Blood Vessels

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Chapter 21

• Blood Vessels

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Direction of Flow

• Heart to aorta to arteries to arterioles to
  capillaries.
• Capillaries to venules to veins to vena cava to
  heart.

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Arteries

• Veins

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• 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

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Capillaries1. Continuous2. Fenestrated3.
Sinusoid
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Venous valves
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Blood Distribution

• 12 pulmonary vessels
• 8 heart
• 15 systemic arteries and arterioles
• 5 capillaries
• 60 systemic veins and venules

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Venous flow occurs by1. muscle contraction2.
respiratory pump3. valve assistance4.
Ventricular relaxation
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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

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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

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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

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Blood PressureInfluenced by

• Peripheral resistance
• Heart efficiency
• Blood viscosity
• Total blood vessel length
• Arteriole elasticity
• Blood volume

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Hormones that affect BP

• Renin angiotensin
• Epinephrine and norepinephrine
• Antidiuretic hormone
• Atrial natriuretic peptide

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Autoregulation of BP

• Physical changes
• Vasodilating and constricting chemicals

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Major Branches of the Aorta

• Coronary arteries
• Brachiocephalic
• Left common carotid
• Left subclavian
• Celiac
• Superior mesenteric artery
• Renals
• Ovarian / testicular
• Inferior mesenteric

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Minor Branches of the Aorta

• Pericardial Thoracic
• Bronchial Lumbar
• Esophageal Suprarenal
• Mediastinal
• Intercostal
• Phrenic

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Celiac circulation
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Abdominal arteries
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Arterial supply and venous drainage of the liver
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Hypertension

• Systole gt 140
• Diastole gt 90
• Causes diet high in fat and sodium, obesity,
  older age, race, heredity, stress, and smoking.

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Words to Learn

• Aneurysm Shock
• Angiogram Sphygmomanometer
• Diuretic Korotkoff sounds
• Phlebitis Angiogenesis
• Phlebotomy Hypotension
• Thrombophlebitis Occlusion
• Syncope White Coat Hypertension
• Tachycardia Edema