure at the heart
• And pressure at peripheral capillary beds

• Flow (F)
• Is proportional to the pressure difference (∆P)
• Divided by R

• Measuring Pressure
1. Blood pressure (BP)
• Arterial pressure (mm Hg)
2. Capillary hydrostatic pressure (CHP)
• Pressure within the capillary beds
3. Venous pressure
• Pressure in the venous system

• Circulatory Pressure
• ∆P across the systemic circuit (about 100 mm Hg)
• Circulatory pressure must overcome total peripheral
resistance
• R of entire cardiovascular system

• Total Peripheral Resistance
• Vascular resistance
• Blood viscosity
• Turbulence

• Vascular Resistance
• Due to friction between blood and vessel walls
• Depends on vessel length and vessel diameter
• Adult vessel length is constant
• Vessel diameter varies by vasodilation and
vasoconstriction
• R increases exponentially as vessel diameter
decreases

• Viscosity
• R caused by molecules and suspended materials
in a liquid
• Whole blood viscosity is about four times that of
water

• Turbulence
• Swirling action that disturbs smooth flow of liquid
• Occurs in heart chambers and great vessels
• Atherosclerotic plaques cause abnormal turbulence

Figure 21-9 Factors Affecting Friction and Vascular Resistance
Friction and Vessel Length
Friction and Vessel Diameter
Vessel Length versus Vessel Diameter
Factors Affecting Vascular Resistance
Internal surface
area = 1
Internal surface area = 2
Resistance to flow = 1
Flow = 1
Resistance
to flow = 2
Flow = 2
1/
Greatest resistance,
slowest flow near surfaces
Least
resistance,
greatest flow
at center
Diameter = 2 cm
Diameter = 1 cm
Resistance to
flow = 1
Resistance to
flow = 16
Plaque deposit Turbulence
Turbulence

• An Overview of Cardiovascular Pressures
• Vessel diameters
• Total cross-sectional areas
• Pressures
• Velocity of blood flow

Figure 21-10a Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and
Blood Velocity within the Systemic Circuit
Vessel
diameter
(cm)
Vessel diameter

Figure 21-10b Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and
Total cross-sectional area of vessels
Cross-
sectional
area
(cm2
)

Figure 21-10c Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and
Average blood pressure
Average
blood
pressure
(mm Hg)

Figure 21-10d Relationships among Vessel Diameter, Cross-Sectional Area, Blood Pressure, and
Velocity of blood flow
Velocity
of blood
flow
(cm/sec)

• Arterial Blood Pressure
• Systolic pressure
• Peak arterial pressure during ventricular systole
• Diastolic pressure
• Minimum arterial pressure during diastole

• Arterial Blood Pressure
• Pulse pressure
• Difference between systolic pressure and diastolic
pressure
• Mean arterial pressure (MAP)
• MAP = diastolic pressure + 1/3 pulse pressure

• Abnormal Blood Pressure
• Normal = 120/80
• Hypertension
• Abnormally high blood pressure
• Greater than 140/90
• Hypotension
• Abnormally low blood pressure

• Elastic Rebound
• Arterial walls
• Stretch during systole
• Rebound (recoil to original shape) during diastole
• Keep blood moving during diastole

• Pressures in Small Arteries and Arterioles
• Pressure and distance
• MAP and pulse pressure decrease with distance from
heart
• Blood pressure decreases with friction
• Pulse pressure decreases due to elastic rebound

Figure 21-11 Pressures within the Systemic Circuit
Systolic
Pulse
pressure
Diastolic
mm Hg
Mean arterial
pressure

• Venous Pressure and Venous Return
• Determines the amount of blood arriving at right atrium
each minute
• Low effective pressure in venous system

• Venous Pressure and Venous Return
• Low venous resistance is assisted by:
• Muscular compression of peripheral veins
• Compression of skeletal muscles pushes blood
toward heart (one-way valves)
• The respiratory pump
• Thoracic cavity action
• Inhaling decreases thoracic pressure
• Exhaling raises thoracic pressure

• Capillary Pressures and Capillary Exchange
• Vital to homeostasis
• Moves materials across capillary walls by:
• Diffusion
• Filtration
• Reabsorption

• Diffusion
• Movement of ions or molecules
• From high concentration
• To lower concentration
• Along the concentration gradient

• Diffusion Routes
1. Water, ions, and small molecules such as glucose
• Diffuse between adjacent endothelial cells
• Or through fenestrated capillaries
2. Some ions (Na+
, K+
, Ca2+
, Cl−
)
• Diffuse through channels in plasma membranes

• Diffusion Routes
3. Large, water-soluble compounds
• Pass through fenestrated capillaries
3. Lipids and lipid-soluble materials such as O2 and CO2
• Diffuse through endothelial plasma membranes
3. Plasma proteins
• Cross endothelial lining in sinusoids

• Filtration
• Driven by hydrostatic pressure
• Water and small solutes forced through capillary wall
• Leaves larger solutes in bloodstream

• Reabsorption
• The result of osmotic pressure (OP)
• Blood colloid osmotic pressure (BCOP)
• Equals pressure required to prevent osmosis
• Caused by suspended blood proteins that are too large
to cross capillary walls

Figure 21-12 Capillary Filtration
Capillary
hydrostatic
pressure
(CHP) Amino acid
Blood protein
Glucose
Ions
Interstitial
fluid
Hydrogen
bond
Water
molecule
Small solutes
Endothelial
cell 2
Endothelial
cell 1

• Interplay between Filtration and Reabsorption
1. Ensures that plasma and interstitial fluid are in
constant communication and mutual exchange
2. Accelerates distribution of:
• Nutrients, hormones, and dissolved gases
throughout tissues

3. Assists in the transport of:
• Insoluble lipids and tissue proteins that cannot
enter bloodstream by crossing capillary walls
4. Has a flushing action that carries bacterial toxins and
other chemical stimuli to:
• Lymphatic tissues and organs responsible for
providing immunity to disease

• Net hydrostatic pressure
• Forces water out of solution
• Net osmotic pressure
• Forces water into solution
• Both control filtration and reabsorption through
capillaries

• Factors that Contribute to Net Hydrostatic
Pressure
1. Capillary hydrostatic pressure (CHP)
2. Interstitial fluid hydrostatic pressure (IHP)
• Net capillary hydrostatic pressure tends to push water
and solutes:
• Out of capillaries
• Into interstitial fluid

• Net Capillary Colloid Osmotic Pressure
• Is the difference between:
1. Blood colloid osmotic pressure (BCOP)
2. Interstitial fluid colloid osmotic pressure (ICOP)
• Pulls water and solutes:
• Into a capillary
• From interstitial fluid

• Net Filtration Pressure (NFP)
• The difference between:
• Net hydrostatic pressure
• Net osmotic pressure
NFP = (CHP – IHP) – (BCOP – ICOP)

