General knowledge about cardiovascular system

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General knowledge about cardiovascular system
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5 Classes of Blood Vessels

• Arteries
• carry blood away from heart
• Arterioles
• Are smallest branches of arteries

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5 Classes of Blood Vessels

• Capillaries
• are smallest blood vessels
• location of exchange between blood and
  interstitial fluid

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5 Classes of Blood Vessels

• Venules
• collect blood from capillaries
• Veins
• return blood to heart

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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

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The Smallest Blood Vessels

• Capillaries
• Have small diameter and thin walls
• Chemicals and gases diffuse across walls

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The Anatomy of Blood Vessels

• Arteries, veins, and capillaries
• Have different functions
• Have different structures

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Structure of Vessel Walls
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Arteries and Veins

• Walls have 3 layers
• tunica intima
• tunica media
• tunica externa

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The Tunica Intima

• Is the innermost layer
• Includes
• the endothelial lining
• connective tissue layer

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Internal Elastic Membrane

• In arteries, is a layer of elastic fibers in
  outer margin of tunica intima

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Tunica Media

• Is the middle layer
• Contains concentric sheets of smooth muscle in
  loose connective tissue
• Binds to inner and outer layers

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Tunica Media

• Exterman elastic membrane of the tunica media
• separates tunica media from tunica externa

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Tunica Externa

• Is outer layer
• Contains connective tissue sheath
• Anchors vessel to adjacent tissues

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Tunica Externa

• In arteries
• contain collagen
• elastic fibers
• In veins
• contain elastic fibers
• smooth muscle cells

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Vasa Vasorum

• Small arteries and veins
• In walls of large arteries and veins
• Supply cells of tunica media and tunica externa

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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

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Arteries vs. Veins

• Vein lining contracts, artery lining does not
• Artery lining folds
• Arteries more elastic
• Veins have valves

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Arteries and Pressure

• Elasticity allows arteries to absorb pressure
  waves that come with each heartbeat

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Contractility

• Arteries change diameter
• Controlled by sympathetic division of ANS

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Structure of Blood Vessels
Figure 21-2
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Artery Characteristics

• From heart to capillaries, arteries change
• from elastic arteries
• to muscular arteries
• to arterioles

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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

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Muscular Arteries

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

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Arterioles

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

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Artery Diameter

• Small muscular arteries and arterioles
• changes with sympathetic or endocrine stimulation
• constricted arteries oppose blood flow

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Resistance (R)

• The force opposing blood flow
• Resistance vessels
• arterioles

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Aneurysm

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

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Capillaries

• Are smallest vessels with thin walls
• Microscopic capillary networks permeate all
  active tissues

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Capillary Function

• Location of all exchange functions of
  cardiovascular system
• Materials diffuse between blood and interstitial
  fluid

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Capillary Structure

• Endothelial tube, inside thin basal lamina
• No tunica media
• No tunica externa
• Diameter is similar to red blood cell

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Capillary Structure
Figure 21-4
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2 Types of Capillaries

1. Continuous capillaries
2. Fenestrated capillaries

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Continuous Capillaries

• Have complete endothelial lining
• Are found in all tissues except epithelia and
  cartilage

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Functions of Continuous Capillaries

• Permit diffusion of
• water
• small solutes
• Lipid-soluble materials
• Block
• blood cells
• plasma proteins

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Specialized Continuous Capillaries

• Are in CNS and thymus
• Have very restricted permeability
• e.g., the bloodbrain barrier

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Fenestrated Capillaries

• Have pores in endothelial lining
• Permit rapid exchange of water and larger
  solutes
• between plasma and interstitial fluid

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Fenestrated Capillaries

• Are found in
• choroid plexus
• endocrine organs
• kidneys
• intestinal tract

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Sinusoids

• Areas in
• liver
• spleen
• bone marrow
• endocrine organs
• Have gaps between adjacent endothelial cells

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Sinusoids

• Permit free exchange
• of water and large plasma proteins
• between blood and interstitial fluid
• Phagocytic cells monitor blood at sinusoids

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Capillary Networks
Figure 21-5
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Capillaries Networks

