Lecture on the Cardiovascular System

1. Lecture on the Cardiovascular System www.AssignmentPoint.com

2. Key concepts: 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.

3. 1 aorta & 1 pulmonary trunk ~ 2.5 cm 10 bio capillaries (~ length 5,000 miles) ?

4. 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.)

5. 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

6. 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

7. 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

8.  2 - 9 mm ~ 4 mm External and internal jugular, brachial & femoral veins External and internal carotids, brachial & femoral arteries

9.  ~ 10-50 µm  ~ 30 µm

10. 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 mucosaChoroid plexus, endocrine glands, kidneys Most body regions

11. 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.

12. 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

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

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. Gross Anatomy of Circulatory System Pulmonary & Systemic Circulations

18. Right ventricle into pulmonary trunk to pulmonary arteries to lungs Return by way of 4 pulmonary veins to left atrium Pulmonary Circuit Fig 22.9

19. Brachiocephalic trunk 1 Left subclavian 3 Systemic Circuit Aortic Arch Left common carotid 2

20. 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

21. Circle of Willis

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

23. 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

24. 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

25. 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

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