• 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

• Capillary Exchange
• 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

Figure 21-13 Forces Acting across Capillary Walls
KEY
Arteriole
Filtration
CHP (Capillary
hydrostatic pressure)
Venule
BCOP (Blood colloid
osmotic pressure)
NFP (Net filtration
pressure)
24 L/day 20.4 L/day
No net fluid
movement
Reabsorption
35
mm
Hg
25
mm
Hg
25
mm
Hg
25
mm
Hg
25
mm
Hg
18
mm
Hg
NFP = +10 mm Hg NFP = 0 NFP = −7 mm Hg
CHP > BCOP
Fluid forced
out of capillary
CHP = BCOP
No net
movement
of fluid
BCOP > CHP
Fluid moves
into capillary

• Capillary Dynamics
• Hemorrhaging
• Reduces CHP and NFP
• Increases reabsorption of interstitial fluid (recall of fluids)
• Dehydration
• Increases BCOP
• Accelerates reabsorption
• Increase in CHP or BCOP
• Fluid moves out of blood
• Builds up in peripheral tissues (edema)

21-3 Cardiovascular Regulation
• Tissue Perfusion
• Blood flow through the tissues
• Carries O2 and nutrients to tissues and organs
• Carries CO2 and wastes away
• Is affected by:
1. Cardiac output
2. Peripheral resistance
3. Blood pressure

• Cardiovascular Regulation Changes Blood
Flow to a Specific Area
1. At an appropriate time
2. In the right area
3. Without changing blood pressure and blood flow
to vital organs

• Controlling Cardiac Output and Blood Pressure
• Autoregulation
• Causes immediate, localized homeostatic adjustments
• Neural mechanisms
• Respond quickly to changes at specific sites
• Endocrine mechanisms
• Direct long-term changes

Figure 21-14 Short-Term and Long-Term Cardiovascular Responses
Autoregulation
Local vasodilators
released
HOMEOSTASIS
RESTORED
HOMEOSTASIS DISTURBED
HOMEOSTASIS
Local decrease
in resistance
and increase in
blood flow
Inadequate
local blood
pressure and
blood flow
Normal
blood pressure
and volume
• Physical stress (trauma,
high temperature)
• Chemical changes
(decreased O2 or pH,
increased CO2 or
prostaglandins)
• Increased tissue activity
Autoregulation is due
to opening and closing
precapillary sphincters
due to local release of
vasodilator or
vasoconstrictor
chemicals from
the tissue.
Start

Figure 21-14 Short-Term and Long-Term Cardiovascular Responses
Central Regulation
Stimulation of
receptors sensitive
to changes in
systemic blood
pressure or
chemistry
Endocrine mechanisms
HOMEOSTASIS
RESTORED
Neural
mechanisms
Activation of
cardiovascular
centers
Stimulation
of endocrine
response
Long-term increase
in blood volume
and blood pressure
Short-term
elevation of blood
pressure by
sympathetic
stimulation of the
heart and
peripheral
vasoconstriction
Central regulation involves
neuroendocrine mechanisms
that control the total systemic
circulation. This regulation
involves both the
cardiovascular centers
and the vasomotor centers.
If autoregulation is ineffective

• Autoregulation of Blood Flow within Tissues
• Adjusted by peripheral resistance while cardiac output
stays the same
• Local vasodilators accelerate blood flow at tissue
level
• Low O2 or high CO2 levels
• Low pH (acids)
• Nitric oxide (NO)
• High K+
or H+
concentrations
• Chemicals released by inflammation (histamine)
• Elevated local temperature

• Autoregulation of Blood Flow within Tissues
• Adjusted by peripheral resistance while cardiac output
stays the same
• Local vasoconstrictors
• Examples: prostaglandins and thromboxanes
• Released by damaged tissues
• Constrict precapillary sphincters
• Affect a single capillary bed

• Neural Mechanisms
• Cardiovascular (CV) centers of the medulla oblongata
• Cardiac centers
• Cardioacceleratory center increases cardiac
output
• Cardioinhibitory center reduces cardiac output

• Vasomotor Center
1. Control of vasoconstriction
• Controlled by adrenergic nerves (NE)
• Stimulates smooth muscle contraction in arteriole walls
2. Control of vasodilation
• Controlled by cholinergic nerves (NO)
• Relaxes smooth muscle
• Vasomotor Tone
• Produced by constant action of sympathetic
vasoconstrictor nerves

• Reflex Control of Cardiovascular Function
• Cardiovascular centers monitor arterial blood
• Baroreceptor reflexes
• Respond to changes in blood pressure
• Chemoreceptor reflexes
• Respond to changes in chemical composition,
particularly pH and dissolved gases

• Baroreceptor Reflexes
• Stretch receptors in walls of:
1. Carotid sinuses (maintain blood flow to brain)
2. Aortic sinuses (monitor start of systemic circuit)
3. Right atrium (monitors end of systemic circuit)

• Baroreceptor Reflexes
• When blood pressure rises, CV centers:
1. Decrease cardiac output
2. Cause peripheral vasodilation
• When blood pressure falls, CV centers:
1. Increase cardiac output
2. Cause peripheral vasoconstriction

Figure 21-15 Baroreceptor Reflexes of the Carotid and Aortic Sinuses
Responses to Increased
Baroreceptor Stimulation
Baroreceptors
stimulated
HOMEOSTASIS
DISTURBED
Rising blood
pressure
Cardioinhibitory
centers stimulated
Cardioacceleratory
centers inhibited
Vasomotor centers
inhibited
Decreased
cardiac
output
Vasodilation
occurs
HOMEOSTASIS
RESTORED
Blood pressure
declines
HOMEOSTASIS
Normal range
of blood
pressure
Start

Figure 21-15 Baroreceptor Reflexes of the Carotid and Aortic Sinuses
HOMEOSTASIS
Normal range
of blood
pressure
HOMEOSTASIS
DISTURBED
HOMEOSTASIS
RESTORED
Falling blood
pressure
Blood pressure
rises
Baroreceptors
inhibited
Vasoconstriction
occurs
Increased
cardiac
output
Vasomotor centers
stimulated
Cardioacceleratory
centers stimulated
Cardioinhibitory
centers inhibited
Responses to Decreased
Baroreceptor Stimulation
Start

• Chemoreceptor Reflexes
• Peripheral chemoreceptors in carotid bodies and
aortic bodies monitor blood
• Central chemoreceptors below medulla oblongata:
• Monitor cerebrospinal fluid
• Control respiratory function
• Control blood flow to brain

• Chemoreceptor Reflexes
• Changes in pH, O2, and CO2 concentrations
• Produced by coordinating cardiovascular and
respiratory activities

Figure 21-16 The Chemoreceptor Reflexes
Increasing CO2 levels,
decreasing pH
and O2 levels
Respiratory centers in
the medulla oblongata
stimulated
Respiratory rate
increases
Increased cardiac
output and blood
pressure
Cardioacceleratory
centers stimulated
Cardioinhibitory
centers inhibited
Respiratory Response
Cardiovascular
Responses
Effects on
Cardiovascular Centers
Vasomotor centers
stimulated
Vasoconstriction
occurs
Normal pH, O2,
and CO2 levels in
blood and CSF
HOMEOSTASIS
Elevated CO2 levels,
decreased pH and O2
levels in blood and CSF
HOMEOSTASIS
DISTURBED
Start
Decreased CO2 levels,
increased pH and O2
levels in blood and CSF
HOMEOSTASIS
RESTORED
Reflex Response
Chemoreceptors
stimulated

