402
isorders of the blood vessels are directly or indi-
rectly responsible for many human diseases. Arterial
diseases, such as stroke and coronary heart disease, are
responsible for more morbidity and mortality than any
other type of disease. Hypertension, or elevation of the
arterial blood pressure, is probably the most common
of all health problems in adults and is the leading risk
factor for cardiovascular disorders. Although venous
diseases are less common, they also cause clinically
significant problems. The discussion in this chapter is
organized into four parts: blood vessel structure and
function, disorders of the arterial circulation, disor-
ders of the arterial blood pressure, and disorders of the
venous circulation.
Blood Vessel Structure and
Function
The walls of arteries and veins are composed of three
layers called tunica: an outer layer called the
tunica
externa,
a middle layer called the
tunica media
, and
an inner layer called the
tunica intima
(Fig. 18-1). The
tunica externa is composed primarily of loosely woven
collagen fibers that protect the blood vessel and anchor
it to the surrounding structures. It is infiltrated with
nerve fibers and, in larger vessels, a system of tiny blood
vessels called the
vasa vasorum.
The tunica media is
composed mainly of circularly arranged smooth mus-
cle cells and sheets of elastin. Larger arteries have an
external elastic lamina that separates the tunica media
from the tunica externa. The tunica intima consists of
a single layer of flattened endothelial cells with mini-
mal underlying subendothelial connective tissue. As the
main cellular component of the blood vessel wall, the
endothelial and smooth muscle cells play an important
role in the pathogenesis of many blood vessel diseases.
D
Disorders of
Blood Flow and
Blood Pressure
18
C h a p t e r
Blood Vessel Structure and Function
Endothelial Cells
Vascular Smooth Muscle Cells
Disorders of the Arterial Circulation
Hyperlipidemia
Lipoprotein Metabolism and Transport
Low-Density Lipoproteins
High-Density Lipoproteins
Hypercholesterolemia
Atherosclerosis
Epidemiology and Risk Factors
Pathogenesis and Mechanisms of
Development
Clinical Manifestations
Vasculitis
Arterial Disease of the Extremities
Peripheral Arterial Disease
Thromboangiitis Obliterans
Raynaud Phenomenon
Aneurysms and Dissection
Aortic Aneurysms
Aortic Dissection
Disorders of Arterial Blood Pressure
Mechanisms of Blood Pressure Regulation
Short-Term Regulation
Long-Term Regulation
Measurement of Blood Pressure
Hypertension
Primary (Essential) Hypertension
Secondary Hypertension
Target-Organ Damage
Diagnosis and Treatment
Hypertensive Crisis
Hypertension in Special Populations
High Blood Pressure in Pregnancy
High Blood Pressure in Children and
Adolescents
High Blood Pressure in the Elderly
Orthostatic Hypotension
Etiology
Diagnosis and Treatment
Disorders of the Venous Circulation
Venous Circulation of the Lower Extremities
Varicose Veins and Venous Insufficiency
Varicose Veins
Chronic Venous Insufficiency
Venous Thrombosis
Etiology
Clinical Manifestations
Diagnosis and Treatment
