General knowledge about cardiovascular
system
5 Classes of Blood Vessels
1. Arteries:
–
carry blood away from heart
2. Arterioles:
–
Are smallest branches of arteries
5 Classes of Blood Vessels
3. Capillaries:
–
–
are smallest blood vessels
location of exchange between blood and
interstitial fluid
5 Classes of Blood Vessels
4. Venules:
–
collect blood from capillaries
5. Veins:
–
return blood to heart
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
The Smallest Blood Vessels
• Capillaries
• Have small diameter and thin walls
• Chemicals and gases diffuse across
walls
The Anatomy of Blood Vessels
• Arteries, veins, and capillaries
• Have different functions
• Have different structures
Structure of Vessel Walls
Arteries and Veins
• Walls have 3 layers:
– tunica intima
– tunica media
– tunica externa
The Tunica Intima
• Is the innermost 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
Tunica Media
• Is the middle layer
• Contains concentric sheets of smooth
muscle in loose connective tissue
• Binds to inner and outer layers
Tunica Media
• Exterman elastic membrane of the
tunica media:
– separates tunica media from tunica
externa
Tunica Externa
• Is outer layer
• Contains connective tissue sheath
• Anchors vessel to adjacent tissues
Tunica Externa
• In arteries:
– contain collagen
– elastic fibers
• In veins:
– contain elastic fibers
– smooth muscle cells
Vasa Vasorum
• Small arteries and veins
• In walls of large arteries and veins
• Supply cells of tunica media and tunica
externa
Arteries vs. Veins
• Arteries and veins run side-by-side
• Arteries have thicker walls and higher
blood pressure
• Collapsed artery has small, round
lumen
• Vein has a large, flat lumen
Arteries vs. Veins
• Vein lining contracts, artery lining does
not
• Artery lining folds
• Arteries more elastic
• Veins have valves
Arteries and Pressure
• Elasticity allows arteries to absorb
pressure waves that come with each
heartbeat
Contractility
• Arteries change diameter
• Controlled by sympathetic division of
ANS
Structure of Blood Vessels
Figure 21-2
Artery Characteristics
• 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:
– changes with sympathetic or endocrine
stimulation
– constricted arteries oppose blood flow
Resistance (R)
• The force opposing blood flow
• Resistance vessels:
– arterioles
Aneurysm
• A bulge in an arterial wall
• Is caused by weak spot in elastic fibers
• Pressure may rupture vessel
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 basal
lamina
• No tunica media
• No tunica externa
• Diameter is similar to red blood cell
Capillary Structure
Figure 21-4
2 Types of Capillaries
1. Continuous capillaries
2. Fenestrated capillaries
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
– Lipid-soluble materials
• Block:
– blood cells
– plasma proteins
Specialized
Continuous Capillaries
• Are in CNS and thymus
• Have very restricted permeability
• e.g., the blood–brain barrier
Fenestrated Capillaries
• Have pores in endothelial lining
• Permit rapid exchange of water and
larger solutes:
– between plasma and interstitial fluid
Fenestrated Capillaries
• Are found in:
–
–
–
–
choroid plexus
endocrine organs
kidneys
intestinal tract
Sinusoids
• Areas in:
–
–
–
–
liver
spleen
bone marrow
endocrine organs
• Have gaps between adjacent
endothelial cells
Sinusoids
• Permit free exchange:
– of water and large plasma proteins
– between blood and interstitial fluid
• Phagocytic cells monitor blood at
sinusoids
Capillary Networks
Figure 21-5
Capillaries Networks
• Capillary bed or capillary plexus
• Connect 1 arteriole and 1 venule
Thoroughfare Channels
• Direct capillary connections between
arterioles and venules
• Controlled by smooth muscle segments
(metarterioles)
Collaterals
• Multiple arteries that contribute to 1
capillary bed
• Allow circulation if 1 artery is blocked
• Arterial anastomosis:
– fusion of 2 collateral arteries
Arteriovenous Anastomoses
• Direct connections between arterioles
and venules
• Bypass the capillary bed
Capillary Sphincter
• Guards entrance to each capillary
• Opens and closes, causing capillary
blood to flow in pulses
Veins
• Collect blood from capillaries in tissues
and organs
• Return blood to heart
Veins vs. Arteries
• Are larger in diameter
• Have thinner walls
• Carry lower blood pressure
3 Vein Categories
1. Venules:
–
–
very small veins
collect blood from capillaries
3 Vein Categories
2. Medium-sized veins:
–
–
thin tunica media and few smooth
muscle cells
tunica externa with longitudinal bundles
of elastic fibers
3 Vein Categories
3. Large veins:
–
–
–
have all 3 tunica layers
thick tunica externa
thin tunica media
Valves in the Venous System
Figure 21-6
Vein Valves
• Folds of tunica intima
• Prevent blood from flowing backward
• Compression pushes blood toward
heart
Venous Blood Distribution
• 1/3 of venous blood is in the large
venous networks of the liver, bone
marrow, and skin
Veins Response to Blood Loss
• Vasomotor centers stimulate
sympathetic nerves:
– systemic veins constrict (venoconstriction)
• veins in liver, skin and lungs redistribute
venous reserve
What are the principle
blood vessels and functional
characteristics of the
special circulation to the
brain, heart, and lungs?