• CNS Activities and the Cardiovascular
Centers
• Thought processes and emotional states can
elevate blood pressure by:
• Cardiac stimulation and vasoconstriction

• Hormones and Cardiovascular Regulation
• Hormones have short-term and long-term effects
on cardiovascular regulation
• For example, E and NE from adrenal medullae
stimulate cardiac output and peripheral
vasoconstriction

• Antidiuretic Hormone (ADH)
• Released by neurohypophysis (posterior lobe of pituitary)
• Elevates blood pressure
• Reduces water loss at kidneys
• ADH responds to:
• Low blood volume
• High plasma osmotic concentration
• Circulating angiotensin II

• Angiotensin II
• Responds to fall in renal blood pressure
• Stimulates:
1. Aldosterone production
2. ADH production
3. Thirst
4. Cardiac output and peripheral vasoconstriction

• Erythropoietin (EPO)
• Released at kidneys
• Responds to low blood pressure, low O2 content in
blood
• Stimulates red blood cell production

Figure 21-17a The Hormonal Regulation of Blood Pressure and Blood Volume
HOMEOSTASIS
Factors that
compensate for
decreased blood
pressure and
volume
Increased red blood
cell formation
Thirst stimulated
Antidiuretic hormone
released
Angiotensin II Effects
Combined Short-Term
and Long-Term Effects
Endocrine Response
of Kidneys
Renin release leads
to angiotensin II
activation
Erythropoietin (EPO)
is released
Increased cardiac
output and
peripheral
vasoconstriction
Sympathetic activation
and release of adrenal
hormones E and NE
Long-term
Short-term
Increased
blood
pressure
Increased
blood
volume
Decreasing blood
pressure and
volume
Start
Blood pressure
and volume fall
HOMEOSTASIS
DISTURBED HOMEOSTASIS
RESTORED
Normal blood
pressure and
volume
Blood pressure
and volume rise
Aldosterone secreted
Angiotensin II

• Natriuretic Peptides
• Atrial natriuretic peptide (ANP)
• Produced by cells in right atrium
• Brain natriuretic peptide (BNP)
• Produced by ventricular muscle cells
• Respond to excessive diastolic stretching
• Lower blood volume and blood pressure
• Reduce stress on heart

Figure 21-17b The Hormonal Regulation of Blood Pressure and Blood Volume
HOMEOSTASIS
Factors that compensate for
increased blood pressure and
volume
Increasing blood
pressure and
volume
HOMEOSTASIS
RESTORED
Declining blood
pressure and
volume
Normal
blood pressure
and volume
HOMEOSTASIS
DISTURBED
Rising blood
pressure and
volume
Natriuretic
peptides released
by the heart
Increased water loss in
urine
Reduced thirst
Inhibition of ADH,
aldosterone, epinephrine,
and norepinephrine
release
Peripheral vasodilation
Reduced blood
volume
Combined
Effects
Increased Na+
loss in
urine
Responses to ANP
and BNP

21-4 Cardiovascular Adaptation
• Blood, Heart, and Cardiovascular System
• Work together as unit
• Respond to physical and physiological changes (for
example, exercise and blood loss)
• Maintain homeostasis

• The Cardiovascular Response to Exercise
• Light Exercise
• Extensive vasodilation occurs increasing
circulation
• Venous return increases with muscle contractions
• Cardiac output rises
1. Venous return (Frank–Starling principle)
2. Atrial stretching

• The Cardiovascular Response to Exercise
• Heavy Exercise
• Activates sympathetic nervous system
• Cardiac output increases to maximum
• About four times resting level
• Restricts blood flow to “nonessential” organs (e.g.,
digestive system)
• Redirects blood flow to skeletal muscles, lungs, and
heart
• Blood supply to brain is unaffected

Table 21-2 Changes in Blood Distribution during Exercise

• Exercise, Cardiovascular Fitness, and Health
• Regular moderate exercise
• Lowers total blood cholesterol levels
• Intense exercise
• Can cause severe physiological stress

Table 21-3 Effects of Training on Cardiovascular Performance
Subject Heart
Weight
(g)
Stroke
Volume
(mL)
Heart
Rate
(BPM)
Cardiac
Output
(L/min)
Blood Pressure
(systolic/
diastolic)
Nonathlete (rest) 300 60 83 5.0 120/80
Nonathlete
(maximum)
104 192 19.9 187/75
Trained athlete
(rest)
500 100 53 5.3 120/80
Trained athlete
(maximum)
167 182 30.4 200/90*
*Diastolic pressures of athletes during maximum activity have not been
accurately measured.

• The Cardiovascular Response to Hemorrhaging
• Entire cardiovascular system adjusts to:
• Maintain blood pressure
• Restore blood volume

• Short-Term Elevation of Blood Pressure
• Carotid and aortic reflexes
• Increase cardiac output (increasing heart rate)
• Cause peripheral vasoconstriction
• Sympathetic nervous system
• Triggers hypothalamus
• Further constricts arterioles
• Venoconstriction improves venous return

• Short-Term Elevation of Blood Pressure
• Hormonal effects
• Increase cardiac output
• Increase peripheral vasoconstriction (E, NE, ADH,
angiotensin II)

• Shock
• Short-term responses compensate after blood losses
of up to 20% of total blood volume
• Failure to restore blood pressure results in shock

• Long-Term Restoration of Blood Volume
• Recall of fluids from interstitial spaces
• Aldosterone and ADH promote fluid retention and
reabsorption
• Thirst increases
• Erythropoietin stimulates red blood cell production

Figure 21-18 Cardiovascular Responses to Hemorrhaging and Blood Loss
Normal blood
pressure and
volume
Extensive bleeding
reduces blood
pressure and
volume
HOMEOSTASIS
DISTURBED
Responses
coordinated by the
endocrine system
Responses
directed by the
nervous system
Falling blood
pressure and
volume
Long-Term Hormonal Response
ADH, angiotensin II, aldosterone,
and EPO released
Blood pressure
and volume rise
HOMEOSTASIS
RESTORED
Cardiovascular Responses
Peripheral
vasoconstriction;
mobilization of
venous reserve
Increased
cardiac
output
Elevation
of blood
volume
Stimulation of
baroreceptors and
chemoreceptorsPain, stress,
anxiety, fear
Higher Centers
Stimulation of
cardiovascular
centers
General
sympathetic
activation
HOMEOSTASIS

• Vascular Supply to Special Regions
• Through organs with separate mechanisms to control
blood flow
• Three important examples
1. Brain
2. Heart
3. Lungs

• Blood Flow to the Brain
• Is top priority
• Brain has high oxygen demand
• When peripheral vessels constrict, cerebral vessels
dilate, normalizing blood flow

• Stroke
• Also called cerebrovascular accident (CVA)
• Blockage or rupture in a cerebral artery
• Stops blood flow

