Transcript CH 22: The Cardiovascular System: Vessels & Circulation

CH 22: The Cardiovascular
System:
Vessels & Circulation
 Histological
Organization of Blood
Vessels
 Pulmonary
& Systemic Circulation
 Circulatory
Changes at Birth
1 aorta & 1 pulmonary trunk
2.5 cm
10 bio capillaries (~ length 5,000 miles)
?
Histology
of
Blood
Vessels

Tunica interna or intima (endothelium + c.t.)

Tunica media (muscle + c.t.)

Tunica externa or adventitia
(thick layer of c.t.)
Arteries vs. Veins
Distinguishing Arteries from Veins:

Artery walls thicker (more muscle
and elastic fibers)

Additional: internal & external elastic
Fig 2-1c
membrane
in histology slide:

Arterial walls contract; endothelium
cannot contract: pleated appearance

Veins collapse
Fig 2-1a
large vein
elastic arteries
muscular arteries
medium-sized vein
venules
arterioles
capillaries
Superior & inferior
vena cavae and their
tributaries
Pulmonary trunk & aorta
and their major branches
~ 4 mm
2 - 9 mm
External carotid,
brachial & femoral
arteries
~ 10 -50 µm
~ 30 µm
Different Types of Capillaries:
Choroid plexus,
endocrine organs,
kidneys
(special case: sinusoids)
~ 8 µm
Most body regions
Sinusoids

Resemble fenestrated capillaries, yet
 irregular
 have
shapes
longer pores
 thinner
(or no) basement membranes

Blood movement very slow

Location?
Capillary Bed
= Capillary region serving a body area

BF controlled via arterioles

Precapillary sphincter at entrance to
each capillary

Arteriovenous anastomosis
From Capillary Bed Blood Returns to Heart
3 exceptions!!! ??

Hypophyseal portal system

Hepatic portal system

In kidney nephrons
Fig 22-26
Fig 19-6
Uneven Distribution of Blood
Total blood volume: ?
65 -70% in veins (= blood reservoir)
Walls of veins easily stretch and recoil depending
on volume changes
30-35% in heart, arteries and
capillaries
Why are valves
found in
veins but not
in arteries?
Do all veins have valves?
some
Blood Vessel Pathologies
p 768
 Aneurysms
 Problems with venous valve
function

Loss of elasticity and resilience in c.t.
throughout body due to ??

Found where especially?
 Atherosclerosis ( = type of Arteriosclerosis)
thickening and toughening of arterial walls
Pathogenesis covered in Physiology
Gross Anatomy
of
Circulatory System
Pulmonary &
Systemic Circulations
Aortic Arch
Left common
2
carotid
Brachiocephalic
1
artery
3
Left subclavian
Circle of Willis = Cerebral Arterial Circle
= Ring of vessels
surrounding the
pituitary gland (ring
shaped anastomosis)
ic
Brain can receive blood
from carotids or
vertebrals
(significance?)
v
Descending aorta
• thoracic aorta
• abdominal aorta
Abdominal aorta
Common iliac
External iliac
Femoral
Circulation Changes at Birth

Fetus gains O2 from?

Umbilical arteries and vein

Two passage ways to bypass lung:
Foramen ovale
 Ductus arteriosus

back
Circle of Willis
Abdominal Aorta:
back
Fetal Circulation
back
Foramen ovale