Special Circulation
• Through organs with separate
mechanisms to control blood flow:
– brain
– heart
– lungs
Blood Flow to the Brain
• Is top priority
• Brain has high oxygen demand
• When peripheral vessel constrict,
cerebral vessels dilate, normalizing
blood flow
Heart Attack
• A blockage of coronary blood flow
• Can cause:
–
–
–
–
angina
tissue damage
heart failure
death
Pulmonary Blood Pressure
• In pulmonary capillaries:
– is low to encourage reabsorption
• If capillary pressure rises:
– pulmonary edema occurs
Circulation Patterns
Figure 21-18
3 Distribution Patterns
1. Peripheral artery and vein
distribution:
–
is the same on right and left, except
near the heart
3 Distribution Patterns
2. The same vessel:
–
may have different names in different
locations
3 Distribution Patterns
3. Tissues and organs usually have
multiple arteries and veins:
–
vessels may be interconnected by
anastomoses
What are the major
arteries and veins of
the pulmonary circuit
and the areas they serve?
The Pulmonary Circuit
Figure 21-19
The Pulmonary Circuit (1 of 3)
1. Deoxygenated blood arrives at heart
from systemic circuit:
–
–
passes through right atrium and ventricle
enters pulmonary trunk
The Pulmonary Circuit (2 of 3)
2. At the lungs:
–
–
CO2 is removed
O2 is added
The Pulmonary Circuit (3 of 3)
3. Oxygenated blood:
–
–
returns to the heart
is distributed to systemic circuit
Pulmonary Vessels
• Pulmonary arteries:
– carry deoxygenated blood
• Pulmonary veins:
– carry oxygenated blood
Pulmonary Arteries
• 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 Veins
• Capillary networks around alveoli:
– join to form venules
• Venules:
– join to form 4 pulmonary veins
• Pulmonary veins:
– empty into left atrium
What are the major
arteries and veins of
the systemic circuit and
the areas they serve?
