blood vessels-veins-arteries-capillaries-venule-arteriole- class:9-chapter no.9

Описание: In this video lecture you all will learn about blood vessels. Blood vessels is the third part of blood circulatory system.
Its function is to transport blood to all parts of body.
Blood vessels includes arteries, veins and capillaries.
Arteries:
Arteries are the blood vessels that carry blood from heart to body tissues.
All the arteries carry oxygenated blood with the exception of pulmonary artery.
The walls of an artery is composed of three layers.
The outer layer is made up of connective tissues.
The middle layer is made up of smooth muscles which is more elastic than veins.
The Inner most layer is made up of endothelial cells.
the internal cavity where the blood flows is called as lumen.
The arteries further divides into arterioles.
Arteries enter into tissues and divide into capillaries.
Capillaries:
Capillaries are the smallest blood vessels present in tissues.
These are formed by the sub-divisions of arterioles.
The exchange of materials between blood and tissues fluid is carried through capillaries.
Capillaries is made up of one outer covering cell called as endothelium cells.
Molecules of digestive food , oxygen and water can pass through them these tissues and waste products enter into these tissues.
Veins:
Veins carry blood from body tissues to heart.
All veins have oxygenated blood exception of pulmonary vein.
The walls of an veins is composed of three layers.
The outer layer is made up of connective tissues.
The middle layer is made up of smooth muscles which less elastic then arteries.
the Inner most layer is made up of endothelial cells.
The lumen of veins is broader than that of arteries.
Capillaries combine to form venule and venules join to form veins.
Veins have flaps called valves that prevent the backflow of blood.
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