Histology of Blood vessels and heart PDF

College of Applied Medical sciences.. Department of Medical Laboratory. technology Histology of Blood vessels and heart  Artery Types of Blood Vessels  capillary Blood travels through three type...

College of Applied Medical sciences.. Department of Medical Laboratory. technology Histology of Blood vessels and heart  Artery Types of Blood Vessels  capillary Blood travels through three types of vessels:- Vein Types of Blood Vessels General structure of blood vessels Blood vessels wall is formed of three layers (tunics): 1- Tunica intima. 2- Tunica media. 3- Tunica adventitia. 1-Tunica intima: - It is the innermost coat. - consists of Simple squamous epithelium known as endothelial cells. - Internal elastic lamina formed of elastin. - It is well developed in muscular arteries. 2- Tunica media: - It is the middle coat.. - Circular arranged smooth muscle cells. Variable amount of elastic fibers, reticular fibers. In capillaries and postcapillary venules tunica media is replaced by pericytes. 3- Tunica adventitia: - It is the outermost layer. - It consists of longitudinally arranged elastic and type I collagen fibers together with some smooth muscle cells in certain large vessels. Vasa vasorum.  Definition: These are small arteries that present and branch in the tunica adventitia to nourish the both adventitia and parts of media of large blood vessels.  They are more frequent in veins.  The inner part of vessels is nourished from the blood in their lumens by diffusion.  Types of arteries Elastic arteries Muscular Arteriole arteries  Larger artery  Medium sized  Smallest e.g aorta to small arteries (0.3- arteries 10 µm)  Deliver blood to capillary  Less muscle  More muscle  Small one has  More elastic  Less elastic only two layers fibers fibers endothelium and tunica media. Types of capillaries 1- Continuous 2.Fenestrated 3.Sinusoidal Capillaries Capillaries (Discontinuous) Capillaries: Have no pores or Have pores or These are irregular blood channels with a fenestrate in its fenestrate in their diameter of 30 to to wall that are or 60- wall. 80nm in diameter 40μm that lack diaphragm. covered by diaphragm. (allow allow exchange of exchange of substances substances between the between the blood and blood and tissues tissues) well developed basal The basal lamina is The basal lamina that lamina continuous are discontinuous present in muscle, Present in pancreas, Sinusoids are present in nervous and connective intestines and endocrine the liver, endocrine tissues. glands. glands, bone marrow Capillaries of the renal and lymphoid organs. glomeruli has no diaphragm. The Heart  Heart It’s wall consists of three tunics; 1- The internal wall termed Endocardium, 2-Myocardium 3-Epicardium  Endocardium: consists of A- Endothelium- inner-simple squamous epithelium. B- Smooth Muscle and Connective tissue C- Subendocardial Layer: loose connective tissue.  The myocardium: It contains the cardiac muscles and blood vessels.  Epicardium: fibroelastic connective tissue, blood vessels, lymphatics and adipose tissue. References Basic histology Functional histology High- yield histology