Blood flows from the heart through arteries and arterioles to capillaries, then through venules and veins back to the heart. Capillaries form the microcirculation and are the site of nutrient and waste exchange between blood and tissues. They are composed of a single layer of simple squamous epithelium. Blood pressure is influenced by peripheral resistance, heart function, blood viscosity, vessel length and elasticity, and blood volume. It can be regulated through physical and chemical changes in the body.

1. Human Anatomy
Blood Vessels
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2. Direction of Flow
Heart to aorta to arteries to
arterioles to capillaries.
Capillaries to venules to veins to
vena cava to heart.

3. Arteries
Veins

5. • Capillaries form Microcirculation
• Microscopic vessels that connect arterioles to venules
• Found near every cell in the body but more extensive in
highly active tissue (muscles, liver, kidneys & brain)
•entire capillary bed fills with blood when tissue is active
•lacking in epithelia, cornea and lens of eye & cartilage
• Function is exchange of nutrients & wastes between
blood and tissue fluid
• Structure is single layer of simple squamous epithelium
and its basement membrane

6. Capillaries:
1. Continuous
2. Fenestrated
3. Sinusoid

7. Venous valves

8. Blood Distribution
 12% pulmonary vessels
 8 % = heart
 15% = systemic arteries and arterioles
 5% = capillaries
 60% = systemic veins and venules

10. Venous flow occurs by:
1. muscle contraction
2. respiratory pump
3. valve assistance
4. Ventricular
relaxation

11. Varicose Veins
 Twisted, dilated superficial veins
 caused by leaky venous valves
 congenital or mechanically stressed from prolonged standing
or pregnancy
 allow backflow and pooling of blood
 extra pressure forces fluids into surrounding tissues
 nearby tissue is inflamed and tender
 Deeper veins not susceptible because of support of
surrounding muscles

12. Anastomoses
 Union of 2 or more arteries supplying the same body
region
 blockage of only one pathway has no effect
 circle of willis underneath brain
 coronary circulation of heart
 Alternate route of blood flow through an anastomosis is
known as collateral circulation
 can occur in veins and venules as well
 Alternate routes to a region can also be supplied by
nonanastomosing vessels

14. Pulse Pressure
 Pulse pressure = systole - diastole
 MAP = diastolic pressure + pulse pressure/3
 MAP = mean arterial pressure
 MAPB = diastole + 1/3 (systole – diastole)
 MAPB = mean arterial blood pressure

17. Blood Pressure
Influenced by:
 Peripheral resistance
 Heart efficiency
 Blood viscosity
 Total blood vessel length
 Arteriole elasticity
 Blood volume

20. Hormones that affect BP
 Renin angiotensin
 Epinephrine and norepinephrine
 Antidiuretic hormone
 Atrial natriuretic peptide

22. Autoregulation of BP
 Physical changes
 Vasodilating and constricting chemicals

27. Major Branches of the Aorta
 Coronary arteries
 Brachiocephalic
 Left common carotid
 Left subclavian
 Celiac
 Superior mesenteric artery
 Renals
 Ovarian / testicular
 Inferior mesenteric

28. Minor Branches of the Aorta
 Pericardial Thoracic
 Bronchial Lumbar
 Esophageal Suprarenal
 Mediastinal
 Intercostal
 Phrenic

33. Celiac circulation

34. Abdominal arteries

44. Arterial supply and venous
drainage of the liver

51. Hypertension
 Systole > 140
 Diastole > 90
 Causes: diet high in fat and sodium, obesity, older age,
race, heredity, stress, and smoking.

52. Words to Learn
 Aneurysm Shock
 Angiogram Sphygmomanometer
 Diuretic Korotkoff sounds
 Phlebitis Angiogenesis
 Phlebotomy Hypotension
 Thrombophlebitis Occlusion
 Syncope White Coat
Hypertension
 Tachycardia Edema