• Blood Flow to the Heart
• Through coronary arteries
• Oxygen demand increases with activity
• Lactic acid and low O2 levels
• Dilate coronary vessels
• Increase coronary blood flow

• Blood Flow to the Heart
• Epinephrine
• Dilates coronary vessels
• Increases heart rate
• Strengthens contractions

• Heart Attack
• A blockage of coronary blood flow
• Can cause:
• Angina (chest pain)
• Tissue damage
• Heart failure
• Death

• Blood Flow to the Lungs
• Regulated by O2 levels in alveoli
• High O2 content
• Vessels dilate
• Low O2 content
• Vessels constrict

21-5 Pulmonary and Systemic Patterns
• Three General Functional Patterns
1. Peripheral artery and vein distribution is the same on
right and left, except near the heart
2. The same vessel may have different names in
different locations
3. Tissues and organs usually have multiple arteries
and veins
• Vessels may be interconnected with anastomoses

Figure 21-19 A Schematic Overview of the Pattern of Circulation
Brain
Upper limbs
Lungs
Pulmonary
circuit
(veins)
LA
Left
ventricle
Systemic
circuit
(arteries)
Kidneys
Spleen
Digestive
organs
Gonads
Lower limbs
Liver

Figure 21-19 A Schematic Overview of the Pattern of Circulation
Brain
Upper limbs
Lungs
Pulmonary
circuit
(arteries)
RA
Right
ventricle
Systemic
circuit
(veins)
Kidneys
Liver
Digestive
organs
Gonads
Lower limbs

21-6 The Pulmonary Circuit
• Deoxygenated Blood Arrives at Heart from
Systemic Circuit
• Passes through right atrium and right ventricle
• Enters pulmonary trunk
• At the lungs
• CO2 is removed
• O2 is added
• Oxygenated blood
• Returns to the heart
• Is distributed to systemic circuit

• Pulmonary Vessels
• Pulmonary arteries
• Carry deoxygenated blood
• Pulmonary trunk
• Branches to left and right pulmonary arteries
• Pulmonary arteries
• Branch into pulmonary arterioles
• Pulmonary arterioles
• Branch into capillary networks that surround alveoli

• Pulmonary Vessels
• Pulmonary veins
• Carry oxygenated blood
• Capillary networks around alveoli
• Join to form venules
• Venules
• Join to form four pulmonary veins
• Pulmonary veins
• Empty into left atrium

Figure 21-20 The Pulmonary Circuit
Ascending aorta
Superior vena cava
Right lung
Right pulmonary
arteries
Right pulmonary
veins
Inferior vena cava
Descending aorta

Figure 21-20 The Pulmonary Circuit
Aortic arch
Pulmonary trunk
Left lung
Left pulmonary
arteries
Left pulmonary
veins
Alveolus
Capillary
CO2
O2

21-7 The Systemic Circuit
• The Systemic Circuit
• Contains 84% of blood volume
• Supplies entire body
• Except for pulmonary circuit

• Systemic Arteries
• Blood moves from left ventricle
• Into ascending aorta
• Coronary arteries
• Branch from aortic sinus

Figure 21-21 An Overview of the Major Systemic Arteries
Vertebral
Right subclavian
Brachiocephalic
trunk
Ascending
aorta
Aortic arch
Celiac trunk
Brachial
Right common carotid
Left common carotid
Left subclavian
Axillary
Pulmonary trunk
Descending aorta
Diaphragm
Renal
Superior mesenteric
Gonadal
Inferior mesenteric
Common iliac
Internal iliac
Radial
Ulnar
External
iliac
Femoral
Palmar
arches Deep
femoral

Figure 21-21 An Overview of the Major Systemic Arteries
Femoral
Popliteal
Posterior tibial
Anterior tibial
Fibular
Plantar arch
Descending
genicular
Dorsalis pedis

• The Aorta
• The ascending aorta
• Rises from the left ventricle
• Curves to form aortic arch
• Turns downward to become descending aorta

Figure 21-22a Arteries of the Chest and Upper Limb
Suprascapular
Thyrocervical trunk
Right subclavian
Axillary
Lateral thoracic
Anterior humeral
circumflex
Posterior humeral
circumflex
Subscapular
Deep brachial
Intercostal arteries
Brachial
Ulnar recurrent arteries
Right common carotid
Left common carotid
Vertebral
Brachiocephalic trunk
Left subclavian
Aortic arch
Ascending aorta
Thoracic aorta
Heart
Internal thoracic
Abdominal aorta
Ulnar collateral arteries
Thoracoacromial
Arteries of the chest and upper
limb, a diagrammatic view

Figure 21-22b Arteries of the Chest and Upper Limb
Right vertebral Right
common
carotid
Left
common
carotid
Left
vertebral
Left
thyrocervical
trunkLeft
subclavian
Brachiocephalic
trunk
Right thyrocervical
trunk
Right
subclavian
Right axillary
Right internal
thoracic
Left
internal
thoracic Left
axillary
AORTIC
ARCH
ASCENDING
AORTA
THORACIC
AORTA
(see Fig. 21−25)
Left
brachial
Left
ulnar
Left
radial
ABDOMINAL
AORTA
(see Fig. 21−26)
LEFT
VENTRICLE
Right brachial
Right radial Right ulnar
Connected by anastomoses
of palmar arches that supply
digital arteries
To structures of the
arm
Forearm,
radial side
Forearm,
ulnar side
Muscles of the right
pectoral region and
axilla
Skin and muscles of
chest and abdomen,
mammary gland (right
side), pericardium
Spinal cord, cervical vertebrae
(right side); fuses with left vertebral,
forming basilar artery after entering
cranium via foramen magnum
Muscles, skin, tissues of
neck, thyroid gland,
shoulders, and upper back
(right side)
A flowchart of the arteries of the chest and upper limb

• Branches of the Aortic Arch
• Deliver blood to head, neck, shoulders, and upper
limbs
1. Brachiocephalic trunk
2. Left common carotid artery
3. Left subclavian artery

• The Subclavian Arteries
• Leaving the thoracic cavity:
• Become axillary artery in arm
• And brachial artery distally

• The Brachial Artery
• Divides at coronoid fossa of humerus
• Into radial artery and ulnar artery
• Fuse at wrist to form:
• Superficial and deep palmar arches
• Which supply digital arteries

Figure 21-22a Arteries of the Chest and Upper Limb
Arteries of the chest and upper
limb, a diagrammatic view
Radial
Anterior crural
interosseous
Ulnar
Deep palmar
arch
Superficial
palmar arch
Digital arteries

• The Common Carotid Arteries
• Each common carotid divides into:
• External carotid artery - supplies blood to structures of the
neck, lower jaw, and face
• Internal carotid artery - enters skull and delivers blood to brain
• Divides into three branches
1. Ophthalmic artery
2. Anterior cerebral artery
3. Middle cerebral artery