• Capillary bed or capillary plexus
• Connect 1 arteriole and 1 venule

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Thoroughfare Channels

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

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Collaterals

• Multiple arteries that contribute to 1 capillary
  bed
• Allow circulation if 1 artery is blocked
• Arterial anastomosis
• fusion of 2 collateral arteries

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Arteriovenous Anastomoses

• Direct connections between arterioles and venules
• Bypass the capillary bed

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Capillary Sphincter

• Guards entrance to each capillary
• Opens and closes, causing capillary blood to flow
  in pulses

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Veins

• Collect blood from capillaries in tissues and
  organs
• Return blood to heart

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Veins vs. Arteries

• Are larger in diameter
• Have thinner walls
• Carry lower blood pressure

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3 Vein Categories

• Venules
• very small veins
• collect blood from capillaries

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3 Vein Categories

• Medium-sized veins
• thin tunica media and few smooth muscle cells
• tunica externa with longitudinal bundles of
  elastic fibers

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3 Vein Categories

• Large veins
• have all 3 tunica layers
• thick tunica externa
• thin tunica media

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Valves in the Venous System
Figure 21-6
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Vein Valves

• Folds of tunica intima
• Prevent blood from flowing backward
• Compression pushes blood toward heart

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Venous Blood Distribution

• 1/3 of venous blood is in the large venous
  networks of the liver, bone marrow, and skin

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Veins Response to Blood Loss

• Vasomotor centers stimulate sympathetic nerves
• systemic veins constrict (venoconstriction)
• veins in liver, skin and lungs redistribute
  venous reserve

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What are the principle blood vessels and
functional characteristics of the special
circulation to the brain, heart, and lungs?
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Special Circulation

• Through organs with separate mechanisms to
  control blood flow
• brain
• heart
• lungs

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Blood Flow to the Brain

• Is top priority
• Brain has high oxygen demand
• When peripheral vessel constrict, cerebral
  vessels dilate, normalizing blood flow

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Heart Attack

• A blockage of coronary blood flow
• Can cause
• angina
• tissue damage
• heart failure
• death

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Pulmonary Blood Pressure

• In pulmonary capillaries
• is low to encourage reabsorption
• If capillary pressure rises
• pulmonary edema occurs

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Circulation Patterns
Figure 21-18
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3 Distribution Patterns

• Peripheral artery and vein distribution
• is the same on right and left, except near the
  heart

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3 Distribution Patterns

• The same vessel
• may have different names in different locations

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3 Distribution Patterns

• Tissues and organs usually have multiple arteries
  and veins
• vessels may be interconnected by anastomoses

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What are the major arteries and veins of the
pulmonary circuit and the areas they serve?
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The Pulmonary Circuit
Figure 21-19
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The Pulmonary Circuit (1 of 3)

• Deoxygenated blood arrives at heart from systemic
  circuit
• passes through right atrium and ventricle
• enters pulmonary trunk

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The Pulmonary Circuit (2 of 3)

• At the lungs
• CO2 is removed
• O2 is added

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The Pulmonary Circuit (3 of 3)

• Oxygenated blood
• returns to the heart
• is distributed to systemic circuit

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Pulmonary Vessels

• Pulmonary arteries
• carry deoxygenated blood
• Pulmonary veins
• carry oxygenated blood

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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

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Pulmonary Veins

• Capillary networks around alveoli
• join to form venules
• Venules
• join to form 4 pulmonary veins
• Pulmonary veins
• empty into left atrium

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What are the major arteries and veins of the
systemic circuit and the areas they serve?
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Major Systemic Arteries
Figure 21-20
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The Systemic Circuit

• Contains 84 of blood volume
• Supplies entire body
• except for pulmonary circuit

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Arteries of the Chest and Upper Limbs
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Systemic Arteries

• Blood moves from left ventricle
• into ascending aorta
• Coronary arteries
• branch from aortic sinus

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The Aorta

• The ascending aorta
• rises from the left ventricle
• curves to form aortic arch
• turns downward to become descending aorta

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Branches of the Aortic Arch

• Deliver blood to head and neck
• brachiocephalic trunk
• left common carotid artery
• left subclavian artery

