Transcript CH 22: The Cardiovascular System: Vessels & Circulation

CH 22: The Cardiovascular
System:
Vessels & Circulation
Keyconcepts:

Describe the histological similarities and
differences of the blood vessels

Explain the pattern and names of the major arteries
and veins of the pulmonary & systemic circulations

Describe the circulatory changes that occur at
birth, and the ones occurring with exercise.
1 aorta & 1 pulmonary trunk
~ 2.5 cm
10 bio capillaries (~ length 5,000 miles)
?
Histology
of
Blood
Vessels
1.
Tunica interna or intima (endothelium + c.t.)
2.
Tunica media (muscle + c.t.)
3.
Tunica externa or adventitia
(thick layer of c.t.)
Distinguishing Arteries from Veins:

Artery walls thicker (more muscle
and elastic fibers)

Additional: internal & external elastic
membranes
Fig 22.1
Artefacts when fixing slides:

Arterial walls contract; endothelium
cannot contract: pleated appearance

Veins collapse
Compare to Fig 22.1
elastic arteries
large vein
muscular arteries
medium-sized vein
arterioles
venules
capillaries
Arteries – ALWAYS carry blood away from heart
Veins – ALWAYS return blood to heart,
contain about 2/3 body's blood at any given time
Largest, conducting arteries – lead
directly from heart, subject to high
pressures
Superior & inferior
vena cava and their
tributaries
Pulmonary trunk & aorta
and their major branches
 2 - 9 mm
External and internal
jugular, brachial &
femoral veins
 ~ 4 mm
External and internal
carotids, brachial &
femoral arteries
 ~ 10-50 µm
 ~ 30 µm
Capillaries
Only endothelium
Variably permeable
 ~ 8 µm
Characterized by circular fenestrae or
pores that penetrate the endothelium permit exchange of larger molecules.
somewhat
permeable
Most body regions
Intestinal mucosa Choroid plexus,
endocrine glands, kidneys
Sinusoids

Resemble fenestrated capillaries, yet
1.
irregular shapes
2.
have longer pores
3.
thinner (or no) basement membranes

Blood movement very slow

Found in the liver, heart, etc.
sometimes called sinusoidal capillary.
Capillary Bed
= Capillary region supplying a body area

Metarteriole – shunt - preferred channel through a
capillary bed

Precapillary sphincter - closes bed temporarily
to redistribute blood flow

Arteriovenous anastomosis:
interconnections , alternative routes of supply
Fig 22.4
Normal: From capillary bed into
veins and back to heart
3 exceptions

Hypophysis
Fig 19.6
_________________

Liver
Fig 22.26
_________________

In kidney nephrons
Uneven Distribution of Blood
Total blood volume: ?
65 -70% in veins (= blood reservoir)
lumen is larger than in corresponding arteries
30-35% in heart, arteries and
capillaries
Table 22.7
Why are valves found in
veins but not in
arteries?
Do all veins have
valves?
Venous
valve
pathology ?
Blood Vessel Pathologies
1.
2.
Aneurysms
Atherosclerosis
= type of
Arteriosclerosis)
thickening and
toughening of
arterial walls
Pathogenesis covered in
Physiology
Gross Anatomy
of
Circulatory System
Pulmonary &
Systemic Circulations
Pulmonary Circuit
Right ventricle into
pulmonary trunk to
pulmonary arteries
to lungs
Return by way of 4
pulmonary veins to
left atrium
Fig 22.9
Systemic Circuit
Aortic Arch
Left common
2
carotid
Brachiocephalic
1
trunk
3
Left subclavian
Circle of Willis = Cerebral Arterial Circle
= Ring of vessels
surrounding pituitary
gland - supplies
cerebrum and
cerebellum
Brain can receive blood
from carotids or
Fig 22.13
vertebrals
(significance?)
ic
v
Circle of Willis
Descending aorta
• thoracic aorta
• abdominal aorta
Abdominal aorta
Common iliac
External iliac
Femoral
Descending Aorta
- Thoracic Area
Bronchial arteries - supply
bronchi and lungs
Pericardial arteries - supply
pericardium
Mediastinal arteries - supply
mediatinal structures
Esophageal arteries - supply
esophagus
Paired intercostal arteriesthoracic wall
Superior phrenic arteries supply diaphragm
Fig 22.17
Descending Aorta
- Abdominal Area
Celiac trunc - 3 branches – to liver,
gallbladder, esophagus,
stomach, duodenum, pancreas,
and spleen
Superior mesenteric– to pancreas
and duodenum, small intestine
and colon
Paired suprarenal - to adrenal
glands
Paired renal – to kidneys
Paired gonadal – to testes or
ovaries
Inferior mesenteric – to terminal
colon and rectum
Paired lumbar – to body wall
Fig 22.17
Circulation
Changes at Birth
No blood coming from placenta
Ductus venosus becomes
ligamentum venosus
(=ligamentum teres)
Foramen ovale closes & becomes
fossa ovale
Ductus arteriosus closes and
becomes ligamentum arteriosum
Umbilical vein and arteries degenerate
Patent foramen ovale
For more congenital circulatory
problems see p. 606