Major Systemic Arteries
Figure 21-20
The Systemic Circuit
• Contains 84% of blood volume
• Supplies entire body:
– except for pulmonary circuit
Arteries of the Chest
and Upper Limbs
Systemic Arteries
• Blood moves from left ventricle:
– into ascending aorta
• Coronary arteries:
– branch from aortic sinus
The Aorta
• The ascending aorta:
– rises from the left ventricle
– curves to form aortic arch
– turns downward to become descending
aorta
Branches of the Aortic Arch
• Deliver blood to head and neck:
– brachiocephalic trunk
– left common carotid artery
– left subclavian artery
The Brachiocephalic Trunk
• Branches to form:
– right subclavian artery
– right common carotid artery
The Subclavian Arteries
• Branches within thoracic cavity:
– internal thoracic artery
– vertebral artery
– thyrocervical trunk
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
Radial and Ulnar Arteries
• Fuse at wrist to form:
– superficial and deep palmar arches
– which supply digital arteries
Arteries of the Neck and Head
The Common Carotid Arteries
• Carry blood to head and neck
• Each common carotid divides into:
– external carotid artery
– internal carotid artery
The External Carotid
• Supplies structures of:
– neck
– lower jaw
– face
Arteries of the Brain
The Internal Carotid Artery
• Enters skull and divides into:
– opthalmic artery
– anterior cerebral artery
– middle cerebral artery
The Vertebral Arteries
• Also supply brain with blood supply
• Left and right vertebral arteries:
– arise from subclavian arteries
– enter cranium through foramen magnum
– fuse to form basilar artery
The Basilar Artery
• Branches to form posterior cerebral
arteries
• Posterior cerebral arteries:
– become posterior communicating arteries
Anastomoses
• The cerebral arterial circle
interconnects:
– the internal carotid arteries
– and the basilar artery
Arteries of the Trunk
The Descending Aorta
• Is divided by diaphragm into:
– thoracic aorta
– abdominal aorta
Arteries of the Trunk
Branches of the Thoracic Aorta
• Are anatomically grouped into:
– visceral
– parietal
4 Visceral Branches
• Supply organs of the chest:
–
–
–
–
bronchial arteries
pericardial arteries
esophogeal arteries
mediastinal arteries
2 Parietal Branches
• Supply chest wall:
– intercostal arteries
– superior phrenic arteries
The Abdominal Aorta
• Divides at terminal segment of the
aorta into:
– left common iliac artery
– right common iliac artery
Branches of the Abdominal Aorta
• Unpaired branches:
– major branches to visceral organs
• Paired branches:
–
–
–
–
to body wall
kidneys
urinary bladder
structures outside abdominopelvic cavity
Arteries of the
Abdominopelvic Organs
3 Unpaired Branches
of the Abdominal Aorta
• Celiac trunk, divides into:
– left gastric artery
– splenic artery
– common hepatic artery
• Superior mesenteric artery
• Left mesenteric artery
5 Paired Branches of
the Abdominal Aorta
1.
2.
3.
4.
5.
Inferior phrenic arteries
Suprarenal arteries
Renal arteries
Gonadal arteries
Lumbar arteries
The Abdominal Aorta
• Divides to form:
– right and left common iliac arteries
– middle sacral artery
The Common Iliac Arteries
• Divide to form:
– internal iliac artery
– external iliac artery
Arteries of the Lower Limbs
The External Iliac Arteries
• Pass through abdominal wall
• Becomes femoral arteries
The Femoral Artery
• Branches to:
– deep femoral artery
• Becomes popliteal artery:
– posterior to knee
The Popliteal Artery
• Branches to form:
– posterior tibial artery
– anterior tibial artery
The Anterior Tibial Artery
• Becomes dorsalis pedis artery at the
ankle
The Posterior Tibial Artery
• Gives rise to the fibular artery
• Divides at ankle to form:
– medial and lateral plantar arteries
• Dorsal arch and plantar arch:
– supply distal foot and toes
Major Systemic Veins
Complementary
Arteries and Veins
• Run side by side
• Branching patterns of peripheral veins
are more variable
Differences in Artery
and Vein Distribution
• In neck and limbs:
– 1 set of arteries (deep)
– 2 sets of veins (1 deep, 1 superficial)
• Venous system controls body
temperature
All Systemic Veins
• Drain into either:
– superior vena cava (SVC)
– or inferior vena cava (IVC)
Veins of the Head,
Neck, and Brain
The Superior Vena Cava (SVC)
• Receives blood from:
–
–
–
–
–
head
neck
chest
shoulders
upper limbs
The Dural Sinuses
• Superficial cerebral veins and small
veins of the brain stem:
– empty into network of dural sinuses
5 Cerebral Sinuses
1.
2.
3.
4.
5.
