Download LIVER Hepatic Portal Vein

Cardiovascular system Blood Vessels
Anatomy Chap. 22
Basic Anatomy of Circulatory routes
Carry blood
towards the
heart
Connect
capillaries to
veins
Arteries
Veins
Carry blood
away from
the heart
Arterioles
Venules
Capillaries
Allow for “exchange”
(filtration/reabsorption) of
O2/CO2, nutrients/wastes
Control blood
flow into
capillaries &
help regulate
BP
Structure of Blood Vessels
Arteries & Veins
Both are comprised of 3 layers of tissue surrounding
“lumen” through which blood will flow: tunica interna,
tunica media & tunica externa
Structural difference between arteries & veins
primarily due to differences in pressure of blood
flowing within
Arteries & Veins
Tunica Interna – innermost endothelium of simple squamous
epithelium + basement membrane
 Arteries – have an “internal elastic lamina” of elastic CT
to allow for expansion under pressure
 Veins – may have “valves” (folds of endothelium + CT)
to prevent backflow of blood due to low pressure
Arteries & Veins
Tunica Media – middle layer containing smooth muscle (for
contractility/vasoconstriction) & elastic CT (for elasticity)
 Arteries – have relatively thick tunica media allowing for
significant vasoconstriction & elasticity
 Elastic/conducting arteries – relatively more elastic tissue than
smooth muscle; ie. aorta, pulmonary trunk, etc.
 Muscular/distributing arteries - relatively more muscle tissue than
elastic tissue; ie. brachial, femoral, etc.
 Veins – relatively thin tunica media therefore no
significant constriction/elasticity
Arteries & Veins
Tunica Externa (a.k.a. adventitia) – made of collagenous CT
 Arteries – thin layer
 Veins – thickest layer of vein, trying to support against
gravity & low pressure
Arteries & Veins
Arterioles & Venules
Very small, almost microscopic vessels with only 2 layers of tissue
surrounding lumen
 Arterioles – endothelium (tunica interna) + very thin layer of
smooth muscle cells (tunica media); regulate blood flow to tissues
& affect arterial blood pressure
 Venules – endothelium (tunica interna) + thin layer of CT (tunica
externa)
Capillaries
 Microscopic, very thin-walled
vessels comprised of endothelium
with basement membrane; allows
for filtration and reabsorption
 Found in all tissues of the body
except for those that are
“avascular”
 Usually form branching networks
(“capillary beds”) within tissues for
increased surface area
 blood flow into capillaries may be
regulated by “pre- capillary
sphincters”
 may have a central or
“thoroughfare” channel that
provides direct connection
between “metarteriole” (terminal
end of arteriole) & venule
Capillaries can be classified as
continuous, fenestrated, or sinusoids
Circulatory
Routes overview
Circulatory Routes – Pulmonary
Circuit
Circulatory Routes – Systemic circuit
 Arterial blood from left ventricle into
ascending aorta
 Venous return to right atrium through
SVC, IVC & coronary sinus
Left common carotid artery
Brachiocephalic
trunk
Ascending aorta
(gives off
coronary
arteries)
Left subclavian artery
Aortic arch
Thoracic (descending) aorta
Abdominal aorta
Common iliac
arteries
Systemic
circuit Arteries
Systemic
circuit Veins
Cerebral circulation
Cerebral arterial
circle (“circle of
Willis):
Basilar artery
(from union of
vertebral
arteries) +
Internal carotid
arteries
Hepatic portal circulation
Venous blood flow from
GIT & spleen to liver –
ensures delivery of
nutrients to liver first
I
V
C
A
O
R
T
A
LIVER
Hepatic Veins
(blood mixes
in sinusioids)
Hepatic Portal Vein
Hepatic portal circulation
 Cystic vein, left
gastric vein, splenic
vein, inferior &
superior mesenteric
veins Hepatic
portal vein
 Hepatic portal vein
(deoxygenated/nutrie
nt rich blood) +
Hepatic artery
(oxygenated blood)
sinusoids of liver
 Sinusoids of liver 
Hepatic veins  IVC
Fetal Circulation
Placenta – O2/CO2 &
nutrient/waste between
mom & baby
Umbilical cord – (2)
umbilical arteries (baby 
mom) & (1) umbilical vein
(mom  baby)
Umbilical vein
(O2/nutrient rich
blood)  hepatic
portal vein & ductus
venosus  IVC  Rt.
atrium
Rt. Atrium  some blood to rt.
Ventricle, most shunts across
foramen ovale in interatrial septum 
lt. atrium  lt. ventricle
Fetal Circulation
Blood from Rt. Ventricle
 pulmonary trunk 
across ductus arteriosus
to aorta
Aorta  systemic arteries
internal iliac arteries 
umbilical arteries 
placenta
Fetal Circulation- Changes at Birth
 Umbilical vein  ligamentum
teres (round ligament)
 Umbilical arteries  lateral
umbilical ligaments
 Ductus venosus 
ligamentum venosum
 Foramen ovale  fossa ovalis
 Ductus arteriosus 
ligamentum arteriosum
 Placenta delivered
(“afterbirth”)
Upper extremity arteries & veins