1. 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.

2. 1 aorta & 1 pulmonary trunk
~ 2.5 cm
10 bio capillaries (~ length 5,000 miles) ?

3. 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.)

4. 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

5. Arteries – ALWAYS carry blood away from heart
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

6. Pulmonary trunk & aorta and their major branches
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

7.  mm
 ~ 4 mm
External and internal jugular, brachial & femoral veins
External and internal carotids, brachial & femoral arteries

8.  ~ µm
 ~ 30 µm

9. Capillaries Only endothelium Variably permeable Most body regions
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

10. 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.
In liver and bone marrow

11. 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

12. Normal: From capillary bed into veins and back to heart
3 exceptions
Hypophysis _________________
Liver _________________
In kidney nephrons
Fig 19.6
Fig 22.26

13. ?

14. 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

15. Why are valves found in veins but not in arteries?
Do all veins have valves?
Venous valve pathology ?

16. Blood Vessel Pathologies
Aneurysms
Atherosclerosis = type of Arteriosclerosis) thickening and toughening of arterial walls
Pathogenesis covered in Physiology

17. Abdominal Aortic Aneurysm Repair
Cerebral aneurysms
Most common type: berry aneurysm
Usually occur at the bifurcations and branches of the large arteries located at the Circle of Willis

18. Gross Anatomy of Circulatory System
Pulmonary &
Systemic Circulations

19. 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

20. Systemic Circuit Aortic Arch Left common carotid Brachiocephalic trunk2
Brachiocephalic
trunk 1
Left subclavian 3

21. 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?) ic v
Fig 22.13

22. Circle of Willis

23. Descending aorta • thoracic aorta • abdominal aorta Abdominal aorta
Common iliac
External iliac
Femoral

24. 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

25. 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

26. 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

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