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The Brachiocephalic Trunk

• Branches to form
• right subclavian artery
• right common carotid artery

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The Subclavian Arteries

• Branches within thoracic cavity
• internal thoracic artery
• vertebral artery
• thyrocervical trunk

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The Subclavian Arteries

• Leaving the thoracic cavity
• become axillary artery in arm
• and brachial artery distally

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The Brachial Artery

• Divides at coronoid fossa of humerus
• into radial artery and ulnar artery

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Radial and Ulnar Arteries

• Fuse at wrist to form
• superficial and deep palmar arches
• which supply digital arteries

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Arteries of the Neck and Head
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The Common Carotid Arteries

• Carry blood to head and neck
• Each common carotid divides into
• external carotid artery
• internal carotid artery

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The External Carotid

• Supplies structures of
• neck
• lower jaw
• face

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Arteries of the Brain
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The Internal Carotid Artery

• Enters skull and divides into
• opthalmic artery
• anterior cerebral artery
• middle cerebral artery

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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

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The Basilar Artery

• Branches to form posterior cerebral arteries
• Posterior cerebral arteries
• become posterior communicating arteries

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Anastomoses

• The cerebral arterial circle interconnects
• the internal carotid arteries
• and the basilar artery

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Arteries of the Trunk
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The Descending Aorta

• Is divided by diaphragm into
• thoracic aorta
• abdominal aorta

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Arteries of the Trunk
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Branches of the Thoracic Aorta

• Are anatomically grouped into
• visceral
• parietal

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4 Visceral Branches

• Supply organs of the chest
• bronchial arteries
• pericardial arteries
• esophogeal arteries
• mediastinal arteries

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2 Parietal Branches

• Supply chest wall
• intercostal arteries
• superior phrenic arteries

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The Abdominal Aorta

• Divides at terminal segment of the aorta into
• left common iliac artery
• right common iliac artery

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Branches of the Abdominal Aorta

• Unpaired branches
• major branches to visceral organs
• Paired branches
• to body wall
• kidneys
• urinary bladder
• structures outside abdominopelvic cavity

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Arteries of the Abdominopelvic Organs
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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

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5 Paired Branches of the Abdominal Aorta

• Inferior phrenic arteries
• Suprarenal arteries
• Renal arteries
• Gonadal arteries
• Lumbar arteries

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The Abdominal Aorta

• Divides to form
• right and left common iliac arteries
• middle sacral artery

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The Common Iliac Arteries

• Divide to form
• internal iliac artery
• external iliac artery

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Arteries of the Lower Limbs
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The External Iliac Arteries

• Pass through abdominal wall
• Becomes femoral arteries

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The Femoral Artery

• Branches to
• deep femoral artery
• Becomes popliteal artery
• posterior to knee

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The Popliteal Artery

• Branches to form
• posterior tibial artery
• anterior tibial artery

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The Anterior Tibial Artery

• Becomes dorsalis pedis artery at the ankle

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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

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Major Systemic Veins
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Complementary Arteries and Veins

• Run side by side
• Branching patterns of peripheral veins are more
  variable

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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

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All Systemic Veins

• Drain into either
• superior vena cava (SVC)
• or inferior vena cava (IVC)

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Veins of the Head, Neck, and Brain
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The Superior Vena Cava (SVC)

• Receives blood from
• head
• neck
• chest
• shoulders
• upper limbs

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The Dural Sinuses

• Superficial cerebral veins and small veins of the
  brain stem
• empty into network of dural sinuses

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5 Cerebral Sinuses

1. Superior and inferior sagittal sinuses
2. Petrosal sinuses
3. Occipital sinus
4. Left and right transverse sinuses
5. Straight sinus

120
Cerebral Veins

• Great cerebral vein
• drains to straight sinus
• Other cerebral veins
• drain to cavernous sinus
• which drains to petrosal sinus

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The Left and Right Transverse Sinuses

• Converge to form sigmoid sinus
• which leaves skull as internal jugular vein

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Vertebral Veins

• Empty into brachiocephalic veins of chest

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Superficial Veins of the Head

