CH 22: The Cardiovascular System: Vessels

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CH 22 The Cardiovascular SystemVessels
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.

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• 1 aorta 1 pulmonary trunk
• 2.5 cm
• 10 bio capillaries ( length 5,000 miles)
• ?

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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.)

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Distinguishing Arteries from Veins

• Artery walls thicker (more muscle and elastic
  fibers)
• Additional internal external elastic membranes
• Artefacts when fixing slides
• Arterial walls contract endothelium cannot
  contract pleated appearance
• Veins collapse

Fig 22.1
Compare to Fig 22.1
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• elastic arteries
• muscular arteries
• arterioles

large vein medium-sized vein 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
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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
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? 2 - 9 mm
? 4 mm
External and internal carotids, brachial
femoral arteries
External and internal jugular, brachial
femoral veins
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? 10-50 µm
? 30 µm
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Capillaries
Only endothelium Variably permeable
? 8 µm

Characterized by circular fenestrae or pores that
penetrate the endothelium -permit exchange of
larger molecules.
somewhat permeable
Intestinal mucosa Choroid plexus, endocrine
glands, kidneys
Most body regions
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Sinusoids

• Resemble fenestrated capillaries, yet
• irregular shapes
• have longer pores
• thinner (or no) basement membranes
• Blood movement very slow
• Found in the liver, heart, etc. sometimes called
  sinusoidal capillary.

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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
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Normal From capillary bed into veins and back to
heart

• 3 exceptions
• Hypophysis _________________
• Liver _________________
• In kidney nephrons

Fig 19.6
Fig 22.26
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?
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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
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• Why are valves found in veins but not in
  arteries?
• Do all veins have valves?

Venous valve pathology ?
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Blood Vessel Pathologies

• Aneurysms
• Atherosclerosis type of Arteriosclerosis)
  thickening and toughening of arterial walls
• Pathogenesis covered in Physiology

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Cerebral aneurysms Most common type berry
aneurysm
Usually occur at the bifurcations and branches of
the large arteries located at the Circle of
Willis
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Gross Anatomy of Circulatory System
Pulmonary Systemic Circulations
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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
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Systemic Circuit
Aortic Arch
Left common carotid
2
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Circle of Willis Cerebral Arterial Circle

• Ring of vessels surrounding pituitary gland -
  supplies cerebrum and cerebellum
• Brain can receive blood from carotids or
  vertebrals (significance?)

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Fig 22.13
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Circle of Willis
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Descending aorta thoracic aorta  abdominal
aorta
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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 arteries- thoracic wall
• Superior phrenic arteries - supply diaphragm
  

Fig 22.17
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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
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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

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Patent foramen ovale
The End
For more congenital circulatory problems see p.
606