BLOOD VESSELS I

Histology 2016-2017
Department of Anatomy &Histology: Dr.Rajaa Ali
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BLOOD VESSELS I
INTRODUCTION
Blood vessels deliver nutrients, oxygen and hormones to cells of the body and remove metabolic waste products and CO2 from them through blood. Exchange of these substances takes place at the capillary level.

TYPES OF BLOOD VESSELS
Histologically there are five main types of blood vessels. They are:
Arteries
o Large artery (elastic artery)
o Medium sized artery (muscular artery)
Arterioles
Capillaries
o Continuous capillary
o Fenestrated capillary
o Sinusoidal capillary
Venules
Veins
o Medium-sized vein
o Large vein



STRUCTURE
All blood vessels have the same basic structure (Fig. 10.1). Each has three coats or tunics, namely,
(a) Tunica intima
It is composed of lining endothelium (simple squamous epithelium) and subendothelial connective tissue.
(b) Tunica media
This layer is made of smooth muscle and connective tissue.
(c) Tunica adventitia
It is constituted of fibroelastic connective tissue.