Figure 21-23 Arteries of the Neck and Head
Second rib
Internal thoracic
Axillary
Subclavian
Suprascapular
Transverse cervical
Thyrocervical
trunk
Carotid sinus
Vertebral
Internal carotid
Inferior thyroid
Basilar
Posterior cerebral
Carotid canal
Cerebral arterial circle
Ophthalmic
Middle cerebral
Anterior cerebral
ClavicleFirst rib

Figure 21-23 Arteries of the Neck and Head
Branches of the
External Carotid
Superficial
temporal
Maxillary
Occipital
Facial
Lingual
External
carotid
Common carotid
Brachiocephalic
trunk
ClavicleFirst rib

• The Vertebral Arteries
• Also supply brain with blood
• Left and right vertebral arteries
• Arise from subclavian arteries
• Enter cranium through foramen magnum
• Fuse to form basilar artery
• Branches to form posterior cerebral arteries
• Posterior cerebral arteries
• Become posterior communicating arteries

• Anastomoses
• The cerebral arterial circle (or circle of Willis)
interconnects:
• The internal carotid arteries
• And the basilar artery

Figure 21-24a Arteries of the Brain
Anterior
cerebral
Ophthalmic
Internal
carotid (cut)
Middle
cerebral
Pituitary
gland
Posterior
cerebral
Cerebellar
Anterior
communicating
Cerebral Arterial Circle
Anterior cerebral
Posterior
communicating
Posterior cerebral
Basilar
Vertebral
Inferior surface

Figure 21-24b Arteries of the Brain
Middle
cerebral
Anterior
cerebral
Ophthalmic
Cerebral arterial
circle
Internal carotid
Lateral view
Posterior
cerebral
Basilar
Vertebral

• The Descending Aorta
• Thoracic aorta
• Supplies organs of the chest
• Bronchial arteries
• Pericardial arteries
• Esophageal arteries
• Mediastinal arteries
• Supplies chest wall
• Intercostal arteries
• Superior phrenic arteries

Figure 21-25a Major Arteries of the Trunk
Aortic arch
Internal thoracic
Thoracic aorta
Somatic Branches of
the Thoracic Aorta
Intercostal arteries
Superior phrenic
Inferior phrenic
A diagrammatic view, with most of the
thoracic and abdominal organs removed

Visceral Branches of
the Thoracic Aorta
Bronchial arteries
Esophageal arteries
Mediastinal arteries
Pericardial arteries

• The Descending Aorta
• Abdominal Aorta
• Divides at terminal segment of the aorta into:
• Left common iliac artery
• Right common iliac artery
• Unpaired branches
• Major branches to visceral organs
• Paired branches
• To body wall
• Kidneys
• Urinary bladder
• Structures outside abdominopelvic cavity

Diaphragm
Adrenal
Renal
Gonadal
Lumbar
Terminal segment
of the aorta
Common iliac
Median sacral

Celiac Trunk
Left gastric
Splenic
Common hepatic
Superior mesenteric
Abdominal aorta
Inferior mesenteric

Figure 21-26 Arteries Supplying the Abdominopelvic Organs
Branches of the
Common Hepatic Artery
Hepatic artery proper (liver)
Gastroduodenal (stomach
and duodenum)
Cystic (gallbladder)
Right gastric (stomach)
Right gastroepiploid
(stomach and duodenum)
Superior pancreatico-
duodenal (duodenum)
Ascending colon
Superior Mesenteric
Artery
Inferior pancreatico-
duodenal (pancreas and
duodenum)
Middle colic (cut)
(large intestine)
Right colic (large intestine)
Ileocolic (large intestine)
Intestinal arteries (small
intestine)
Liver
Pancreas
Small intestine
Rectum

Figure 21-26 Arteries Supplying the Abdominopelvic Organs
Stomach
The Celiac Trunk
Common hepatic
Left gastric
Splenic
Spleen
Branches of the
Splenic Artery
Left gastroepiploic
(stomach)
Pancreatic
(pancreas)
Inferior Mesenteric
Artery
Left colic (colon)
Sigmoid (colon)
Rectal (rectum)
Sigmoid colon
Rectum
Small intestine
Pancreas

• Arteries of the Pelvis and Lower Limbs
• Femoral artery
• Deep femoral artery
• Becomes popliteal artery
• Posterior to knee
• Branches to form:
• Posterior and anterior tibial arteries
• Posterior gives rise to fibular artery

Figure 21-25b Major Arteries of the Trunk
A flowchart showing major arteries of the trunk
Left
common
iliac
Pelvis and
left lower
limb
Pelvis
and right
lower
limb
Right common
iliac
Right external
iliac
Left
internal
iliac
Left external
iliac
Right
internal
iliac
Superior
gluteal
Obturator
Internal
pudendal
Lateral
sacral
Lateral rotators of
hip; rectum, anus,
perineal muscles,
external genitaliaIlium, hip
and thigh
muscles, hip
joint and
femoral head
Hip muscles,
hip joint
Pelvic muscles, skin,
viscera of pelvis (urinary
and reproductive organs),
perineum, gluteal region,
and medial thigh
Skin and
muscles of
sacrum

Figure 21-27a Arteries of the Lower Limb
Common
iliac
External
iliac
Superior
gluteal
Inguinal
ligament
Deep
femoral
Lateral
femoral
circumflex
Medial
femoral
circumflex
Femoral
Internal
iliac
Lateral
sacral
Internal
pudendal
Obturator
Descending
genicular
Anterior view

Figure 21-27a Arteries of the Lower Limb
Anterior view
Popliteal
Anterior tibial
Posterior
tibial
Fibular
Dorsalis pedis
Medial plantar
Lateral plantar
Dorsal arch
Plantar arch

Figure 21-27b Arteries of the Lower Limb
Posterior view
Medial
femoral
circumflex
Femoral
Internal
pudendal
Obturator
Superior gluteal
Right external
iliac
Deep femoral
Lateral femoral
circumflex
Descending
genicular

Figure 21-27b Arteries of the Lower Limb
Posterior view
Popliteal
Anterior tibial
Posterior
tibial
Fibular

Figure 21-27c Arteries of the Lower Limb
Deep
femoral
Femoral
Descending
genicular
Popliteal
Fibular
Posterior
tibial
Anterior
tibial
Medial
femoral
circumflex
Lateral
femoral
circumflex
Thigh
Hip joint, femoral head, deep
muscles of the thigh
Skin of leg,
knee joint
Leg and
footQuadriceps
muscles
Adductor muscles,
obturator muscles,
hip joint
Connected by anastomoses of
dorsalis pedis, dorsal arch, and
plantar arch, which supply distal
portions of the foot and the toes
EXTERNAL ILIAC
A flowchart of blood flow to a lower limb

• Systemic Veins
• Complementary Arteries and Veins
• Run side by side
• Branching patterns of peripheral veins are more variable
• In neck and limbs
• One set of arteries (deep)
• Two sets of veins (one deep, one superficial)
• Venous system controls body temperature

