Artery histological structure:
1. Arteries are thick-walled vessels carrying oxygenated blood (except for the pulmonary artery, which carries deoxygenated blood to the lungs for oxygenation).
2. All arteries originate from the heart and transport blood away from it.
3. Arteries consist of three layers: tunica externa, tunica media, and tunica interna.
4. Tunica externa (adventitia) is the outermost, thickest layer, composed of connective tissue with elastic and collagen fibers.
5. Tunica media, the middle layer, is thick and made up of smooth muscle fibers and elastic fibers, providing resilience against high blood pressure during ventricular systole.
6. Tunica interna (intima), the innermost layer, is composed of endothelium and an elastic layer.
Capillary Histological structure :
1. Capillaries, the smallest and thinnest blood vessels, form through the division of arterioles.
2. Capillary walls are made up of endothelium or squamous epithelium.
3. Capillary walls are permeable, allowing the passage of water and dissolved substances.
4. Capillaries facilitate the exchange of respiratory gases, nutrients, and excretory products through their walls.
5. Capillaries unite to form venules.
The diagram is given below-