Superior and inferior sagittal sinuses
Petrosal sinuses
Occipital sinus
Left and right transverse sinuses
Straight sinus
Cerebral Veins
• Great cerebral vein:
– drains to straight sinus
• Other cerebral veins:
– drain to cavernous sinus
– which drains to petrosal sinus
The Left and Right
Transverse Sinuses
• Converge to form sigmoid sinus:
– which leaves skull as internal jugular vein
Vertebral Veins
• Empty into brachiocephalic veins of
chest
Superficial Veins of the Head
• Converge to form:
– temporal, facial, and maxillary veins
Veins of the Neck
• Temporal and maxillary veins:
– drain to external jugular vein
• Facial vein:
– drains to internal jugular vein
Veins of the Abdomen and Chest
Veins of the Hand
• Digital veins:
– empty into superficial and deep palmar
veins
– which interconnect to form palmar venous
arches
Superficial Veins of the Forearm
• Superficial arch empties into:
– cephalic vein
– median antebrachial vein
– median cubital vein
Deep Veins of the Forearm
• Deep palmar veins drain into:
– radial and ulnar veins
– which fuse above elbow to form brachial
vein
The Brachial Vein
• Merges with basilic vein
• To become axillary vein
Veins of the Upper Arm
• Cephalic vein joins axillary vein:
– to form subclavian vein
The Subclavian Vein
• Merges with external and internal
jugular veins:
– to form brachiocephalic vein
– which enters thoracic cavity
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 SVC
• Azygous vein and hemiazygous vein
which receive blood from:
– intercostal veins
– esophageal veins
– veins of other mediastinal structures
Tributaries of the
Superior Vena Cava
Tributaries of the
Inferior Vena Cava
The Inferior Vena Cava (IVC)
• Collects blood from organs inferior to
the diaphragm
Veins of the Lower Limbs
Veins of the Foot
• Capillaries of the sole:
– drain into a network of plantar veins
– which supply the plantar venous arch
The Plantar Network
• Drains into deep veins of leg:
– anterior tibial vein
– posterior tibial vein
– fibular vein
Deep Veins of the Leg
• Join to become popliteal vein:
– anterior tibial vein
– posterior tibial vein
– fibular vein
The Dorsal Venous Arch
• Collects blood from:
– superior surface of foot
– digital veins
The Dorsal Venous Arch
• Drains into 2 superficial veins:
1. great saphenous vein:
• which drains into femoral vein
2. small saphenous vein:
• which drains into popliteal vein
The Popliteal Vein
• Becomes the femoral vein
• At the femur
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
Veins of the Abdomen
6 Major Tributaries of the
Abdominal Inferior Vena Cava
1.
2.
3.
4.
5.
6.
Lumbar veins
Gonadal veins
Hepatic veins
Renal veins
Suprarenal veins
Phrenic veins
The Hepatic Portal System
The Hepatic Portal System
• Connects 2 capillary beds
• Delivers nutrient-laden blood:
– from capillaries of digestive organs
– to liver sinusoids for processing
5 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
5 Tributaries of the
Hepatic Portal Vein
4. Left and right gastric veins:
–
drains part of stomach
5. Cystic vein:
–
drains gallbladder
Blood Processed in Liver
• After processing in liver sinusoids,
blood collects in hepatic veins and
empties into inferior vena cava
Fetal Circulation
• Embryonic lungs and digestive tract
nonfunctional
• Respiratory functions and nutrition
provided by placenta
Placental Blood Supply
Figure 21-33a
Placental Blood Supply
• Blood flows to the placenta:
– through a pair of umbilical arteries
– which arise from internal iliac arteries
– and enter umbilical cord
Placental Blood Return
• Blood returns from placenta:
– in a single umbilical vein
– which drains into ductus venosus
• Ductus venosus:
– empties into inferior vena cava
The Neonatal Heart
Figure 21-33b
Before Birth
• Fetal lungs are collapsed
• O2 provided by placental circulation
At Birth
• Newborn breathes air
• Lungs expand
• Pulmonary circulation provides O2
2 Fetal Pulmonary
Circulation Bypasses
1. Foramen ovale:
–
–
–
interatrial opening
covered by valve-like flap
directs blood from right to left atrium
2. Ductus arteriosus:
–
–
short vessel
connects pulmonary and aortic trunks
Cardiovascular Changes at Birth
• Pulmonary vessels expand
• Reduced resistance allows blood flow
• Rising O2 causes ductus arteriosus
constriction
• Rising left atrium pressure closes
foramen ovale
Congenital
Cardiovascular Problems
Figure 21-34
Congenital
Cardiovascular Problems
• Develop if proper circulatory changes
do not occur at birth