Figure 21-28 An Overview of the Major Systemic Veins
Vertebral
External jugular Internal jugular
Brachiocephalic
Superior vena cava
Intercostal veins
Inferior vena cava
Renal
Gonadal
Subclavian
Axillary
Brachial
Basilic
Hepatic veins
Median cubital
Radial
Ulnar
Median antebrachial
Palmar venous arches
Digital veins
Lumbar veins
Left and right
common iliac
External iliac
Internal iliac
Deep
femoral
Femoral
Superficial veins
Deep veins
KEY

Figure 21-28 An Overview of the Major Systemic Veins
Superficial veins
Deep veins
KEY
Femoral
Posterior tibial
Anterior tibial
Great saphenous
Popliteal
Small saphenous
Fibular
Plantar venous arch
Dorsal venous arch

• The Superior Vena Cava (SVC)
• Receives blood from the tissues and organs of:
• Head
• Neck
• Chest
• Shoulders
• Upper limbs

Figure 21-29c Major Veins of the Head, Neck, and Brain
Superior sagittal sinus
Superficial cerebral veins
Inferior sagittal sinus
Great cerebral
Straight sinus
Petrosal sinuses
Right transverse sinus
Occipital sinus
Sigmoid sinus
Occipital
Temporal
Deep cerebral
Cavernous sinus
Maxillary
Facial
Vertebral
External jugular
Right subclavian
Axillary
Clavicle
First rib
Veins draining the brain and the superficial
and deep portions of the head and neck.
Internal jugular
Right brachiocephalic
Left brachiocephalic
Superior vena cava
Internal thoracic

• The Dural Sinuses
• Superficial cerebral veins and small veins of the brain
stem
• Empty into network of dural sinuses
• Superior and inferior sagittal sinuses
• Petrosal sinuses
• Occipital sinus
• Left and right transverse sinuses
• Straight sinus

Figure 21-29b Major Veins of the Head, Neck, and Brain
Straight
sinus
Occipital
sinus
Right transverse
sinus Right
sigmoid sinus
Inferior sagittal
sinus
Superior sagittal
sinus
Great
cerebral
vein
Cavernous
sinus
Petrosal sinuses
Internal jugular
Vertebral vein
A lateral view of the brain
showing the venous
distribution.

• Cerebral Veins
• Great cerebral vein
• Drains to straight sinus
• Other cerebral veins
• Drain to cavernous sinus
• Which drains to petrosal sinus
• Vertebral Veins
• Empty into brachiocephalic veins of chest

Figure 21-29a Major Veins of the Head, Neck, and Brain
An inferior view of the brain, showing the
venous distribution.
Occipital sinus
Straight sinus
Transverse sinus
Cerebellar veins
Sigmoid sinus
Internal jugular
Cerebral veins
Cavernous sinus
Petrosal sinus
Superior sagittal,
sinus (cut)

• Superficial Veins of the Head and Neck
• Converge to form:
• Temporal, facial, and maxillary veins
• Temporal and maxillary veins
• Drain to external jugular vein
• Facial vein
• Drains to internal jugular vein

• Veins of the Hand
• Digital veins
• Empty into superficial and deep palmar veins
• Which interconnect to form palmar venous arches

• Veins of the Hand
• Superficial arch empties into:
• Cephalic vein
• Median antebrachial vein
• Basilic vein
• Median cubital vein
• Deep palmar veins drain into:
• Radial and ulnar veins
• Which fuse above elbow to form brachial vein

Figure 21-30 The Venous Drainage of the Abdomen and Chest
Palmar venous
arches
Digital veins
Ulnar
Median antebrachial
Radial
Cephalic
Anterior crural interosseous
Basilic
Median cubital
Deep veins
Superficial veins
KEY

• The Brachial Vein
• Merges with basilic vein
• To become axillary vein
• Cephalic vein joins axillary vein
• To form subclavian vein
• Merges with external and internal jugular veins
• To form brachiocephalic vein
• Which enters thoracic cavity

Deep veins
Superficial veins
KEY
Adrenal veins
Phrenic veins
Basilic
INFERIOR VENA CAVA
Intercostal veins
Hemiazygos
Accessory hemiazygos
Cephalic
Axillary
Brachiocephalic
Highest intercostal
Subclavian
External jugular
Internal jugular
Vertebral
Brachial

• Veins of the Thoracic Cavity
• Brachiocephalic vein receives blood from:
• Vertebral vein
• Internal thoracic vein
• The Left and Right Brachiocephalic Veins
• Merge to form the superior vena cava (SVC)

• Tributaries of the Superior Vena Cava
• Azygos vein and hemiazygos vein, which receive
blood from:
1. Intercostal veins
2. Esophageal veins
3. Veins of other mediastinal structures

Medial sacral
Deep veins
Superficial veins
KEY
External iliac
Internal iliac
Common iliac
Lumbar
veins
Gonadal
veins
Renal veins
Hepatic
veins
Internal
thoracic
Azygos
Esophageal
veins
Mediastinal
veins
SUPERIOR
VENA CAVA

Figure 21-31a Flowcharts of Circulation to the Superior and Inferior Venae Cavae
Tributaries of the superior vena cava
Right
vertebral
Collect blood
from vertebrae
and body wall
Left
intercostal
veins
Hemiazygos
Left
brachiocephalic
Collects blood
from cranium, face,
and neck
Collect blood
from structures
of anterior
thoracic wall
Left
internal
jugular
Right
internal
jugular
Left and
right internal
thoracic
veins
Esophageal
veins
Azygos
Collect blood
from the
mediastinum
Right
external
jugular
Right
subclavian
Right
axillary
Mediastinal
veins
Right
brachiocephalic
Veins of the
right upper
limb
Right
intercostal
veins
Collect blood
from vertebrae
and body wall
Collect blood
from the
eophagus
KEY
Superficial veins
Deep veins
SUPERIOR
VENA CAVA
RIGHT
ATRIUM
Collects blood
from cranium, spinal
cord, vertebrae
Left
vertebral
Through highest
intercostal vein

Figure 21-31a Flowcharts of Circulation to the Superior and Inferior Venae Cavae
Tributaries of the superior vena cava
KEY
Superficial veins
Deep veins
Venous network
of wrist and hand
Left cephalic Left basilic
Left
axillary
Left
brachial
Left
subclavian
Left
brachiocephalic
Left
external
jugular
Left
ulnar
Left
radial
Radial
side of
forearm
Ulnar
side of
forearm
Collects blood
from lateral surface
of upper limb
Collects blood
from medial surface
of upper limb
Collects blood from
forearm, wrist, and
hand
Collects blood from
neck, face, salivary
glands, scalp
Interconnected by median
cubital vein and median
antebrachial network

• The Inferior Vena Cava (IVC)
• Collects blood from organs inferior to the
diaphragm

• Veins of the Foot
• Capillaries of the sole
• Drain into a network of plantar veins
• Which supply the plantar venous arch
• Drain into deep veins of leg:
• Anterior tibial vein
• Posterior tibial vein
• Fibular vein
• All three join to become popliteal vein

• The Dorsal Venous Arch
• Collects blood from:
• Superior surface of foot
• Digital veins
• Drains into two superficial veins
1. Great saphenous vein (drains into femoral vein)
2. Small saphenous vein (drains into popliteal vein)