• Converge to form
• temporal, facial, and maxillary veins

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Veins of the Neck

• Temporal and maxillary veins
• drain to external jugular vein
• Facial vein
• drains to internal jugular vein

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Veins of the Abdomen and Chest
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Veins of the Hand

• Digital veins
• empty into superficial and deep palmar veins
• which interconnect to form palmar venous arches

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Superficial Veins of the Forearm

• Superficial arch empties into
• cephalic vein
• median antebrachial vein
• median cubital vein

128
Deep Veins of the Forearm

• Deep palmar veins drain into
• radial and ulnar veins
• which fuse above elbow to form brachial vein

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The Brachial Vein

• Merges with basilic vein
• To become axillary vein

130
Veins of the Upper Arm

• Cephalic vein joins axillary vein
• to form subclavian vein

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The Subclavian Vein

• Merges with external and internal jugular veins
• to form brachiocephalic vein
• which enters thoracic cavity

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Veins of the Thoracic Cavity

• Brachiocephalic vein receives blood from
• vertebral vein
• internal thoracic vein

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The Left and Right Brachiocephalic Veins

• Merge to form the superior vena cava (SVC)

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Tributaries of the SVC

• Azygous vein and hemiazygous vein which receive
  blood from
• intercostal veins
• esophageal veins
• veins of other mediastinal structures

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Tributaries of the Superior Vena Cava
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Tributaries of the Inferior Vena Cava
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The Inferior Vena Cava (IVC)

• Collects blood from organs inferior to the
  diaphragm

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Veins of the Lower Limbs
139
Veins of the Foot

• Capillaries of the sole
• drain into a network of plantar veins
• which supply the plantar venous arch

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The Plantar Network

• Drains into deep veins of leg
• anterior tibial vein
• posterior tibial vein
• fibular vein

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Deep Veins of the Leg

• Join to become popliteal vein
• anterior tibial vein
• posterior tibial vein
• fibular vein

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The Dorsal Venous Arch

• Collects blood from
• superior surface of foot
• digital veins

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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

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The Popliteal Vein

• Becomes the femoral vein
• At the femur

145
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

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The External Iliac Veins

• Are joined by internal iliac veins
• to form right and left common iliac veins

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The Right and Left Common Iliac Veins

• Merge to form the inferior vena cava

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Veins of the Abdomen
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6 Major Tributaries of the Abdominal Inferior
Vena Cava

• Lumbar veins
• Gonadal veins
• Hepatic veins
• Renal veins
• Suprarenal veins
• Phrenic veins

150
The Hepatic Portal System
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The Hepatic Portal System

• Connects 2 capillary beds
• Delivers nutrient-laden blood
• from capillaries of digestive organs
• to liver sinusoids for processing

152
5 Tributaries of the Hepatic Portal Vein

• Inferior mesenteric vein
• drains part of large intestine
• Splenic vein
• drains spleen, part of stomach, and pancreas
• Superior mesenteric vein
• drains part of stomach, small intestine, and part
  of large intestine

153
5 Tributaries of the Hepatic Portal Vein

• Left and right gastric veins
• drains part of stomach
• Cystic vein
• drains gallbladder

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Blood Processed in Liver

• After processing in liver sinusoids, blood
  collects in hepatic veins and empties into
  inferior vena cava

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Fetal Circulation

• Embryonic lungs and digestive tract nonfunctional
• Respiratory functions and nutrition provided by
  placenta

156
Placental Blood Supply
Figure 21-33a
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Placental Blood Supply

• Blood flows to the placenta
• through a pair of umbilical arteries
• which arise from internal iliac arteries
• and enter umbilical cord

158
Placental Blood Return

• Blood returns from placenta
• in a single umbilical vein
• which drains into ductus venosus
• Ductus venosus
• empties into inferior vena cava

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The Neonatal Heart
Figure 21-33b
160
Before Birth

• Fetal lungs are collapsed
• O2 provided by placental circulation

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At Birth

• Newborn breathes air
• Lungs expand
• Pulmonary circulation provides O2

162
2 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

163
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

164
Congenital Cardiovascular Problems
Figure 21-34
165
Congenital Cardiovascular Problems

• Develop if proper circulatory changes do not
  occur at birth