Lecture 19
Circulatory System II
21-1
Capillary Network
• Capillary network made
of arterial and venous
capillaries
• Venules drain network
• Blood flows into small
veins, medium and large
veins
• Valves
Fig. 23.5
– Allow blood to flow
toward heart but not in
opposite direction
21-2
Systemic Circulation: Veins
• Return blood from body to right atrium
• Major veins
– Coronary sinus (heart)
– Superior vena cava (head, neck, thorax, upper
limbs)
– Inferior vena cava (abdomen, pelvis, lower
limbs)
• Types of veins
– Superficial, deep, sinuses
21-3
How Do the Three Types of
Veins Differ?
• Superficial veins
– Closer to the surface of the body
• Deep veins
– Typically found deeper in the body and usually next to
major arteries
– Typically share names with arteries (e.g. femoral vein
next to femoral artery)
• Sinuses
– A modified, slightly expanded vein that lacks smooth
muscle
– Incapable of changing diameter
21-4
Veins Draining the Heart
Fig. 22.9
• Cardiac veins (Great and Small)
– Drain the left and right sides of the heart
• Venous blood collects in coronary sinus
– Empties into right atrium
21-5
Venous Sinuses of the Cranium
• Dural venous sinuses
receive blood that has
circulated through the
brain and orbit
• Blood from these
sinuses empties into
internal jugular vein
• Internal jugular vein
exits skull through the
jugular foramen
between temporal and
occipital bones
Dural venous
sinuses
Internal jugular vein
Fig. 23.11
21-6
Veins of Head and Neck
Vertebral vein
External jugular vein
Internal jugular vein
Subclavian vein
Right brachiocephalic
vein
Fig. 23.10
• Vertebral veins
– Travel with vertebral artery through transverse foramina of
cervicals
– Drain cervicals, spinal cord, deep neck muscles
21-7
Review Question
Fusion of the brachiocephalic veins will form the
(a) Subclavian vein
(b) Inferior vena cava
(c) External jugular vein
(d) Superior vena cava
(e) Axillary vein
21-8
Veins of Shoulder and Upper
Limb
Subclavian vein
• Deep veins
– Radial and ulnar
veins (paired)
– Brachial vein that
connects with
axillary vein
Axillary vein
Cephalic vein
Basilic vein
Brachial veins
• Superficial veins
– Basilic vein
(becomes axillary
vein)
– Cephalic vein
• Axillary vein
becomes subclavian
vein beneath
clavicle
Radial veins
Fig. 23.19
Ulnar veins
Superficial veins
Deep veins
21-9
Veins of Abdomen and Pelvis
Diaphragm
Right renal vein
Left renal vein
Inferior vena cava
Left common iliac vein
Left external iliac vein
Left internal iliac vein
Left femoral vein
Fig. 23.13
21-10
Hepatic Portal System
Inferior vena
cava
Diaphragm
Liver
Hepatic portal
vein
Duodenum
Pancreas (cut)
Superior mesenteric
vein
Ascending colon
• Portal system
– Begins and ends in capillaries
– Heart not part of system
Stomach
Gastric veins
Spleen
Splenic vein
Inferior mesenteric
vein
Descending
colon
Small intestine
Fig. 23.16
• Hepatic portal system
– Begins with viscera of abdomen
– Ends with liver
21-11
Veins of Pelvis and Lower Limb
• Deep veins
– Anterior and
posterior tibial
veins
– Popliteal vein
– Femoral vein
Anterior view
Posterior view
Common iliac vein
External iliac vein
Internal iliac vein
Femoral vein
Great saphenous
vein
• Superficial veins
Popliteal vein
– Great saphenous
vein
• External iliac
vein
• Internal iliac vein
Anterior tibial
veins
Posterior tibial
veins
Great saphenous
vein
Deep veins
Superficial veins
Fig. 23.20
21-12
Valves in Veins
-Found in medium size veins
-Allow a one-way direction of blood back to
the heart
Varicose Veins
-Found in superficial veins because there isn’t
skeletal muscles around the vein.
-Hemorroids
21-13
Points to Remember
1. Three major types of veins: superficial,
deep and sinuses
2. Venous blood carried to heart by coronary
sinus, superior vena cava and inferior vena
cava
3. Hepatic portal system - not connected
directly to heart
21-14
Questions?
21-15