• The Popliteal Vein
• Becomes the femoral vein
• Before entering abdominal wall, receives blood from:
• Great saphenous vein
• Deep femoral vein
• Femoral circumflex vein
• Inside the pelvic cavity
• Becomes the external iliac vein

• The External Iliac Veins
• Are joined by internal iliac veins
• To form right and left common iliac veins
• The right and left common iliac veins
• Merge to form the inferior vena cava

Figure 21-32a Venous Drainage from the Lower Limb
External iliac
Common iliac
Internal iliac
Gluteal
Internal pudendal
Lateral sacral
Obturator
Femoral
Femoral circumflex
Deep femoral
Femoral
Great saphenous
Popliteal
Small
saphenous
Anterior tibial
Posterior tibial
Fibular
Dorsal venous arch
Plantar venous arch
Digital
An anterior view

Figure 21-32b Venous Drainage from the Lower Limb
External iliac
Gluteal
Internal pudendal
Obturator
Femoral
Femoral circumflex
Deep femoral
Femoral
Great saphenous
Popliteal
Small
saphenous
Anterior tibial
Posterior tibial
Fibular
A posterior view

Figure 21-32c Venous Drainage from the Lower Limb
EXTERNAL ILIAC
Small
saphenous
Femoral
Popliteal
Fibular
Posterior
tibial
Anterior
tibial
Extensive anastomoses interconnect
veins of the ankle and foot
Great
saphenous
KEY
Superficial veins
Deep veins
Collects blood
from the
superficial veins
of the lower limb
Collects blood
from the thigh
Collects blood
from superficial
veins of the leg
and foot
A flowchart of venous circulation from a lower limb
Deep
femoral

• Major Tributaries of the Abdominal Inferior Vena
Cava
1. Lumbar veins
2. Gonadal veins
3. Hepatic veins
4. Renal veins
5. Adrenal veins
6. Phrenic veins

• The Hepatic Portal System
• Connects two capillary beds
• Delivers nutrient-laden blood
• From capillaries of digestive organs
• To liver sinusoids for processing

Tributaries of the Hepatic Portal Vein
1. Inferior mesenteric vein
• Drains part of large intestine
2. Splenic vein
• Drains spleen, part of stomach, and pancreas
3. Superior mesenteric vein
• Drains part of stomach, small intestine, and part of large
intestine
4. Left and right gastric veins
• Drain part of stomach
• Cystic vein
• Drains gallbladder

• Blood Processed in Liver
• After processing in liver sinusoids (exchange
vessels):
• Blood collects in hepatic veins and empties into
inferior vena cava

Figure 21-33 The Hepatic Portal System
Inferior vena cava
Hepatic
Cystic
Hepatic portal
Pancreaticoduodenal
Superior Mesenteric
Vein and Its Tributaries
Middle colic (from
transverse colon)
Right colic (ascending
colon)
Ileocolic (Ileum and
ascending colon)
Intestinal (small intestine)
Pancreas
Liver

Figure 21-33 The Hepatic Portal System
Left gastric
Right gastric
Stomach
Spleen
Pancreas
Left gastroepiploic
(stomach)
Right gastroepiploic
(stomach)
Pancreatic
Descending colon
Splenic Vein and Its
Tributaries
Inferior Mesenteric
Vein and Its Tributaries
Left colic (descending
colon)
Sigmoid
(sigmoid colon)
Superior rectal (rectum)

Figure 21-31b Flowcharts of Circulation to the Superior and Inferior Venae Cavae
Tributaries of the inferior vena cava
Superior
gluteal
veins
Internal
pudendal
veins
Obturator
veins
Lateral
sacral
veins
Blood from
veins in left
lower limb
Left
external
iliac
Left internal
iliac
Right
external
iliac
Right internal
iliac
Blood from
veins in right
lower limb
Right
common
iliac
Left
common
iliac
Collect blood from the pelvic muscles,
skin, urinary and reproductive organs
of pelvic cavity
Collect blood from
the kidneys
Collect blood from
the diaphragm
Collect blood from
the adrenal
glands
Collect blood from
the spinal cord
and body wall
Collect blood from
the liver
Collect blood from
the gonads (testes
or ovaries)
Hepatic
veins
Gonadal
veins
Lumbar
veins
Phrenic
veins
Adrenal
veins
Renal
veins
RIGHT
ATRIUM
INFERIOR
VENA CAVA
KEY
Superficial veins
Deep veins

21-8 Fetal and Maternal Circulation
• Fetal and Maternal Cardiovascular Systems
Promote the Exchange of Materials
• Embryonic lungs and digestive tract nonfunctional
• Respiratory functions and nutrition provided by
placenta

• Placental Blood Supply
• Blood flows to the placenta
• Through a pair of umbilical arteries that arise from internal
iliac arteries
• Enters umbilical cord
• Blood returns from placenta
• In a single umbilical vein that drains into ductus venosus
• Ductus venosus
• Empties into inferior vena cava

• Before Birth
• Fetal lungs are collapsed
• O2 provided by placental circulation

• Fetal Pulmonary Circulation Bypasses
• Foramen ovale
• Interatrial opening
• Covered by valve-like flap
• Directs blood from right to left atrium
• Ductus arteriosus
• Short vessel
• Connects pulmonary and aortic trunks

• Cardiovascular Changes at Birth
• Newborn breathes air
• Lungs expand
• Pulmonary vessels expand
• Reduced resistance allows blood flow
• Rising O2 causes ductus arteriosus constriction
• Rising left atrium pressure closes foramen ovale
• Pulmonary circulation provides O2

Figure 21-34a Fetal Circulation
Placenta
Aorta
Foramen ovale (open)
Ductus arteriosus (open)
Pulmonary trunk
Liver Inferior
vena cava
Ductus
venosus
Umbilical
vein
Umbilical
cord
Blood flow to and from
the placenta in full-term
fetus (before birth)
Umbilical
arteries

Figure 21-34b Fetal Circulation
Blood flow through the
neonatal (newborn) heart
after delivery
Inferior
vena cava
Right ventricle
Left ventricle
Right atrium
Foramen ovale
(closed)
Left atrium
Pulmonary trunk
Ductus arteriosus
(closed)

Figure 21-35 Congenital Heart Problems
Normal Heart Structure
Most heart problems reflect
deviations from the normal
formation of the heart and its
connections to the great vessels.

• Patent Foramen Ovale and Patent Ductus
Arteriosus
• In patent (open) foramen ovale blood recirculates
through pulmonary circuit instead of entering left
ventricle
• The movement, driven by relatively high systemic
pressure, is a “left-to-right shunt”
• Arterial oxygen content is normal, but left ventricle must
work much harder than usual to provide adequate
blood flow through systemic circuit

• Patent Foramen Ovale and Patent Ductus
Arteriosus
• Pressures rise in the pulmonary circuit
• If pulmonary pressures rise enough, they may force
blood into systemic circuit through ductus arteriosus
• A patent ductus arteriosus creates a “right-to-left shunt”
• Because circulating blood is not adequately
oxygenated, it develops deep red color
• Skin develops blue tones typical of cyanosis and infant
is known as a “blue baby”

Patent Foramen Ovale and Patent Ductus Arteriosus
If the foramen ovale remains open, or patent,
blood recirculates through the pulmonary
circuit instead of entering the left ventricle. The
movement, driven by the relatively high
systemic pressure, is called a “left-to-right
shunt.” Arterial oxygen content is normal, but
the left ventricle must work much harder than
usual to provide adequate blood flow through
the systemic circuit. Hence, pressures rise in the pulmonary
circuit. If the pulmonary pressures rise enough, they may
force blood into the systemic circuit through the ductus
arteriosus. This condition—a patent ductus arteriosus—
creates a “right-to-left shunt.” Because the circulating blood
is not adequately oxygenated, it develops a deep red color.
The skin then develops the blue tones typical of cyanosis and
the infant is known as a “blue baby.”
Patent ductus
arteriosus
Patent
foramen
ovale

• Tetralogy of Fallot
• Complex group of heart and circulatory defects that
affect 0.10 percent of newborn infants
1. Pulmonary trunk is abnormally narrow (pulmonary
stenosis)
2. Interventricular septum is incomplete
3. Aorta originates where interventricular septum
normally ends
4. Right ventricle is enlarged and both ventricles thicken
in response to increased workload

Tetralogy of Fallot
ventricle is enlarged and both ventricles
thicken in response to the increased workload.
The tetralogy of Fallot (fa-LO) is a complex
group of heart and circulatory defects that
affect 0.10 percent of newborn infants. In this
condition, (1) the pulmonary trunk is abnor-
mally narrow (pulmonary stenosis), (2) the
interventricular septum is incomplete, (3) the
aorta originates where the interventricular
septum normally ends, and (4) the right
¯
Patent ductus
arteriosus
Pulmonary
stenosis
Ventricular
septal defect
Enlarged
right ventricle

• Ventricular Septal Defect
• Openings in interventricular septum that separate
right and left ventricles
• The most common congenital heart problems,
affecting 0.12 percent of newborns
• Opening between the two ventricles has an effect
similar to a connection between the atria
• When more powerful left ventricle beats, it ejects blood
into right ventricle and pulmonary circuit

Ventricular Septal Defect
Ventricular septal defects are openings in the inter-
ventricular septum that separate the right and left ven-
tricles. These defects are the most common congenital
heart problems, affecting 0.12 percent of newborns. The
opening between the two ventricles has an effect simi-
lar to a connection between the atria: When the more
powerful left ventricle beats, it ejects blood into the
right ventricle and pulmonary circuit.
Ventricular
septal defect
Ventricular
septum

• Atrioventricular Septal Defect
• Both the atria and ventricles are incompletely
separated
• Results are quite variable, depending on extent of
defect and effects on atrioventricular valves
• This type of defect most commonly affects infants with
Down’s syndrome, a disorder caused by the presence
of an extra copy of chromosome 21

In an atriovenricular septal defect, both the atria and
ventricles are incompletely separated. The results are
quite variable, depending on the extent of the defect
and the effects on the atrioventricular valves. This
type of defect most commonly affects infants with
Down’s syndrome, a disorder caused by the presence
of an extra copy of chromosome 21.
Atrioventricular Septal Defect
Atrial
defect
Ventricular
defect

• Transposition of Great Vessels
• The aorta is connected to right ventricle instead of to
left ventricle
• The pulmonary artery is connected to left ventricle
instead of right ventricle
• This malformation affects 0.05 percent of newborn
infants

In the transposition of great vessels, the
aorta is connected to the right ventricle
instead of to the left ventricle, and the
pulmonary artery is connected to the left
ventricle instead of the right ventricle.
This malformation affects 0.05 percent of
newborn infants.
Transposition of the Great Vessels
Patent ductus
arteriosus
Aorta
Pulmonary
trunk

21-9 Effects of Aging and the Cardiovascular
System
• Cardiovascular Capabilities Decline with Age
• Age-related changes occur in:
• Blood
• Heart
• Blood vessels

System
• Three Age-Related Changes in Blood
1. Decreased hematocrit
2. Peripheral blockage by blood clot (thrombus)
3. Pooling of blood in legs
• Due to venous valve deterioration

System
• Five Age-Related Changes in the Heart
1. Reduced maximum cardiac output
2. Changes in nodal and conducting cells
3. Reduced elasticity of cardiac (fibrous) skeleton
4. Progressive atherosclerosis
5. Replacement of damaged cardiac muscle cells by
scar tissue

System
• Three Age-Related Changes in Blood Vessels
1. Arteries become less elastic
• Pressure change can cause aneurysm
2. Calcium deposits on vessel walls
• Can cause stroke or infarction
3. Thrombi can form
• At atherosclerotic plaques

21-9 Cardiovascular System Integration
• Many Categories of Cardiovascular Disorders
• Disorders may:
• Affect all cells and systems
• Be structural or functional
• Result from disease or trauma

Figure 21-36 System Integrator: The Cardiovascular System
S Y S T E M I N T E G R A T O R
Body System Cardiovascular System Body SystemCardiovascular System
IntegumentarySkeletalMuscularNervousEndocrine
IntegumentarySkeletalMuscularNervousEndocrine
Page165Page275Page369Page543Page632
The section on vessel
distribution demonstrated the
extent of the anatomical
connections between the
cardiovascular system and other
organ systems. This figure
summarizes some of the physiological
relationships involved.
The most extensive communication
occurs between the cardiovascular and
lymphatic systems. Not only are the two
systems physically interconnected, but
cells of the lymphatic system also move
from one part of the body to another
within the vessels of the cardiovascular
system. We examine the lymphatic
system in detail, including its role in the
immune response, in the next chapter.
The CARDIOVASCULAR System
Stimulation of mast cells produces
localized changes in blood flow and
capillary permeability
Provides calcium needed for normal
cardiac muscle contraction; protects
blood cells developing in red bone
marrow
Skeletal muscle contractions assist in
moving blood through veins; protects
superficial blood vessels, especially
in neck and limbs
Controls patterns of circulation in
peripheral tissues; modifies heart
rate and regulates blood pressure;
releases ADH
Erythropoietin regulates production
of RBCs; several hormones elevate
blood pressure; epinephrine
stimulates cardiac muscle, elevating
heart rate and contractile force
Distributes hormones throughout
the body; heart secretes ANP and
BNP
Endothelial cells maintain
blood—brain barrier; helps
generate CSF
Delivers oxygen and nutrients,
removes carbon dioxide, lactic
acid, and heat during skeletal
muscle activity
Transports calcium and phosphate
for bone deposition; delivers EPO to
red bone marrow, parathyroid
hormone, and calcitonin to
osteoblasts and osteoclasts
Delivers immune system cells to
injury sites; clotting response seals
breaks in skin surface; carries away
toxins from sites of infection;
provides heat
Lymphatic
Page807
Respiratory
Page857
Digestive
Page910
Urinary
Page992
Reproductive
Page1072

169 Ch 21_lecture_presentation

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